Solar-driven water splitting at 13.8% solar-to-hydrogen efficiency(pubs.acs.org)
pubs.acs.org
Solar-driven water splitting at 13.8% solar-to-hydrogen efficiency
https://pubs.acs.org/doi/10.1021/acssuschemeng.1c03565
273 comments
LiFePO batteries are also getting a lot of love from the marine community. I recently installed one on my boat to replace three lead acid and the weight savings alone will make up the difference in cost in fuel savings over the course of the year, not to mention the current generation last longer than lead acid in that environment.
Pedantry alert.
Lithium iron phosphate is lithium-ion. What Tesla is doing is changing the cathode material from Lithium nickel cobalt aluminium oxides (NCA) to Lithium iron phosphate (LFP). Other cathodes materials include LMO, LCO and NMC.
NCA has the best energy density, LFP is the best in everything else, including price, NMC is somewhat in the middle and LCO and LMO are becoming obsolete.
Lithium iron phosphate is lithium-ion. What Tesla is doing is changing the cathode material from Lithium nickel cobalt aluminium oxides (NCA) to Lithium iron phosphate (LFP). Other cathodes materials include LMO, LCO and NMC.
NCA has the best energy density, LFP is the best in everything else, including price, NMC is somewhat in the middle and LCO and LMO are becoming obsolete.
That's not a comparison. Hydrogen goes Sun -> storage -> DC. Solar panels go Sun -> DC -> storage -> DC. You're comparing (Sun -> storage) against (DC -> storage -> DC). You need to include hydrogen fuel cell efficiency and solar panel efficiency for a (Sun -> .. storage .. -> DC) comparison.
This method goes Sun -> Hydrogen -> DC
100kwh of Solar energy generates 13.8kWh of Hydrogen, which is about 50% efficent thus generates 7kWh of DC
Going direct to DC is 23%, and the battery layer drops that to 20%, so 20kWh - about 3 times as efficient if you are using storage.
That's not bad, there are many applications where you'll take the extra land/solar take to provide the flexibility and density hydrogen can provide. Sure not for normal grid connected and static usage, but for mobile and temporary usage.
And that's not to mention all the other uses of hydrogen in industry that, without this method, would have to be generated by Sun->DC->Electrolysis
100kwh of Solar energy generates 13.8kWh of Hydrogen, which is about 50% efficent thus generates 7kWh of DC
Going direct to DC is 23%, and the battery layer drops that to 20%, so 20kWh - about 3 times as efficient if you are using storage.
That's not bad, there are many applications where you'll take the extra land/solar take to provide the flexibility and density hydrogen can provide. Sure not for normal grid connected and static usage, but for mobile and temporary usage.
And that's not to mention all the other uses of hydrogen in industry that, without this method, would have to be generated by Sun->DC->Electrolysis
Solar cells are inefficient, and we should just get power off batteries instead?
That's not an argument for anything, and doesn't have anything to do with the article.
That's not an argument for anything, and doesn't have anything to do with the article.
This is electrical to kinetic energy, which is an entirely different story.
The sun basically provides unlimited energy, so efficiency isn't as important.
The sun basically provides unlimited energy, so efficiency isn't as important.
This is a critical point.
All of the hottest utility-scale storage technologies have really quite poor round-trip efficiency, but it doesn't matter. Lower efficiency requirements so radically reduce the system cost that you add more cheap generating capacity on top, and come out ahead.
There is not now, and never will be, any shortage of available land area for solar panels. Almost every place you can think of to put them improves the place. On a reservoir, crop land, pasture land, canal, they reduce evaporation, and run cooler than in the desert. On crop and pasture land, they reduce heat stress and water demand in the plants, improving yield and irrigation efficiency. On roofs and parking lots, they slow sun damage. On parking lots they even keep the rain off.
All of the hottest utility-scale storage technologies have really quite poor round-trip efficiency, but it doesn't matter. Lower efficiency requirements so radically reduce the system cost that you add more cheap generating capacity on top, and come out ahead.
There is not now, and never will be, any shortage of available land area for solar panels. Almost every place you can think of to put them improves the place. On a reservoir, crop land, pasture land, canal, they reduce evaporation, and run cooler than in the desert. On crop and pasture land, they reduce heat stress and water demand in the plants, improving yield and irrigation efficiency. On roofs and parking lots, they slow sun damage. On parking lots they even keep the rain off.
> AC-DC-AC conversion is around 98%-99% efficiency now.
I'd really like to see some citations with specifiic BOMs of equipment that can accomplish this, because the datacenter industry would like to have something like that, but it's my understanding that the efficiency is nowhere near that 98-99% figure.
I'd really like to see some citations with specifiic BOMs of equipment that can accomplish this, because the datacenter industry would like to have something like that, but it's my understanding that the efficiency is nowhere near that 98-99% figure.
I might be mistaken on storing hydrogen, but all that takes in a high pressure container. I can imagine putting those solar-to-hydrogen plants up at sunny but remote places with plenty of space. Once a month when the containers are full a train comes along, unhooks cars with empty containers and goes off with the full ones. If you were to do that with any sort of battery you'd need two batteries, one be charged, one being used/discharged elsewhere, and your battery (for lack of a better term) efficiency (Total cost of usage?) basically halves.
Likewise the other way, say you need power at a building site for a couple of years, you can do that by delivering hydrogen bottles to replenish your generator, rather than having to take charged batteries and swap them out somehow.
I love LFP batteries and feel they are not given enough importance in the energy transition future. I was wondering by chance if there is a way to estimate the material amount used in these batteries to check if their limiting factor in scaling is lower than typical high Nickel batteries. I was wondering if Phosphate is a concern if not Lithium.
The original technology is properly lithium-nickel dioxide. Elements such as manganese, cobalt and aluminum appear as minor constituents. Both Li-NiO2 and Li-FePO4 are based on conduction of lithium ions in the electrolyte ("Lead-acid" would be sulfate-ion by this naming convention; alkaline batteries are hydroxide-ion).
It's also about energy/kilogram, especially in Aviation.
Electricity-to-electricity efficiency should not be compared with solar-to-electricity efficiency.
The typical solar panel is maybe 25% efficient or less. The typical steam engine is maybe 50% efficient. Once things are in the form of electricity, we have a large variety of options for efficient transport and storage.
But sometimes electricity isn't useful. Li-Ion will never be light enough for a serious airplane for example, while hydrogen _IS_ light enough for an airplane. (But maybe too volumetric, as every practical H2 airplane engine relies upon high-pressure storage or even cryogenics to keep H2 at a small enough volume).
EDIT: If we think of it as chemistry... perhaps we can make liquid fuels out of H2 like coal liquefaction turns one fuel source into another. After all, classical fuels are nothing more than carbon + hydrogen + energy... and H2 is a very efficient form of storing energy for that reaction. Or maybe we learn to just use H2 directly? There are fuel cells and engines running on H2 today, but I'm always worried about the volume of H2 (requiring either compression or cyrogenics before you reach practicality).
The typical solar panel is maybe 25% efficient or less. The typical steam engine is maybe 50% efficient. Once things are in the form of electricity, we have a large variety of options for efficient transport and storage.
But sometimes electricity isn't useful. Li-Ion will never be light enough for a serious airplane for example, while hydrogen _IS_ light enough for an airplane. (But maybe too volumetric, as every practical H2 airplane engine relies upon high-pressure storage or even cryogenics to keep H2 at a small enough volume).
EDIT: If we think of it as chemistry... perhaps we can make liquid fuels out of H2 like coal liquefaction turns one fuel source into another. After all, classical fuels are nothing more than carbon + hydrogen + energy... and H2 is a very efficient form of storing energy for that reaction. Or maybe we learn to just use H2 directly? There are fuel cells and engines running on H2 today, but I'm always worried about the volume of H2 (requiring either compression or cyrogenics before you reach practicality).
> perhaps we can make liquid fuels out of H2
You're describing hydrocarbons.
The most-common element in the universe married to the most-common four-bonding element. Using solar panels to synthesize Jet A is probably a better path forward than redesigning every plane in the world to trawl a balloon or carry a pressure vessel.
There's a reason pretty much all of Earth's biology uses hydrocarbons as its fuel of choice.
You're describing hydrocarbons.
The most-common element in the universe married to the most-common four-bonding element. Using solar panels to synthesize Jet A is probably a better path forward than redesigning every plane in the world to trawl a balloon or carry a pressure vessel.
There's a reason pretty much all of Earth's biology uses hydrocarbons as its fuel of choice.
> There's a reason pretty much all of Earth's biology uses hydrocarbons as its fuel of choice.
I feel you are suggesting the reason is because it's an ideal energy transport mechanism, while ignoring the (not insignificant) fact that almost all the hydrocarbons we've used so far have been, effectively, free energy.
Or at the least, incur a cost that we have not yet had to contend with.
I feel you are suggesting the reason is because it's an ideal energy transport mechanism, while ignoring the (not insignificant) fact that almost all the hydrocarbons we've used so far have been, effectively, free energy.
Or at the least, incur a cost that we have not yet had to contend with.
> while ignoring the (not insignificant) fact that almost all the hydrocarbons we've used so far have been, effectively, free energy
The reference to biology using hydrocarbons as its preferred energy store is one to fat, not fossil fuels.
That’s far from free energy. And life likely wound up that way because its precursors—hydrogen and carbon—are readily available, it’s energy dense both volumetrically and by mass, it’s safe and it can be converted into various forms of energy directly and easily.
Ultimately, the big unknown is the cost of synthesising Jet A. I think it will be low enough that it blows the hydrogen hypothesis out of the water, but I don’t have more than a hunch to go off.
The reference to biology using hydrocarbons as its preferred energy store is one to fat, not fossil fuels.
That’s far from free energy. And life likely wound up that way because its precursors—hydrogen and carbon—are readily available, it’s energy dense both volumetrically and by mass, it’s safe and it can be converted into various forms of energy directly and easily.
Ultimately, the big unknown is the cost of synthesising Jet A. I think it will be low enough that it blows the hydrogen hypothesis out of the water, but I don’t have more than a hunch to go off.
> And life likely wound up that way because its precursors—hydrogen and carbon—are readily available, it’s energy dense both volumetrically and by mass, it’s safe and it can be converted into various forms of energy directly and easily.
Yes. Most of the available energy is in the hydrogen bonds, but if you want to 'tame' neat hydrogen by binding it to something else, from all the stuff in the periodic table carbon is pretty much the optimal choice.
> Ultimately, the big unknown is the cost of synthesising Jet A. I think it will be low enough that it blows the hydrogen hypothesis out of the water, but I don’t have more than a hunch to go off.
To the extent one of the inputs to synthetic Jet A is hydrogen, it won't be cheaper as such. So the question really is whether the added cost is low enough that the easier logistics of a room-temperature liquid fuel makes the total cost lower. I'm slightly hopeful that this will eventually be the case.
Yes. Most of the available energy is in the hydrogen bonds, but if you want to 'tame' neat hydrogen by binding it to something else, from all the stuff in the periodic table carbon is pretty much the optimal choice.
> Ultimately, the big unknown is the cost of synthesising Jet A. I think it will be low enough that it blows the hydrogen hypothesis out of the water, but I don’t have more than a hunch to go off.
To the extent one of the inputs to synthetic Jet A is hydrogen, it won't be cheaper as such. So the question really is whether the added cost is low enough that the easier logistics of a room-temperature liquid fuel makes the total cost lower. I'm slightly hopeful that this will eventually be the case.
If we can get it be unleaded in the air - and perhaps a little less loud… I live on a river and also a jet path. It’s like a freeway at night and also the residue from the jet exhaust is rather annoying to clean off the boat…
Jet fuel has never contained lead. Lead is still used in aviation gasoline, used by small propeller planes (larger propeller planes typically use turboprop engines that use jet fuel). But consumption of aviation gasoline is a very small fraction of the consumption of jet fuel.
Jets have actually declined significantly in loudness over the past decades.
> There's a reason pretty much all of Earth's biology uses hydrocarbons as its fuel of choice.
Carbohydrate != hydrocarbon.
Carbohydrate != hydrocarbon.
what’s a little oxygen between friends?
>> perhaps we can make liquid fuels out of H2
> You're describing hydrocarbons.
This is technically correct, but at the right pressure, it becomes politically incorrect.
Right now there is already a huge push against fossil fuels, to the point that countries are setting dates for forbidding internal combustion engines in cars. Note that this will take effect independently of the source of fuel, fossil or otherwise. And methane, which is relatively easy to produce from bio-waste, it is a potent greenhouse gas.
For now, the public is divided. Nobody likes the consequences of global warming but nobody likes to give up the convenience of hydrocarbons.
Give it some time or add some more climate shock, and the public may change opinion to be against all fuels that contain some form of carbon, no matter the origin.
> You're describing hydrocarbons.
This is technically correct, but at the right pressure, it becomes politically incorrect.
Right now there is already a huge push against fossil fuels, to the point that countries are setting dates for forbidding internal combustion engines in cars. Note that this will take effect independently of the source of fuel, fossil or otherwise. And methane, which is relatively easy to produce from bio-waste, it is a potent greenhouse gas.
For now, the public is divided. Nobody likes the consequences of global warming but nobody likes to give up the convenience of hydrocarbons.
Give it some time or add some more climate shock, and the public may change opinion to be against all fuels that contain some form of carbon, no matter the origin.
The problem is cost.
Technically it is quite possible to produce hydrocarbons today. In theory a government could mandate, for example, 25% green hydrocarbons in fuel in 2030.
In practice, nobody will do that because that is political suicide.
The good thing about the current BEV cars is that over the lifetime of the car they are cost effective. I will be disruptive for a while. But we now have enough experience with BEV cars to know that they are a practical solution.
Telling people that they can keep driving ICE cars in the future, without telling them that green hydrocarbons are going to cost a fortune and would prevent everybody except some rich people from actually driving ICE cars does not help.
Of course, that could all change if we can find a cheap way to make green hydrogen at scale. With current technology we need to get rid of ICE cars. We can always revisit that if green hydrogen becomes abundant.
Personally I would also be happy if all burning of hydrocarbons gets removed from cities. There is no reason to keep breathing exhaust gasses other than that the fuel is cheap.
Technically it is quite possible to produce hydrocarbons today. In theory a government could mandate, for example, 25% green hydrocarbons in fuel in 2030.
In practice, nobody will do that because that is political suicide.
The good thing about the current BEV cars is that over the lifetime of the car they are cost effective. I will be disruptive for a while. But we now have enough experience with BEV cars to know that they are a practical solution.
Telling people that they can keep driving ICE cars in the future, without telling them that green hydrocarbons are going to cost a fortune and would prevent everybody except some rich people from actually driving ICE cars does not help.
Of course, that could all change if we can find a cheap way to make green hydrogen at scale. With current technology we need to get rid of ICE cars. We can always revisit that if green hydrogen becomes abundant.
Personally I would also be happy if all burning of hydrocarbons gets removed from cities. There is no reason to keep breathing exhaust gasses other than that the fuel is cheap.
ICEs in cars hurt local air quality and cause significant noise pollution. Even if you eliminate the fossil fuel aspect, it's still worth switching to EVs.
Aeroplanes have no viable alternative right now, and the noise/particulates issue aren't as big of a problem unless you live near an airport.
Aeroplanes have no viable alternative right now, and the noise/particulates issue aren't as big of a problem unless you live near an airport.
> Nobody likes the consequences of global warming but nobody likes to give up the convenience of hydrocarbons.
Nobody wants to give up the convenience of personal transportation using automobiles. And for the United States, a good chunk of which was designed around that this is a serious problem.
Nobody wants to give up the convenience of personal transportation using automobiles. And for the United States, a good chunk of which was designed around that this is a serious problem.
Fischer-Tropsch. But today, it's the reverse, most hydrogen is produced from methane.
Yes, exactly! Or any other hydrocarbon. This is a carbon-neutral process also, as the carbon will come from CO2 in the atmosphere. And we get the bonus of extra oxygen in the air...
