Cogeneration, also known as combined heat and power (CHP), is making good progress as an energy efficient technology in the United States, according to the US Energy Information Administration. Cogen generally means making concurrent use of energy generation technology with heat. For example, thermal (coal, oil or gas) electricity generation puts out large quantities of waste heat. By making use of that heat a cogen facility can improve its energy and economic efficiency. An existing heating plant can often be modified so as to produce electricity as well as steam heat for an industrial plant.
According to EIA, there are nearly 70 gigawatts (GW) of combined heat and power generating capacity in the United States, accounting for almost 7% of total U.S. capacity, with 25 GW in the industrial sector, 2 GW in the commercial sector, and 43 GW in the electric power sector. In 2011, the average capacity factor for generators at industrial CHP plants was 57%, the equivalent of running at full capacity 57% of the time.
Useful thermal output accounts for most CHP fuel consumption, rather than electricity production. CHP systems operate with a wide range of fuels. Natural gas is the most common primary energy source used in combined heat and power stations, followed by coal and biomass (often in the form of waste products at paper mills). The technology choice for a CHP facility depends on available fuel and the amount of generating capacity needed. Reciprocating internal combustion engines are widely used in small-to-medium applications (under 10 MW). Larger systems use industrial boilers, simple-cycle steam turbines, and gas turbines, as well as combined-cycle systems that are similar in design to combined-cycle units used in power production.
Many Canadian energy facilities are still not taking advantage of cogeneration opportunities. Owners often think that they are not appropriately sited, are too small, or have other barriers to expanding a steam heat plant to a cogen facility. The US is showing that cogen can be a real economic and environmental benefit.
For the EIA report visit http://www.eia.gov/todayinenergy/detail.cfm?id=8250