• Pipoca@lemmy.world
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    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
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      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.