Re:Why Is Hydroelectricity So Green, and yet Unfashionable?
by philipkglass on Thursday October 27, 2022 @09:06PM
(#33366226)
The facility you linked produces and stores chemical fuel, and can't even convert it back into electricity.
No, the project includes using Mitsubishi M501JAC combined-cycle gas turbines to turn the hydrogen back into electricity:
https://www.powermag.com/aces-deltas-giant-utah-salt-cavern-...
https://power.mhi.com/products/gasturbines/lineup/m501j
This turbine has a rated combined-cycle efficiency of 64%.
Production of hydrogen is more than 70% efficient in the best current commercial electrolyzers:
https://www.nrel.gov/docs/fy04osti/36705.pdf
Round-trip efficiency is much lower than 80%, but not as low as you have written here.
Re:Why Is Hydroelectricity So Green, and yet Unfashionable?
by pencilguin on Friday October 28, 2022 @12:15AM
(#33367619)
Industrial-scale electrolysers will soon be well over 90% efficient.
Re:Why Is Hydroelectricity So Green, and yet Unfashionable?
by nomel on Friday October 28, 2022 @03:55AM
(#33368771)
Any terms I can search to understand these advances? I seemed to remember learning that boring old electrolysis was around 30% efficient!
Re:Why Is Hydroelectricity So Green, and yet Unfashionable?
by pencilguin on Friday October 28, 2022 @04:32AM
(#33368985)
Re:Why Is Hydroelectricity So Green, and yet Unfashionable?
by ClumsyPilot on Friday October 28, 2022 @04:20AM
(#33368918)
why are turbines used in place of potentially more efficient fule cells?
Re:Why Is Hydroelectricity So Green, and yet Unfashionable?
by AstralStorm on Friday October 28, 2022 @05:51AM
(#33369484)
Cost. Fuel cells require quality manufactured membranes that also require regular maintenance and replacement. Getting volume with them is also a hard problem.
Re:Why Is Hydroelectricity So Green, and yet Unfashionable?
by scythe on Thursday October 27, 2022 @09:27PM
(#33366401)
Thermochemical hydrogen offers the best prospect for hydrogen production if it can be worked out, because the whole-process efficiency from solar or nuclear heat can exceed the practical limits of water electrolysis. Most recent work focuses on the copper chloride process (which uses an electrolytic step) [1]. The best purely thermal cycle is sulfur-iodine, but running the process sustainably has yet to be achieved due to the corrosive nature of the intermediates.
1: https://www.sciencedirect.com/science/article/pii/S019689041...
Hydroelectric, compressed air and batteries have round trip efficiency of ~80%.
https://www.sciencedirect.com/topics/engineering/compressed-...
The facility you linked produces and stores chemical fuel, and can't even convert it back into electricity. It is really easy to store insane quantity of fuel, just like we can store loads of oil.
The kicker is that production of Hydrogen and other e-fuelds is less than 50% efficient, and converting them back to electricity is another 50% loss. Compression for storage and transportation mean further losses. So the overall round-trip efficiency is expected to be about 25% or lower.
It is probably possible to build an economy based on e-fuels, and that's what many oil companies are pushing for. They are probably the only viable way to achieve seasonal storage. It's a different set of tradeoffs.