Solar Reactor Works at Night

Cloudy days and even nighttime are no match for a new solar reactor that can keep chugging even when sunlight is in short supply.

The reactor, which is in the prototype stage, concentrates and stores solar energy and simultaneously uses it to run a chemical process. Designed by a team from the German Aerospace Center (DLR), the reactor has a smaller loss of efficiency than most solar systems that store heat, because part of the solar energy collected goes straight to the chemical process as long as the sun is up. But because it can pull energy from storage, it can also run at times when there is no light, and at times when transient declines in solar energy — like a cloud passing — might otherwise slow the reactor.

Solar reactors usually work either directly, by capturing sunlight and using the heat to drive a reaction process, or indirectly, by capturing sunlight, storing the heat in a fluid or ceramic solid, and then pulling the heat back out to run the reaction. Indirect systems can work when the sun is not shining brightly, but heat is always lost in the process. “We were trying to have the benefits of both an indirect and a direct...