Human-powered air-compressor and energy storage system(solar.lowtechmagazine.com)
solar.lowtechmagazine.com
Human-powered air-compressor and energy storage system
https://solar.lowtechmagazine.com/2023/07/human-powered-air-compressor-and-energy-storage-system/
56 comments
I love lowtechmag, but it's almost a rule they are economical with details too, and often to hide a (pretty obvious) compromise that not everyone would be willing to make.
On top of that humans are very bad at converting fuel into work.
"In a rapidly changing world where inexpensive and reliable energy going forward is no longer a given"
In such a world a steam engine will give you more useful output for the same input - you could literally burn your food in the steam engine and get more useful work vs eating the food.
This kind of thing only makes sense in a world that has not invented steam engines, or at the minimum using an animal that can eat grass that you can't. (And even then burning the grass will give you more work.)
"In a rapidly changing world where inexpensive and reliable energy going forward is no longer a given"
In such a world a steam engine will give you more useful output for the same input - you could literally burn your food in the steam engine and get more useful work vs eating the food.
This kind of thing only makes sense in a world that has not invented steam engines, or at the minimum using an animal that can eat grass that you can't. (And even then burning the grass will give you more work.)
According to [1], human ‘fuel’ efficiency on a bike is about 20%. That is way ahead of any simple piston powered steam engine (should be below 10%, citation needed) that you would install in a workshop.
[1] https://physics.stackexchange.com/questions/46788/how-effici...
[1] https://physics.stackexchange.com/questions/46788/how-effici...
Steam engines are closer to 40% efficient, not 10%.
And they can burn the entire fuel, unlike a person who can only eat the choice parts and must waste large portions. (For example corn - the person can only eat the kernels, the steam engine can productively use the husk and the cob.)
Also, your 20% figure is for energy absorbed after digestion (they check via oxygen consumption), but digestion itself is wasteful - lots of usable fuel is not absorbed when someone eats, and is emitted as waste.
It's really not even close.
It's a problem also for comparing bicycles vs cars - even though they are heavier, cars are surprisingly efficient compared to the entire production process of delivering food to humans (lots of energy is used in the farm).
If I remember my figures correctly 2 people in a car is more efficient than 1 omnivore on a bicycle. And a single person in a car is more efficient (less CO2 emitted) than a carnivore on a bicycle.
(The car comparison depends a lot on what the person eats.)
And they can burn the entire fuel, unlike a person who can only eat the choice parts and must waste large portions. (For example corn - the person can only eat the kernels, the steam engine can productively use the husk and the cob.)
Also, your 20% figure is for energy absorbed after digestion (they check via oxygen consumption), but digestion itself is wasteful - lots of usable fuel is not absorbed when someone eats, and is emitted as waste.
It's really not even close.
It's a problem also for comparing bicycles vs cars - even though they are heavier, cars are surprisingly efficient compared to the entire production process of delivering food to humans (lots of energy is used in the farm).
If I remember my figures correctly 2 people in a car is more efficient than 1 omnivore on a bicycle. And a single person in a car is more efficient (less CO2 emitted) than a carnivore on a bicycle.
(The car comparison depends a lot on what the person eats.)
Steam turbines can easily reach 40% efficiency. Simple (single expansion) steam piston engines are much less efficient, usually well below 10%.
Sources or calculations please and please elaborate on the system boundaries. Thx in advance.
The extremely obvious compromise is that you need to have a high-PSI air tank on hand as well as a donor bike. The donor bike can probably be gotten for very cheap or free, but the tank...
I looked at the prices of 80-gal 200 PSI rated tanks online, and the conclusion is...not great.
It's going to run you roughly $1000, for which you can realistically buy a whole set of cordless battery powered tools AND an outlet-powered air compressor on top of that.
I looked at the prices of 80-gal 200 PSI rated tanks online, and the conclusion is...not great.
It's going to run you roughly $1000, for which you can realistically buy a whole set of cordless battery powered tools AND an outlet-powered air compressor on top of that.
> I looked at the prices of 80-gal 200 PSI rated tanks online, and the conclusion is...not great.
Or you can get a bunch of empty propane tanks for a few bucks and call it a day…
Or you can get a bunch of empty propane tanks for a few bucks and call it a day…
The point is that this solution works without access to electricity and is resilient to the loss of industrial supply chains
How are you going to make an air tank that can handle 200 PSI without industrial supply chains?
