Environmental Benefits

Basic Information

CHP Environmental Benefits Tools and Resources

CHP Emissions Calculator: compares the anticipated air emissions from a CHP system to those of a separate heat and power system.
ENERGY STAR^® CHP Awards: recognizes CHP projects for their environmental leadership to analyze the emissions reductions for your own facility.

Combined heat and power (CHP) systems offer considerable environmental benefits when compared with purchased electricity and onsite-generated heat. By capturing and utilizing heat that would otherwise be wasted from the production of electricity, CHP systems require less fuel than equivalent separate heat and power systems to produce the same amount of energy.

Because less fuel is combusted, greenhouse gas emissions, such as carbon dioxide (CO₂), as well as criteria air pollutants like nitrogen oxides (NO_x) and sulfur dioxide (SO₂), are reduced. The following diagram shows the magnitude of reduced CO₂ emissions of a 5 megawatt (MW) natural gas-fired CHP system compared with separate heat and power used to produce the same energy output.

Conventional Generation vs. CHP: CO₂ Emissions

This graphic shows the emission differences of separate heat and power versus combined heat and power (or CHP). The separate heat and power system emits 49 kilotons of carbon dioxide per year (13 kilotons from the boiler and 36 kilotons from the power plant), while the CHP system, with its higher efficiency, emits 23 kilotons of carbon dioxide per year.

This diagram illustrates the CO₂ emissions output from power and thermal energy generation for two systems: (1) a separate heat and power system with a fossil fuel-fired power plant (emissions based on the U.S. fossil mix) and a natural gas-fired boiler; and (2) a 5 megawatt combustion-turbine CHP system powered by natural gas. The separate heat and power system emits a total of 49,000 tons of CO₂ per year (13 kilotons from the boiler and 36 kilotons from the power plant), while the CHP system, with its higher efficiency, emits 23,000 kilotons of CO₂ per year.

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Since its inception in 2001, the CHP Partnership has assisted more than 160 projects representing 3,460 MW of new CHP capacity. On an annual basis, these projects will prevent the emission of more than 2.5 million metric tons of CO₂ equivalent.

To analyze the emission reductions for your own facility, please utilize the CHP Emissions Calculator, which compares the anticipated air emissions from a CHP system to those of a separate heat and power system.

Verifying Environmental Benefits

EPA's Greenhouse Gas Technology Center has developed technology verification reports that certify the emissions benefits associated with CHP:

Monetizing Environmental Benefits

The environmental benefits of CHP can be quantified and in many cases, monetized. Many states have renewable portfolio standards or emissions trading programs for which CHP may qualify for tradable credits. For more information, please visit the Monetizing Environmental Benefits page.

Additional Resources

The CHP Partnership collaborates with other government and nongovernmental agencies and programs that are interested in promoting the environmental benefits of CHP. The following resources provide further insights into the benefits of CHP for reducing air emissions:

An Integrated Assessment of the Energy Savings and Emissions-Reduction Potential of Combined Heat and Power (PDF), (12 pp, 47K, About PDF) , Northeast-Midwest Institute, American Council for an Energy-Efficient Economy (ACEEE), and International District Energy Association (IDEA), June 1999.
Air Emissions Benefits of CHP (PDF), (23 pp, 816K, About PDF) , EPA's CHP Partnership, August 2004. Presentation to the Air Innovations Conference, Chicago, Illinois. Discusses the emission benefits of CHP with a focus on the refinery and casino/hotel markets.

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