This type of battery is thermal energy storage, where instead of storing electricity directly, it is converted to heat (or cold) in our refrigerators or HVAC systems. In this future, where we’ll have excess (solar) energy in the middle of the day, it is critical to store that away to keep our refrigerators cold and homes warm overnight. This is not radical, nor is it expensive—people already run water heaters when electricity is cheap and store the hot water for later use.
