Scientists develop the first solar fuels reactor that works at night

Researchers have developed the world’s first solarfuels reactor that is able to function at night. Called CONTISOL, the solar fuels reactor is capable of producing fuel such as hydrogen without the intensive greenhouse gas emissions caused by creating the fuel from burning natural gas. CONTISOL is able to run at all hours of the day because it relies on concentrated solar power (CSP), which allows for thermal energy storage. Notably, the reactor uses air, which is abundant, accessible, and non-corrosive, in order to store and transfer heat within the device. “It can pull air in just out of the atmosphere and then runs it through the heat exchanger to store the heat,” explained study lead author Justin Lapp, “and then it can vent that air out once it is cool.”

In a traditional solar fuels reactor, the process depends upon the solar thermal heat provided by the sun. When the sun disappears at night, so too does its energy. Scientists at the German Aerospace Center (DLR) developed their all-hours solar fuels reactor by combining two previously developed systems. “So the main idea of CONTISOL was to build two reactors together,” said Lapp. “One where sunlight is directly doing chemical processing; the other side for storing energy. In the chemical channels, the high temperatures of the material drives the chemical reaction and you get a change from reactants to products within those channels.” This balancing act provides CONTISOL with stable temperatures and an efficient heat source for powering reactions that create fuels like hydrogen.

So far, the team has only developed a small-scaleprototype that is capable of operating at 850 degrees Celsius with an energy output of 5kW. “This scale is a scientific prototype simply for us to understand how to control it. It wouldn’t be commercialized at 5 kW,” said Lapp. “Commercially, 1-5 MW would be about the smallest for industrial-scale reactors, and they could scale to 100 MW or even larger.” Though still in its early stages, a full-scale CONTISOL system would allow for low-impact access to clean hydrogen fuel when fully developed and deployed.