4 ms·

Unless you need hydrogen for a capability that only hydrogen has it is much more efficient to use solar electricity either directly or to charge batteries.

mrleinad 4y ago
In those parts of the globe where it makes sense to use solar, and during the day, yes. For everything else, you need a way to store the energy that can be measured in weeks, not hours. You also need to transport it. And you need to stabilize the energy output not to be entirely dependent on whether the sun shines. That's why hydrogen might be a good energy reservoir.
- kwhitefoot 4y ago
  > a way to store the energy that can be measured in weeks, My Tesla Model S does that pretty efficiently. And for static batteries there are plenty of alternatives that don't use difficult to source elements. > You also need to transport it. We have a grid to do that already, with HVDC interconnects we can even sell it to places where the sun is not shining.
jillesvangurp 4y ago
Yes hydrogen is has a pretty terrible volumetric energy density. In gas form stored at 200 bar, you'd need about 18 truckloads to math the amount of fuel in a single truck load of petrol. In liquid form stored at a few degrees above zero it gets a bit better. It's "only" 2.5 times less dense than lng. Of course cooling and keeping the gas at that temperature is not free. It takes energy. And as it heats up, you have to boil some of it off. So, it doesn't store that well for longer time in liquid form. So, that makes shipping or trucking around hydrogen spectacularly uneconomical. Most hydrogen produced today is used onsite. Mainly for things like fertilizer production. Moving hydrogen around at scale is an unsolved problem. Gas pipes (after they are re-enforced) could work of course. But some of it would leak. And hydrogen mixed with air is not a good thing to have in your house. The same property also makes using hydrogen as a fuel in planes or shipping unpractical: most of your plane/ship would be taken up by the enormous volume of hydrogen you'd need to move it around. Michael Liebreich's hydrogen ladder is a good reference here. https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-michael-liebreich/ https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-mic... In it he organizes different use cases by their economical value. Things like road transport and domestic heating are at the bottom of the scale (i.e. you could do it but it would be very inefficient and costly). Near the top are some of the more realistic things, some of which are already being done. Instead of moving hydrogen to where you implement those use cases (e.g. steel making), it would be more practical/logical to move the use case to where you can produce the hydrogen the cheapest. The bigger the energy need, the higher the savings. You basically compete on energy cost.
makeitdouble 4y ago
The bet seems to on the cost/tradeoffs of producing batteries vs producing hydrogen generators. If at some point producing hydrogen generators can become more affordable and sustainable than batteries (especially from countries will low rare earth resources) it would be a win for them.

mrleinad 4y ago

In those parts of the globe where it makes sense to use solar, and during the day, yes. For everything else, you need a way to store the energy that can be measured in weeks, not hours. You also need to transport it. And you need to stabilize the energy output not to be entirely dependent on whether the sun shines. That's why hydrogen might be a good energy reservoir.

kwhitefoot 4y ago
> a way to store the energy that can be measured in weeks, My Tesla Model S does that pretty efficiently. And for static batteries there are plenty of alternatives that don't use difficult to source elements. > You also need to transport it. We have a grid to do that already, with HVDC interconnects we can even sell it to places where the sun is not shining.

jillesvangurp 4y ago

Yes hydrogen is has a pretty terrible volumetric energy density. In gas form stored at 200 bar, you'd need about 18 truckloads to math the amount of fuel in a single truck load of petrol. In liquid form stored at a few degrees above zero it gets a bit better. It's "only" 2.5 times less dense than lng. Of course cooling and keeping the gas at that temperature is not free. It takes energy. And as it heats up, you have to boil some of it off. So, it doesn't store that well for longer time in liquid form. So, that makes shipping or trucking around hydrogen spectacularly uneconomical. Most hydrogen produced today is used onsite. Mainly for things like fertilizer production. Moving hydrogen around at scale is an unsolved problem. Gas pipes (after they are re-enforced) could work of course. But some of it would leak. And hydrogen mixed with air is not a good thing to have in your house. The same property also makes using hydrogen as a fuel in planes or shipping unpractical: most of your plane/ship would be taken up by the enormous volume of hydrogen you'd need to move it around. Michael Liebreich's hydrogen ladder is a good reference here. https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-michael-liebreich/ https://www.linkedin.com/pulse/clean-hydrogen-ladder-v40-mic... In it he organizes different use cases by their economical value. Things like road transport and domestic heating are at the bottom of the scale (i.e. you could do it but it would be very inefficient and costly). Near the top are some of the more realistic things, some of which are already being done. Instead of moving hydrogen to where you implement those use cases (e.g. steel making), it would be more practical/logical to move the use case to where you can produce the hydrogen the cheapest. The bigger the energy need, the higher the savings. You basically compete on energy cost.

makeitdouble 4y ago

The bet seems to on the cost/tradeoffs of producing batteries vs producing hydrogen generators. If at some point producing hydrogen generators can become more affordable and sustainable than batteries (especially from countries will low rare earth resources) it would be a win for them.