Alternative Fuels: Compressed Natural Gas (CNG)
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Background
Compressed Natural Gas (CNG) is a gasoline and diesel fuel alternative consisting primarily of methane. The gas is associated with other fossil fuels (coal or oil) and is created by methanogenic organisms in landfills. The gas is extracted from the source and compressed to a high pressure where it can be stored in a vehicle fuel tank.
Research Studies
CARB funded several studies that examine the emissions effect of natural gas. The first is the effect of natural gas fuel composition on vehicles study, which was conducted by the University of California at Riverside. This study examined the emission effects that lower Methane Number and higher Wobbe Index gas supplies may have on light and heavy-duty engines. CARB partially funded the heavy duty emission testing portion of the study. The second is the Tool for Emission Processing of LNG Expansion Scenarios (TEMPLES) study, which was developed by the University of California at Irvine (UCI). This study is a predictive model used to estimate changes in GHG and criteria pollutant emissions from mobile and stationary sources. The research studies culminated with reports covering the effect of gas quality on vehicle emissions and with a model that examines the air quality impact of changes to gas quality.
- Evaluation of the Performance and Air Pollutant Emissions of Vehicles Operating on Various Natural Gas Blends – Heavy-Duty Vehicle Testing – Phase 1, April 2014
- Evaluation of the Performance and Air Pollutant Emissions of Vehicles Operating on Various Natural Gas Blends – Phase 2, March 2015
- Impacts of Natural Gas Composition on Air Quality – An Assessment Using TEMPLES Model – Phase 1, May 2014
- Impacts of Natural Gas Composition on Air Quality – An Assessment Using TEMPLES Model – Phase 2, March 7, 2016
Converting Vehicles to Compressed Natural Gas Fuel
Individuals interested in converting gasoline or diesel vehicles to operate on an alternative fuel must ensure that the alternative fuel retrofit systems have been certified by CARB. For more information on converting a vehicle to run on compressed natural gas fuel, and for the list of certified retrofit systems for various vehicle makes and models, please visit CARB's web page that covers Certification of Alternative Fuel Retrofit Systems
Current Regulations
Related Links
- Low Carbon Fuel Standard
- Alternative Fuels Data Center - U.S. Department of Energy
- Alternative Fuels Program - U.S. EPA
- Drive Clean California - Search for CNG vehicles and learn more about CNG fuel
Contact
For more information about the Compressed Natural Gas Motor Vehicle Fuels, please contact the Fuels Program.