Abstract: A single nonfired heat source, such as a diesel engine, drives a hydraulic pump. The hydraulic pump in turn is coupled in a hydraulic circuit with a back-pressure valve which loads the hydraulic pump and hence the diesel engine. The engine also circulates a heat exchanging fluid, such as engine coolant through a second circuit. Water or engine coolant is circulated through the second circuit by means of a pump driven by the diesel engine. An exhaust gas heat exchanger coupled to the exhaust gases from the engine may also be included within the water coolant, the exhaust gases or both, and is then transferred to noncirculating deicing fluid in a storage tank. Heat developed within the hydraulic circuit which loads the engine is also transferred to the noncirculating fluid in the storage tank.