There have been a number of U.S. federal and state incentive programs seeking to promote biodiesel and alternative fuels, such as the Energy Policy Act of 1992 (Public Law 102-486), which includes provisions for purchasing alternative fuel vehicles at the state and federal level. Another incentive program is the Cellulosic Biofuel Producer Tax Credit. A number of incentive programs expired in December 2011, causing concern among producers and investors. Some states have implemented biodiesel/bioheat programs, such as Vermont, Massachusetts, and Maine, as well as several major cities, such as Baltimore, Boston, and New York. Most of these programs are mandating a certain level (generally a few percent) of biodiesel/bioheat. Even though the science of nonfood feedstock biodiesel is sound, the production levels have been below expectations. For example, the U.S. Department of Energy estimated that cellulosic output would produce a billion gallons of biodiesel by 2018, which is far below the congressional mandate of 7 billion gallons. The reasons for the low production levels range from limited financial and governmental policy support to challenges of the production and usability of cellulosic biodiesel