Existing and developing methods for harnessing waste heat
In the United States, only about one-eighth of the fuel people burn is converted into useful work. For a variety of reasons — losses during transmission of electrical power, simple laws of thermodynamics, friction and other inefficiencies — the other seven-eighths of the energy goes unused.
The statistics are slightly better for power plants that use fossil fuels: Only two-thirds of the energy locked in the fuel ends up as waste heat, says Thomas R. Casten, an economist and chairman of Recycled Energy Development in Westmont, Ill. In many parts of the world, and especially in developed nations, power plants are typically located far from urban areas. So, he and colleague Phil Schewe of the American Institute of Physics note in the January-February American Scientist that heat is simply dumped into the environment: While electricity can easily be transmitted long distances