SoCal Funds Westport HPDI CNG Work

8 December 2004

The California South Coast Air Quality Management District (AQMD) made a $1.95 million award to Westport Innovations to advance further the development of Westport’s proprietary High Pressure Direct Injection (HPDI) natural gas fuel systems (earlier post) for heavy-duty truck engines.

Under the program, Westport will continue developing its HPDI natural gas fuel systems for 450 hp Cummins ISX engines to meet approaching emissions regulations for NO_x and PM emissions set by the EPA and California Air Resources Board (CARB).

The AQMD contribution is part of a larger heavy-duty truck program undertaken by Westport and its partners. Westport recently announced a US $1.5 million cost-sharing subcontract with the U.S. Department of Energy's National Renewable Energy Laboratory.

Current medium- and heavy-duty natural gas engines use lean-burn spark ignition technology to achieve low emissions with full-load efficiencies slightly lower than those of conventional diesel engines. Part-load efficiencies for the natural gas engines, however, are much lower than those of diesel engines.

The Westport HPDI system directly injects a small quantity of pilot diesel fuel into the engine cylinder to provide diesel-like compression ignition for natural gas. This gives the engine the efficiency and low-speed torque advantages of compression ignition while using natural gas as the primary fuel.

With HPDI engines, approximately 95% of diesel consumed in a diesel heavy-duty truck is displaced with natural gas. HPDI natural gas engines can produce approximately 50% less NOx, 90% less PM, and 15%-25% less carbon dioxide emissions than equivalent diesel engines, according to Westport.