There are a bunch that are already made. I think this setup is really impractical, but once you have it, you aren't reliant on the supply chain to feed the power plant, but you are reliant on it for finding a source of food to power the human pedaling.
For the tank:
> There are many used air compressors for sale that have faulty motors or pumps, and are therefore quite inexpensive
And the pneumatic parts/equipment:
> An additional benefit of using compressed air for energy is the low cost of air tools. The current trend is pushing toward more battery powered equipment, so people are selling off their “outdated” pneumatic tools.
> There are many used air compressors for sale that have faulty motors or pumps, and are therefore quite inexpensive
And the pneumatic parts/equipment:
> An additional benefit of using compressed air for energy is the low cost of air tools. The current trend is pushing toward more battery powered equipment, so people are selling off their “outdated” pneumatic tools.
A healthy cyclist might average 200-250w over an hour, or an FTP of 200-250. One horsepower is ~735w, so ~5kw for the 7hp compressor. The cyclist putting in a really high degree of effort needs to pedal for 20x-25x as long as the compressor to do the same amount of work.
A 7hp compressor delivers in the range of 1m3/min@6bar or roughly 35cfm@90psi. The output can vary a lot depending on how the compressor is optimized though. Air tool air use varies as well, a sand blaster or paint sprayer will have different needs. But an air tool like a disc sander or die grinder or air hammer or impact wrench will be in the 5cfm range or a little under .2m3/min. So for an hour of tool use the compressor needs to run for 8.5 minutes or 2 hours and 50 minutes of cycling.
A 7hp compressor delivers in the range of 1m3/min@6bar or roughly 35cfm@90psi. The output can vary a lot depending on how the compressor is optimized though. Air tool air use varies as well, a sand blaster or paint sprayer will have different needs. But an air tool like a disc sander or die grinder or air hammer or impact wrench will be in the 5cfm range or a little under .2m3/min. So for an hour of tool use the compressor needs to run for 8.5 minutes or 2 hours and 50 minutes of cycling.
The hint is in him having a 7hp (quite powerful) compressor that apparently runs enough to be running up his electric bill.
I'm perplexed by the comment about "empty tanks." In these systems the tank is almost never empty because pneumatic tools are pretty useless below a certain pressure; you can't just use them until they're empty. The impact guns I've used became tonka toys around 40 psi or so, if that.
The compressor might get shut off for the night, and sure, there are some air leaks - but the next morning when the shop opens, it's not empty.
Maybe the reason this dude's compressor is eating him out of house and home is because he's got a bunch of leaks he isn't addressing...
I'm perplexed by the comment about "empty tanks." In these systems the tank is almost never empty because pneumatic tools are pretty useless below a certain pressure; you can't just use them until they're empty. The impact guns I've used became tonka toys around 40 psi or so, if that.
The compressor might get shut off for the night, and sure, there are some air leaks - but the next morning when the shop opens, it's not empty.
Maybe the reason this dude's compressor is eating him out of house and home is because he's got a bunch of leaks he isn't addressing...
Huh? Nowhere does the author suggest that the electric powered system was "eating him out of house and home". The motivation here was clearly resiliency and creativity. He also mentions the importance of addressing leaks too.
"Empty tanks" is probably just shorthand for "pressure too low to run the tools".
"Empty tanks" is probably just shorthand for "pressure too low to run the tools".
If it takes 7hp(5200w) for 5m, let's say a person can do 100w, so they will take 52x as long, so 260m total. Broken up between 7 sessions a day for a week means each session is only 5 minutes.
Also, I'm curious whether it takes more energy to fill the tanks from 60 to 80 psi vs 80 to 100 psi. Filling the tank until its full is not really a useful metric, would be more interesting to learn how much pedaling continuous operation requires.
I think it’s harder to go 80–100 than it is from 60–80.
I’m both cases, you need to stuff the same volume of additional air into the tank, but in the 80–100 case, the resistance to the stuffing is higher.
At least I think that’s how it works. Assuming spherical cows and an ideal gas.
I’m both cases, you need to stuff the same volume of additional air into the tank, but in the 80–100 case, the resistance to the stuffing is higher.
At least I think that’s how it works. Assuming spherical cows and an ideal gas.
It must be harder. If it wasn’t, you’d be able to get to arbitrary pressures with a constant force. So, in the extreme, if you can get the air to 15 psi with your lungs, you’d be able to get the air to 1000 psi with your lungs, too.