> And we get the bonus of extra oxygen in the air...
Why would this be desirable?
Why would this be desirable?
Lowering the density of surface co2 could result in a reduction of the cognitive impairment caused by the already-increased co2 levels. It would also mean combustible fuels of all sorts would burn more efficiently.
/s, mostly
/s, mostly
> You're describing hydrocarbons.
Well yes. But I'm also aware that H2 is a component in the synthetic production of those hydrocarbons. Using the H2 directly could prove beneficial. But if not, then we can always convert it into some combination of C and H and burn that instead.
Either way: producing H2 from clean sources (like this weird chemical solar panel thingy) is a good thing.
Well yes. But I'm also aware that H2 is a component in the synthetic production of those hydrocarbons. Using the H2 directly could prove beneficial. But if not, then we can always convert it into some combination of C and H and burn that instead.
Either way: producing H2 from clean sources (like this weird chemical solar panel thingy) is a good thing.
Hydrogen also should enable more hydrocarbons to be produced from biomass, by hydrodeoxygenation: (CH2O)n + n H2 --> (CH2)n + n H2O.
IIRC traditional Fischer-Tropsch synthesis of liquid hydrocarbons from coal or biomass is about 30-40% efficient. Partly because the C:H ratio of the source material is not the same as the end product (the excess goes up the smokestack), but also because part of the energy embodied in the source is needed to run the reaction itself.
Adding hydrogen can fix both of these problems, enabling efficiency up to 150% (compared to the energy in the source material, not including the hydrogen). This is kind of a big deal, since for large-scale carbon-neutral production of synthetic hydrocarbons the bottleneck is the source of carbon. Hydrogen can be produced (nearly) carbon-free in unlimited quantities, but barring a breakthrough in DAC technology where is your sustainable source of carbon? And no, we don't want to replace pristine rain forests with biomass plantations.
Adding hydrogen can fix both of these problems, enabling efficiency up to 150% (compared to the energy in the source material, not including the hydrogen). This is kind of a big deal, since for large-scale carbon-neutral production of synthetic hydrocarbons the bottleneck is the source of carbon. Hydrogen can be produced (nearly) carbon-free in unlimited quantities, but barring a breakthrough in DAC technology where is your sustainable source of carbon? And no, we don't want to replace pristine rain forests with biomass plantations.
What's wrong with biomass plantations as a source of renewable carbon, assuming you don't build them on rainforests?
From a biodiversity point of view. Everything.
The generic problem with biomass is the low overall efficiency of photosynthesis. It doesn't work well when it gets too cold or hot, and can use huge amounts of water.
You could use other elements than C to bind the hydrogen, for example Si. But they are difficult to produce, toxic, unstable and the SiO2 would clog up nozzles
Silanes as Fuel for Aerospace Propulsion
https://ui.adsabs.harvard.edu/abs/2009TrSpT...7.Pa33S/abstra...
Silanes as Fuel for Aerospace Propulsion
https://ui.adsabs.harvard.edu/abs/2009TrSpT...7.Pa33S/abstra...
There was an article on here the other day about a new approach to generating electricity from ammonia. The downside, though, is that creating ammonia needs H2 feedstock, which is often made by stripping the carbon off of methane obtained from natural gas.
If this is a useful way to get H2 feedstock for producing ammonia, that’s interesting on its own!
If this is a useful way to get H2 feedstock for producing ammonia, that’s interesting on its own!
We used to make refrigerators using ammonia as the working gas, too, but concentrated ammonia kills.
Exposure to high concentrations of ammonia in air causes immediate burning of the eyes, nose, throat and respiratory tract and can result in blindness, lung damage or death. Inhalation of lower concentrations can cause coughing, and nose and throat irritation.
Also the energy density of liquid ammonia is only about half that of liquid hydrocarbons. In the family of nitrogen fuels there's also hydrazine, which is much spiffier, but if you're worried about the toxicity of ammonia, well.. Yeah, maybe we don't want civilians filling up their cars with hydrazine.
The benefit of nitrogen fuels as a carbon-neutral fuel is that getting nitrogen from the atmosphere is a lot easier than extracting carbon dioxide from the atmosphere.
The benefit of nitrogen fuels as a carbon-neutral fuel is that getting nitrogen from the atmosphere is a lot easier than extracting carbon dioxide from the atmosphere.
> while hydrogen _IS_ light enough for an airplane
If you do the watt-hours per kilogram calculation the very best lithium ion batteries are something like 255Wh/kg right now.
Hydrogen fuel cell systems for small to medium sized UAS are somewhere in the 700-800Wh/kg range right now, including the weight of the (rather heavy, seriously engineered) ultra high pressure carbon fiber wrapped tanks needed for it, piping, and fuel cell.
Something like a tank of Jet-A fuel is >4000Wh/kg.
Hydrogen itself is light, the tankage systems needed to reliably contain a large volume of it on an aircraft are not.
If you do the watt-hours per kilogram calculation the very best lithium ion batteries are something like 255Wh/kg right now.
Hydrogen fuel cell systems for small to medium sized UAS are somewhere in the 700-800Wh/kg range right now, including the weight of the (rather heavy, seriously engineered) ultra high pressure carbon fiber wrapped tanks needed for it, piping, and fuel cell.
Something like a tank of Jet-A fuel is >4000Wh/kg.
Hydrogen itself is light, the tankage systems needed to reliably contain a large volume of it on an aircraft are not.
If you've got H2 on a plane it's probably lighter to just feed it to the jet engine directly rather than try to replace that with a fuel cell/motor combo which will not buy you enough efficiency gain to compensate for its weight.
Or maybe not. It's not the weight of the fuel cell/motor combo that is the limiting factor, but the weight of the H2 storage tanks. An H2 jet engine will probably [0] be less efficient than a fuel cell + motor, so more H2 storage is required in order to reach a comparable performance.
[0] Considering the Carnot efficiency of a jet engine at ~30%, a combination of fuel cell (~60%), motor (~95%) and propeller (~80%) will still beat it by a factor of 1.5.
[0] Considering the Carnot efficiency of a jet engine at ~30%, a combination of fuel cell (~60%), motor (~95%) and propeller (~80%) will still beat it by a factor of 1.5.
> Li-Ion will never be light enough for a serious airplane
Not everybody agrees with that. https://en.wikipedia.org/wiki/Electric_aircraft#Commercial_p... says over a hundred electric designs are in development.
I think some of them can be called serious airplanes.
Not everybody agrees with that. https://en.wikipedia.org/wiki/Electric_aircraft#Commercial_p... says over a hundred electric designs are in development.
I think some of them can be called serious airplanes.
I think what OP meant by "serious airplane" was something that could compete with at least a regional jet for short-distance passenger transport (~50-100 seats with at least 500nm range). Almost all battery-electric aircraft in production or on the drawing board are either proofs-of-concept or geared toward hobby use, flight training, or extremely short-range air taxi services (Harbour Air is a fantastic example of a current company for whom battery-electric aircraft make sense for some commercial missions). They're serious in the sense that some of them will fly well enough to become commercially viable, but not serious in the sense of challenging current turbofan airliners for a significant share of the air transport market.
https://venturi.aero/#highlights claims 50 passengers, 1,000 km, and 40% reduction in operating costs.
The site doesn’t give much more info that that, so I don’t think they’re further than the drawing board, though.
I considered this might be a scam or a “give us money and we’ll see whether this really can be done”, but being a startup with Delft roots (https://en.wikipedia.org/wiki/TU_Delft_Faculty_of_Aerospace_...) gives them some credibility, I think.
The site doesn’t give much more info that that, so I don’t think they’re further than the drawing board, though.
I considered this might be a scam or a “give us money and we’ll see whether this really can be done”, but being a startup with Delft roots (https://en.wikipedia.org/wiki/TU_Delft_Faculty_of_Aerospace_...) gives them some credibility, I think.
Yeah, I have the feeling that they're still very much in the initial design phase, but even so 100% electric doesn't even imply battery-electric (and even if Venturi does plan on doing battery-electric, as their site vaguely implies, there's a good change they're basing their numbers off of an experimental battery chemistry that's being tested to replace lithium ion). Hydrogen fuel cells offer energy densities comparable to liquid fuels, although as mentioned previously they have volumetric issues due to the requirement for high-pressure and/or cryogenic storage of the hydrogen. I think the approach that these guys (https://en.wikipedia.org/wiki/Wright_Electric) are taking is more likely to work out in the near term, since their main problem is finding places in an existing airframe to store a bunch of hydrogen tanks.
I think it would be kind of cool if we all get stuck where we were and couldn't use air travel anymore due to no fossil fuels. Maybe I just like retro stuff too much.
Or restart the zeppelin-age, travel at 150km/h with windows open hanging from a giant hydrogen filled structure (not enough helium to replace all aircraft).
It's already happening, see https://www.gov.uk/government/news/world-record-raf-flight-p...
> perhaps we can make liquid fuels out of H2
We can make methane, which is a lot easier to store than hydrogen.
https://en.wikipedia.org/wiki/Sabatier_reaction
We can make methane, which is a lot easier to store than hydrogen.
https://en.wikipedia.org/wiki/Sabatier_reaction
And transport. We already have an existing infrastructure for methane.
The 25% panel efficiency isn't a particularly relevant metric, and doesn't play in storage. A cost or area metric is more relevant economically.
I think that's a very important point. For example if generating fuel from algae was only 0.5% efficient, it may not matter if the process can be conducted in open ocean.
The typical mono-si solar panel is about 20-22% efficiency. For poly-si this drops to about 15%, but are cheaper and therefore still sees a lot of demand. Solar water-splitting at 13.8% is well in the range of feasible competitiveness as long as it is cheap to build.
Mono panels were 75% of the market in 2020, I read.
A concern I'd have with this water splitting is getting the water in and the hydrogen out (and separated from the oxygen). Wires are easier than pipes.
Doing this with ordinary PV also means the hydrogen production can be dispatchable. When PV output is tight, just stop making hydrogen and use the electrical power directly.
A concern I'd have with this water splitting is getting the water in and the hydrogen out (and separated from the oxygen). Wires are easier than pipes.
Doing this with ordinary PV also means the hydrogen production can be dispatchable. When PV output is tight, just stop making hydrogen and use the electrical power directly.
Keeping the hydrogen output separate from the water input and oxygen output is easy. You feed water in to the bottom of a U shaped container. You put the hydrogen-producing electrode in one half of the U and the oxygen-producing one in the other. The hydrogen and oxygen bubble up out of the water into separate collectors.
That only works with separate electrode systems; in-panel splitting (where the panel has a sheet of water directly over a catalyst) evolve both gases in the same place.
For larger installations pipes are easier than wires.
Why is that? I would guess solid-state (electrons in wire) is more reliable than moving-parts (fluids in pipes).
And it's easier to connect two wires than it is to connect two pipes.
All the little tubing collecting the hydrogen stream trickling out of these things seems like it would be a nightmare to create and maintain.
All the little tubing collecting the hydrogen stream trickling out of these things seems like it would be a nightmare to create and maintain.
Over short distances sure, but once you're talking thousands of km a pipeline is way simpler.
That's nice, but it doesn't help the local collection network in the solar field. Using large separate electrolyzers driven by conventional PV lets you avoid that.
Unless the destination of the electricity is also next to the local collection network the pipeline can be simpler. It's certainly not going to be a worse idea.
You didn't understand what I said. I'm not arguing about a pipeline. I'm arguing about all the little hydrogen carrying piping in the solar field. This is needed to bring together all that hydrogen being generated at the hydrogen-generating solar collectors, before it even gets to a pipeline.
Simpler just to avoid all that and generate the hydrogen at large separate electrolyzers at the side of the utility-scale solar field (say), and then inject into the pipeline.
Simpler just to avoid all that and generate the hydrogen at large separate electrolyzers at the side of the utility-scale solar field (say), and then inject into the pipeline.
Should be noted that that will work too. In fact that is the plan for most facilities. However, you will still need a separate electrolysis facility. With this you just pipe hydrogen into bigger pipes. It could be cheaper to implement it this way.
For a household size connection sure, but once you're looking at extremely high voltages the electrical solution becomes hard. It's a totally different kind of cable and has very different problems to deal with. Meanwhile a pipe fundamentally doesn't change whether it's 1in or 48in wide.
The certainty with which you make all these obviously completely wrong statements is baffling.
Really, electricity distribution is a solved problem, and has been for more than a century. And here you are arguing that something that is in very minor use at the moment is 'easier', in spite of many challenges still be to solved before it can operate at scale. I'll just leave this link here and I would very much appreciate it if you stopped making all these assertions without qualification as though possess some kind of oracle because it is bordering on the ridiculous.
https://www.energy.gov/eere/fuelcells/hydrogen-pipelines
Your whole comment history is nothing but an endless stream of assertions without evidence including ones that are 'not even wrong'. That's not the level that I expect for this site and you are not doing us a service with this. I also do not understand why the only subject you are interested in is pushing the Hydrogen angle for more than it is worth.
Really, electricity distribution is a solved problem, and has been for more than a century. And here you are arguing that something that is in very minor use at the moment is 'easier', in spite of many challenges still be to solved before it can operate at scale. I'll just leave this link here and I would very much appreciate it if you stopped making all these assertions without qualification as though possess some kind of oracle because it is bordering on the ridiculous.
https://www.energy.gov/eere/fuelcells/hydrogen-pipelines
Your whole comment history is nothing but an endless stream of assertions without evidence including ones that are 'not even wrong'. That's not the level that I expect for this site and you are not doing us a service with this. I also do not understand why the only subject you are interested in is pushing the Hydrogen angle for more than it is worth.
Piping gases is also a solved problem. It existed even before electricity. I sound certain because I'm certainty right. If anything it's bit amusing to see supposedly smart people have so much trouble accepting the existence of 18-19th century technology.
FYI, coal gas is about 50% hydrogen and is two centuries old: https://en.wikipedia.org/wiki/Coal_gas#Composition
FYI, coal gas is about 50% hydrogen and is two centuries old: https://en.wikipedia.org/wiki/Coal_gas#Composition
Nice to see ya posting around here. Always a pleasure.
I'm not as pro-Hydrogen as you but I see some potential benefits for sure :-)
I'm not as pro-Hydrogen as you but I see some potential benefits for sure :-)
Great thing about Jet A, it's actually pretty hard to get burning.
Hydrogen: See Hindenburg.
I would rather not fly in a bomb. I just don't see it being viable for planes.
We're starting to see short distance small planes electrify and then long haul will probably go synthetic fuels over the next 10 years.
Hydrogen: See Hindenburg.
I would rather not fly in a bomb. I just don't see it being viable for planes.
We're starting to see short distance small planes electrify and then long haul will probably go synthetic fuels over the next 10 years.
I read something that says Hindenburg was more about the mix of the gas and the material of the blimp. Properly mixed H2 doesn’t burn (it explodes quickly, which is what powers an ICE).
I agree though, planes and H2 probably don’t mix. Jet fuel should not be a priority to replace with H2. Priority should be given to static applications before trying to apply it to moving vehicles.
I agree though, planes and H2 probably don’t mix. Jet fuel should not be a priority to replace with H2. Priority should be given to static applications before trying to apply it to moving vehicles.
You are right. The issue with the Hindenberg was not the hydrogen. It was the coating.
The main concern for hydrogen as a fuel now is the high pressures. If the pressure vessel is damaged it explodes due to mechanical forces. This is not impossible to work around. Consider, for example, that gas tanks can already be punctured and lead to fires; it takes a fair accounting of the risks to really rule out hydrogen as a fuel.
The main concern for hydrogen as a fuel now is the high pressures. If the pressure vessel is damaged it explodes due to mechanical forces. This is not impossible to work around. Consider, for example, that gas tanks can already be punctured and lead to fires; it takes a fair accounting of the risks to really rule out hydrogen as a fuel.
