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I really don't get hydrogen. Yes, it has the highest possible energy density (for chemicals) but that is about it. That is the only thing it has going for it. E

I really don't get hydrogen. Yes, it has the highest possible energy density (for chemicals) but that is about it. That is the only thing it has going for it. Everything else is either equal or worse than other options: - It is the smallest atom so it diffuses through every other material, thus you get something similar to self discharge in batteries. Yes, you can make the walls bigger to slow down the process, but that makes it also very heavy and expensive to store. - It only reaches its advantage of the energy density at either insanely high pressure or low temperature. Both come with their own technical challenges and make it either impractical or down right dangerous (not considering its spontaneous combustion). - It is highly explosive and very easy to ignite. Should it ever leak and mix with air, it is bound to lead to a catastrophe. This is actually much worse than with regular gasoline or even batteries. Now, what would be better IMO? Small / short hydrocarbons such as methane (a gas at room temperature) or methanol (a liquid at room temperature): - Methane is still dangerous to handle, but well understood and even allowed to be used in housing. Methanol on the other hand is hard to ignite and can be mixed with water to make it inflammable, thus completely safe to store. Even this water methanol solution can still be directly used in fuel cells. - A leak of methane is still disastrous, especially if it does not burn because of its environmental impact. However, a complete spill of methanol is barely any issue at all compared to all the other options. It quickly dilutes and is bio degradable. - A downside is the reduced energy density, but storage is really easy and cheap so that should make up for that. - It can easily work with existing infrastructure. Pipelines, storage tanks and trucks all exists already and methane as well as methanol are among the most traded chemicals in the world. - Combustion engines could continue to be used, they wouldn't need a catalyst anymore and not produce any toxic gases such as carbon-monoxide. Also, the practical power efficiency of fuel cells is not that much better than that of combustion engines. Though, that might be because way more R&D optimization went into combustion engines so far. The last two are important points, people often forget the tremendous environmental impact of completely replacing all infrastructure. Just like hydrogen, most methane and methanol today comes from other hydrocarbons, in other words fossil fuels. However, that could change e.g. by using solar power and electrolysis / electrocatalysis. So my point is, the world should bury the hydrogen idea and go for methanol instead. Please correct me if I am wrong in any of these points, I am here to learn ;)

ZeroGravitas 4y ago
Combustion engines are pretty crap tech compared with other options. No-one really wants to use them, and even if they did, they'd be as electricity generators in hybrid vehicles, just as any hydrogen usage would be. The uses of hydrogen in transport would be for fleets, where they already do weird things like use CNG or recycled vegetable oil to run the engines for pollution and carbon reasons, so switching to hydrogen isn't really as big a deal as it would for home users, who are not going to be using hydrogen, because battery EVs are just so much better for that use case. Cars (and most other tech) are going to age out, there's low hanging fruit that can be replaced now (e.g. urban driving) at a cost saving and that frees up existing ICE vehicles to be moved to other areas, to replace even older ICE vehicles that are getting scrapped because they are too costly and polluting to run. You are correct that in future, the cheapest and cleanest sources of methane and methanol will be making them from green hydrogen (SpaceX is doing this in Texas), but there's no good reason to burn them (unless you need zero-carbon rocket fuel or kerosene) so they'll mostly be chemical feedstocks.
hedora 4y ago
People overestimate how dangerous hydrogen is. It disperses more rapidly than natural gas / propane / methane, and isn’t a liquid like gasoline. People always think of the Hindenburg disaster as an example of how dangerous Hydrogen is, but forget that the shell was made of a chemical that is now used for solid state jet fuel. The bigger safety issue with hydrogen is that it is a compressed gas. Modern fiberglass tanks (mostly) solve that problem by twisting apart when they catastrophically fail (instead of launching shrapnel). I don’t know how the chemistry works for carbon-neutral methanol production, but you likely already have all the feedstock required for hydrogen generation readily available at your house (water, oxygen and electricity). Also, commercial hydrogen crackers already exist, and are in test deployment. The way I think about hydrogen fuel cells is that they have minimal infrastructure requirements (you don’t have to run natural gas lines / tankers anywhere, and water and electricity are more universally available), and their embodied carbon is (mostly) constant with increasing range, unlike batteries, where it’s (mostly) proportional to range.

ZeroGravitas 4y ago

Combustion engines are pretty crap tech compared with other options. No-one really wants to use them, and even if they did, they'd be as electricity generators in hybrid vehicles, just as any hydrogen usage would be. The uses of hydrogen in transport would be for fleets, where they already do weird things like use CNG or recycled vegetable oil to run the engines for pollution and carbon reasons, so switching to hydrogen isn't really as big a deal as it would for home users, who are not going to be using hydrogen, because battery EVs are just so much better for that use case. Cars (and most other tech) are going to age out, there's low hanging fruit that can be replaced now (e.g. urban driving) at a cost saving and that frees up existing ICE vehicles to be moved to other areas, to replace even older ICE vehicles that are getting scrapped because they are too costly and polluting to run. You are correct that in future, the cheapest and cleanest sources of methane and methanol will be making them from green hydrogen (SpaceX is doing this in Texas), but there's no good reason to burn them (unless you need zero-carbon rocket fuel or kerosene) so they'll mostly be chemical feedstocks.

hedora 4y ago

People overestimate how dangerous hydrogen is. It disperses more rapidly than natural gas / propane / methane, and isn’t a liquid like gasoline. People always think of the Hindenburg disaster as an example of how dangerous Hydrogen is, but forget that the shell was made of a chemical that is now used for solid state jet fuel. The bigger safety issue with hydrogen is that it is a compressed gas. Modern fiberglass tanks (mostly) solve that problem by twisting apart when they catastrophically fail (instead of launching shrapnel). I don’t know how the chemistry works for carbon-neutral methanol production, but you likely already have all the feedstock required for hydrogen generation readily available at your house (water, oxygen and electricity). Also, commercial hydrogen crackers already exist, and are in test deployment. The way I think about hydrogen fuel cells is that they have minimal infrastructure requirements (you don’t have to run natural gas lines / tankers anywhere, and water and electricity are more universally available), and their embodied carbon is (mostly) constant with increasing range, unlike batteries, where it’s (mostly) proportional to range.