California Code, Public Utilities Code - PUC § 2840.4

(a) Combined heat and power systems produce both electricity and thermal energy from a single fuel input, thus achieving much greater efficiency than the usual separate systems for producing these forms of energy, and reducing consumption of fuel.

(b) Combined heat and power systems recover heat that would otherwise be wasted in separate energy applications, and use this heat to avoid consumption of fuel that would otherwise be required to produce heat.

(c) Gigawatthours of potential useful electricity and millions of British thermal units of thermal energy could be derived from unused waste heat that is currently being vented into the atmosphere.