Diffusion is also a problem. A very efficient form to store hydrogen is a solid block of metal, which of course comes with similar restrictions as batteries, if not worse.
Right, but consider a punctured gas tank vs... well, have you played "spot the COPVs in the SpaceX explosion"? They spit fire and zoom around like party balloons. Good fun from a distance, but if I had to pick one to ride with every day, it's an easy choice in favor of the gas tank.
Do you know what the fuel is? Rockets are unique in that they carry a significant amount of oxidizer with them. A hydrogen container is unlikely to zoom around spitting fire, there's too much fuel for how much oxygen there is and it rises very quickly.
There are still dangers, but practically I'm not sure they are that much worse than a gasoline fire. There are also systems that reduce the pressures needed, like activated carbon beds. Research on them stalled mostly because there was no good way to generate H2.
There are still dangers, but practically I'm not sure they are that much worse than a gasoline fire. There are also systems that reduce the pressures needed, like activated carbon beds. Research on them stalled mostly because there was no good way to generate H2.
I thought the fact that H2 burns invisibly combined with the fact that it goes boom once the burning mixture is stoichiometric is the big risk with H2 over typical hydro-carbon-based fuels, which burn a bright orange and are surprisingly hard to blow up.
The Mythbusters did a show on this exact thing with spraypaint, hairspray, and propane canisters. They didn't explode even when wrapped with flaming rags, but sometimes the released material would combust. In some cases the gas rushing out actually extinguished the flame.
You rarely by accident get a stoichiometric mix. With a slow leak into an enclosed container is usually how it happens. Otherwise there is too much fuel to O2 in the atmosphere.
People really need to stop trying to sound smart by thinking of imagined dangers. That is what stopped nuclear power, it's what's stopping hydrogen as a fuel, it's what's stopping gene therapy research, etc. Get over yourself.
You rarely by accident get a stoichiometric mix. With a slow leak into an enclosed container is usually how it happens. Otherwise there is too much fuel to O2 in the atmosphere.
People really need to stop trying to sound smart by thinking of imagined dangers. That is what stopped nuclear power, it's what's stopping hydrogen as a fuel, it's what's stopping gene therapy research, etc. Get over yourself.
> People really need to stop trying to sound smart
> Get over yourself.
Right back atcha.
Good grief, "stoichiometric mixture" is not a reasonable person's danger threshold. The mechanical energy alone is terrifying, which was the point of bringing up COPVs.
While we're at it, let's put giant flywheels in chemical cars to do regenerative breaking. They'll probably have less mechanical energy than the titanic so they're probably no big deal, right? Right.
> Get over yourself.
Right back atcha.
Good grief, "stoichiometric mixture" is not a reasonable person's danger threshold. The mechanical energy alone is terrifying, which was the point of bringing up COPVs.
While we're at it, let's put giant flywheels in chemical cars to do regenerative breaking. They'll probably have less mechanical energy than the titanic so they're probably no big deal, right? Right.
Look, this stuff has been studied and you can find it with just a little bit of looking. How this conversation has been going is a bunch of chaff gets thrown up and then people are expected to answer.
I'm doing as best I can. I happened to have a coworker who was involved in alternative fuels research, specifically the H2 cylinders that operated at lower pressures using a carbon substrate. But even if you don't use that you can still construct and secure the container so it splits instead of shatters and contains most or all of the debris. You can install a shield bulkhead into the car to deflect debris to the ground. You can do loads of things.
You are not original, you are not the first person to raise these concerns, and very competent people have been working on them.
https://xkcd.com/793/
I'm doing as best I can. I happened to have a coworker who was involved in alternative fuels research, specifically the H2 cylinders that operated at lower pressures using a carbon substrate. But even if you don't use that you can still construct and secure the container so it splits instead of shatters and contains most or all of the debris. You can install a shield bulkhead into the car to deflect debris to the ground. You can do loads of things.
You are not original, you are not the first person to raise these concerns, and very competent people have been working on them.
https://xkcd.com/793/
Those gas tanks are more risky when you have constraints on weight and material of the tank, like in moving vehicles. I agree though, people unfairly disqualify hydrogen on this risk only.
https://en.wikipedia.org/wiki/Hindenburg_disaster#Incendiary...
They tested the incendiary paint hypothesis on the TV show Mythbusters.
The MythBusters concluded that the paint may have contributed to the disaster, but that it was not the sole reason for such rapid combustion.
They tested the incendiary paint hypothesis on the TV show Mythbusters.
The MythBusters concluded that the paint may have contributed to the disaster, but that it was not the sole reason for such rapid combustion.
Ah, you're right. I wasn't remembering the details exactly. But the burning material that falls is the skin and can be better fireproofed to let the hydrogen escape upwards.
> I would rather not fly in a bomb. I just don't see it being viable for planes.
As opposed to the kerosene fueled bombs we're flying in right now?
I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach.
As opposed to the kerosene fueled bombs we're flying in right now?
I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach.
> I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach.
You might be surprised how good WW2-era scientists were at chemistry and science.
The earlier poster has a point. Gasoline, Diesel, and Kerosene have all been studied extensively (especially in the 1930s and 1940s BECAUSE of preparations for WW2). The safety of soldiers was paramount even to the Nazis.
War machines: be they airplanes, tanks, or battleships, were all going to be exposed to enemy fire and explosions. These fuels (Kerosene and Diesel in particular) were chosen because they're extremely safe: high flash points and even higher auto-ignition points.
That means that kerosene __literally__ can't catch on fire at room temperature. You need to warm up kerosene before its appropriate to burn (Of course, once its burning it will warm up the rest of the kerosene and keep burning. But this isn't some super-explosive volatile chemical we're talking about here)
Gasoline is still safe, but not as safe as the other two (-40C Flash Point). Gasoline was safer than a lot of the other petroleum products that were investigated back then, and was still chosen as a fuel for war machines.
---------
The same is not necessarily true for H2. H2 will explode at any temperature (even near absolute zero).
You might be surprised how good WW2-era scientists were at chemistry and science.
The earlier poster has a point. Gasoline, Diesel, and Kerosene have all been studied extensively (especially in the 1930s and 1940s BECAUSE of preparations for WW2). The safety of soldiers was paramount even to the Nazis.
War machines: be they airplanes, tanks, or battleships, were all going to be exposed to enemy fire and explosions. These fuels (Kerosene and Diesel in particular) were chosen because they're extremely safe: high flash points and even higher auto-ignition points.
That means that kerosene __literally__ can't catch on fire at room temperature. You need to warm up kerosene before its appropriate to burn (Of course, once its burning it will warm up the rest of the kerosene and keep burning. But this isn't some super-explosive volatile chemical we're talking about here)
Gasoline is still safe, but not as safe as the other two (-40C Flash Point). Gasoline was safer than a lot of the other petroleum products that were investigated back then, and was still chosen as a fuel for war machines.
---------
The same is not necessarily true for H2. H2 will explode at any temperature (even near absolute zero).
> You might be surprised how good WW2-era scientists were at chemistry and science.
I'm well aware of chemical prowess in that period, especially on the German part. They had a bunch of Nobel prize winners.
However, that's why I said "close-to-wartime". First of all, in case you weren't aware, the Hindenburg was supposed to use helium but due to a lack of helium in Germany (I think it was primarily due to American export restrictions), they had to use hydrogen.
I don't know of other limitations for the Hindenburg, per se, but knowing the overall German shortages of the period, I wouldn't be surprised if they had other structural issues with the Hindenburg itself, especially since it wasn't designed to be used with hydrogen.
On top of this, the Hindenburg design was from the late 20s, 1929, I believe.
If materials science, modeling, etc haven't advanced since 1929, I'll eat a shoe. If we're somehow worse at managing hydrogen after almost 100 years, I'll eat the other shoe.
I'm well aware of chemical prowess in that period, especially on the German part. They had a bunch of Nobel prize winners.
However, that's why I said "close-to-wartime". First of all, in case you weren't aware, the Hindenburg was supposed to use helium but due to a lack of helium in Germany (I think it was primarily due to American export restrictions), they had to use hydrogen.
I don't know of other limitations for the Hindenburg, per se, but knowing the overall German shortages of the period, I wouldn't be surprised if they had other structural issues with the Hindenburg itself, especially since it wasn't designed to be used with hydrogen.
On top of this, the Hindenburg design was from the late 20s, 1929, I believe.
If materials science, modeling, etc haven't advanced since 1929, I'll eat a shoe. If we're somehow worse at managing hydrogen after almost 100 years, I'll eat the other shoe.
A comparison with the Hindenburg isn't useful in any case. To put enough hydrogen in a car to get a reasonable number of miles, you need to compress it to 10,000psi. The Hindenburg is basically atmospheric pressure.
10k psi actually makes hydrogen safer (chemically). Consider it a form of positive pressure - there is much less risk of air getting into the tank.
The Hindenburg crew had to regularly test the hydrogen cells for oxygen content.
The Hindenburg crew had to regularly test the hydrogen cells for oxygen content.
> War machines: be they airplanes, tanks, or battleships, were all going to be exposed to enemy fire and explosions. These fuels (Kerosene and Diesel in particular) were chosen because they're extremely safe: high flash points and even higher auto-ignition points.
I'm not sure those were really the reasons for the choices that were made in most cases. Airplanes of the era used gasoline engines because Otto engines provided much better power/weight than the diesel engines of that time. For submarines, I'm not sure safety was a bigger factor than being able to use the same(?) fuel oil that the predominantly steam powered surface fleets were using, and that diesel engines provided better fuel economy than gasoline ones.
One place where safety might(?) have been a factor was that the USSR decided to power its tanks with diesel, whereas the other major combatants used gasoline engines in their tanks. I'm sure this prevented a lot of fiery demises for Soviet tank crews.
I'm not sure those were really the reasons for the choices that were made in most cases. Airplanes of the era used gasoline engines because Otto engines provided much better power/weight than the diesel engines of that time. For submarines, I'm not sure safety was a bigger factor than being able to use the same(?) fuel oil that the predominantly steam powered surface fleets were using, and that diesel engines provided better fuel economy than gasoline ones.
One place where safety might(?) have been a factor was that the USSR decided to power its tanks with diesel, whereas the other major combatants used gasoline engines in their tanks. I'm sure this prevented a lot of fiery demises for Soviet tank crews.
> The safety of soldiers was paramount even to the Nazis.
I wouldn't say paramount: https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet
(the Komet had a tendency to blow itself and its pilots up due to the hypergolic fuel)
I wouldn't say paramount: https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet
(the Komet had a tendency to blow itself and its pilots up due to the hypergolic fuel)
This has some interesting comparisons between hydrogen and gasoline as fuel, in terms of historical experimentation as to the effects of rupturing or destroying tanks holding one or the other: https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is.... Not my field so I'd be interested in if this more or less reflective of current knowledge on the subject.
Even if H2 isn't used directly, there are likely chemical processes that can convert it into some form that is more useful.
EDIT: That's what its called. H2 is a component of Syngas (https://en.wikipedia.org/wiki/Syngas). Syngas can then be further processed into kerosene, gasoline, or other fuels we use.
EDIT: That's what its called. H2 is a component of Syngas (https://en.wikipedia.org/wiki/Syngas). Syngas can then be further processed into kerosene, gasoline, or other fuels we use.
Batteries have much lower capacity, lower cost efficiency of storage, and lower weight efficiency of storage. They’re also slower to charge and slower to discharge.
Batteries are great for storing electricity efficiently as you say, but that only matters when electricity is marginally expensive (sourced from fossil fuels for example). However, if you have a cheap enough marginal cost of electricity, hydrogen is a better option because of the much cheaper fixed cost of hydrogen storage per kWH.
A good way to see this: what option would you choose for storage if electricity on demand was free but only during certain parts of the day? A hydrogen tank or batteries? A hydrogen tank is cheaper. And clean energy is essentially free besides the fixed cost of the windmill/solar panel.
Batteries are great for storing electricity efficiently as you say, but that only matters when electricity is marginally expensive (sourced from fossil fuels for example). However, if you have a cheap enough marginal cost of electricity, hydrogen is a better option because of the much cheaper fixed cost of hydrogen storage per kWH.
A good way to see this: what option would you choose for storage if electricity on demand was free but only during certain parts of the day? A hydrogen tank or batteries? A hydrogen tank is cheaper. And clean energy is essentially free besides the fixed cost of the windmill/solar panel.
> Batteries are great for storing electricity efficiently
In some cases not even that. Modern Lithium-ion batteries are quite good, but self-discharge still is 2-3%/month. So, if you want to store for months (say charging a battery using the summer sun to heat a house in winter), you easily lose 10% to self-discharge, in addition to what you lose between charging and discharging.
https://en.wikipedia.org/wiki/Self-discharge#Typical_self-di... says NiMH batteries even lose 30% per month.
In some cases not even that. Modern Lithium-ion batteries are quite good, but self-discharge still is 2-3%/month. So, if you want to store for months (say charging a battery using the summer sun to heat a house in winter), you easily lose 10% to self-discharge, in addition to what you lose between charging and discharging.
https://en.wikipedia.org/wiki/Self-discharge#Typical_self-di... says NiMH batteries even lose 30% per month.
It also says "Low self-discharge NiMH : As low as 0.25% per month ... introduced in 2005 by Sanyo, branded Eneloop "
70-85% retained after a year is a lot better. Charge in the same charger. I used to use regular NiMH infrequently, the worst way to use them. Low sd way better for that application. Also NiMH doesn't lose capacity delivering high currents like AA alkaline does.
70-85% retained after a year is a lot better. Charge in the same charger. I used to use regular NiMH infrequently, the worst way to use them. Low sd way better for that application. Also NiMH doesn't lose capacity delivering high currents like AA alkaline does.
> They’re also slower to charge and slower to discharge.
Yes, but this is changing and there are a number of very interesting options.
https://en.wikipedia.org/wiki/Lithium-titanate_battery
Yes, but this is changing and there are a number of very interesting options.
https://en.wikipedia.org/wiki/Lithium-titanate_battery
Very cool, there are definitely use cases where batteries are necessary (like moving vehicles) and it’s great to see advancement in battery tech.
EDIT: These batteries seem to be even less energy dense than Li-ion which is one of the weaknesses of batteries in comparison to hydrogen.
EDIT: These batteries seem to be even less energy dense than Li-ion which is one of the weaknesses of batteries in comparison to hydrogen.
Yes, that is their shortcoming for now, but for solar storage and such they are an interesting option.
For renewable energy, low efficiency is not a problem per se: you can make as much as you want. The article also mentions that they don’t need rare materials for the electrolyser, which means it will be cheaper. Lithium, that modern batteries require, is quite rare.
There is plenty of demand for millions of tons of hydrogen for uses that batteries are not useful for, notably, nitrogen fertilizer. Thus, advances in hydrogen production are interesting irrespective of ones views of hydrogen vs batteries.
Talking about efficiency with solar seems purely academic to me. Considering it's just there, it doesn't really matter what percentage of the potential energy you're capturing, just the absolute cost per watt of extraction.
There is another dimension at play here: solar is about 1KW/sq meter so efficiency directly translates into less area for the same output.
An interesting bit about the original paper linked -- from the abstract:
> The trimetallic NiFeMo electrocatalyst takes the shape of nanometer-sized flakes anchored to a fully carbon-based current collector comprising a nitrogen-doped carbon nanotube network, which in turn is grown on a carbon fiber paper support. This catalyst electrode contains solely Earth-abundant materials, and the carbon fiber support renders it effective despite a low metal content.
I don't know anything about chemistry so I'll have to take their word on the fact that the elements they use are abundant.
The two concerns for area are:
1) The cost of panels to cover the area
2) The cost of the area itself, and the availability of a ton of empty space in a convenient location
If they are using abundant materials, the first is not as much of a concern, compared to photovoltaics. Since they are producing some sort of fuel rather than directly producing electricity, transmission efficiency is not really a concern*. So maybe we could plop a bunch of these things down in some sunny middle-of-nowhere desert.
