Originally posted by Leo Enticknap
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While there have been many small improvements over the years to existing designs, they eventually add up to quite a lot, to the point that nowadays electric vehicles are a reality, whereas about 30 or so years ago, we still lacked usable battery designs. Still, a real breakthrough using something more abundant and less ecologically taxing than lithium seems to be difficult. There are few if any other elements with the same electrochemical potential as lithium and finding molecular configurations that somehow mimic that same electrochemical potential, while not impossible, seems more like a search for the lucky lottery number to me. I guess that's why a real breakthrough still hasn't been made. Maybe we need to settle on lithium and start mining it from asteroids.
As for hydrogen, its association with the Hindenburg in popular culture is not for nothing. The builders and operators of rigid airships spent nearly four decades trying to manage the risk caused by the stuff, and in many ways they had a simpler engineering problem, because they weren't trying to burn it to release energy: simply contain it, stop it from mixing with oxygen, and prevent any sources of ignition from getting near it. As not just the Hindenburg, but literally dozens of other airships that were destroyed in hydrogen fires, notably several pre-WWI passenger Zeppelins, the Dixmude, and the R101, demonstrated, that problem was never fundamentally able to be solved. Given that in a hydrogen-powered vehicle, you actually want to ignite the hydrogen, the risk of that ignition getting out of control and turning your car into a bomb would seem to be unacceptably high.
Another problem is the energy density of hydrogen, which is far less than gasoline. This is bad news for vehicle design, as you'll need much bigger tanks.
As for storage safety, there have been some interesting developments like the storage of hydrogen in carbon "nanoflakes". Those "flakes" bind with hydrogen molecules/atoms under pressure and release them back at lower pressure, yet at a far slower pace. Hence, a breach in a hydrogen storage container would release the amount of ignitable hydrogen at a much slower pace, reducing the risk of a hydrogen explosion considerably.
While those solutions seem to work pretty well, they usually don't help to increase the storage density of hydrogen, which remains a problem.
Then, finally, there is this problem with hydrogen production. Ironically, most hydrogen we produce today comes from carbon sources. While water would be great source for hydrogen, splitting water into hydrogen and oxygen still requires tons of energy, despite a lot of research into "low and medium temperature catalysts" for the electrolysisâ of water.
A sustainable energy cycle using hydrogen as fuel may eventually technically possible, but it's clear that we're missing quite a lot of pieces in this puzzle. Unfortunately, just like the lithium battery thing, you often hear a lot of fuzz about new inventions, but many of those eventually prove to be impractical at scale or over-hyped.
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