Storing excess energy in firebricks for later use

In some areas, like Germany, California, and Iowa, so much renewable energy is sometimes generated that the price of electricity drops to nearly zero. This is uneconomical for power plants. Storing energy for later use means the power plants get a better price and the grid doesn’t fluctuate as much. Stored energy now is primarily done with pumped hydro and batteries, plus molten salt (in some solar thermal plants.)

Researchers are now looking at the ancient technology of firebricks. Excess electricity is converted to heat and stored in firebricks enclosed in insulated casing. The heat can be used for industrial purposes or converted back to electricity. A big advantage of firebricks is the cost is way less than batteries or pumped hydro.

Firebrick technology isn’t there yet for grid-scale power. However, it probably will be soon.

But by diverting much of that excess output into thermal storage by heating a large mass of firebrick, then selling that heat directly or using it to drive turbines and produce power later when it’s needed, FIRES could essentially set a lower limit on the market price for electricity, which would likely be about the price of natural gas. That, in turn, could help to make more carbon-free power sources, such as solar, wind, and nuclear, more profitable and thus encourage their expansion.

Once the amount of generating capacity provided by solar power reaches about 15 percent of the total generating mix, or when wind power reaches 30 percent of the total, building such installations can become unprofitable unless there is a sufficient storage capacity to absorb the excess for later use.

At present, the options for storing excess electricity are essentially limited to batteries or pumped hydroelectric systems. By contrast, the low-tech firebrick thermal storage system would cost anywhere from one-tenth to one-fortieth as much as either of those options.