Generation and consumption of electricity need to match every given second. Traditional power plants—nuclear, coal—cannot increase generation fast enough during daily peaks of demand. Excess demand causes a variation in the frequency of the transmission that can damage equipment connected to the grid.

The traditional solution is to combine base-load power plants with peaking power plants. The base-load plants generate more electricity than projected demand, therefore unused energy is continuously wasted.  The peaking plants are immediately switched on when base load is not enough. These peaking plants are very expensive but they sit idle for most of the day—or the year—therefore underutilized capital is continuously wasted.

To minimize energy waste and capital underutilization different methods for grid energy storage have been developed over the years. As an example, pumped hydro. Here, water is pumped uphill during the night—when electricity demand is lower—to run downhill through electric turbines during the day—when demand is higher. A brute force approach to energy storage.

Large batteries are a much more precise and efficient method. Several different battery technologies have been tried: nickel-cadmium, sodium-ion, liquid metal, etc. These batteries have limited lifespans and high maintenance; besides being quite expensive.