Emissions Comparison of Alternative Fuels in an Advanced Automotive Diesel Engine

Measurements of exhaust emissions were conducted for six alternative diesel fuels in a 2.2L, direct-injection diesel engine. Triplicate 13-mode, steady-state test sequences were performed for each fuel, as well as an ASTM D975 low sulfur No. 2 diesel (2DLS) control fuel, which served as the baseline. The alternative fuels include California Reference fuel, a low-sulfur diesel, a Fischer-Tropsch diesel, and three blends: 20 percent Fischer-Tropsch/80 percent low-sulfur diesel; 20 percent biodiesel/80 percent low-sulfur diesel; and 15 percent DMM/85 percent low-sulfur diesel. All six alternative fuel formulations demonstrated benefits by reducing particulate matter (PM) emissions without significant increases in oxides of nitrogen (NOx). The largest decrease in PM emissions was achieved with the 15 percent DMM blend. On average, over the 13 test points, the DMM blend reduced PM emissions by 52 percent in comparison to the baseline diesel fuel.