ARB Posts Draft Technical Analysis for California’s Low Carbon Fuel Standard; Ambitious, But Achievable
9 May 2007
|Production costs and GHG emissions for fossil hydrocarbon fuels. Click to enlarge.|
The California Air Resources Board has posted a draft technical analysis produced by the University of California in response to the governor’s Executive Order S-1-07, the Low Carbon Fuel Standard (LCFS). (Earlier post.)
An initial goal of the LCFS order requires a 10% reduction in the greenhouse gas emissions (GHG) intensity of all passenger vehicle fuels sold in California by 2020. The study concludes that the goals of the LCFS are ambitious, but achievable.
On the basis of a study of a wide range of vehicle fuel options, we find a 10 percent reduction in the carbon intensity of transportation fuels by 2020 attainable, but an ambitious target. With some vehicle and fuel combinations, a reduction of 15 percent may be possible. All of the technical options to reduce GHG emissions from the transportation sector (e.g. biofuel production and electric vehicles) have technical and economic uncertainties that need further evaluation and research, but there are many different options, of which many show great potential to lower the global warming impact of transportation fuels.
The LCFS requires fuel providers to measure the global warming intensity (GWI) of their products, measured on a per-unit-energy basis, and to reduce this value over time. “Global warming intensity” is a measure including not only greenhouse gases (GHGs) but also other processes (like land use changes that may result from biofuel production) that may affect the climate.
The study authors used grams of carbon dioxide equivalent per megajoule of finished fuel (gCO2e/MJ)—adjusted for inherent differences in the in-use energy efficiency of different fuels (e.g. electricity and hydrogen)—as the GWI unit of measure in the study.
To evaluate the technical feasibility of the proposed LCFS, the review team used 12 light-duty vehicle and fuel scenarios. The analysis considers population and economic growth, fleet turnover rates, and the effects of AB1493 (Pavley)—the law mandating the reduction of greenhouse gas emissions from new vehicles beginning in 2009.
The reviewers considered potential reductions in carbon intensity in heavy duty and off-road applications separately. They ignored emission reductions due to changes in oil production and refining, and the potential use of offsets from other sectors or from geologic sequestration of CO2.
These simplifying assumptions were made to permit the scenario analysis to be completed with the time and resources available, and are not policy recommendations.
Six of the scenarios meet or exceed a 10% carbon intensity reduction by 2020, including two that attain a 15 percent reduction.
These scenarios all contain plausible combinations of technological innovation and investment in low-carbon fuel production and distribution infrastructure, although opinions may differ about how easy or difficult they will be to achieve.
This analysis suggests that 5 percent reduction in carbon intensity is feasible with electric drive vehicles alone. However, electric drive vehicles comprise a tiny fraction of the light duty fleet today and significant technological innovation would be needed to gain large market penetration. Because vehicles last a long time, the fleet turns over relatively slowly, limiting the ability of changes in vehicle technology to make near-term contributions to lowering the GWI of fuels.
On the other hand, because they may not require substantial vehicle modifications, changes in fuel type and composition can happen more quickly, so we find that multiple scenarios could lead to the attainment of a 2020 carbon intensity reduction target of 10 percent.
For instance, if low-GHG biofuels are commercialized as in scenario D10, there may be no need for any change in vehicles in California and only modest changes to fuel delivery infrastructure.
Even if no technological innovation in biofuel production occurs, it may be that biofuels could still be used to lower carbon intensity by up to 15 percent by 2020, although such a strategy has considerable uncertainty associated with it. Up to 4 billion gallons of “mid-GHG” biofuels may be needed, over a four-fold increase from current consumption. More analysis is needed, however, to determine how such an expansion of biofuel production could be accomplished in an environmentally acceptable manner.
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