[alkonaut]

No one is claiming it is storing electricity. I think people who use imperial (BTU) units for heat but SI units for electric power some times get confused by what power really is and what a battery is.

Something that stores _energy_ is a battery. Not necessarily electric energy. You can absolutely have a battery with mechanical energy (wound up springs), a battery with kinetic energy (a weight in a shaft) a battery with nuclear energy (Thermal reactor in a satellite), a battery with thermal energy (silo full of very hot sand) or a battery with chemical energy such as a Li-ion battery.

This stores 100 MWh heat energy, so it is a battery.

From wikipedia:

> Energy storage is the capture of energy produced at one time for use at a later time to reduce imbalances between energy demand and energy production. A device that stores energy is generally called an accumulator or battery.