Biofuels, such as ethanol, can displace the use of non-renewable energy sources in transportation. ...
... "Keys to the Future: An important way to limit future transportation greenhouse gas emissions is to increase reliance on fuels made from renewable resources. For example, Argonne National Laboratory has estimated that it is possible to achieve emission reductions of up to 25 percent by switching to corn-based ethanol fuels now; and, with wider use, a reduction of about 30 percent might be possible ...
An emerging issue only beginning to be discussed by the public in 1975 was the potential for global climate change resulting from the buildup of greenhouse gases in the atmosphere. One of the most important of these greenhouse gases is carbon dioxide, and transportation is a major source of this. In 1975, transportation produced 350 million metric tons of carbon dioxide (CO2) emissions, and the atmosphere carried 330 parts per million CO2 by volume. Today, transportation produces nearly 500 million metric tons of CO2 per year, and atmospheric loading is estimated to be about 370 parts per million—1.3 times pre-industrial levels. 
Transportation will always require energy. Achieving sustainable energy for transportation will require that pollutant emissions fall faster than traffic grows, that greenhouse gas emissions are controlled to acceptable levels, that dependence on oil is reduced, and that energy resources for transportation expand faster than they are consumed.
The USDOT is laying the foundation for this broad-based approach to sustainability as related to transportation. The Department has formed a Center for Climate Change and Environmental Forecasting, which is conducting research and development solutions that can address long-term environmental problems while accomplishing other national transportation goals. The Center is the USDOT’s focal point for technical expertise on transportation and climate change. One of its primary goals is to develop compliance and multimodal approaches to reduce transportationrelated greenhouse gases. The USDOT also has launched Smart Growth initiatives focused on the interaction between transportation investments and land use. These, and related initiatives, will address both current and future challenges in enhancing and preserving communities and the natural environment. " ...
Biofuels Support Greenhouse Gas Reduction: Via U.S. Department of Transportation: Bureau of Transportation Statistics: The Changing Face of Transportation (PDF), BTS00-007 ...
