In the operation of power plants and other systems in the generation of power, there is usually the rejection of large amounts of thermal energy at relatively low temperatures. Some of those low temperature sources of energy are useful to space heating which does not require high temperature sources while in many other situations, and, in fact, more typically, high temperature sources of thermal energy (i.e., oil burning furnaces) are degraded for use in situations requiring more low grade heat (i.e., space heating).
There are ways which have been developed to make greater use of low temperature sources of thermal energy, even at temperatures not high enough for space heating. One such method is the so-called heat pump, which is the reversed refrigeration cycle. This method has the drawback of requiring the use of direct electrical power for its operation.