Alternative Fuels: Compressed Natural Gas (CNG)
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.
The current CARB CNG specification has been undergoing review for a possible update. CARB staff has temporarily put the review effort on hold while ASTM International is developing a fuel quality specification for natural gas used as a motor vehicle fuel (See ASTM Work Item (WK) 40094). The work item is currently going through the ballot process. CARB staff has been participating in the work item development and will wait until the item completes balloting before deciding whether the current CARB specification needs to be amended.
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
- 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
For more information about the Compressed Natural Gas Motor Vehicle Fuels, please contact Alexander Mitchell.
Archived Meetings & Workshops
|Description & Materials
|May 19, 2010
|Public Meeting in Sacramento from 9:00 a.m. to 12:00 p.m. to Discuss Compressed Natural Gas (CNG) Fuel Specifications.
|August 3, 2005
Public Consultation Meeting in Sacramento from 10:00 a.m. to 3:00 p.m. to Discuss a Draft Proposed Concept to Revise the Motor Vehicle CNG Specifications.
|February 17 and 18, 2005
Change of Date: Natural Gas Quality Workshop Notice
The California Energy Commission and the California Public Utilities Commission will conduct a joint workshop to address natural gas quality issues on February 17 and 18, 2005 in San Francisco, CA.
December 8 and 9, 2004
Natural Gas Quality Workshop Notice
The workshop is being conducted in collaboration with the California Air Resources Board and the California Department of Conservation’s Division of Oil, Gas, and Geothermal Resources.
May 9, 2002
Notice of Cancellation
The Hearing for consideration of amendments to the California Alternative Fuels for Motor Vehicle Regulations has been cancelled. A new notice will be published at least 45 days in advance of the public hearing.
March 28, 2002
Notice of Change Location
The Meeting Location for Public Hearing scheduled on May 16, 2002 for considering the adoption of Proposed Amendments to the Compressed Natural Gas and Liquefied Petroleum Gas Specifications in the California Alternative Fuels for Motor Vehicle Regulations has been changed.
February 19, 2002
Notice of Postponement
The Public Hearing scheduled on February 21, 2002 for considering the adoption of: Proposed Amendments to the Compressed Natural Gas and Liquefied Petroleum Gas Specifications in the California Alternative Fuels for Motor Vehicle Regulations has been postponed.
February 14 and 15, 2002
December 21, 2001
|Proposed Amendments to the Compressed Natural Gas and Liquefied Petroleum Gas Specifications in the California Alternative Fuels for Motor Vehicle Regulations. For more information please go to the formal rulemaking area.
March 7, 2001
June 21, 2000
|October 29, 1998
Workshop Notice for October 29, 1998 Re: Evaluation of the Motor Vehicle Fuel Specifications for Compressed Natural Gas