Another way to see that is to consider two tanks at different pressures that are connected to each other, and ask yourself why air will flow from the higher pressure one to the lower pressure one.
Another way to see that is to consider two tanks at different pressures that are connected to each other, and ask yourself why air will flow from the higher pressure one to the lower pressure one.
In theory if the resistance to the stuffing is higher, then it also pushes the air out harder - i.e. it's a wash.
Except that it's not, because when you compress air you heat it, and all the heat energy is gone. This is why compressed air is a terrible energy storage method.
The hotter you heat the air (higher PSI) the more energy you waste.
Except that it's not, because when you compress air you heat it, and all the heat energy is gone. This is why compressed air is a terrible energy storage method.
The hotter you heat the air (higher PSI) the more energy you waste.
Wouldn’t the air not be pushing against my piston? It’s already in the tank and the piston is being pushed by atmospheric pressure for the next gulp.
Good note on the heat. I’ll wrap my whole setup in a blanket to recover that ;)
Good note on the heat. I’ll wrap my whole setup in a blanket to recover that ;)
It does heat and you do lose some energy there, but not enough to lose all of the compression applied
It was good to find this forum- I have been looking for constructive feedback on my human-powered air compressor.
I have been working on the project for 3 months, and I am still making many improvements as I use the machine. The configuration featured in the LowTech Magazine has been updated considerably, and I am now getting close to the performance limits of the basic design.
If anyone has any questions or suggestions, please feel free to comment.
Some quick replies to previous comments: -The amount of pedaling needed to keep the tank topped off depends on the amount at which air is emptied from the tank. -A steam engine powered design would be cool to see, but not currently in my skill set. Steam power might also prove challenging in an indoor environment. -The total cost to build this machine was roughly $1000USD in parts, but I could have lowered the costs considerably by sourcing more used components. I also bought some parts to try that were updated to an improved design. I did just score another 80gal tank for $20USD, so the deals are out there if you take the time to look for them. -The pedaling effort is easiest when the tank is empty, and gets progressively harder as you build pressure. -The air system has no noticeable leaks, and I monitored tank pressure closely for a few weeks with no measurable pressure loss. -Energy will not get cheaper.
Some quick replies to previous comments: -The amount of pedaling needed to keep the tank topped off depends on the amount at which air is emptied from the tank. -A steam engine powered design would be cool to see, but not currently in my skill set. Steam power might also prove challenging in an indoor environment. -The total cost to build this machine was roughly $1000USD in parts, but I could have lowered the costs considerably by sourcing more used components. I also bought some parts to try that were updated to an improved design. I did just score another 80gal tank for $20USD, so the deals are out there if you take the time to look for them. -The pedaling effort is easiest when the tank is empty, and gets progressively harder as you build pressure. -The air system has no noticeable leaks, and I monitored tank pressure closely for a few weeks with no measurable pressure loss. -Energy will not get cheaper.
Informative read! This article sheds light on the potential of solar energy for rural communities. Empowering them with clean, sustainable solutions is a significant step towards a greener future.
Article is wrong about energy. Gonna keep getting cheaper. For instance, that's the long term trend:
https://www.usinflationcalculator.com/inflation/electricity-...
Reliability is a little less of a given, but it's not unreasonable to expect grid operators to seek to continue making profits.
https://www.usinflationcalculator.com/inflation/electricity-...
Reliability is a little less of a given, but it's not unreasonable to expect grid operators to seek to continue making profits.
You're probably correct, but these are times of great uncertainty and I wouldn't currently be willing to lay any bets one way or the other.
There's nothing wrong with exercising design skills to address living without reliable (or any) electricity. If nothing else, it's a hobby and keeps your mental juices flowing. If such bad times never happen, you still get the benefits that come with such projects. If they do happen, such skills can become invaluable. And there are many parts of the world where the reality is that something like this could be practically useful right now.
There's nothing wrong with exercising design skills to address living without reliable (or any) electricity. If nothing else, it's a hobby and keeps your mental juices flowing. If such bad times never happen, you still get the benefits that come with such projects. If they do happen, such skills can become invaluable. And there are many parts of the world where the reality is that something like this could be practically useful right now.
