ARB Research Seminar

This page updated June 19, 2013

Life Cycle Emissions from Alternative Fuels in Heavy Vehicles

Professor Tom Beer, Commonwealth Scientific and Industrial Research Organization (CSIRO), Atmospheric Research Division, Aspendale, VIC, Australia

July 30, 2001
Cal EPA Headquarters, 1001 "I" Street, Sacramento, California

CSIRO Report


Professor Beer has examined available information on low and ultra-low sulfur diesel and alternative fuels for heavy vehicles in terms of their emissions of greenhouse gases and air pollutants. This is done within a life-cycle framework that considers both the pre-combustion emissions and the tailpipe emissions during combustion. This approach is sometimes called the full fuel-cycle or the "wheel-to-wheel" emissions (even though the raw materials for bio-fuels do not come from wells) and considers the chain of feedstock production, feedstock transportation, fuel production, fuel distribution and, finally, vehicle use.

The fuels examined were low sulfur diesel (LSD), ultra-low sulfur diesel (ULS), compressed natural gas (CNG), liquefied natural gas (LNG), liquefied petroleum gas (LPG), ethanol, diesohol, canola oil, bio-diesel, and waste oil.

Greenhouse gas emissions bio-diesel has the lowest greenhouse gas emissions on a life-cycle basis. In fact, bio-diesel emits larger quantities Of C02 than conventional fuels, but as most of this is from renewable carbon stocks, that fraction is not counted towards the greenhouse gas emissions from the fuel. Ethanol comes next and then the gaseous fuels (LPG, CNG, LNG). The life-cycle emissions of greenhouse gases from diesel are reduced if waste oil is used as a diesel extender, but the processing energy required to generate LSD and ULS in Australia increase their greenhouse gas emissions compared to diesel fuel. The extra energy required to liquefy and cool LNG means that it has the highest life-cycle greenhouse gas emissions of all the fuels that were considered.

We used a risk-weighted scoring system, based on estimates of human health risk, to rank the fuels. On a life-cycle basis, the gaseous fuels (LPG, CNG) give the lowest contribution to air pollution on this criterion. In the case of urban buses, LSD and ULS come next (though these results are based on only one UK test), then ethanol. The use of waste oil as a diesel extender increases air pollution. Bio-diesel scores poorly in relation to air quality because its production and use generates considerable amounts of particulate matter.

Speaker Biography

Professor Tom Beer coordinates the CSIRO Environmental Risk Network, and is an adjunct Professor in the Graduate College of Management of Southern Cross University. Professor Beer is chair of the Commission on Risk and Sustainability (Geo Risk Commission) of the International Union of Geodesy and Geophysics ( During 1999 he organized the all-union Symposium on Geophysical Hazard and Risks at the IUGG assembly in Birmingham.

Professor Beer is an international expert on environmental risk, including greenhouse gas and air quality issues. During 2000 Professor Beer coordinated a team that provided assistance to the Australian Greenhouse Office in the evaluation life-cycle emissions from alternative fuels used in heavy vehicles. In addition, he wrote the urban pollution section of the atmospheric chapter of the Australian 2001 State of the Environment report.

Professor Beer is a member of the National Committee for the Environment of the Australian Academy of Science. He serves as a member of the Standards Australia committees on risk management, and risk management systems. Professor Beer's present editorial activities include the Editorship of the journal Natural Hazards and positions as a member of the Editorial Board of Environment International, and as a guest editor for Mathematical and Computer Modeling. He is the author of nine books and over one hundred articles in refereed journals.

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