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The biomass cogeneration plant pictured here is running at full capacity in Hennigsdorf, Germany. It has saved around 25 million liters of heating oil and reducing the city's CO2 output by 25,000 tons.

Coal- and gas-fired power plants produce large amounts of waste heat. Cogeneration systems, also known as combined heat and power (CHP), capture excess heat from electricity production and put the otherwise-forfeited thermal energy to work. It can be used at or near the site for district heating or to create additional electricity. Cogeneration avoids greenhouse gas emissions to the extent that it reduces reliance on fossil fuels for heating and electricity.

Many of the cogeneration systems currently online are found in the industrial sector. In countries such as Denmark and Finland, cogeneration makes up a significant part of the energy mix largely because of its use in district heating systems. In Denmark, around 80 percent of district heating and more than 60 percent of electricity demand is met by CHP.

The opportunity to reduce emissions and save money through cogeneration is significant because of the inherent low efficiency of electrical generation. From a financial viewpoint, adoption makes sense for many industrial and commercial uses, as well as for some residential uses. Cogeneration makes it possible to produce more energy with the same amount, and cost, of fuel.


power plants…34 percent efficient: EIA. Electric Power Annual 2015. Washington, D.C.: U.S. Energy Information Administration, 2016

internal combustion engine…wasted heat: Orr, B., A. Akbarzadeh, M. Mochizuki, and R. Singh. “A Review of Car Waste Heat Recovery Systems Utilising Thermoelectric Generators and Heat Pipes.” Applied Thermal Engineering 101 (2016): 490-495; U.S. Department of Energy. “Where the Energy Goes: Gasoline Vehicles.”

[U.S.] cogeneration…energy-intensive industries: DOE and EPA. Combined Heat and Power: A Clean Energy Solution. Washington, D.C.: U.S. Department of Energy, 2012.

Finland’s district heating…cogeneration: Fernandez Pales, Araceli. The IEA CHP and DHC Collaborative: CHP/DHC Country Scorecard: Finland. Paris: International Energy Agency, 2013.

Denmark…CHP…dates back to 1903: Kerr, Tom. The IEA CHP and DHC Collaborative: CHP/DHC Country Scorecard: Denmark. Paris: International Energy Agency, 2008.

district heating and…electricity…met by CHP: Kerr, Denmark.

MIT…challenged by the local utility: Zumbrun, Joshua. “The Most Efficient Power Plants.” Forbes. July 7, 2008.

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