Natural gas enters the reformer, where it is converted to hydrogen and carbon monoxide before being fed into the fuel cells. A blower moves air into the fuel cells. Electrochemical reactions between the fuel and air in the fuel cells result in the generation of DC electricity. The hot exhaust from the fuel cell is piped to the double-effect chiller, where it boils a dilute chemical solution in the chiller’s high-temperature generator. In heating mode, this heat gets transferred to the building’s ventilation system by condensing the chemical solution over a heat exchanger supplied with circu- lating water. Alternately, when used to air condition, the exhaust heat is turned into refrigeration by using an absorber, compressor, condenser, and evaporator. This refrigeration is transferred to the building by circulating cold water from the evaporator to coils in the building’s ventilation system. The result is clean exhaust.