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[-] JohnDClay@sh.itjust.works 1 points 1 year ago

But a hydrogen battery has much much better specific energy than lithium ion. So you can have a much longer range.

[-] Pipoca@lemmy.world 1 points 1 year ago* (last edited 1 year ago)

Hydrogen is very light, so the energy per kilogram is quite high.

However, hydrogen is also naturally not very dense. Hydrogen at 1 atmosphere has a tiny fraction of the energy of a similar volume of batteries. Pressurized hydrogen is similarly dense to a battery, and liquid hydrogen is about twice as dense.

So to make hydrogen dense, you need a very thick, heavy tank to hold the pressurized hydrogen. That significantly cuts into your weight advantages.

Add to that, fuel cells are very inefficient at converting hydrogen to usable electricity.

[-] JohnDClay@sh.itjust.works 1 points 1 year ago

Maybe I'm missing other conversion factors, but hydrogen has a volumetric energy density of 9MJ/L which is about 2.5kWh/L compared to about 1.7kWh/L for the newest Tesla batteries. So hydrogen is more energy dense than batteries even by volume.

[-] Pipoca@lemmy.world 1 points 1 year ago

Aren't those the numbers for liquid hydrogen?

[-] JohnDClay@sh.itjust.works 1 points 1 year ago

Oh maybe. That would make extra complications. Looks like low pressure gas is 0.5 kWh/L which is more in line with what you were saying.

this post was submitted on 21 Sep 2023
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