Hydrogen is considered an alternative fuel under the Energy Policy Act of 1992. The interest in hydrogen as an alternative transportation fuel stems from its ability to power fuel cells in zero-emission vehicles, its potential for domestic production, and the fuel cell's potential for high efficiency. In fact, a fuel cell is two to three times more efficient than an internal combustion engine running on gasoline. Hydrogen can also fuel internal combustion engines, but unlike with fuel cells, it will produce tailpipe emissions and is less efficient. Several vehicle manufacturers have begun making light-duty hydrogen vehicles available in select regions like southern and northern California where there are hydrogen fueling stations.