The simultaneous production of power and another form of useful thermal energy from a single fuel-consuming process. The most common cogeneration systems being constructed today utilize combustion or co-combustion processes to produce electricity via a turbine as the principal product and steam and/or hot water as by-products. The electricity generally is sold to a utility or used for adjacent industrial processes and the steam and hot water generally are exported to adjacent companies for industrial process uses and for space heating. When combusting fuels in typical boilers, cogeneration is significantly more energy efficient than the generation of electricity alone. Approximately 75 percent of the energy value in the fuel can be extracted in a cogeneration facility compared to approximately 35 percent when electricity is produced solely. (Singer, Joseph G., "Combustion Fossil Power," Fourth Edition, Combustion Engineering, Inc., Windsor, Conn., 1991; Lund, Herbert F., "The McGraw-Hill Recycling Handbook," McGraw-Hill, Inc., New York, 1993).