Designing for lack of access to global supply chains that currently exist makes this more of a design exercise rather than a practical solution. That is to say, with money, just buy a couple hundred watts of consumer-grade available solar (eg by Jackery; not a collection of no-name eBay special parts that you need to be an electrical engineer to setup), a solar inverter, a large battery pack for storage, and then a charger for battery packs for tools, instead of an air compressor-based system and this bicycle thing. This is practically useful right now, and can be ordered via HomeDepot.com. Yes, this is harder to arrange without access to HomeDepot, which most of the world doesn't have, and it's not the cheapest of systems, but a) that's a lot of bicycling; b) solar power is finally here and accessible and c) as long as we do have access to global supply chains, might as well use it.
If you're really worried, buying a bunch of backup/spare parts in case we do lose global supply chains seems like a far more viable solution. If you're really that worried about losing access, there are steps you can take, like buying copper plates and photo-resist to make your own, really shitty solar cells, from "scratch", or buying 18650 lithium ion batteries and a 3d printer (along with a plastic recycler) to print your own tool batteries from renewable plastic. If bad times never happen, then what of what practical use is it to know which wild plants in my area are edible and which ones are poisonous, or which storage unit has 10 years worth of MREs inside?
People are free to invest time and money in whatever hobby they want, and in case of global (or local) calamity, my prepper friend is my going to be my first stop. I just personally don't believe it's an especially useful hobby, any more than, say, my hobby of Lego building, which has super useful practical applications in my daily life as a Duplo builder for my nephews.
If you're really worried, buying a bunch of backup/spare parts in case we do lose global supply chains seems like a far more viable solution. If you're really that worried about losing access, there are steps you can take, like buying copper plates and photo-resist to make your own, really shitty solar cells, from "scratch", or buying 18650 lithium ion batteries and a 3d printer (along with a plastic recycler) to print your own tool batteries from renewable plastic. If bad times never happen, then what of what practical use is it to know which wild plants in my area are edible and which ones are poisonous, or which storage unit has 10 years worth of MREs inside?
People are free to invest time and money in whatever hobby they want, and in case of global (or local) calamity, my prepper friend is my going to be my first stop. I just personally don't believe it's an especially useful hobby, any more than, say, my hobby of Lego building, which has super useful practical applications in my daily life as a Duplo builder for my nephews.
(Just as a preface, I'm not actually a prepper at all and don't think that civilization is about to end. But I do enjoy at least being familiar with ways to accomplish things in the absence of infrastructure.)
> just buy a couple hundred watts of consumer-grade available solar [...]
For my own disaster preparedness, this is exactly what I've done. And I use it when I go car camping. But, as you point out, it's not exactly cheap so is less suitable for parts of the world that are more likely to suffer from infrastructure breakdown (or are lacking the infrastructure entirely).
But there's also an undeniable appeal to knowing how to accomplish things like high pressure air when you don't have electricity at all.
> If bad times never happen, then what of what practical use is it to know which wild plants in my area are edible and which ones are poisonous
I think that there's great value in knowing things like this even if it's not of practical use to you. Like knowing how to sew & repair clothing even if you never need to make your own clothes. It's amazing how often knowledge in one domain can give you insight into solving problems in other, completely unrelated domains. The more in your mental hopper, the better.
> I just personally don't believe it's an especially useful hobby
Sure, depending on what you mean by "useful". I think that all hobbies are useful in some form, even if that use is just exercising your brain.
> just buy a couple hundred watts of consumer-grade available solar [...]
For my own disaster preparedness, this is exactly what I've done. And I use it when I go car camping. But, as you point out, it's not exactly cheap so is less suitable for parts of the world that are more likely to suffer from infrastructure breakdown (or are lacking the infrastructure entirely).
But there's also an undeniable appeal to knowing how to accomplish things like high pressure air when you don't have electricity at all.
> If bad times never happen, then what of what practical use is it to know which wild plants in my area are edible and which ones are poisonous
I think that there's great value in knowing things like this even if it's not of practical use to you. Like knowing how to sew & repair clothing even if you never need to make your own clothes. It's amazing how often knowledge in one domain can give you insight into solving problems in other, completely unrelated domains. The more in your mental hopper, the better.
> I just personally don't believe it's an especially useful hobby
Sure, depending on what you mean by "useful". I think that all hobbies are useful in some form, even if that use is just exercising your brain.
He's probably a typical person that looks at the dire conditions in his mismanaged small locality, and thinks the entire world is like that.
Nice setup although I remember that the efficiency of air tools is very low like around 1%. That’s also why they get replaced a lot.
