Batteries, especially that sort of cheaper battery, would be great for diurnal load leveling.
Long term storage is probably more hydrogen and mass thermal storage. The tradeoff would be capital cost per unit stored energy vs. efficiency.
Storage competes with and complements two other approaches: overinstallation of generation capacity w. curtailment, and dispatchable demand.
Curtailment involves installing more wind and PV than you need, and curtailing its output when supply > demand. A study in Minnesota found that this was cheaper than adding storage up to about 70% of the electrical power supply. Of course this creates dirt-cheap power during the curtailed periods that people can find use for (industrial thermal storage, production of hydrogen in low capital cost membraneless electrolyzers).
Dispatchable demand would involve redesign of industrial processes to operate in fits and starts. For example, today's aluminum cells do not respond well to inconstant power sources (their either freeze up or overheat and damage the lining). This was fine when the cheapest power sources were baseload sources. But perhaps an aluminum technology could be developed that would be more forgiving of variation and outages, to exploit the new situation where intermittent power is becoming the cheapest.
Of course, another approach is to move those industrial processes down close to the equator, where there is little seasonal variation in insolation. High latitude countries may become industrially disadvantaged in a renewable powered world.
> Long term storage is probably more hydrogen and mass thermal storage.
I was thinking about how multiple big heating packs[1] would stack up. Seems the Wikipedia reference[2] has the topic well covered. Tricky but possible. And apparently (duh) not a novel idea by any means[3][4].
Though the references I could find were mostly for home-size installations or for actual heating packs. Here in Norway we're blessed with lots of mountains with lakes, so we can do pumped hydro for latent storage. But for flatter countries (say our neighbors Denmark), is grid-size PCM storage viable?
I was thinking more in terms of artificial geothermal. The time constant for a sphere of bedrock to cool off goes as the square of the radius, and can easily be made to be many years. These would be very large installations, of course.
Another option for seasonal variation is to overbuild. Build enough solar for winter and just discard or figure out something to do with the excess power supply in summer.
(I'm not sure that would be cheaper, it's just another possibility.)
Multi day storage is always an issue. X kWh stored over Y hours takes X kWh of storage but X/Y kw of generation capacity. Start talking 50 hours and the cost difference becomes huge.
PS: Though batteries inherently have some emergency storage capacity as daily deep discharge is inefficient.
Methanol is an alternative to hydrogen. With current technologies it is less efficient to produce it and then generate electricity in fuel cells, but storing it is trivial.
All countries already have infrastructure for strategic gas reserves that are sufficiently sized to cover demand for long periods. So storing renewable energy via power-to-gas processes is probably the way to go.
Long term = weeks to seasonal
Batteries, especially that sort of cheaper battery, would be great for diurnal load leveling.
Long term storage is probably more hydrogen and mass thermal storage. The tradeoff would be capital cost per unit stored energy vs. efficiency.
Storage competes with and complements two other approaches: overinstallation of generation capacity w. curtailment, and dispatchable demand.
Curtailment involves installing more wind and PV than you need, and curtailing its output when supply > demand. A study in Minnesota found that this was cheaper than adding storage up to about 70% of the electrical power supply. Of course this creates dirt-cheap power during the curtailed periods that people can find use for (industrial thermal storage, production of hydrogen in low capital cost membraneless electrolyzers).
Dispatchable demand would involve redesign of industrial processes to operate in fits and starts. For example, today's aluminum cells do not respond well to inconstant power sources (their either freeze up or overheat and damage the lining). This was fine when the cheapest power sources were baseload sources. But perhaps an aluminum technology could be developed that would be more forgiving of variation and outages, to exploit the new situation where intermittent power is becoming the cheapest.
Of course, another approach is to move those industrial processes down close to the equator, where there is little seasonal variation in insolation. High latitude countries may become industrially disadvantaged in a renewable powered world.