SAN FRANCISCO - JANUARY 18:  A compressed natural gas (CNG) hose dispenses gas to a Honda Civic at a clean energy fuel station January 18, 2007 in San Francisco, California. California governor Arnold Schwarzenegger signed executive order S-01-07 establishing the world's first low carbon standard for transportation fuels in the state of California. The order will reduce dependence on oil and will lower carbon intensity of California's passenger vehicle fuels by at least 10 percent by 2020. Getty Images logo Getty Images 35 months ago

SAN FRANCISCO - JANUARY 18: A compressed natural gas (CNG) hose dispenses gas to a Honda Civic at a clean energy fuel station January 18, 2007 in San Francisco, California. California governor Arnold Schwarzenegger signed executive order S-01-07 establishing the world's first low carbon standard for transportation fuels in the state of California. The order will reduce dependence on oil and will lower carbon intensity of California's passenger vehicle fuels by at least 10 percent by 2020.