US Patent 7020387 Hybrid water heater

A tankless water heater powered by a fuel cell. In preferred embodiments, a fuel cell powered water heater in which the fuel cell is electrically connected to the electrical system of the building in which the water heater is installed as well as to the public electrical power grid for providing emergency power to the building and/or power to the public electrical power grid, respectively. In alternative preferred embodiments, a tankless, solid oxide fuel cell powered water heater which utilizes heat from exhaust gases to heat input oxidant gases and, optionally, can be cooled by routing excess heat to the exterior of the building on hot days.