Geothermal may beat batteries for energy storage

Geothermal may beat batteries for energy storage
spectrum.ieee.org

FWIW, the link to the Google article is much more interesting: https://cloud.google.com/blog/products/infrastructure/google...

"Geothermal power is considered to be renewable because any projected heat extraction is small compared to the Earth's heat content. The Earth has an internal heat content of 10^31 joules (3·10^15 TWh), approximately 100 billion times the 2010 worldwide annual energy consumption.[...] About 20% of this is residual heat from planetary accretion; the remainder is attributed to past and current radioactive decay of naturally occurring isotopes." -- https://en.wikipedia.org/wiki/Geothermal_energy#Renewability...

Converting electricity into heat and then back into electricity is a lossy process that is constrained by the second law of thermodynamics. Basically generating heat is easy and efficient. But converting it back to electricity is typically less than 50% efficient. Basically, it's several energy conversions in one process: you use electricity to produce heat, heat to produce mechanical energy, and then mechanical energy to produce electricity. All of those steps are lossy, some more than others. And it multiplies. It adds up to less than 50% efficiency, at best.

Lithium ion batteries are much better at over 90% efficiency. But they are relatively expensive for large amounts of storage. So they don't scale. But they have no moving parts and you can scale the capacity at which they absorb and release energy pretty much linearly. Which is why they are popular for balancing the grid.

Pumped hydro, which is a type of battery that has a relatively large amount of deployed capacity in some countries (many gwh of power stored) is both efficient and cost effective. But it's highly dependent on terrain. Yet parts of Canada run almost exclusively on hydro and pumped hydro.

Are they heating the steam from a geothermal source, higher than the source's temperature, and sending it back down the geothermal well when power is cheap? And then later run the steam through a turbine when power is expensive?

Or are they using cheap power to pump water into the well at high pressure, to force it it deeper into the fractured rock? And then later use the extra steam to produce power?

Or something else?