[organsnyder]

Yeah, I don't understand the use-case for hydrogen here. Why convert from electricity -> hydrogen -> electricity if everything is stationary? I suppose it could be useful for storage or long-distance transmission, but it seems like it would be much less efficient than other, simpler options.

[philipkglass]

It's because hydrogen scales up to much greater energy capacity.

"Chevron joins Mitsubishi in 300 GWh hydrogen storage project as construction continues"

https://www.utilitydive.com/news/chevron-mitsubishi-hydrogen...

The ACES project aims to use electrolysis to produce up to 100 metric tons of hydrogen per day, which will be stored in naturally occurring salt caverns at the site. The caverns have a potential storage capacity of 300 GWh of energy, according to Mitsubishi Power, which is developing ACES jointly with now Chevron-owned Magnum Development.

For comparison, last year the largest battery system in the world was the Moss Landing project in California with 3 GWh of capacity:

https://www.energy-storage.news/moss-landing-worlds-biggest-...

The largest pumped hydro station in the US stores 24 GWh:

https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta...

At 300 gigawatt hours this underground hydrogen storage system can store more energy than all utility scale batteries in the US combined.

[organsnyder]

Do we need that much storage, though? Presumably we won't have the hydrogen-powered generation capacity to use that much energy quickly, so the comparison to utility-scale batteries isn't quite apples-to-apples.

From the article about the Chevron project:

> The project will initially provide fuel to the Intermountain Power Project, an 840-MW blended gas power plant also under construction in Delta, but Chevron believes there will be opportunities to supply hydrogen to the transportation and industrial sectors as well.

So even if the hydrogen storage facility was full, we're still limited to 840 MW of generation capacity. Sure, we get ~350 hours of runtime, but that's not really needed.

The Bath County Pumped Storage Station has 3003 MW of generation potential, with 11 hours of runtime from full.

Looks like the Moss Landing project is rated to be able to discharge 1/4 of its capacity per hour, so that 3 GWh facility can provide 750 MW. Batteries also have the advantage of being able to be sited much closer to the end user.

[philipkglass]

It's a demonstration project to show how a renewable powered system can cope with weeks of bad weather. If deep decarbonization doesn't actually require weeks of storage, not many systems like this will get built in the future. But if they are required at least we'll know how to build them.

[cassepipe]

Even storage is a nightmare. That thing really wants to leak.