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Australia struggling with oversupply of solar power
(www.abc.net.au)
This is a most excellent place for technology news and articles.
Desalination, aluminum recycling, ad infinitum. Anyone who says excess solar is an insurmountable problem is manipulating you.
Hydrogen/electro chemistry is another use of too much batteries.
Speaking of too much battery, an EV range is often 3-5 times daily use (60km average per day is vehicle average, but many use less). It's not a big deal to have several days worth of fuel in your tank, and so V2G is a good way to have too much batteries, and let consumers profit from their vehicle. This is the app that exterminates oil and other FFs. Hydrogen or your listed apps are good ways to drain having too much battery charge for the next day.
I expect to eventually see a lot of storage as long term investment, especially gravity, flywheel, and molten salt due to cheap safety.
Batteries are getting cheaper, and have high charge/discharge rates. Flywheels can maybe double as AC/DC conversion, but their role is closer to a capacitor than a battery.
What distinguishes H2 is that it is transportable/exportable energy, that also has alternate chemical uses. It is ideal aviation fuel. Sure making it has some expense/loss, but storing it is $1/kwh electric (also contains heat energy that when used in a fuel cell matches the typical domestic hot water energy fraction). Transporting H2 energy by truck is cheaper than electricity by wire. Because H2 can be produced at convenience (solar surplus), and made available for user convenience later, it can be cheaper energy overall, and improve the total utilization of renewable+battery/static storage systems.