* I guess is we consider vehicles to transport fuel, which must themselves burn fuel, to in some sort of abstract sense be part of the transmission efficiency, this computation could be pretty complicated.
> The trimetallic NiFeMo electrocatalyst takes the shape of nanometer-sized flakes anchored to a fully carbon-based current collector comprising a nitrogen-doped carbon nanotube network, which in turn is grown on a carbon fiber paper support. This catalyst electrode contains solely Earth-abundant materials, and the carbon fiber support renders it effective despite a low metal content.
I don't know anything about chemistry so I'll have to take their word on the fact that the elements they use are abundant.
The two concerns for area are:
1) The cost of panels to cover the area
2) The cost of the area itself, and the availability of a ton of empty space in a convenient location
If they are using abundant materials, the first is not as much of a concern, compared to photovoltaics. Since they are producing some sort of fuel rather than directly producing electricity, transmission efficiency is not really a concern*. So maybe we could plop a bunch of these things down in some sunny middle-of-nowhere desert.
* I guess is we consider vehicles to transport fuel, which must themselves burn fuel, to in some sort of abstract sense be part of the transmission efficiency, this computation could be pretty complicated.
To answer your question regarding commonality/ready availability -
Carbon, Nitrogen, and Iron are cheap and easy (you’re likely within body length of a large quantity right now). 32% of the earths mass is estimated to be Iron. $1/lb or less in massive quantities.
Nickel and Molybdenum are slightly harder to find, but not by much - nickel makes up 1.8% of the earth by mass and is a reasonably common metal in everyday manufacturing. It’s currently at $3.97/lb spot price at tonne quantities. Moly is in everything from greases to steels, and while typically not used in large bulk quantities alone, is available for such [https://tradingeconomics.com/commodity/molybden] at looks like $23/lb give or take.
So all commonly available elements, albeit (nanotubes) not necessarily in the form desired just yet.
Carbon, Nitrogen, and Iron are cheap and easy (you’re likely within body length of a large quantity right now). 32% of the earths mass is estimated to be Iron. $1/lb or less in massive quantities.
Nickel and Molybdenum are slightly harder to find, but not by much - nickel makes up 1.8% of the earth by mass and is a reasonably common metal in everyday manufacturing. It’s currently at $3.97/lb spot price at tonne quantities. Moly is in everything from greases to steels, and while typically not used in large bulk quantities alone, is available for such [https://tradingeconomics.com/commodity/molybden] at looks like $23/lb give or take.
So all commonly available elements, albeit (nanotubes) not necessarily in the form desired just yet.
I think cost of installation / maintenance per sq meter is the real kicker. There's actually a lot of still available space for solar panels (reservoirs being the favourite one I just discovered).
Area isn't a particularly limiting factor for most applications.
That's opposite of my knowledge about this but I'm a decade+ out of date, so possibly this isn't as much a factor as it used to be, but the cost of the ground was a substantial factor in solar installations in days past.
It is one of the most limiting factors for solar, when everything is accounted for.
You either put it really far away (increasing transmission losses and right of way issues for the much longer lines), or you put it closer and then have to deal with expensive land or difficult environmental reviews.
It is not AS BIG of an issue as it could be - for instance 30% efficient cells vs 23% efficient cells, the lower efficiency’s cost vs space usually favors the lower efficiency, but it’s still very strong overall.
You either put it really far away (increasing transmission losses and right of way issues for the much longer lines), or you put it closer and then have to deal with expensive land or difficult environmental reviews.
It is not AS BIG of an issue as it could be - for instance 30% efficient cells vs 23% efficient cells, the lower efficiency’s cost vs space usually favors the lower efficiency, but it’s still very strong overall.
As long as we have land for corn as feedstock for Ethanol, land is not an issue. You get a lot more energy from PV than from the equivalent acreage of plants.
All of the world's existing pasturage is prime territory for solar installations. Adding solar to a pasture makes it better pasture, reduces evaporation, and cools the panels vs. desert installation.
Plants generally max out the amount of solar radiation they can absorb early in the day, so are not handicapped at all by partial shade. In fact, most benefit from it in numerous ways.
Installed between rows in active farmland, solar reduces water demand by up to 50%, which is a really huge benefit. Reducing heat and evaporation stress improves crop yields. So, a farm could move from barely getting by to solidly profitable by installing solar, even before selling the power. The panels just need to be placed so as not to interfere with driving a tractor between them.
So, no, there is absolutely no shortage of land for solar installations.
Plants generally max out the amount of solar radiation they can absorb early in the day, so are not handicapped at all by partial shade. In fact, most benefit from it in numerous ways.
Installed between rows in active farmland, solar reduces water demand by up to 50%, which is a really huge benefit. Reducing heat and evaporation stress improves crop yields. So, a farm could move from barely getting by to solidly profitable by installing solar, even before selling the power. The panels just need to be placed so as not to interfere with driving a tractor between them.
So, no, there is absolutely no shortage of land for solar installations.
Sure, but you also don't need dedicated land for solar, giving cost savings options vs other plants that need dedicated space. There are so many available installation locations that overlap roofs, parking lots, even projects sharing farmland, reservoirs/canal paths.
All of which drive up costs per installed megawatt. You’re talking about marginal (as in, in the margins), which can produce significant power - but is expensive and has side effects on habitations that many people are currently willing to overlook but won’t be the case forever.
Racking and wiring is one of the dominant costs in any solar installation, and a big flat desert is cheaper both to install and maintain than almost every other option by a pretty hefty margin.
Racking and wiring is one of the dominant costs in any solar installation, and a big flat desert is cheaper both to install and maintain than almost every other option by a pretty hefty margin.
As far as I can tell the “side effects” are beneficial synergies - I love having shade in parking lots for example. You should also be saving on real estate costs if you already had a primary use for the real estate.
Maybe the solar cost efficiency taken alone is reduced, but the system efficiency of the real estate use goes up as does the ownership value for the property owner.
Maybe the solar cost efficiency taken alone is reduced, but the system efficiency of the real estate use goes up as does the ownership value for the property owner.
> The safety is better, too - lithium iron phosphate batteries don't have the thermal runaway problem.
Relatedly, LFP are just rugged as heck batteries. They tend to have double or more the life-cycle count. 5000 cycle count before getting down to 80% capacity? In many cases yes. That's pretty impressive, and a great boon to overall lifecycle/long-term costs. Even if you're getting less energy-density, or even less energy-store/$, that battery is going to live at least 2x the effective lifespan (barring accidents, major defects, &c).
In general, anything built for high current tends but lower energy density tends to have much more ruggedness. Sanyo’s UR18650E is Li(NiMnCo)O2, for example, but in one paper shows 4X the lifecycle count of the extremely well regarded O.G. of LFP, the A123 ANR26650M1-A[1]. Even though it's considered a "lithium ion". And uses some of the rarer/more expensive materials. (Edit: re-reading the paper more closely, I'm less willing to embrace this conclusion. The A123 remains around 2000 cycle count regardless of depth of discharge pattern, while the li-ion drops to 1000 around 50% DoD.)
Not that phosphorous (The P in LFP) is projected to remain cheap/available forever. 2 days ago, talking more about phosphor's availability specifically with regard to agriculture (and rather alarmistly), "Phosphorus is essential to life and the world is running out of it"[2].
[1] http://www.jocet.org/vol7/511-C0056.pdf
[2] https://medium.com/climate-conscious/peak-phosphorus-may-be-... https://news.ycombinator.com/item?id=29244529 (2 days ago, 2 comments)
Relatedly, LFP are just rugged as heck batteries. They tend to have double or more the life-cycle count. 5000 cycle count before getting down to 80% capacity? In many cases yes. That's pretty impressive, and a great boon to overall lifecycle/long-term costs. Even if you're getting less energy-density, or even less energy-store/$, that battery is going to live at least 2x the effective lifespan (barring accidents, major defects, &c).
In general, anything built for high current tends but lower energy density tends to have much more ruggedness. Sanyo’s UR18650E is Li(NiMnCo)O2, for example, but in one paper shows 4X the lifecycle count of the extremely well regarded O.G. of LFP, the A123 ANR26650M1-A[1]. Even though it's considered a "lithium ion". And uses some of the rarer/more expensive materials. (Edit: re-reading the paper more closely, I'm less willing to embrace this conclusion. The A123 remains around 2000 cycle count regardless of depth of discharge pattern, while the li-ion drops to 1000 around 50% DoD.)
Not that phosphorous (The P in LFP) is projected to remain cheap/available forever. 2 days ago, talking more about phosphor's availability specifically with regard to agriculture (and rather alarmistly), "Phosphorus is essential to life and the world is running out of it"[2].
[1] http://www.jocet.org/vol7/511-C0056.pdf
[2] https://medium.com/climate-conscious/peak-phosphorus-may-be-... https://news.ycombinator.com/item?id=29244529 (2 days ago, 2 comments)
meta-note: this post has bounced up and down, 1, 2, 1, 2, 3, 1, 2. something like that. i just find that weird. hn has some weird downvoting behaviors that i really don't understand at all. maybe there's something legit downvotable or that people don't like? this seems like an innocuous post to me. i don't see the reason for it to keep getting negged.
apologies. i know discussing meta-topics is against the rules. i just really dont understand why there's an ongoing basis against this content becoming popular. it's so weird to me. i want to believe there's genuine real authentic behavior behind the votes happening here & elsewhere, but it feels so so weird to see this kind of straightforward telling constantly bounded, rising, then flattened back down, again and again. it instills a larger sense of disbelief, feels like there are vulgar reactionary forces about, which is not at all a conspiracy mindset i want to fall into.
apologies. i know discussing meta-topics is against the rules. i just really dont understand why there's an ongoing basis against this content becoming popular. it's so weird to me. i want to believe there's genuine real authentic behavior behind the votes happening here & elsewhere, but it feels so so weird to see this kind of straightforward telling constantly bounded, rising, then flattened back down, again and again. it instills a larger sense of disbelief, feels like there are vulgar reactionary forces about, which is not at all a conspiracy mindset i want to fall into.
You left out the solar to electric efficiency. If that's 30% (which is an upper limit if you produce the best solar cells you can) batteries have twice as efficient a round trip loop from the sun. In return, they are far less mobile and heavier to ship once loaded. Meanwhile, we can talk about moving around H2 via pipelines. Or simply higher energy storage for big uses. (Less energy spent dragging around batteries). Plus, the batteries do require lithium, which is pretty nasty stuff to get.
Other people have responded about circumstances where hydrogen-as-fuel (or fuel component) might still make sense; without commenting on that, it's important to also note that hydrogen is an important industrial feedstock, independent of its potential energy applications (it's critical to producing fertilizer, among other things), and industrial hydrogen pretty much all comes from natural gas at present. Given that we need at least some hydrogen anyway, figuring out better ways to produce it is worthwhile.
In that scenario, total levelized cost is the more important criterion that efficiency -- if these things convert solar energy less efficiently, but the contraption is cheaper than solar panels plus conventional electrolyzers because it's simpler or uses cheaper materials or whatever, it might still be the more economical bet.
In that scenario, total levelized cost is the more important criterion that efficiency -- if these things convert solar energy less efficiently, but the contraption is cheaper than solar panels plus conventional electrolyzers because it's simpler or uses cheaper materials or whatever, it might still be the more economical bet.
And where exactly does the energy stored in a battery come from, do you imagine?
This is PV powered production of hydrogen. Yes, the PV electricity could go directly to a battery, granted. But the PV cell is only about 20% efficient in that conversion. (Lab results are up to 30%.)
There are use cases where rather than an electrical transmission line needing to span an ocean, energy could be stored chemically (e.g. in hydrogen, or hydrocarbons produced from them) and transported like LNG across an ocean.
The claim of 95% round trip efficiency is basically relevant if the the energy is to be consumed (or placed on a grid) near the point of production. Otherwise 65% (13%/20%) efficiency for chemical energy that can be physically transported is not too bad.
Hydrogen is a battery from the perspective of a renewable energy system. If it is produced as a byproduct of a fossil fuel (as is commonly done) IMHO, it is not a renewable resource at all. Producing it from solar PV is a completely different kettle of fish.
This is PV powered production of hydrogen. Yes, the PV electricity could go directly to a battery, granted. But the PV cell is only about 20% efficient in that conversion. (Lab results are up to 30%.)
There are use cases where rather than an electrical transmission line needing to span an ocean, energy could be stored chemically (e.g. in hydrogen, or hydrocarbons produced from them) and transported like LNG across an ocean.
The claim of 95% round trip efficiency is basically relevant if the the energy is to be consumed (or placed on a grid) near the point of production. Otherwise 65% (13%/20%) efficiency for chemical energy that can be physically transported is not too bad.
Hydrogen is a battery from the perspective of a renewable energy system. If it is produced as a byproduct of a fossil fuel (as is commonly done) IMHO, it is not a renewable resource at all. Producing it from solar PV is a completely different kettle of fish.
yea, but batteries are still quite expensive (I mean on a grid scale) and the cost does not get better with scale. Storing H2 is much cheaper and will also probably scale sublinearly (simplified: you pay for the wall of the tank and the wall is only volume^(3/2)). Also, h2 can be transported, traded, ... whatever, batteries are impractical for this and cables also have limitations.
However, I see one big down to hydrogen. You can't tell how it was made, you rely on a promise that it's green, while it may actually be from methane... maybe with carbon storage, but you never know when that is gonna leak out. This might be a big loophole for fossil fuel corps / states
However, I see one big down to hydrogen. You can't tell how it was made, you rely on a promise that it's green, while it may actually be from methane... maybe with carbon storage, but you never know when that is gonna leak out. This might be a big loophole for fossil fuel corps / states
Apparently there are also some major patents that have expired or are expiring soon, which I hope means that costs will drop and we'll start seeing more LiFePO4 battery manufacturers outside of China where the vast majority are made now.
> BYD, which is the biggest producer of batteries in the world, sells shipping container sized lithium iron phosphate sized battery packs for large scale solar backup.
Tesla has been playing in that space too with their Megapack.
https://www.tesla.com/en_AU/blog/introducing-megapack-utilit...
There was a pretty bad fire with them in Australia. https://www.reuters.com/technology/tesla-megapack-fire-austr...
Tesla has been playing in that space too with their Megapack.
https://www.tesla.com/en_AU/blog/introducing-megapack-utilit...
There was a pretty bad fire with them in Australia. https://www.reuters.com/technology/tesla-megapack-fire-austr...
It is a stretch to call it a bad fire. One of the battery containers caught fire, and caused a second to be lost for reasons I don't know. The fire didn't spread, did not destroy the facility and did not require extensive downtime for repairs. Which is pretty nice to know as the fear was that one spark would send the whole facility up in a fireball.
> It is a stretch to call it a bad fire. One of the battery containers caught fire,
I suppose it's relative, but it seems it's a very good thing that only one caught because
> A giant Tesla battery pack caught on fire at a building in Australia, and it took 150 firefighters and four days to contain the blaze.
https://www.msn.com/en-us/news/technology/after-tesla-megapa...
150 firefighters taking 4 days to put it out. It certainly could have been worse, but I don't think it's a stretch to say it was pretty bad.
I suppose it's relative, but it seems it's a very good thing that only one caught because
> A giant Tesla battery pack caught on fire at a building in Australia, and it took 150 firefighters and four days to contain the blaze.
https://www.msn.com/en-us/news/technology/after-tesla-megapa...
150 firefighters taking 4 days to put it out. It certainly could have been worse, but I don't think it's a stretch to say it was pretty bad.
[deleted]
>So batteries are way ahead on efficiency.
Conversion efficiency is a different thing than storage efficiency or transmission efficiency.
Unless your gas tank is leaking, it's efficiency as a portable energy storage device approaches 100%, especially for modern vapor sealed vehicles.
Conversion efficiency is a different thing than storage efficiency or transmission efficiency.
