Comment by jl6
3 years ago
That 70% energy loss in round trip conversion to hydrogen doesn’t look so bad if the alternative is 100% loss by not running the turbines.
3 years ago
That 70% energy loss in round trip conversion to hydrogen doesn’t look so bad if the alternative is 100% loss by not running the turbines.
That really depends on the capex of the hydrogen equipment. It has to be extremely low to justify not curtailing.
True.
I suspect that grid-scale electrolysis is near the very bottom of the economies-of-scale-S-curve and will have a promising future not just in power2gas2power, but also in producing the green hydrogen inputs needed for synthetic hydrocarbon fuels for hard-to-electrify applications like aviation.
Technically it depends on the levelized cost of hydrogen, which encompasses capex, opex, and a slew of other relevant inputs. Similar "levelized cost" formulas are used throughout the utility sector to make these kinds of decisions; what makes green hydrogen unique is simply that it is undergoing a spike in research and development right now that is drastically changing some of the inputs to the LCOH equation.
https://www.nrel.gov/docs/fy09osti/46267.pdf
This are good models for roughly continual usage of the equipment, but they don't model the use cases of operating capacity factors less than 60% for electrolysis, and it's likely that the capacity factor of electrolysis equipment powered by excess wind would be <10%. At that point, the capex beings to dominate nearly all other factors.
I in fact used to be somewhat optimistic about hydrogen as a long term storage mechanism for our excess renewables, until I saw models like these from NREL. Now I am extremely skeptical of any hydrogen from electrolysis unless it's from something like solar+storage facilities. (Which are actually being proposed now, which is very exciting!)
3 replies →
Why are electrolyzers so expensive? The glass ones used in school labs are stupidly simple — just some glassware and a couple of electrodes — so why are they so expensive on an industrial scale?
Industrial electrolyzers are usually https://en.wikipedia.org/wiki/Polymer_electrolyte_membrane_e... which is a bit more complicated. But you also need to consider storing the hydrogen and turning it back into electricity.
Storing the hydrogen and transporting it to where it is needed is probably the bigger problem. Hydrogen embrittles metal.