The transportation sector is the largest source of U.S. greenhouse gas emissions. While transportation sector emissions have fallen by 6.1% from their 2005 peak, transportation sector emissions grew about 21.5% from 1990 to 2016, largely driven by increased demand for travel based on economic and population growth, low fuel prices, and urban sprawl. To change this trajectory, the states shown on this map have enacted low carbon fuel standards (LCFS) and alternative fuel standards. Please also see the C2ES map outlining additional Clean Vehicles Policies and Incentives.  

An LCFS aims to reduce greenhouse gas emissions from transportation fuels without prescribing the fuel type. It is a life-cycle intensity standard, which means that (a) it looks at the whole life cycle of the fuel –producing it, moving it, and using it in a vehicle engine, and (b) it is measured not in absolute emissions, but rather in intensity – for example, grams of greenhouse gases per unit of fuel energy. Typically, an LCFS requires a regulated fuel provider to reduce its average fuel carbon intensity by some amount from a defined baseline year. For instance, California’s LCFS requires fuel suppliers to reduce their carbon intensity by 20% by 2030 from a 2010 baseline. LCFS programs typically allow for trading and banking of emission credits in order to enhance flexibility and support innovation. 

Alternative Fuel Standards requires a certain percentage of total gasoline or diesel sold to be sourced from alternative fuels, such as cellulosic and noncellulosic ethanol and biodiesel. These vary in structure from state to state and are sometimes referred to as renewable fuel standards and biodiesel mandates.   

Last Updated: January 2019