Unless your gas tank is leaking, it's efficiency as a portable energy storage device approaches 100%, especially for modern vapor sealed vehicles.
A lot of the discussion here is around hydrogen fuel cells for cars and aviation. Which would be cool. But the real reason we need “green” hydrogen now is for making steel and cement: https://www.vox.com/energy-and-environment/2019/10/10/209042...
Apart from the humanitarian catastrophe, does anyone else feel vexed, at the enormous resources and man-hours lost because of the bombing campaigns in conflicts? One could argue, that efforts towards achieving inter-national harmony is also vital in reducing humanity's carbon footprint.
It's a good point: can any imagined use of hydrogen for cars even begin to compete with all the other demands for it? They might always outbid the car owners.
For aviation, LH2 has such fantabulous efficiencies that we can expect to see all serious air transport switched over by 2050 (providing civilization doesn't collapse first).
For aviation, LH2 has such fantabulous efficiencies that we can expect to see all serious air transport switched over by 2050 (providing civilization doesn't collapse first).
Aviation won’t be using LH2. The volume required makes it not feasible. Not to mention the cooling requirements. Look at the volumetric energy density of it compared to other fuels.
Volume is very cheap on board aircraft, so volumetric energy density doesn't matter. What costs is weight. On weight, LH2 clobbers everything, by a very long way.
https://news.ycombinator.com/item?id=29206505
https://news.ycombinator.com/item?id=29206505
That article shows a graph of cement cost increases from alternative energy use, and says:
> As you can see, every low-carbon alternative raises costs more than 50 percent above baseline. The only ones that don’t raise it more than 100 percent are CCS (of the heat source only), blue hydrogen, or resistive electric in places with extremely cheap and plentiful carbon-free energy.
> The alternative that climate hawks would most prefer, the carbon-free option that would work best for most applications, is green hydrogen. But that currently raises costs between 400 and 800 percent. Ouch.
Green hydrogen is by far the most expensive option. 3-4 times more expensive than electric heat. That's the direct opposite of "the real reason we need “green” hydrogen now is for making [...] cement".
This new work will hopefully make green hydrogen cheaper. But if you're using electricity to make that hydrogen, i don't think it can ever be cheaper than electric heating.
> As you can see, every low-carbon alternative raises costs more than 50 percent above baseline. The only ones that don’t raise it more than 100 percent are CCS (of the heat source only), blue hydrogen, or resistive electric in places with extremely cheap and plentiful carbon-free energy.
> The alternative that climate hawks would most prefer, the carbon-free option that would work best for most applications, is green hydrogen. But that currently raises costs between 400 and 800 percent. Ouch.
Green hydrogen is by far the most expensive option. 3-4 times more expensive than electric heat. That's the direct opposite of "the real reason we need “green” hydrogen now is for making [...] cement".
This new work will hopefully make green hydrogen cheaper. But if you're using electricity to make that hydrogen, i don't think it can ever be cheaper than electric heating.
Sorry I didn't mean it was more viable for that purpose, I meant it's more essential. We already know how to make good electric cars and power them with green-ish energy. For cement and steel we have barely even started making them "green" and they make a huge amount of our total greenhouse gas input.
I don't get why people are acting like it's an either or scenario. That said, one pro for hydrogen, is should be easily burnable in the current natural gas plants, which should easily cover off peak times without the need for batteries.
Another thing. I think we should question any plan that requires more mass mineral extraction than necessary. It's not as if mining is an environmentally neutral thing, and there is more to restoring our planet that just getting surviving climate change.
Another thing. I think we should question any plan that requires more mass mineral extraction than necessary. It's not as if mining is an environmentally neutral thing, and there is more to restoring our planet that just getting surviving climate change.
The UK is going to mix hydrogen and natural gas through the current infrastructure. They're currently building dozens of hydrogen plants and each one that comes online will increase the hydrogen until it's 100%.
Really brilliant as the UK will be way ahead in global production.
There's a good YouTube video explainer, search "just have a think blue hydrogen"
Here's government link
https://www.gov.uk/government/news/uk-government-launches-pl...
Really brilliant as the UK will be way ahead in global production.
There's a good YouTube video explainer, search "just have a think blue hydrogen"
Here's government link
https://www.gov.uk/government/news/uk-government-launches-pl...
Stupendously massive production capacity of H2 will be needed for every plausible climate disaster mitigation scenario. If you want to synthesize CH4 or other hydrocarbons from captured CO2, or to synthesize NH3 for fertilizer, or for fuel, or for storage, you need H2 first.
To fuel aircraft efficiently, you want a great deal of LH2. Anywhere LH2 aircraft fly, kerosene-fueled aircraft will be simply unable to compete. That will start on major international routes, with airports synthesizing LH2 on demand from grid power, banking it when spot price is lowest. The only thing that will save carriers loaded up with kerosene craft is the limit on how fast the LH2 aircraft can be manufactured.
Carbon-neutral steel production will depend on really huge amounts of H2, in place of coal or natural gas. Existing fertilizer production lines can inject H2 with the natural gas, and increase its fraction as more becomes available. At some point, as the carbon fraction decreases, electric heating will become more economical than burning injected gas for heat. Ultimately, improving catalysts will make the whole process more efficient than ever.
NH3 made with green hydrogen is a likely fuel for retrofitted long-distance shipping, where ships need only new fuel tanks and plumbing to switch over. Probably legislation will be needed to drive this change fast enough.
Cars with high-pressure H2 tanks are beginning to be practical, and are much lighter and cheaper to make than lithium-battery cars. When the car is lighter, the motor and drive train can be lighter too, and it takes less energy to accelerate them. In the short term, though, batteries are clearly winning. It is hard to be sure which will win, long term, but batteries have a huge first-mover advantage.
You can burn H2 directly in a natural-gas plant, or mixed into natural gas. So, as H2 production capacity grows, an increasing fraction of gas input to these systems will be H2. Ultimately, fuel cells driven from pure H2 will start to take over as prices of improved catalysts fall.
For utility-scale storage, bulk underground H2 is a much simpler and more reliable proposition than millions of battery cells, even though round-trip efficiency is poor. As top-line generating cost plummets, efficiency matters less. All the hottest storage systems (iron-air, hydrogen) are low roundtrip-efficiency.
To fuel aircraft efficiently, you want a great deal of LH2. Anywhere LH2 aircraft fly, kerosene-fueled aircraft will be simply unable to compete. That will start on major international routes, with airports synthesizing LH2 on demand from grid power, banking it when spot price is lowest. The only thing that will save carriers loaded up with kerosene craft is the limit on how fast the LH2 aircraft can be manufactured.
Carbon-neutral steel production will depend on really huge amounts of H2, in place of coal or natural gas. Existing fertilizer production lines can inject H2 with the natural gas, and increase its fraction as more becomes available. At some point, as the carbon fraction decreases, electric heating will become more economical than burning injected gas for heat. Ultimately, improving catalysts will make the whole process more efficient than ever.
NH3 made with green hydrogen is a likely fuel for retrofitted long-distance shipping, where ships need only new fuel tanks and plumbing to switch over. Probably legislation will be needed to drive this change fast enough.
Cars with high-pressure H2 tanks are beginning to be practical, and are much lighter and cheaper to make than lithium-battery cars. When the car is lighter, the motor and drive train can be lighter too, and it takes less energy to accelerate them. In the short term, though, batteries are clearly winning. It is hard to be sure which will win, long term, but batteries have a huge first-mover advantage.
You can burn H2 directly in a natural-gas plant, or mixed into natural gas. So, as H2 production capacity grows, an increasing fraction of gas input to these systems will be H2. Ultimately, fuel cells driven from pure H2 will start to take over as prices of improved catalysts fall.
For utility-scale storage, bulk underground H2 is a much simpler and more reliable proposition than millions of battery cells, even though round-trip efficiency is poor. As top-line generating cost plummets, efficiency matters less. All the hottest storage systems (iron-air, hydrogen) are low roundtrip-efficiency.
I am speaking completely out of ignorance on this, so someone with a bit more familiarity with both physics and chemistry might be able to clarify.
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From what I understand, one of the biggest issues with trying to replace commercial cross-country jets [1] with electric alternatives is due to the fact that there isn't enough energy density in a battery to make that possible, and as a result, airplanes are a huge polluter towards climate change.
Would it make more sense to try and make hydrogen jets, at least if we can make the hydrogen relatively efficiently?
[1] I know jets really only make sense with fuel, replace "jet" with "big airplane"
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From what I understand, one of the biggest issues with trying to replace commercial cross-country jets [1] with electric alternatives is due to the fact that there isn't enough energy density in a battery to make that possible, and as a result, airplanes are a huge polluter towards climate change.
Would it make more sense to try and make hydrogen jets, at least if we can make the hydrogen relatively efficiently?
[1] I know jets really only make sense with fuel, replace "jet" with "big airplane"
Elemental hydrogen has this problem: it is hard to store. You need low temperatures, high pressure, and corrosion resistant containers. But there is one weird trick: if you bind hydrogen to carbon atoms, then you get best of both worlds. The fuel remains energetic and yet is relatively unreactive outside of combustion and is easy to store. Perfect for aviation.
H2 is not hard to store in liquified form, LH2. You just need good insulation. Earth is excellent insulation.
For aviation, sticking on a carbon that outweighs your hydrogens by almost 8x gives up a huge efficiency advantage. The efficiency advantage overcomes inconvenience of handling cryogenic LH2. My bet is the tanks will be nacelles slung under the wings alongside the engines.
For aviation, sticking on a carbon that outweighs your hydrogens by almost 8x gives up a huge efficiency advantage. The efficiency advantage overcomes inconvenience of handling cryogenic LH2. My bet is the tanks will be nacelles slung under the wings alongside the engines.
I wonder what efficiencies look like for making hydrocarbons from atmospheric CO2 and water.
Not great, not terrible [https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_proces...]
Not price competitive with fossil fuels, but then not much is - hard to beat ‘mega joules for free*’ as it were.
Not price competitive with fossil fuels, but then not much is - hard to beat ‘mega joules for free*’ as it were.
Not disagreeing but just reminding.
It’s hard to compete with “let everyone else in the world pay for the true cost of this energy”.
That’s what makes fossil affordable and why we need carbon taxes right this second.
It’s hard to compete with “let everyone else in the world pay for the true cost of this energy”.
That’s what makes fossil affordable and why we need carbon taxes right this second.
Not wonderful, since atmospheric CO2 is so dilute. You need either a hefty carbon tax or a ban on oil extraction to make the economics work. https://en.wikipedia.org/wiki/Synthetic_fuel
Our current spike in natural gas and oil prices is something of a dry run for what carbon taxes would look like. So far it doesn't seem like the approval ratings of the governing party can survive it.
Our current spike in natural gas and oil prices is something of a dry run for what carbon taxes would look like. So far it doesn't seem like the approval ratings of the governing party can survive it.
Isn't that basically what trees do? Solar-powered, too!
Came across this recently:
https://en.m.wikipedia.org/wiki/Powerpaste
It might pan out and reduce issues with hydrogen leakage
https://en.m.wikipedia.org/wiki/Powerpaste
It might pan out and reduce issues with hydrogen leakage
The powerpaste is magnesium oxide. One magnesium atom weights around as much as 24 hydrogen atoms.
Thus for every hydrogen molecule you have to carry around 13 times the weight in magnesium oxide. Aka: This stuff is very heavy. Not exactly the thing you want on planes.
Thus for every hydrogen molecule you have to carry around 13 times the weight in magnesium oxide. Aka: This stuff is very heavy. Not exactly the thing you want on planes.
Short answer: yes, hydrogen jets are probably the future. Electrochemical batteries fundamentally lack the required mass to energy ratio necessary for air travel. But there's a lot of challenges to actually powering an aircraft via hydrogen, and it's probably not going to happen for a while.
The long answer:
* The question is moot until we have widespread decarbonization of the energy grid. Currently, our hydrogen mostly comes from steam reformation - splitting methane, CH4, into 2H2 + CO - which emits carbon dioxide. Once our electrical production is carbon-free, then we can think of producing hydrogen and powering vehicles with that. Electrolysis can serve as a carbon-free source of hydrogen, if the electricity is produced from a carbon-free source. There are more efficient forms of hydrogen production, like thermochemical hydrogen production with heat provided by nuclear reactors.
* Once carbon-free hydrogen production becomes available, then there's the question of building hydrogen powered vehicles. Hydrogen is the most energy dense fuel by unit of mass, except for nuclear fuels, but it's about half the energy density by unit of volume compared to hydrocarbons. Substituting fossil fuels with hydrogen is probably more feasible in container ships than aircraft. Hydrogen containment, be it pressurized or liquid-cryogenic, scales better at higher capacities as there is a better volume to surface-area ratio. Aircraft wings (long and skinny) are basically the worst shape for hydrogen containment. Past examples of hydrogen powered aircraft stored it in the fuselage [1], which would sacrifice cargo and passenger space.
* Lastly, for aircraft there's also the question of making engines that don't produce greenhouse gases. High-temperature hydrogen gas turbines will also produce nitrous oxides, which are greenhouse gases. This can be mitigated by running turbines at lower temperatures, but that reduces efficiency. There's also the idea of using hydrogen fuel cells to produce electricity to run turbines, but fuel cells and electrical motors don't have as good power to weight ratios as combustion turbines.
I'm much more optimistic about converting maritime transport to hydrogen fuels than aircraft. That said, the military is very interested in hydrogen planes. One of the limiting factors in modern naval warfare is fuel to fly planes. With hydrogen powered planes, a carrier could produce hydrogen with its nuclear reactors giving carriers an effectively unlimited source of aviation fuel. If they figure it out, hopefully the tech propagates to civil air transport.
1. https://en.wikipedia.org/wiki/Tupolev_Tu-155
The long answer:
* The question is moot until we have widespread decarbonization of the energy grid. Currently, our hydrogen mostly comes from steam reformation - splitting methane, CH4, into 2H2 + CO - which emits carbon dioxide. Once our electrical production is carbon-free, then we can think of producing hydrogen and powering vehicles with that. Electrolysis can serve as a carbon-free source of hydrogen, if the electricity is produced from a carbon-free source. There are more efficient forms of hydrogen production, like thermochemical hydrogen production with heat provided by nuclear reactors.
* Once carbon-free hydrogen production becomes available, then there's the question of building hydrogen powered vehicles. Hydrogen is the most energy dense fuel by unit of mass, except for nuclear fuels, but it's about half the energy density by unit of volume compared to hydrocarbons. Substituting fossil fuels with hydrogen is probably more feasible in container ships than aircraft. Hydrogen containment, be it pressurized or liquid-cryogenic, scales better at higher capacities as there is a better volume to surface-area ratio. Aircraft wings (long and skinny) are basically the worst shape for hydrogen containment. Past examples of hydrogen powered aircraft stored it in the fuselage [1], which would sacrifice cargo and passenger space.
* Lastly, for aircraft there's also the question of making engines that don't produce greenhouse gases. High-temperature hydrogen gas turbines will also produce nitrous oxides, which are greenhouse gases. This can be mitigated by running turbines at lower temperatures, but that reduces efficiency. There's also the idea of using hydrogen fuel cells to produce electricity to run turbines, but fuel cells and electrical motors don't have as good power to weight ratios as combustion turbines.
I'm much more optimistic about converting maritime transport to hydrogen fuels than aircraft. That said, the military is very interested in hydrogen planes. One of the limiting factors in modern naval warfare is fuel to fly planes. With hydrogen powered planes, a carrier could produce hydrogen with its nuclear reactors giving carriers an effectively unlimited source of aviation fuel. If they figure it out, hopefully the tech propagates to civil air transport.
1. https://en.wikipedia.org/wiki/Tupolev_Tu-155
The natural form for aviation fuel is liquified hydrogen, LH2, sidestepping worries about embrittlement. LH2 is so much more efficient as an avaition fuel, despite problems handling ultra-cold liquids, that kerosene-powered aircraft will be simply unable to compete anywhere LH2 craft are in use. The rate of collapse in value of kerosene aircraft will be limited only by the rate that we can build out new or retrofitted LH2 aircraft.
