[amarant]

I think hydrogen has a place as a energy source, but cars are not it.

There are some projects aiming to use it for steel production for example, and in a few areas where batteries aren't feasible, such as long distance flights.

But hydrogen never had a chance at competing with batteries where batteries are an option. In part due to energy inefficiencies in it's production(I'm assuming green hydrogen, since otherwise, What's the point)

[pfdietz]

Hydrogen (or a related e-fuel made from hydrogen) is likely essential for a fully renewable grid, especially at high latitude. Not much of the total energy flow would go through hydrogen, but replacing that component with overprovisioning or batteries could be very very expensive. The hydrogen would be stored underground as a compressed gas, not as liquid. Done right, the energy of compression would be (mostly) recovered when the hydrogen was burned in a turbine.

[more_corn]

That story doesn’t make any goddamned sense.

[pfdietz]

It's not difficult to understand.

The mismatch between supply and demand is a function of time whose Fourier transform has components at various frequencies. There will be a strong component around 1 per 24 hours, which batteries will be good for, but there will also be much longer period components (seasonal, or from rare extended solar and wind combined outages, so called "Dunkelflauten").

Hydrogen (or other e-fuels) are well suited to the latter. For those storage needs, round trip efficiency is far less important compared to minimizing the per energy storage capacity capital cost. That's because there will be many fewer cycles over which to amortize the latter (while the contribution of round trip efficiency to levelized cost of storage is not so affected.) The per energy storage capacity cost of hydrogen is two orders of magnitude less than that of batteries.

To see this effect in action, go to https://model.energy/ and get it to solve for the minimum cost combination of solar, wind, batteries and hydrogen to supply a steady power output in Germany. Then, disable hydrogen and solve again. The cost nearly doubles.

[bombcar]

In any place hydrogen can be used, you’re probably honestly much better off with natural gas or propane unless you literally cannot have a carbon atom involved.

Liquid fuel is so energy dense that if you have to synthesize it and remove an equivalent amount of carbon from the atmosphere it’s probably still easier and cheaper than hydrogen.

[ianburrell]

There are places where the density of hydrogen doesn't matter. One is long-term storage, where can pump hydrogen underground and then burn it when solar and wind are low. Another is steel production where need high heat, and can store it in big tanks on site. Finally, is ships which have plenty of volume. Planes probably can't use hydrogen.

For ships and planes, we may be able to use lower carbon synthetic fuels like ammonia or methanol, and not have to go as far for synthetic fuels.

Pulling carbon dioxide directly out of the atmosphere is really inefficient. There may be cheaper ways to sequester carbon but they won't give you CO2 for making fuels. Hydrogen is definitely more efficient.

[amarant]

Planes can in fact use hydrogen, though I suppose there might be tradeoffs in not aware of

https://en.m.wikipedia.org/wiki/Hydrogen-powered_aircraft

[ianburrell]

The problem with hydrogen powered airplanes is that hydrogen tanks are heavy and use lots of space. It should be possible to make hydrogen powered planes but they would have to be completely redesigned to work, and may lose range and payload. While with liquid fuels, at least the non-cryogenic ones, can use existing designs and maybe even retrofit existing planes.

[amarant]

Except natural gas is a fossil fuel. The name is somewhat misleading.

I'm not aware of any way to create synthetic propane using renewable energy sources, but that might be my ignorance speaking. A quick googling indicates it's not possible, but I'm happy to be proven wrong here if you want to provide a reference I didn't find.

Easier and cheaper doesn't really cut it for the climate. Petroleum is easy and cheap, and so is coal. Both are terrible ideas in the long run though

[amarant]

Which specific liquid fuels do you mean?

I guess the most important factor is how much energy is lost in synthesizing/burning it. Do you have those numbers available?

I know methane can be synthesised, but it requires you to first make hydrogen, and then you'll lose an additional 50-60% energy in turning hydrogen into methane.

For any large scale operation I can't imagine that kind of energy loss is acceptable, hydrogen storage is difficult, but not THAT difficult