A reversible fuel cell (RFC) is a fuel cell that can consume chemical A to produce electricity and chemical B and be reversed to consume electricity and chemical B to produce chemical A. A hydrogen fuel cell, for example, uses hydrogen (H2) and oxygen (O2) to produce electricity and water (H2O); a reversible hydrogen fuel cell could also use electricity and water to produce hydrogen and oxygen[1][2].
By definition, the process of any fuel cell could be reversed. However, a given device is usually optimized for operating in one mode and may not be built in such a way that it can be operated backwards. Fuel cells operated backwards generally do not make very efficient systems unless they are purpose-built to do so. Because of this, fuel cells operated in forward-reverse mode are not suited for energy storage systems in small and medium scale.
Although most fuel cells operated in the reverse mode are sold as learning kits or curiosities, there are emerging uses for a reversible fuel cell particularly around the on-board production of hydrogen in motor vehicles using thermoelectric recovery.