A massive amount of power is lost in air tools. They're also painfully loud, the hose is annoying in a variety of ways, and the air system in the shop is expensive to install and involves periodic maintenance.
Most mechanics use battery tools these days. Impact drivers for all but the biggest stuff, with handheld drivers having enough torque to work on a lot of suspension components easily, and there are even electric ratchet drivers now with sufficient torque for a lot of smaller stuff under the hood that require little more space than a hand ratchet, and no room for swing needed.
Battery tools are faster, quieter, easier to control. The system scales linearly in capacity, charging speed, etc. Add two mechanics to your shop where you're only using air? You're looking at thousands of dollars to upgrade a compressor, maybe a tank too.
If you're concerned about still being a mechanic when you lose power, put a solar panel on the roof, attach it to a MPPT solar charger and a couple of car batteries you recycle from customers' cars, and have an inverter ready to switch on if you need it.
What mechanic has the energy to pedal this thing just to work? What mechanic does so little work with their tools that the system can be infrequently refilled by a guy taking an hour or more to fill the tank?
This is at best useful for a shadetree mechanic and the article is fetishizing low-tech BS with no practicality. Replacing a 7hp compressor that was chewing up his electric bill...with something he pedals? If it was chewing up his electric bill, then there's no way he could replace it by pedaling.
Most mechanics use battery tools these days. Impact drivers for all but the biggest stuff, with handheld drivers having enough torque to work on a lot of suspension components easily, and there are even electric ratchet drivers now with sufficient torque for a lot of smaller stuff under the hood that require little more space than a hand ratchet, and no room for swing needed.
Battery tools are faster, quieter, easier to control. The system scales linearly in capacity, charging speed, etc. Add two mechanics to your shop where you're only using air? You're looking at thousands of dollars to upgrade a compressor, maybe a tank too.
If you're concerned about still being a mechanic when you lose power, put a solar panel on the roof, attach it to a MPPT solar charger and a couple of car batteries you recycle from customers' cars, and have an inverter ready to switch on if you need it.
What mechanic has the energy to pedal this thing just to work? What mechanic does so little work with their tools that the system can be infrequently refilled by a guy taking an hour or more to fill the tank?
This is at best useful for a shadetree mechanic and the article is fetishizing low-tech BS with no practicality. Replacing a 7hp compressor that was chewing up his electric bill...with something he pedals? If it was chewing up his electric bill, then there's no way he could replace it by pedaling.
I mostly agree, but the first part is not universally true.
My 30cfm compressor is 45db. Basically noiseless. You can easily have a normal conversation with it running. The air itself makes more noise than the compressor. It is happy with any duty cycle from 0-100%. Maintenance interval is about every 5 years. It produces oil free air. I can use it for breathing air (spray finishing) and not worry about things as much (I have proper gas sensors on that part anyway but it's nice to know i won't get poisoned by oil in some fashion)
I pay for this in efficiency. A oil sealed rotary screw would be about 30% more efficient (maybe a little more) but have some carry over and be about 65db. Not hugely noisy but still.
My pneumatic sanders have much lower vibration (30-40%), are quieter, smaller, weigh a lot less, and are essentially maintenance free. They can be repaired easily if I ever need to because they are very simple devices. The mechanism lends itself well to really good dust collection.
As a result They are much nicer to use than even the nicest electric festool and mirka sanders (I have both). The electrics are massively improved over two decades ago but still.
I don't woodwork or metalwork without mask or ear protection at all times so even if they were noisier I'd be fine.
The air drops are set up to be convenient from anywhere in the shop.
All that said, I do agree with the rest and the main point- for most people, battery is a better bet. I use what I do for convenience and comfort, not for cost or effectiveness.
There are times using air is just a better way of doing that than batteries.
My 30cfm compressor is 45db. Basically noiseless. You can easily have a normal conversation with it running. The air itself makes more noise than the compressor. It is happy with any duty cycle from 0-100%. Maintenance interval is about every 5 years. It produces oil free air. I can use it for breathing air (spray finishing) and not worry about things as much (I have proper gas sensors on that part anyway but it's nice to know i won't get poisoned by oil in some fashion)
I pay for this in efficiency. A oil sealed rotary screw would be about 30% more efficient (maybe a little more) but have some carry over and be about 65db. Not hugely noisy but still.
My pneumatic sanders have much lower vibration (30-40%), are quieter, smaller, weigh a lot less, and are essentially maintenance free. They can be repaired easily if I ever need to because they are very simple devices. The mechanism lends itself well to really good dust collection.
