Cogeneration also referred to as combined heat and power (CHP) has many benefits if it is properly sized, designed, constructed, and controlled. The strategy of using a prime mover to drive a generator producing electricity and using the heat generated in the process can result in overall efficiencies greater than 90%. The ability to capture and use the waste heat and the difference in the cost to produce the electricity locally rather than buying it for the grid (spark spread) is what drives the economics of CHP. The prime movers are typically reciprocating engines or gas turbines and the waste heat is recovered through heat exchangers which produce useful energy in the form of hot water or steam. Cogeneration is available in packaged units at smaller sizes (> 1000 kW) and custom designed and field constructed for larger systems. CHP is capital intensive and the interconnection to the utility and system controls can be complex. In spite of the complexities, cogeneration can have economic benefits beyond return on investment, including improved resiliency and relieving overburdened electrical distribution systems.