Low-carbon emission

The main components of automobile exhaust are carbon dioxide (CO₂) and water vapor (H₂O). Carbon dioxide is the most important anthropogenic greenhouse gas (GHG) and the most significant Greenhouse Gas emitted in the U.S. (with 82-84% of all U.S. emissions). Increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change.

The CO₂ emission standards can be referred to the fuel or to the vehicle :

CO₂ mass emission in vehicles is measured in g/km (g/mi * 0.621371192 = g/km).

Transportation accounts for forty percent of California's annual greenhouse gas emissions, and California relies on petroleum-based fuels for 96 percent of its transportation needs.

The Californian Governor Arnold Schwarzenegger issued an Executive Order in January 2007 for California adopt a Low-Carbon Fuel Standard (LCFS). The LCFS requires oil refineries to ensure that the mix of fuel they sell in the California Market meets, on average, a declining target for greenhouse gas emissions measured in CO₂-equivalent grams per unit of fuel energy sold. By 2020, the LCFS will produce a 10 % reduction in carbon intensity from production and use of transport fuels in California.

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