As a result They are much nicer to use than even the nicest electric festool and mirka sanders (I have both). The electrics are massively improved over two decades ago but still.
I don't woodwork or metalwork without mask or ear protection at all times so even if they were noisier I'd be fine.
The air drops are set up to be convenient from anywhere in the shop.
All that said, I do agree with the rest and the main point- for most people, battery is a better bet. I use what I do for convenience and comfort, not for cost or effectiveness.
There are times using air is just a better way of doing that than batteries.
I was referring to the tools themselves being loud. It's not common for mechanics to be wearing ear protection, and air ratchets and impact guns are VERY loud.
Air tools are not maintenance free. They all require oiling devices inline, or regularly being oiled, and that oil gets into the shop and coats everything; you're also breathing that shit into your lungs. That's why in a lot of mechanic's shops, everything is greasy. Pneumatic tool oil.
You can buy a lot of batteries, tools, and chargers for the cost of installing a hard line air system. That still doesn't address the annoyance of the air hose, which is even worse than electrical cords - less flexible and heavier.
Air tools are not maintenance free. They all require oiling devices inline, or regularly being oiled, and that oil gets into the shop and coats everything; you're also breathing that shit into your lungs. That's why in a lot of mechanic's shops, everything is greasy. Pneumatic tool oil.
You can buy a lot of batteries, tools, and chargers for the cost of installing a hard line air system. That still doesn't address the annoyance of the air hose, which is even worse than electrical cords - less flexible and heavier.
I'm aware of the noise of ratchets.
Hardline air system is ... not a significant cost? You make it sound like it's 10k.
Most shops are using a couple hundred feet of 1" copper, which has gone up in price but it's not that expensive. It would have been wildly cheap a decade ago (6 bucks a stick vs 20)
200ft of 1" copper is, at shitty prices, 200-250 bucks. Fittings for drops another 100 or whatever.
Time to solder it is annoying for sure, but you could press it if you want.
You could also go aluminum pipe systems, etc.
I've spent way more on battery based festool sanders (500-600 a piece) and drill/drivers than i did on hardline for the shop. The pneumatic tools were much less expensive as well. So i definitely disagree there.
Oil gets everywhere in anything working on metal, no matter what. I don't think that is avoidable - it definitely isn't fixed in any way by battery tools. I don't know a mechanic shop of any sort, battery or air based, that isn't a greasy oily mess. Battery tools require maintenance too. Heck, lots of mine want to be oiled regularly which is annoying without in-line oilers.
Your hate of air cords is more than mine - they seem equally as annoying as electrical cords. I can easily make well organized ceiling drops of electrical or air that keeps them out of the way.
If your shop is just running cords all over the place (as plenty of small operations do), it's, at least for me, equally, annoying whether they are electrical or air.
I guess we will just disagree.
Hardline air system is ... not a significant cost? You make it sound like it's 10k.
Most shops are using a couple hundred feet of 1" copper, which has gone up in price but it's not that expensive. It would have been wildly cheap a decade ago (6 bucks a stick vs 20)
200ft of 1" copper is, at shitty prices, 200-250 bucks. Fittings for drops another 100 or whatever.
Time to solder it is annoying for sure, but you could press it if you want.
You could also go aluminum pipe systems, etc.
I've spent way more on battery based festool sanders (500-600 a piece) and drill/drivers than i did on hardline for the shop. The pneumatic tools were much less expensive as well. So i definitely disagree there.
Oil gets everywhere in anything working on metal, no matter what. I don't think that is avoidable - it definitely isn't fixed in any way by battery tools. I don't know a mechanic shop of any sort, battery or air based, that isn't a greasy oily mess. Battery tools require maintenance too. Heck, lots of mine want to be oiled regularly which is annoying without in-line oilers.
Your hate of air cords is more than mine - they seem equally as annoying as electrical cords. I can easily make well organized ceiling drops of electrical or air that keeps them out of the way.
If your shop is just running cords all over the place (as plenty of small operations do), it's, at least for me, equally, annoying whether they are electrical or air.
I guess we will just disagree.
What compressor? I had no idea there were any that were under 100dB.
i mean, even rotary screws are only like 60-70db.
I'm using scroll compressors, which are very quiet. Smaller versions are used in your HVAC system (assuming you have one).