It is not clear whether existing aircraft or designs can be usefully retrofitted for LH2. Existing wing tanks are, in any case, useless for LH2. You need much more room for LH2 tankage, and you might not want a big LH2 tank inboard; there are safety reasons for the fuel in current aircraft being out in the wings. So, maybe the LH2 is carried in nacelles slung under the wing, next to the engines. We will need to build up a great deal of aerogel manufacturing capacity to insulate them.
It is possible that existing wing tankage can be used to carry NH3 to inject, in small proportion, to minimize NOx pollution. Given a bit of surplus N, the N prefers to make N2, and the O prefers to make H2O. E.g., existing natural-gas plants inject NH3 to reduce their NOx output.
For shipping, anhydrous ammonia is probably a better choice of fuel. Existing engines can burn it, so you need only new room-temperature ammonia tanks and new plumbing.
It is not clear whether existing aircraft or designs can be usefully retrofitted for LH2. Existing wing tanks are, in any case, useless for LH2. You need much more room for LH2 tankage, and you might not want a big LH2 tank inboard; there are safety reasons for the fuel in current aircraft being out in the wings. So, maybe the LH2 is carried in nacelles slung under the wing, next to the engines. We will need to build up a great deal of aerogel manufacturing capacity to insulate them.
It is possible that existing wing tankage can be used to carry NH3 to inject, in small proportion, to minimize NOx pollution. Given a bit of surplus N, the N prefers to make N2, and the O prefers to make H2O. E.g., existing natural-gas plants inject NH3 to reduce their NOx output.
For shipping, anhydrous ammonia is probably a better choice of fuel. Existing engines can burn it, so you need only new room-temperature ammonia tanks and new plumbing.
> I know jets really only make sense with fuel, replace "jet" with "big airplane"
‘Jets’ could make sense even without fuel if you consider that jet propulsion [2] is the generation of thrust using a fast-moving stream of fluid. Today’s jet engines are already turbofans [3] where only part of the propelled air passes through the fuel combustion chamber.
[2]: https://en.wikipedia.org/wiki/Jet_propulsion
[3]: https://en.wikipedia.org/wiki/Turbofan
‘Jets’ could make sense even without fuel if you consider that jet propulsion [2] is the generation of thrust using a fast-moving stream of fluid. Today’s jet engines are already turbofans [3] where only part of the propelled air passes through the fuel combustion chamber.
[2]: https://en.wikipedia.org/wiki/Jet_propulsion
[3]: https://en.wikipedia.org/wiki/Turbofan
Airbus has dangled the hydrogen jet concept, but hydrogen presents a lot of problems (low density, cryogenic, leaks through solid metal causing embrittlement).
It probably makes more sense to just synthesize longer hydrocarbons.
It probably makes more sense to just synthesize longer hydrocarbons.
Embrittlement is a product of high-pressure high-temperature storage. LH2 has its own difficulties, but they don't worsen with time.
> It probably makes more sense to just synthesize longer hydrocarbons.
Sorry, ignorance on my end is showing again; wouldn't a longer hydrocarbon still emit CO2 as a by-product since carbons are part of its makeup? Or does a longer hydrocarbon mean that there's a higher hydrogen-to-carbon ratio and therefore the pollution is less horrible?
Sorry, ignorance on my end is showing again; wouldn't a longer hydrocarbon still emit CO2 as a by-product since carbons are part of its makeup? Or does a longer hydrocarbon mean that there's a higher hydrogen-to-carbon ratio and therefore the pollution is less horrible?
Yes, but to make the hydro-carbon, you need to put carbon in. If you extract that from air you’re carbon-neutral.
You can also be carbon-neutral by making that cycle larger: extract carbon from trees, create fuel, burn it, and let new trees you planted convert the CO2 back into wood.
You can also be carbon-neutral by making that cycle larger: extract carbon from trees, create fuel, burn it, and let new trees you planted convert the CO2 back into wood.
It would mean adding carbon. In order to be carbon neutral that carbon would need to extracted from the carbon cycle.
Not my area of expertise either, but I gather that hydrogen is difficult to store in quantity, requiring large heavy pressure vessels, and it has relatively low energy density. Both of which count against using it for commercial flight.
No one would bother with heavy, high-pressure hydrogen containment for large aircraft, so that is a moot point. The clear choice for aircraft is LH2, where it is fantastically more efficient than hydrocarbons.
>airplanes are a huge polluter towards climate change.
This is true on a relative basis: flying across the US puts out a lot of CO2 for a single person.
But on an absolute scale, it's pretty tiny: 2% of total CO2, 12% of transportation CO2.
This is true on a relative basis: flying across the US puts out a lot of CO2 for a single person.
But on an absolute scale, it's pretty tiny: 2% of total CO2, 12% of transportation CO2.
Just the CO2 numbers aren't giving you the right picture, as the other effects multiply the emissions effects of air travel on warming (for example radiative forcing).
That's also why an air travel emissions factor is used by policymakers when talking about its effects.
(Also, US transportation emissions in other sectors, especially road, are enormous in comparison to other countries, for context on the relative comparisons: https://www.statista.com/statistics/1201189/road-transport-s...).
That's also why an air travel emissions factor is used by policymakers when talking about its effects.
(Also, US transportation emissions in other sectors, especially road, are enormous in comparison to other countries, for context on the relative comparisons: https://www.statista.com/statistics/1201189/road-transport-s...).
Jet engines can burn hydrogen.
Then would it make sense for Delta or United or KLM or something to start investing in retrofitting their planes to hydrogen? I would think that governments could give tax incentives to do so, and as a result make planes substantially less horrible for the environment.
Sorry, it would not remotely make sense. Planes store liquid fuel in the wings. They are engineered from square one to optimize for this design. Hydrogen requires either cryo or high pressure, neither are going to fit in the wing spaces. Even if you could physically make it work, you'd have to re-certify the plane, which just wouldn't happen.
A hydrogen plane would have to be designed from the ground up.
A hydrogen plane would have to be designed from the ground up.
Interesting idea. Supply chain issues aside I don’t know if the current gas tanks could be retrofitted for hydrogen. Maybe fuel cells would be easier. Could just shoot water out of its little plane tush as its flying.
Is there enough O2 at plane levels for fuel cells?
Is there enough O2 at plane levels for fuel cells?
The headline is "solar-driven water splitting", but they do this by building an photovoltaic cell and connecting it to an electrolyser, just like everyone already does.
Moreover, the innovation here is that neither the solar cell nor the electrolyser require rare elements. As they say:
> Sustainable water electrolysis requires that the anode and cathode catalysts are noble metal free and contain small amounts of other metals in order to lower system costs and facilitate recycling.
As for efficiency:
> The measured [solar-to-hydrogen] efficiency is improved compared to all previous electrolyzers driven by low-cost [perovskite solar cells] that used solely Earth-abundant electrocatalysts but lower compared to the highest performing perovskite/Si tandem devices that uses noble metal electrocatalysts, which reached an initial efficiency of 17% [solar-to-hydrogen].
So this setup is less efficient than what we already have. But it doesn't require rare elements.
Moreover, the innovation here is that neither the solar cell nor the electrolyser require rare elements. As they say:
> Sustainable water electrolysis requires that the anode and cathode catalysts are noble metal free and contain small amounts of other metals in order to lower system costs and facilitate recycling.
As for efficiency:
> The measured [solar-to-hydrogen] efficiency is improved compared to all previous electrolyzers driven by low-cost [perovskite solar cells] that used solely Earth-abundant electrocatalysts but lower compared to the highest performing perovskite/Si tandem devices that uses noble metal electrocatalysts, which reached an initial efficiency of 17% [solar-to-hydrogen].
So this setup is less efficient than what we already have. But it doesn't require rare elements.
People often say how battery cars are more efficient than fuel cell cars, and we should focus our resources to the former. Some even called fuel cell cars dumb. This is short sighted in my opinion. If fuel cell cars are more popular, it encourages more green hydrogen production and investment. Once there are more green hydrogen, then we can truly decarbonize the chemical and industrial sectors. There are so many industrial processes requiring hydrogen as a reactant. Fuel cell cars can be a catalyst to decarbonize sectors well beyond the auto industry.
Anyone who says thay one is better than the other completely misses the fact that we have enough researchers on this planet to work on both. You never know what applications will make sense for each of the techs.
People are usually talking about being against having tax payer subsides for hydrogen powered consumer vehicles being inexplicably higher than those for battery powered vehicles.
The challenge is cost of energy production, which translates directly into cost per mile when it comes to hydrogen powered vehicles. That matters because when the choice is pay 1x or 3-5x per mile, it's going to be an easy choice for most and hydrogen is going to lose every time. Hydrogen is simply too expensive per mile relative to other options.
That's why battery EVs are so popular; they are clearly cheaper to drive per mile. Especially if you charge them cheaply from your own solar panels, using off peak grid rates, etc. You are basically driving almost for free. In some cases grid operators literally pay consumers to plug their cars in so they can offload excess energy. It's cheaper than shutting down gas powered peaker plants and having to restart them a few hours later.
The article is interesting because it proposes a way that gets production to less than 2x the efficiency difference relative to using solar panels to generate energy in terms of efficiencies (12-15% vs 20-25%). That's impressive. However, it says nothing about the cost of hydrogen because this is an academic article and not an actual product. However it suggests an improvement. For reference, producing hydrogen from wind energy would use about 3-4x the kwh in generated electricity to produce 1kwh of hydrogen.
That's not bad. But even (wrongly) assuming all of that would be converted to motion, that would be about a 3x cost per mile difference already vs. just putting the wind energy straight in your battery. Burning hydrogen has inherent inefficiencies (you produce heat and noise) similar to burning other fuels (20-30% efficiency would be pretty good). And even fuel cells are not that efficient; 60% efficiency is pretty good apparently. And if you are using hydrogen for fueling vehicles, what matters is the cost per mile. So, on top of the production that would be another loss of about 1.5 - 5x on top of the production inefficiencies.
The fantasy of hydrogen in cars and trucks is that it is needed and that the cost doesn't matter. The reality is that there are battery equipped vehicles in almost every weight and vehicle class being produced already with pretty awesome cost per mile that are going to be pretty hard to compete with using hydrogen. It's a no-brainer choice already for a lot of drivers and fleet operators. Sure, their range is not always that impressive. But at about 3-5x the cost per mile difference that's an inconvenience that can be worked with.
The other fantasy is that hydrogen is carbon neutral. The vast majority of hydrogen produced is grey hydrogen. If you want to save some carbon, fuel your car using methane instead of hydrogen. You'll produce a lot of co2 but a lot less than when you use that methane to produce hydrogen which you then burn or use in a fuel cell. That's the sad status quo of hydrogen on the road right now. What little there is neither green, efficient, or cheap. Making it green will raise the prices. Making it less inefficient is going to be a long battle, and until that is done, it will be inherently more expensive.
Green hydrogen when production of that is going to be more meaningful is still going to be useful elsewhere (aviation, shipping, heavy industries). And with wind and solar intermittency that basically means there are going to be surplusses (rather than shortages) because people will over provision to compensate. Hydrogen is a great way to use such excess energy. There's going to be plenty of demand for it. Just not on the road.
That's why battery EVs are so popular; they are clearly cheaper to drive per mile. Especially if you charge them cheaply from your own solar panels, using off peak grid rates, etc. You are basically driving almost for free. In some cases grid operators literally pay consumers to plug their cars in so they can offload excess energy. It's cheaper than shutting down gas powered peaker plants and having to restart them a few hours later.
The article is interesting because it proposes a way that gets production to less than 2x the efficiency difference relative to using solar panels to generate energy in terms of efficiencies (12-15% vs 20-25%). That's impressive. However, it says nothing about the cost of hydrogen because this is an academic article and not an actual product. However it suggests an improvement. For reference, producing hydrogen from wind energy would use about 3-4x the kwh in generated electricity to produce 1kwh of hydrogen.
That's not bad. But even (wrongly) assuming all of that would be converted to motion, that would be about a 3x cost per mile difference already vs. just putting the wind energy straight in your battery. Burning hydrogen has inherent inefficiencies (you produce heat and noise) similar to burning other fuels (20-30% efficiency would be pretty good). And even fuel cells are not that efficient; 60% efficiency is pretty good apparently. And if you are using hydrogen for fueling vehicles, what matters is the cost per mile. So, on top of the production that would be another loss of about 1.5 - 5x on top of the production inefficiencies.
The fantasy of hydrogen in cars and trucks is that it is needed and that the cost doesn't matter. The reality is that there are battery equipped vehicles in almost every weight and vehicle class being produced already with pretty awesome cost per mile that are going to be pretty hard to compete with using hydrogen. It's a no-brainer choice already for a lot of drivers and fleet operators. Sure, their range is not always that impressive. But at about 3-5x the cost per mile difference that's an inconvenience that can be worked with.
The other fantasy is that hydrogen is carbon neutral. The vast majority of hydrogen produced is grey hydrogen. If you want to save some carbon, fuel your car using methane instead of hydrogen. You'll produce a lot of co2 but a lot less than when you use that methane to produce hydrogen which you then burn or use in a fuel cell. That's the sad status quo of hydrogen on the road right now. What little there is neither green, efficient, or cheap. Making it green will raise the prices. Making it less inefficient is going to be a long battle, and until that is done, it will be inherently more expensive.
Green hydrogen when production of that is going to be more meaningful is still going to be useful elsewhere (aviation, shipping, heavy industries). And with wind and solar intermittency that basically means there are going to be surplusses (rather than shortages) because people will over provision to compensate. Hydrogen is a great way to use such excess energy. There's going to be plenty of demand for it. Just not on the road.
Two things are hardly ever spoken about when splitting water:
The pure oxygen is just as useful of a product and can be used to gasify woody biomass, plastics and other waste streams into more useful fuel sources such as syngas, or liquid fuels using the fischer-tropsch process. It is also useful for medical processes.
Second, natural gas lines can utilize something like 10% hydrogen...so we can store a large quantity in our existing infrastructure for use later that day, or in other locations.
The pure oxygen is just as useful of a product and can be used to gasify woody biomass, plastics and other waste streams into more useful fuel sources such as syngas, or liquid fuels using the fischer-tropsch process. It is also useful for medical processes.
Second, natural gas lines can utilize something like 10% hydrogen...so we can store a large quantity in our existing infrastructure for use later that day, or in other locations.
Natural gas pipelines will have to ramp down with fossils though.
One big electricity storage problem is seasonal - eg cold sunless winters. Eg batteries are great for daytime charging your car - but they aren't great for storing up a whole summer's worth of energy to burn in the winter. Hydrogen could do that.
A 3x overbuild of solar+wind in an optimal mix, along with a continental grid and 3 hours worth of batteries is all you need for 99.99% reliability over an entire year.
https://www.nature.com/articles/s41467-021-26355-z
https://www.nature.com/articles/s41467-021-26355-z
I would assume that many/most countries in climates where power interruptions quickly turn into deaths to avoid building in a dependence on an extra-territorial grid for base-level power supply.
It's already a problem in Eurasia with nation states using eg. natural gas delivery as a means to apply political pressure on other states, and this while it is still (relatively) easy to solve energy needs as carbohydrates can be easily transported.
If all border crossing energy/power delivery is through a physical network of cables, adapting if delivery is cutoff would be almost impossible unless all gas/coal/oil plants were kept at/near operating condition.
Hence, yes, the buildout must be some X times necessary power, as much as possible locally. A significant fraction of that generated power should be used to create a) industrial feedstock b) to generate liquids/gas that can be easily used and transported.
The latter in the case some nation is being pressured by energy blockades where the existing grid can not supply enough energy through transmission lines from other bordering states.
It's already a problem in Eurasia with nation states using eg. natural gas delivery as a means to apply political pressure on other states, and this while it is still (relatively) easy to solve energy needs as carbohydrates can be easily transported.
