The idea of converting sunlight, water and carbon dioxide into usable chemical energy—that can be stored like gasoline for extended periods of time—has long been a tantalizing target for scientists.
Solar fuels involved taking carbon dioxide captured from the atmosphere and splitting off carbon atoms from those molecules. Then, by breaking hydrogen atoms off from water, you use that carbon and hydrogen to create hydrocarbons—the same chemical entities that make up the fossil fuels we use today. If researchers can find a way to make these chemical reactions work at scale using solar energy as a catalyst, they'd have a way to turn the sun's energy into a storable medium while recycling carbon dioxide that's already in the atmosphere back into usable chemical fuel.
The science isn't quite there yet, but researchers at Harvard's Nocera Lab, MIT's Grossman Group and the University of North Carolina's Energy Frontier Research Center have made strides over the past decade.