Combined Heat and Power Partnership
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.
- Fuel and Carbon Dioxide Emissions Savings Calculation Methodology for Combined Heat and Power Systems (PDF) (32 pp, 1.3MB) presents a recommended methodology for calculating fuel and CO2 emissions savings from CHP compared to separate heat and power.
- 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 (NOx) 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 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 45,000 tons of CO2 per year (13 kilotons from the boiler and 32 kilotons from the power plant), while the CHP system, with its higher efficiency, emits 23,000 kilotons of CO2 per year.
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 technologies, including waste-to-energy technologies.
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, 45K, 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.