Determination of alternative fuels combustion products: Phase 3 report

This report describes the laboratory efforts to characterize particulate and gaseous exhaust emissions from a passenger vehicle operating on alternative fuels. Tests were conducted at room temperature (nominally 72 F) and 20 F utilizing the chassis dynamometer portion of the FTP for light-duty vehicles. Fuels evaluated include Federal RFG, LPG meeting HD-5 specifications, a national average blend of CNG, E85, and M85. Exhaust particulate generated at room temperature was further characterized to determine polynuclear aromatic content, trace element content, and trace organic constituents. For all fuels except M85, the room temperature particulate emission rate from this vehicle was about 2 to 3 mg/mile. On M85, the particulate emission rate was more than 6 mg/mile. In addition, elemental analysis of particulate revealed an order of magnitude more sulfur and calcium from M85 than any other fuel. The sulfur and calcium indicate that these higher emissions might be due to engine lubricating oil in the exhaust. For RFG, particulate emissions at 20 F were more than six times higher than at room temperature. For alcohol fuels, particulate emissions at 20 F were two to three times higher than at room temperature. For CNG and LPG, particulate emissions were virtually the same at 72 F and 20 F. However, PAH emissions from CNG and LPG were higher than expected. Both gaseous fuels had larger amounts of pyrene, 1-nitropyrene, and benzo(g,h,i)perylene in their emissions than the other fuels