A closer look
Lithium-ion batteries are too expensive and prone to exploding to solve grid storage, so engineers decided to just bake rocks instead. Rondo Energy builds massive thermal batteries that use excess daytime solar power to heat thousands of tons of basic refractory bricks to 1,500 degrees Celsius. These superheated graphite blocks trap the thermal energy for days with zero degradation, radiating the heat back out to create industrial steam or generate electricity long after the sun sets.
