I read his analysis, I found it roughly to be back of the envelope math and I did not think it was authoritative especially when he uses phrases like "my crude estimate" and "my stupid calculation".
The "per-linear-meter power density" what some would call "wave energy flux" represents an order of 5x greater energy density than wind, which is roughly 10x more dense than solar. When T Murphy describes "third string solar" he highlights that a quantity of energy is lost in each conversion, yes but also the density is increased. Similar to following energy starting with biomass, fermenting to dilute alcohol, and distilling to pure ethanol. In this case there is no effort or external energy required for incident solar energy to generate a lesser amount of denser wind energy, and for wind energy to create a smaller still amount of high density wave energy. However, this quantity is still large enough that even a fraction of it converted to electricity represents an quantity of power that I strongly reject to being called "nil" or "puny".
Following a thorough analysis and R&D phase, the important metric, levelized cost of energy, relates to the quantity of material required to construct a device that interacts with a given quantity of power. Operating in a more power dense medium favors lower LCOE. There are challenges with the salt-water environment, that fact doesn't preclude the existence of industries such as trans-oceanic shipping, offshore oil and gas, navigational and observational buoys, and other such endeavors.
Personally I consider it a good thing for an energy technology to be distributed throughout the world, I think it is preferential than having the entire energy resource concentrated in one part of the world. Another benefit it offers is that its availability is decoupled from wind and solar, the waves don't stop at night, and once established continue traveling without wind.
There is no silver bullet and wave energy is no exception, there will always be a finite quantity recoverable, and a certain cost to recover it. However, to determine those specific numbers would require a herculean effort to thoroughly analyze all of the possible wave energy converter designs - which consist of a number of major of typologies, and within each topology an even greater number of specific designs and sizes, each with their own cost and performance, which also varies depending on seastate - you would need to analyze every possible device not just for power converting performance, but for an estimate of suitable materials and construction techniques, and their costs. Only then could you answer the important question, can any quantity of wave energy be economically recovered at a cost competitive with other leading renewable energy sources.
Wave energy would be any type of machine that uses the motion of individual waves or swells, rather than tides.
There is a wide range of ideas, most are at small scale, early stage, and no winner has emerged the same way that wind energy has seen the 3 bladed turbine win out.
Wave energy devices exist using almost any type of power take off mechanism - direct drive electric generators, linear generators, compressed air, and hydraulic actuators. Some may even use propellers in water but that's not as common since direction is always changing.
Well the comment you replied to that you agree with "100%" also said wave energy + tidal energy.
Your method of analysis is assuming we exist in the best of all possible worlds. "Flying machines have been tried time and again" is valid right until wright brothers. "Electric cars have been tried time and again" right before Tesla enters the market.
It's one thing to say "roof top wind" and you can look at the loads an average roof can support, realize it will be a small swept area at a low elevation and conclude that roof top wind couldn't power the building its mounted on. There is no way to write off tidal with the same sort of first principles analysis, the power is there, its a matter of design whether or not it can be captured efficiently.
The existence of fundamentally non-effective wind capturing technologies, such as rooftop windmills, vawts, and kites, does not preclude existance of effective designs aka multi-megawatt 3 bladed wind turbines.
By analogy, just because early attempts to build a concept does not work, can you prove future attempts won't work? As far as I know, the energy potential in the ocean is not disputed, just the initial attempts to build the machines have not been successful. Many attempts at flying machines were unsuccessful before the wright brothers.
Quick note, confusingly throughout this thread people have used the phrase "wave energy" as essentially a synonym for "tidal energy", they are separate technologies sometimes talked about under the combined category of ocean energy or marine hydrokinetics.
Increased power density is indeed one allure of wave energy vs wind. In the same way that wind is concentrated solar energy, studying the mechanisms and origins of waves show they are essentially a form of concentrated wind energy. So if the difficult design challenges are solved, there is potential for greater energy per unit of structural material which some believe could be associated with competitive cost of energy.
Other allures of wave energy include that it is fairly consistent, with some seasonal variations, and its decoupled from solar or wind which decreases the chance that all renewables resources aren't producing at the same time. Of course this is talking about wave energy where oscillations occur with a period of approximately 4-18 seconds rather than tidal with several periods per day, and for these periods of time flow is essentially unidirectional. Tidal energy, like the link in this thread, often uses underwater turbine but wave energy devices rarely use this design.
The "per-linear-meter power density" what some would call "wave energy flux" represents an order of 5x greater energy density than wind, which is roughly 10x more dense than solar. When T Murphy describes "third string solar" he highlights that a quantity of energy is lost in each conversion, yes but also the density is increased. Similar to following energy starting with biomass, fermenting to dilute alcohol, and distilling to pure ethanol. In this case there is no effort or external energy required for incident solar energy to generate a lesser amount of denser wind energy, and for wind energy to create a smaller still amount of high density wave energy. However, this quantity is still large enough that even a fraction of it converted to electricity represents an quantity of power that I strongly reject to being called "nil" or "puny".
Following a thorough analysis and R&D phase, the important metric, levelized cost of energy, relates to the quantity of material required to construct a device that interacts with a given quantity of power. Operating in a more power dense medium favors lower LCOE. There are challenges with the salt-water environment, that fact doesn't preclude the existence of industries such as trans-oceanic shipping, offshore oil and gas, navigational and observational buoys, and other such endeavors.
Personally I consider it a good thing for an energy technology to be distributed throughout the world, I think it is preferential than having the entire energy resource concentrated in one part of the world. Another benefit it offers is that its availability is decoupled from wind and solar, the waves don't stop at night, and once established continue traveling without wind.
There is no silver bullet and wave energy is no exception, there will always be a finite quantity recoverable, and a certain cost to recover it. However, to determine those specific numbers would require a herculean effort to thoroughly analyze all of the possible wave energy converter designs - which consist of a number of major of typologies, and within each topology an even greater number of specific designs and sizes, each with their own cost and performance, which also varies depending on seastate - you would need to analyze every possible device not just for power converting performance, but for an estimate of suitable materials and construction techniques, and their costs. Only then could you answer the important question, can any quantity of wave energy be economically recovered at a cost competitive with other leading renewable energy sources.