It’s odd hydrogen fuel cells wasn’t mentioned in the article.
Cheap, green hydrogen would be a breakthrough in clean energy
71–80 of 254 posts
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#72Ammonia has been mentioned a few times in this thread, but I will expand a bit, because I believe it is the most promising hydrogen-based approach. Essentially, the idea is to use ammonia directly as fuel. There is an ARPA-E funded project (that I'm currently failing to find) that cracks ammonia into hydrogen and nitrogen using heat. They claim that they can create a mixture of H2 and ammonia that will burn at any re…
The downside is that ammonia is a heavier-than-air poison, like chemical weapons from WW1. Its hazards are significant.
- "Anhydrous ammonia is lighter than air and will therefore rise (will not settle in low-lying areas); however, vapors from liquefied gas are initially heavier than air and may spread along the ground."
https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=7&toxid=2
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#73Ammonia has been mentioned a few times in this thread, but I will expand a bit, because I believe it is the most promising hydrogen-based approach. Essentially, the idea is to use ammonia directly as fuel. There is an ARPA-E funded project (that I'm currently failing to find) that cracks ammonia into hydrogen and nitrogen using heat. They claim that they can create a mixture of H2 and ammonia that will burn at any re…
The downside is that ammonia is a heavier-than-air poison, like chemical weapons from WW1. Its hazards are significant. - "Anhydrous ammonia is lighter than air and will therefore rise (will not settle in low-lying areas); however, vapors from liquefied gas are initially heavier than air and may spread along the ground." https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=7&toxid=2
We already synthesize and handle industrially millions of tons of it annually, and have done for going on a century. If there were a worrying problem with ammonia, you would already be hearing about it.
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#74It's too late for hydrogen. For hydrogen to be green is has to either A) be more green than storing the generating power in batteries and using it from there or B) be created with something other than electricity. It's too late for A, batteries are already too good. As for B), feel free to come up with some kind of metamaterial that can produce hydrogen mechanically and in doing so bypass the efficiency loss of elect…
I think maybe for cars it’s over but the energy density argument still favors hydrogen so I’d add another option.
C) provide greater energy density allowing for heavy equipment, trucks, trains, and planes to use electric power.
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#75Earlier quoted context omitted.
The downside is that ammonia is a heavier-than-air poison, like chemical weapons from WW1. Its hazards are significant. - "Anhydrous ammonia is lighter than air and will therefore rise (will not settle in low-lying areas); however, vapors from liquefied gas are initially heavier than air and may spread along the ground." https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=7&toxid=2
We already synthesize and handle industrially millions of tons of it annually, and have done for going on a century. If there were a worrying problem with ammonia, you would already be hearing about it.
- "If there were a worrying problem with ammonia, you would already be hearing about it."
We hear about it pretty regularly,
https://www.google.com/search?q=ammonia+spill+site%3Areddit....
Fortunately the main use of anhydrous ammonia (agriculture) is in sparsely populated places, so its impact is limited. I think it's a questionable idea to put it in urban vehicles though.
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#76I don't see hydrogen playing any role for energy storage or grid demand balancing. Even if all the technical and engineering challenges associated with storing and transporting it safely could be addressed, I just don't see how the economics of green hydrogen is supposed to work. The round-trip energy efficiency of electrolysis-fuel cell is poor - currently about 40%. The counter-argument is that such inefficiency do…
> it means leaving your capital-expensive electrolysis plant idle for half or 2/3rds of the day.
I think that's an exaggeration, and neglects the possibility of overbuilding solar/wind. It may mean leaving your relatively low capital expenditure wind and solar farms 50% underutilized for half the day but the benefit here is that you can guarantee a 95% capacity factor year-round for the expensive electrolysis plant.
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#77It's too late for hydrogen. For hydrogen to be green is has to either A) be more green than storing the generating power in batteries and using it from there or B) be created with something other than electricity. It's too late for A, batteries are already too good. As for B), feel free to come up with some kind of metamaterial that can produce hydrogen mechanically and in doing so bypass the efficiency loss of elect…
Batteries have the serious downsides that (1) they cost more than almost anything else, and (2) cost is per kWh stored, rather than just kW in and per kW out. Flow batteries could mitigate this some where electrolyte is cheap.
Synthetic fuels have the enormous advantages that (1) tankage is super-cheap (negligible cost per kWh), (2) tankage is easily transported, (3) there is unlimited market for them, (4) you can burn them in existing combined-cycle turbines. These advantages easly overwhelm low round-trip efficiency, which is anyway relentlessly increasing.
We will be shipping hydrogen or ammonia from the tropics to Baltic states in winter. It is hard to imagine any viable green alternative, aside from reliance on fallible transmission lines.
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#78I don't see hydrogen playing any role for energy storage or grid demand balancing. Even if all the technical and engineering challenges associated with storing and transporting it safely could be addressed, I just don't see how the economics of green hydrogen is supposed to work. The round-trip energy efficiency of electrolysis-fuel cell is poor - currently about 40%. The counter-argument is that such inefficiency do…
The only reason it's discussed is because the fossil fuel industry has a lot of experience and infrastructure around liquid fuels. It wants a future where there is a new liquid fuel so that it can leverage that experience and infrastructure. They are pouring huge sums into moving the academic and public conversation in the direction of hydrogen - it's like the tobacco companies all over again. Don't trust a word that…
While we do need to be suspicious, we can't reject technical solutions on the grounds that it would be too convenient if it worked. Whatever we do does need to be reasonably convenient.
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#79It's too late for hydrogen. For hydrogen to be green is has to either A) be more green than storing the generating power in batteries and using it from there or B) be created with something other than electricity. It's too late for A, batteries are already too good. As for B), feel free to come up with some kind of metamaterial that can produce hydrogen mechanically and in doing so bypass the efficiency loss of elect…
How do you make ammonia with a battery? The target use case for hydrogen isn't the cases where you can use a battery. It's all the places where that doesn't work.
The hydrogen or ammonia is the battery.
Re: Cheap, green hydrogen would be a breakthrough in clean energy
#80Earlier quoted context omitted.
> For hydrogen to be green is has to either A) be more green than storing the generating power in batteries I thought batteries had some pretty toxic elements inside them? I don’t know much about using hydrogen as a power source so I’m interested to understand how it’s less green than batteries.
Correct. For hydrogen to be green it has to be more green that producing and using batteries. We're already past that point. Well past it, in fact. The generation-to-tires efficiency of BeVs is 77%. For hydrogen it's 33%. Modern fuel cells have an H2 to electricity efficiency of 55%. You could make that 100% and it would still be less green than using batteries.
Round-trip efficiency is not actually very important when generation has zero marginal cost. You just add more panels. It matters, but other things matter more. Panels are very cheap.