40 ms·

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.

by jl6 4y ago

epistasis 4y ago
That really depends on the capex of the hydrogen equipment. It has to be extremely low to justify not curtailing.
- jl6 4y ago
  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.
- kokanee 4y ago
  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 https://www.nrel.gov/docs/fy09osti/46267.pdf
  - epistasis 4y ago
    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!)
    - jl6 4y ago
      Why is solar+storage different?
      - epistasis 4y ago
        It's the only way to build lots of zero carbon baseload right now. Botch cheaper and faster than nuclear, it also regularly gets deployed with an extremely high success rate. Failure of nuclear builds is a huge huge problem that the industry has not been able to solve.
        epistasis 4y ago
        *Botch --> Much.. not sure how I made that typo!
- perilunar 4y ago
  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?
  - adrianN 4y ago
    Industrial electrolyzers are usually https://en.wikipedia.org/wiki/Polymer_electrolyte_membrane_electrolysis 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.
  - pydry 4y ago
    Storing the hydrogen and transporting it to where it is needed is probably the bigger problem. Hydrogen embrittles metal.

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.

by jl6 4y 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.

epistasis 4y ago

That really depends on the capex of the hydrogen equipment. It has to be extremely low to justify not curtailing.

jl6 4y ago
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.
kokanee 4y ago
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 https://www.nrel.gov/docs/fy09osti/46267.pdf
- epistasis 4y ago
  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!)
  - jl6 4y ago
    Why is solar+storage different?
    - epistasis 4y ago
      It's the only way to build lots of zero carbon baseload right now. Botch cheaper and faster than nuclear, it also regularly gets deployed with an extremely high success rate. Failure of nuclear builds is a huge huge problem that the industry has not been able to solve.
      - epistasis 4y ago
        *Botch --> Much.. not sure how I made that typo!
perilunar 4y ago
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?
- adrianN 4y ago
  Industrial electrolyzers are usually https://en.wikipedia.org/wiki/Polymer_electrolyte_membrane_electrolysis 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.
- pydry 4y ago
  Storing the hydrogen and transporting it to where it is needed is probably the bigger problem. Hydrogen embrittles metal.