If all border crossing energy/power delivery is through a physical network of cables, adapting if delivery is cutoff would be almost impossible unless all gas/coal/oil plants were kept at/near operating condition.
Hence, yes, the buildout must be some X times necessary power, as much as possible locally. A significant fraction of that generated power should be used to create a) industrial feedstock b) to generate liquids/gas that can be easily used and transported.
The latter in the case some nation is being pressured by energy blockades where the existing grid can not supply enough energy through transmission lines from other bordering states.
You probably want a 6x overbuild to account for round-trip losses in your storage system. Cost of storage falls very fast as your efficiency requirements are relaxed, which becomes attractive as raw generating cost plummets.
According to the paper you cited, such setup in Germany would cause 100-500 hours of blackouts each year.
Pg&e has performed similarly over the past 10 years, averaged across California.
"continent wide grid" is a key requirement.
or...
we could use space rocks to heat water.
just saying.
we could use space rocks to heat water.
just saying.
There are plenty of other storage solutions that are cheaper than lithium ion batteries and vastly more efficient than hydrogen. Even just cabling energy around is an option. E.g. the UK is looking at a solution for getting a few GW of Moroccan solar energy connected to their grid to supplement their wind power (which they have throughout the year) and modest amounts of solar which is a bit more seasonal.
The fallacy in your argument is assuming there's a need for seasonal storage. That need would only exist if you rely exclusively on solar energy. Which of course people up north don't tend to do and people closer to the equator could actually feasibly do throughout the year.
Plenty of places get by mostly powered by different combinations of renewables. E.g. Norway (wind, hydro), Iceland (geothermal, wind), Scotland (wind, tidal wave power), etc. without a lot of storage.
The fallacy in your argument is assuming there's a need for seasonal storage. That need would only exist if you rely exclusively on solar energy. Which of course people up north don't tend to do and people closer to the equator could actually feasibly do throughout the year.
Plenty of places get by mostly powered by different combinations of renewables. E.g. Norway (wind, hydro), Iceland (geothermal, wind), Scotland (wind, tidal wave power), etc. without a lot of storage.
Geothermal and Hydro are steady sources, not intermittent, so that’s why you don’t need a lot of storage. The hydro dam is the storage.
Geothermal also isn’t renewable unless used very very sparingly, most installations I know of will deplete the source in a few decades, perhaps a century.
Geothermal energy is not going to run out. The sun will go super nova before that happens.
what about those salt brine slurry energy storage? wonder how they're doing now..
https://www.osti.gov/etdeweb/servlets/purl/21390211
https://www.osti.gov/etdeweb/servlets/purl/21390211
We see the value in fuels like diesel being highly energy-dense. If we used the sun to create fuel like hydrogen or electricity, what is against simply creating (purified in some sense) man-made diesel and continue to use combustion engines?
We would not be contributing to the overall contribution of greehouse gases. Some arguments are diesel and friends are safer in storage and transportation than hydrogen.
We would not be contributing to the overall contribution of greehouse gases. Some arguments are diesel and friends are safer in storage and transportation than hydrogen.
The more complex the chemistry, the less economically viable.
Hydrogen is just H2. Diesel is a complex hydrocarbon.
A viable future, would be a highly distributed network of hydrogen stations, with Hydrogen generated from solar energy, with enough reserve capacity to act as a base load plant.
Extracting energy from hydrogen is a well understood process.
Hydrogen is just H2. Diesel is a complex hydrocarbon.
A viable future, would be a highly distributed network of hydrogen stations, with Hydrogen generated from solar energy, with enough reserve capacity to act as a base load plant.
Extracting energy from hydrogen is a well understood process.
Probably makes more sense to do compressed or liquid methane for ground vehicles. Easier to synthesize and cleaner burning.
> what is against simply creating (purified in some sense) man-made diesel and continue to use combustion engines?
Mostly it’s just economics. Either the costs need to come down, or oil prices need to rise.
The way oil prices are headed, that might not take long.
Mostly it’s just economics. Either the costs need to come down, or oil prices need to rise.
The way oil prices are headed, that might not take long.
I assume there are also costs to store and deliver hydrogen fuel? I'd like to see an EROEI comparison of electric vs. hydrogen.
Make ammonia out of it, easier to store and transport.
The closer you can get to both steel mills and pipelines, the better. Steel mills can use the hydrogen to replace metallurgical/coking coal, and the pipeline can accept ammonia for transport. Hydrogen is very hard on pipeline infra, unless mixed at low concentrations with a carrier gas.
A steel mill will make its own hydrogen on demand from wired-in power off the continental grid. Likewise, international airports for LH2 aircraft.
They will bank hydrogen synthesized when grid prices are lowest, in mid-day, when immediate power need is vastly outstripped by solar generating capacity.
They will bank hydrogen synthesized when grid prices are lowest, in mid-day, when immediate power need is vastly outstripped by solar generating capacity.
It also is how they power refrigeration in meat processing to keep the freezers cold. Seems like if you put it next to those manufacturing facilities to power the freezer trucks and facility itself you could save a significant amount of energy and reduce greenhouse gasses.
Probably not as much as you'd think. Ammonia is used as a refrigerant in a closed-loop system. You'll eventually have some leaks and have to recharge the system, but the ammonia isn't a consumable item in this process.
This is the wrong question to ask.
Hydrogen is not for use cases where there is an electric alternative. Electric almost always wins. But there are use cases where there is no electric alternative or none that is available any time soon, most notably chemicals and steel.
Hydrogen is not for use cases where there is an electric alternative. Electric almost always wins. But there are use cases where there is no electric alternative or none that is available any time soon, most notably chemicals and steel.
It's the wrong question to ask but it sure as shit is what it's being promoted as.
Look at the wayward Toyota, they seem to think they can navigate around chemisty to sell their EVs with a hydrogen fuel cell attached.
Look at the wayward Toyota, they seem to think they can navigate around chemisty to sell their EVs with a hydrogen fuel cell attached.
They made a bet on hydrogen, hydrogen cars failed, and they are now sinking in more costs. They are a financial and executive failure, not a scientific one.
There is still use for hydrogen outside of vehicles (and possibly some highly specific scenarios involving vehicles).
There is still use for hydrogen outside of vehicles (and possibly some highly specific scenarios involving vehicles).
Most of the problems with hydrogen for cars comes from how you produce that hydrogen.
Obviously, producing hydrogen from methane to power cars is a stupid idea if your goal is to reduce greenhouse gases.
However, pure electric cars are only successful in some niches, and larger vehicles like buses and lorries just aren't practical yet, whilst hydrogen buses are already a thing. Battery technology has come a long way, but the energy density is still absolute garbage when you compare it to the energy density in any fuel.
If you can produce hydrogen directly from solar power, then the overall efficiency may be less important: the advantages of greatly increased power density, and ease of refueling may make it more appealing.
For battery-powered cars to be the long-term solution, and not just a stop-gap measure, there will need to be a massive breakthrough, to the point that energy densities can be compared with other fuelds.
As petrol/diesel cars are phased out, there will be an increasing number of customers whose needs cannot be met by the current state of electric vehicles, and there will need to exist another option. At that point, maybe hydrogen won't look like such a bad bet...
Obviously, producing hydrogen from methane to power cars is a stupid idea if your goal is to reduce greenhouse gases.
However, pure electric cars are only successful in some niches, and larger vehicles like buses and lorries just aren't practical yet, whilst hydrogen buses are already a thing. Battery technology has come a long way, but the energy density is still absolute garbage when you compare it to the energy density in any fuel.
If you can produce hydrogen directly from solar power, then the overall efficiency may be less important: the advantages of greatly increased power density, and ease of refueling may make it more appealing.
For battery-powered cars to be the long-term solution, and not just a stop-gap measure, there will need to be a massive breakthrough, to the point that energy densities can be compared with other fuelds.
As petrol/diesel cars are phased out, there will be an increasing number of customers whose needs cannot be met by the current state of electric vehicles, and there will need to exist another option. At that point, maybe hydrogen won't look like such a bad bet...
There are electrical buses already that are being used quite extensively, e.g. Moscow has a fleet of electric buses
Hydrogen has good energy/kg, but it has really poor energy/l. Buses are mostly empty space so they more volume limited than weight limited. Battery powered buses are already far more common than Hydrogen buses and the trend will accelerate quickly.
In Europe, battery powered trucks can carry a heavier load than diesel trucks. The weight disadvantage of a battery powered truck is about a tonne. The batteries weigh a lot more than a tonne, but so does the engine, transmission and fuel in a diesel truck. The difference is about a tonne. In Europe, they allow battery trucks to weigh two tonnes more than diesel trucks, so... In America battery powered trucks have a 1000 pound weight limit increase.
Green hydrogen is always going to cost about 10x as much as electricity. Using electricity to electrolyze water, compress the hydrogen, transport the hydrogen, strip off the electrons in a fuel cell, charge a battery and then drive a motor is necessarily a lot less efficient than using than skipping 4 of those steps to charge a battery directly.
And truckers don't care about fuel density, they care about costs.
In Europe, battery powered trucks can carry a heavier load than diesel trucks. The weight disadvantage of a battery powered truck is about a tonne. The batteries weigh a lot more than a tonne, but so does the engine, transmission and fuel in a diesel truck. The difference is about a tonne. In Europe, they allow battery trucks to weigh two tonnes more than diesel trucks, so... In America battery powered trucks have a 1000 pound weight limit increase.
Green hydrogen is always going to cost about 10x as much as electricity. Using electricity to electrolyze water, compress the hydrogen, transport the hydrogen, strip off the electrons in a fuel cell, charge a battery and then drive a motor is necessarily a lot less efficient than using than skipping 4 of those steps to charge a battery directly.
And truckers don't care about fuel density, they care about costs.
> it has really poor energy/l
Compared to fuel yes. Compared to batteries, even at relatively low pressures, I think hydrogen still wins even by volume, and at higher pressures it's an order of magnitude difference.
> In Europe, battery powered trucks can carry a heavier load than diesel trucks.
You mean legally? If we're discussing which option is technologically superior long term, then it doesn't really make sense to argue based on arbitrary laws today. Is there a particular retionale behind the law that would make sense for electric trucks but not hydrogen ones?
> Green hydrogen is always going to cost about 10x as much as electricity.
Possibly, but as more renewable energy sources come online, the problem is going to change from "can we produce enough energy?" to "is the energy available at the right time and place?". Electrical energy is very difficult to store and transport in any significant quantity. We already have to turn off renewables sometimes because they're simply producing too much power when we don't need it. That power may as well go to creating hydrogen than doing nothing.
I don't know that hydrogen specficially will be the long term solution either (after all, something better could always materialize) but current battery technology is definitely not a panacea.
> ... is necessarily a lot less efficient than using than skipping 4 of those steps to charge a battery directly.
High battery/payload weight ratio means you need more energy to get where you're going, which is not typically considered when comparing the efficiency of batteries to hydrogen. Batteries also take a lot of energy to manufacture in the first place, and have a limited lifespan, which is also rarely considered. I think that with some minor efficiency improvements to a couple of steps, and a lowering cost of electricity at "off-peak" times, that the overall equation will shift.
> And truckers don't care about fuel density, they care about costs.
Costs come from a lot of places. Trucks sitting around charging instead of delivering goods are a cost. Reduced range means increased costs. Expensive batteries that have to be replaced every X years are a cost.
Compared to fuel yes. Compared to batteries, even at relatively low pressures, I think hydrogen still wins even by volume, and at higher pressures it's an order of magnitude difference.
> In Europe, battery powered trucks can carry a heavier load than diesel trucks.
You mean legally? If we're discussing which option is technologically superior long term, then it doesn't really make sense to argue based on arbitrary laws today. Is there a particular retionale behind the law that would make sense for electric trucks but not hydrogen ones?
> Green hydrogen is always going to cost about 10x as much as electricity.
Possibly, but as more renewable energy sources come online, the problem is going to change from "can we produce enough energy?" to "is the energy available at the right time and place?". Electrical energy is very difficult to store and transport in any significant quantity. We already have to turn off renewables sometimes because they're simply producing too much power when we don't need it. That power may as well go to creating hydrogen than doing nothing.
I don't know that hydrogen specficially will be the long term solution either (after all, something better could always materialize) but current battery technology is definitely not a panacea.
> ... is necessarily a lot less efficient than using than skipping 4 of those steps to charge a battery directly.
High battery/payload weight ratio means you need more energy to get where you're going, which is not typically considered when comparing the efficiency of batteries to hydrogen. Batteries also take a lot of energy to manufacture in the first place, and have a limited lifespan, which is also rarely considered. I think that with some minor efficiency improvements to a couple of steps, and a lowering cost of electricity at "off-peak" times, that the overall equation will shift.
> And truckers don't care about fuel density, they care about costs.
Costs come from a lot of places. Trucks sitting around charging instead of delivering goods are a cost. Reduced range means increased costs. Expensive batteries that have to be replaced every X years are a cost.
> Possibly, but as more renewable energy sources come online, the problem is going to change from "can we produce enough energy?" to "is the energy available at the right time and place?".
This is the most important point of the economics of renewables. Eg, I think Toyota was too early and applied to the wrong industry (personal vehicles), but not wrong.
For example, burning diesel for electricity (which is done a lot in remote areas and as backup) is really expensive, even just looking at the point of generation and not the externalities. If renewable electricity generation is hovering around the 2c per kWh mark, even with all the losses, H2 starts to make a lot of sense for a lot of energy intensive industries. Even more so when the electricity used to generate it was never going to get even sell for that price because it just wasn't needed.
Renewables have an economic problem currently where every solar panel and wind turbine added to an electricity network will have a lower ROI than previous ones due to their intermittent nature, lowering the return of older assets as well. As their use grows, this problem will get worse and generators will have this large earning potential with an asset generating wasted energy, with a life span measured in several decades. Long tail, lots of opportunity to do more with those assets.
This is the most important point of the economics of renewables. Eg, I think Toyota was too early and applied to the wrong industry (personal vehicles), but not wrong.
For example, burning diesel for electricity (which is done a lot in remote areas and as backup) is really expensive, even just looking at the point of generation and not the externalities. If renewable electricity generation is hovering around the 2c per kWh mark, even with all the losses, H2 starts to make a lot of sense for a lot of energy intensive industries. Even more so when the electricity used to generate it was never going to get even sell for that price because it just wasn't needed.
Renewables have an economic problem currently where every solar panel and wind turbine added to an electricity network will have a lower ROI than previous ones due to their intermittent nature, lowering the return of older assets as well. As their use grows, this problem will get worse and generators will have this large earning potential with an asset generating wasted energy, with a life span measured in several decades. Long tail, lots of opportunity to do more with those assets.
Toyota is not wrong at all. Hydrogen is going to be the future of personal transportation too. EVs are basically unsustainable ideas as they require so much raw materials. Not to mention that we have to have hydrogen to hit zero emissions, but we don't need EVs at all.
I think the efficiency of pure EVs is too good to ignore. I'm not disagreeing that we have to have hydrogen to hit zero emissions, but lots of factors related to personal vehicles where pure EV makes sense. I don't think they will be the only types, possible over time as green hydrogen economics improve we might see more of a mix for sale.
But given how long it will take to build out to 3x renewable generation capacity and then auto makers to change, etc etc I don't think that will be for another 10+ years, but hope I'm wrong.
But given how long it will take to build out to 3x renewable generation capacity and then auto makers to change, etc etc I don't think that will be for another 10+ years, but hope I'm wrong.
It's already starting to happen. It won't be something that happens decades in the future. The disruption of EVs by hydrogen technology is likely a current event.
I think its time we start realizing that much of the "efficiency" argument is an exaggeration or a lie. EVs aren't that efficient especially in cold weather, and fuel cell cars aren't really that far off. The other big issue is the inability to capture excess renewable energy. As we keep on building out more renewables, we're finding out that curtailed energy is growing exponentially. Pretty soon the vast majority of renewable energy will just go to waste. Hydrogen allows to use that energy, but batteries won't. Combined with the huge resource requirements of batteries it's clear that this technology is primed for a major stumble.