Even basic ones are 49-50db. https://www.powerexinc.com/industrial/air/enclosed-scroll-sy... You can do better.
Most people's experience is with piston based reciprocating compressors, which are quite loud. 80+db.
Or little pancake compressors, which are the same.
Most shops move towards rotary screw because they need higher cfm than even 2 stage reciprocating can provide.
I'm using scroll compressors, which are very quiet. Smaller versions are used in your HVAC system (assuming you have one).
Even basic ones are 49-50db. https://www.powerexinc.com/industrial/air/enclosed-scroll-sy... You can do better.
Most people's experience is with piston based reciprocating compressors, which are quite loud. 80+db.
Or little pancake compressors, which are the same.
Most shops move towards rotary screw because they need higher cfm than even 2 stage reciprocating can provide.
I too had a hard time reading the article, with my own criticisms of what I'd do differently or details I wish they'd focus on. Replacing the need for electrical energy with the need for the chemical energy of food doesn't seem particularly great. An air compressor is still a technological device that relies on long supply chains, and keeping a few spare parts around doesn't count.
But I try not to be too knee-jerk critical! Because I am glad someone is doing the work of trying experiments to look at outside the local maximum of our current technology.
I'd think that an infrequently-used air compressor would be a fantastic place to use electricity from peak solar generation. That kind of thing seems closer to a sustainability local maximum than using human power.
But I try not to be too knee-jerk critical! Because I am glad someone is doing the work of trying experiments to look at outside the local maximum of our current technology.
I'd think that an infrequently-used air compressor would be a fantastic place to use electricity from peak solar generation. That kind of thing seems closer to a sustainability local maximum than using human power.
>Replacing the need for electrical energy with the need for the chemical energy of food doesn't seem particularly great.
Seeing as you need exercise anyway to stay healthy, it might as well be doing something useful.
Seeing as you need exercise anyway to stay healthy, it might as well be doing something useful.
I use both power sources, and have used a 3" electric impact on track jobs and it would get hot. Air tools don't get hot, which is great when it is repetitive wrenching.
What a refreshingly clean, quick to load website. I would have done without the email popup. But I can forgive that. If I trust the footer, the server is solar powered in Barcelona.
It does load fast, but I'm pretty sure the ditherpunk aesthetic is bogus. Byte for byte, JPEGs should beat dithered PNGs / GIFs, and they never proved that the end-to-end costs of JPEG encoding and decoding are worse than dithering. It just looks distinct.
I'm not sure how that makes it "bogus". The site also uses CSS styles that technically use more bandwidth than vanilla HTML. The point was never to find the most optimal solution.
> I would have done without the email popup.
With uBlockOrigin blocking all Javascript by default, there is no "email popup".
With uBlockOrigin blocking all Javascript by default, there is no "email popup".
I just wish the article contained the duration of a bike session and the run time of 90 gallons at 100psi.
Myabe its there and I missed it.
Myabe its there and I missed it.
Used in foiling boats in America's cup and similar races.
I believe those use a hydraulic accumulator system rather than compressed air.
Guess what's on the other side of the membrane or piston in a hydraulic accumulator?
I would guess that it would be a metal spring of some sort that doesn't lose energy to thermal side effects of compressing and decompressing gas, for a higher round trip power efficiency. Or else it could be a relatively large gas reservoir so that it doesn't heat or cool the gas too much.
I'm far from foiling boats
would you mind explaining why are these compressors human powered and not gas/battery powered? Is it something from racing code?
Racing code - America's Cup races prohibit stored energy aboard the boat, for example. Exceptions are made for certain springs, valves, and batteries for electronics.
did same thing but smaller scale to use with usb powered devices
https://www.youtube.com/watch?v=fMBtU3irxLo
Author also did something similar with usb and different voltages
https://solar.lowtechmagazine.com/2022/03/how-to-build-a-pra...
Well worth a read!
https://solar.lowtechmagazine.com/2022/03/how-to-build-a-pra...
Well worth a read!
obligatory: fifteen million merits https://www.imdb.com/title/tt2089049/?ref_=ttep_ep2
The main thing I wanted to know from this article is how much peddling it takes to keep the tank filled, and I don't feel like he answered that: how long is a peddling session? If it's 5 minutes, that's about four and a half hours of peddling to fill the tank. If it's 15 minutes, that's about 13 hours. And how often does he empty the tank? How long does it take just to keep it topped up in an average week? Details, man! He must know this if he uses the thing.