Over the past several years, biodiesel use has dramatically increased due to its potential emissions benefits, classification as a low-carbon/renewable fuel and ability to be integrated into diesel fleet applications without significant infrastructure or other substitution issues. Caltrans has largest fleet in California, so biodiesel would provide many benefits in terms of meeting environmental and energy security objectives. However, all aspects of biodiesel use needed to be thoroughly investigated, including potential benefits and liabilities, prior to widespread introduction into the Caltrans fleet. In this research project, the University of California, Riverside (UCR) completed a thorough literature investigation, surveyed current users, attended national technical sessions designing the strategic road-map and reviewing the progress for biodiesel, wrote specifications for Caltrans purchase of biodiesel and carried out a twelve-month field demonstration at Indio. Results of the research and field demonstration showed that biodiesel is a viable option for Caltrans. A caveat moving forward is that each site should carry out a thorough analysis of the implementation to include the cleanliness of their fuel tanks and the assurance that the delivered fuel meets ASTM D6751 specifications and the specified low temperature flow properties.

The research recommended that emissions be measured with Caltrans equipment rather than relying on published values and that work is being carried out in a follow-on Caltrans project.