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I'm not sure hydrogen can be really said to be high density - at least as rocket popelant it is notoriously low density, even in liquid form.
by m4rtink 6y ago
I'm not sure hydrogen can be really said to be high density - at least as rocket popelant it is notoriously low density, even in liquid form.
- WJW 6y agoCompared to battery packs (the main competitor for "green" vehicles) it has a very high energy density.
- masklinn 6y agoIt has a higher energy density but not "very high". Lithium-ion tops out around 2.4 MJ/L, LOH 8~10. Maybe one order of magnitude difference when you use less dense li-ion. Plus that energy density of LOH doesn't take in account the absolute hell that it is to keep stored. Fossil fuels are in the mid-30s by comparison. What LOH does have compared to batteries and even fossil fuels is very high specific energy (energy per kg), it's about triple fossil fuels and a good 2 orders of magnitude better than li-ion. That's why it's been used a lot in rocketry, where mass is a much bigger concern than volume.
- pa7x1 6y agoThere is two densities to care about when talking about energy sources. Energy density per volume unit and energy density per mass unit. Hydrogen has a very high energy density per mass unit (the highest of the chemical reaction energy sources). But lower energy density per volume than Li. The two figures matter for different use cases, cargo-ships and aviation want to optimize for energy density per mass, while small passenger transport (e.g. scooters, cars...) wants to optimize for energy density per volume. Energy density per mass graph: https://en.wikipedia.org/wiki/Energy_density#/media/File:Energy_density.svg https://en.wikipedia.org/wiki/Energy_density#/media/File:Ene...