I think its time we start realizing that much of the "efficiency" argument is an exaggeration or a lie. EVs aren't that efficient especially in cold weather, and fuel cell cars aren't really that far off. The other big issue is the inability to capture excess renewable energy. As we keep on building out more renewables, we're finding out that curtailed energy is growing exponentially. Pretty soon the vast majority of renewable energy will just go to waste. Hydrogen allows to use that energy, but batteries won't. Combined with the huge resource requirements of batteries it's clear that this technology is primed for a major stumble.
Wrong. Hydrogen cars are the future. It's Tesla and the rest that are going to die off by betting on the wrong horse.
Toyota bet on the wrong horse, they just haven't publicly admitted yet and for now the marketing engine is still running on (hydrogen) vapors.
There is also Hyzon, a fuel cell manufacturer that hopes to massively convert trucks to Hydrogen.
There is also Hyzon, a fuel cell manufacturer that hopes to massively convert trucks to Hydrogen.
When I was working in a warehouse as a poor college student we drove electric forklifts inside for obvious reasons.
When the forklift went flat, you got another forklift to remove the battery and replace it with a fresh one.
Tesla tried this once and it wasn't a great success however, if you have a depo with a stack of batteries, you run a fleet of trucks, this makes a lot more sense.
It's something I'm suprised hasn't been floated as a lot of the customers for the electric trucks are fleet customers
When the forklift went flat, you got another forklift to remove the battery and replace it with a fresh one.
Tesla tried this once and it wasn't a great success however, if you have a depo with a stack of batteries, you run a fleet of trucks, this makes a lot more sense.
It's something I'm suprised hasn't been floated as a lot of the customers for the electric trucks are fleet customers
Hydrogen and LNG are used for forklifts the world over. That's exactly what got Toyota into this:
https://toyota-forklifts.eu/solutions/energy-solutions/what-...
https://toyota-forklifts.eu/solutions/energy-solutions/what-...
Battery cars are being disrupted by hydrogen cars. In a decade the shift will be almost entirely towards hydrogen and BEVs will be seen as obsolete.
My current gasoline car has a 500km range. If I can get 400km range on an electric car then I will just pick the car with the cheapest "fuel" costs and that's not going to be hydrogen.
It's going to be hydrogen.
Oh ok. Well thank you for making this prediction, that's got to be why out of all the companies that fielded Hydrogen cars all but two have now switched entirely to BEVs. We must have a different definition of disrupted.
If you know the history of disruption, you'd know that very few companies survive them. "All but two" could the list of dead companies from this, not the survivors.
I'm sure Elon is quaking in his boots. But hey, I've been wrong before so time will tell, I've bookmarked your comment.
He's a fool to not realize the threat. Tesla is almost certain to collapse unless they start making hydrogen cars themselves.
I'll be sure to let him know. Once again, thank you.
Just for added advice: Toyota also makes battery powered cars alongside their hydrogen cars. Tesla however does not make hydrogen powered cars at all. So without getting into details, it's clear that Toyota knows more about how each technology stack up against each other. So for Tesla to be right on this, it means that without having any knowledge of hydrogen cars they still know that it can't work, even over a company that knows something about both.
It can be described as Toyota having both eyes open whereas Tesla is blind in one eye, but still claiming that the latter sees better.
It can be described as Toyota having both eyes open whereas Tesla is blind in one eye, but still claiming that the latter sees better.
Thank you.
Considering how much raw materials you take out of the car, this is a good idea.
Fuel cell cars are electric cars. Since hydrogen is much more plentiful than lithium, it's nearly a certainty that the vast majority of cars will eventually switch over to hydrogen.
This is not too bad. I'd prefer hydrogen fuel cells over massive toxic batteries that we're going to have to dispose safely in a few years, from all those used Teslas! I don't know about other countries, but most of the electricity generated here in Australia is from Coal and Natural gas. That's an unfortunate fact. I don't see any reason to buy an electric car until that changes. In the meantime if the solar driven hydrogen production efficiency increases then we can have an even cleaner future.
What is toxic about lithium-ion batteries? After their life in a car they can still be used for stationary energy storage and can be nearly fully recycled afterwards.
I did not investigate it properly but at first glance the efficiency is obtained via low current density of the electrolyser. That means high efficiency but low volume. That translates to more hardware needed to produce a unit of power.
State of the art electrolyzers are run at 1000x current densities. That roughly means 1000x installation cost.
State of the art electrolyzers are run at 1000x current densities. That roughly means 1000x installation cost.
The best way to understand hydrogen is Liebreich Hydrogen Ladder:
https://www.rechargenews.com/energy-transition/liebreich-oil...
The best use cases for hydrogen are fertilser or in hydrocracking. We currently use primarily natural gas to produce hydrogen.
Urban or commuter cars are one of the worst use case for hydrogen. Electricity and batteries are way better.
The best use cases for hydrogen are fertilser or in hydrocracking. We currently use primarily natural gas to produce hydrogen.
Urban or commuter cars are one of the worst use case for hydrogen. Electricity and batteries are way better.
Congratulations on the advancement, but wow, that's still pretty bad. The only way this would become popular would be through being super cheap.
this will be used as an excuse to expand production of hydrogen made from carbon fuel on the basis that eventually the carbon will be made sustainably. Don’t fall for it.
A google search tells me there are far more efficient processes available, one almost at 25% efficiency. None of them commercially viable yet.
Solves the energy storage problem. Just add tanks.
$2 trillion of tanks and $1 trillion of pipelines, just for North America. Meanwhile, electrical grids already exist.
Why can't we produce hydrogen, store it, and generate power with it?
I imagine the cost of hydrogen storage is significantly less than batteries, thereby offsetting the reduced efficiency of turning solar power into electricity. The main issue we have with solar is storage for when the sun isn't out.
I imagine the cost of hydrogen storage is significantly less than batteries, thereby offsetting the reduced efficiency of turning solar power into electricity. The main issue we have with solar is storage for when the sun isn't out.
The round-trip efficiency is not very high, and fuel cells are still very expensive. Efficiency is becoming less important as top-line generation gets absurdly cheap, and fuel cell catalysts are improving fast.
We'll likely use underground hydrogen storage in the form of salt caverns and expended natural gas reservoirs.
Electrical grids don't store energy. If you wanted to store just 10% of the U.S. electrical generation from summer to winter using lithium-ion batteries, it would cost roughly $42 trillion dollars. Yes, trillion. Storing 10% of the U.S. daily needs for less time (say, one day) is a better story for batteries: only $115 billion.
That's how un-scalable long-term battery storage is. Hydrogen is more so: you can store hydrogen in vast quantities in salt caverns, and move it around. Pumped hydro is best, but sites are limited. Compressed air is another solid contender.
That's how un-scalable long-term battery storage is. Hydrogen is more so: you can store hydrogen in vast quantities in salt caverns, and move it around. Pumped hydro is best, but sites are limited. Compressed air is another solid contender.
You don't need to store that much energy. It's much more cost-efficient to over-provision energy sources. In a few decades we will see solar over-provisioned to 2-3x normal consumption and some battery and that will provide 100% uptime.
The most cost-effective way is a combination of over-provisioning, batteries and hydrogen storage. The exact mix is determined by consumption patterns and local wind/solar conditions. Generally though it's extremely expensive to rely on over-provisioning+batteries alone in places with unreliable weather patterns.
Falling battery prices helps of course but we are very far from a point where we can eliminate the need for hydrogen.
Falling battery prices helps of course but we are very far from a point where we can eliminate the need for hydrogen.
You're overprovisioning at the wrong time with solar, though. What good is 2-3x the power output during the day when you're at 0 during the night? You'd still need 12h of storage or more realistically a mixed energy production setup.
There will be absolutely massive demand for H2, for myriad industrial processes, not limited to ammonia and hydrocarbon synthesis. So, whatever excess power you can generate will find a ready market with anybody equipped to bank H2. And, banking industrial quantities of H2 is cheap, whether you liquify and store in underground tanks, or pump into caverns under moderate pressure.
Maybe in Arizona. In places where clouds is a thing you are looking at weeks of storage. And some of that stored energy would need to be collected months ahead of time. This is simply not doable with batteries, hydrogen storage is absolutely essential.
I think we're in agreement, maybe my phrasing was unclear :-)
My opinion is that we need a mix of energy sources and we need a mix of energy storage solutions.
My opinion is that we need a mix of energy sources and we need a mix of energy storage solutions.
You don't need that much storage. You'd really need at most 12h of peak power, but probably closer to 4h.
A 10k km HVDC line is enough to draw power from places 90 degrees apart in terms of latitude. Similarly, between the east and west coast of the US there's around 3h of a time difference.
Chile is planning on building an even longer cable, so it's entirely in the realm of possibility:
https://www.pv-magazine.com/2021/11/15/chile-wants-to-export...
A 10k km HVDC line is enough to draw power from places 90 degrees apart in terms of latitude. Similarly, between the east and west coast of the US there's around 3h of a time difference.
Chile is planning on building an even longer cable, so it's entirely in the realm of possibility:
https://www.pv-magazine.com/2021/11/15/chile-wants-to-export...
> Electrical grids don't store energy. If you wanted to store just 10% of the U.S. electrical generation from summer to winter using lithium-ion batteries, it would cost roughly $42 trillion dollars. Yes, trillion.
Do you mean 10% of the generation on a typical summer day? Or 10% of the generation of an entire summer?
The problem with this kind of calculation is that battery technology (and cost) is very much a moving target.
LFP would probably be the better choice today. It's cheaper, safer, and can handle far more load cycles. That comes at a cost of a lower energy density, but that hardly matters for utility scale batteries. Tesla's megapacks use LFP already - https://cleantechnica.com/2021/05/11/tesla-transitions-to-lf....
Like you say, there are many other energy storage options like pumped hydro, compressed air, etc. My personal favorite is the train full of concrete that goes up and down a hill (https://interestingengineering.com/concrete-gravity-trains-m...).
Do you mean 10% of the generation on a typical summer day? Or 10% of the generation of an entire summer?
The problem with this kind of calculation is that battery technology (and cost) is very much a moving target.
LFP would probably be the better choice today. It's cheaper, safer, and can handle far more load cycles. That comes at a cost of a lower energy density, but that hardly matters for utility scale batteries. Tesla's megapacks use LFP already - https://cleantechnica.com/2021/05/11/tesla-transitions-to-lf....
Like you say, there are many other energy storage options like pumped hydro, compressed air, etc. My personal favorite is the train full of concrete that goes up and down a hill (https://interestingengineering.com/concrete-gravity-trains-m...).
10% of a whole summer.
Another contender I noticed the other day: build transport cables eight time zones long...
How's the gravity storage going, it looked really promising and simple.
If you count pumped hydro, gravity storage is the #1 storage of the USA.
Turns out that pumping water up-hill and running generators when the water flows backwards is a very efficient energy storage mechanism.
Turns out that pumping water up-hill and running generators when the water flows backwards is a very efficient energy storage mechanism.
Aside from pumped hydro I'm only aware of tiny, one-off pilot projects.
Storage like all the cars we're planning to build anyway? Sorry, but there's something arbitrary about "summer to winter" that you're quoting to fit your narrative here. First of all, Li-ion battery wasn't made to storage energy that long. Second, there are flow batteries for that which will be far better than Hydrogen.
Great! That's cheap for what you get. As soon as we've built out a few $trillion in battery storage, we can get going on long-term hydrogen storage and distribution!
$1 trillion of pipelines? Why?
This is about splitting water using electricity. You can create and use the fuel at the same site. Just need a water pipe and a connection to the grid. Splitting off hydrogen at a separate site is just wastefull.
This is about splitting water using electricity. You can create and use the fuel at the same site. Just need a water pipe and a connection to the grid. Splitting off hydrogen at a separate site is just wastefull.
You ever seen a gas station with enough land to have a huge solar farm attached to it? That's not the norm...
A think you may have missed the part where I wrote "connection to the grid."
My point is create an energy storage station, all you need is water and grid power. No pipelines needed. This hypothetical power storage site would generate hydrogen during the daytime from surplus grid solar, then burn the hydrogen at night delivering the power back to the grid.
To be clear, I'm not necessarily talking about a solution for homeowners. An energy storage facility could cheerfully be as large Diablo Canyon Power Station. It just depends on the efficiencies of everything from the water-splitting process, storage solution, grid losses, and grid capacity.
My point is create an energy storage station, all you need is water and grid power. No pipelines needed. This hypothetical power storage site would generate hydrogen during the daytime from surplus grid solar, then burn the hydrogen at night delivering the power back to the grid.
To be clear, I'm not necessarily talking about a solution for homeowners. An energy storage facility could cheerfully be as large Diablo Canyon Power Station. It just depends on the efficiencies of everything from the water-splitting process, storage solution, grid losses, and grid capacity.
Same reason that we put solar and wind power where land is cheap and transport the electricity to where we need it.
Before people get too excited they might want consider the life time of the cell as indicated over a 10 hour test window.
> high peak solar-to-fuel conversion
does it mean there's a "mean solar-to-fuel conversion" to look for ?
does it mean there's a "mean solar-to-fuel conversion" to look for ?
Cool on the way to sustainable liquid fuels.
so how would a person go about making one of these for use at home?
There are videos on youtube with various home-made h2 generators/splitters.
The issue with doing something useful with it is compression and storage.
While compression is easy, purification is an issue. With certain lower percentages of purity (from very rough memory under 92%, but could be in the 99s) it becomes an explosion risk.
The issue with doing something useful with it is compression and storage.
While compression is easy, purification is an issue. With certain lower percentages of purity (from very rough memory under 92%, but could be in the 99s) it becomes an explosion risk.
Can someone please ELI5?
The abstract looks simple enough? They played with some chemicals / catalysts, and have demonstrated a prototype where they made a "Solar Panel" that turns water (H2O) into 2H2 + O2... aka Hydrogen + Oxygen. The measured efficiency was 13.8%, less efficient than an electric solar panel (20% to 25% efficiency), but possibly the most efficient solar -> hydrogen design discussed so far.
Consider a 25% efficient solar panel -> 50% electrical efficiency to convert H2O into H2 + O2 == 12.5% total efficiency (and a 25% efficient solar panel is a high-end panel). So this design discussed is probably better than the status quo.
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There are internet flame wars over the future of energy and energy storage.
Lithium Ion batteries are one form. Hydrogen is being proposed as a fuel of the future (with Japan showing off Hydrogen torches all over the Olympics earlier this year, as a lot of Japanese companies are pushing Hydrogen as a future fuel)
Consider a 25% efficient solar panel -> 50% electrical efficiency to convert H2O into H2 + O2 == 12.5% total efficiency (and a 25% efficient solar panel is a high-end panel). So this design discussed is probably better than the status quo.
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There are internet flame wars over the future of energy and energy storage.
Lithium Ion batteries are one form. Hydrogen is being proposed as a fuel of the future (with Japan showing off Hydrogen torches all over the Olympics earlier this year, as a lot of Japanese companies are pushing Hydrogen as a future fuel)
Some people didn't like that you could combine bog-standard 20% efficient photovoltaic panels with bog-standard 75% efficient electrolyzers to reach 15% efficiency of conversion of sunlight to hydrogen, and came up with a specialized single-step device...that is only 14% efficient. ;)
Tesla is switching from lithium-ion to lithium iron phosphate for fixed battery installations.[1] The energy per unit weight is somewhat lower, but that doesn't matter much for fixed installations. The safety is better, too - lithium iron phosphate batteries don't have the thermal runaway problem. BYD, which is the biggest producer of batteries in the world, sells shipping container sized lithium iron phosphate sized battery packs for large scale solar backup.
[1] https://www.utilitydive.com/news/tesla-shifts-battery-chemis...