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Advanced Combustion Engines

Although internal combustion engines have been used for more than a century, significant improvements in energy efficiency and emissions reduction are still possible. Because of their relatively low cost, high performance, and ability to use renewable fuels (e.g. ethanol and biodiesel), conventional vehicles with combustion engines will likely dominate the market for at least the next 20 years. The United States can cut its transportation fuel use 20%–40% through commercialization of advanced engines—resulting in greater economic, environmental, and energy security. As hybrids and plug-in hybrids become cost competitive and gain market share, employing advanced combustion engines in these vehicles will enable even greater fuel savings.

The Advanced Combustion Engine R&D subprogram of the U.S. Department of Energy's Vehicle Technologies Program (VTP) is improving the fuel economy of passenger vehicles (cars and light trucks) and commercial vehicles (medium-duty and commercial trucks) by increasing the efficiency of the engines that power them. Work is done in collaboration with industry, national laboratories, and universities, as well as in conjunction with the FreedomCAR and Fuels Partnership for passenger vehicle applications and the 21st Century Truck Partnership for commercial vehicle applications. More information about the subprogram can be found in the brochure Advanced Combustion Engine R&D: Goals, Strategies, and Top Accomplishments (PDF 1.1 MB). Download Adobe Reader.

Passenger and Commercial Vehicle Goals

More than 230 million cars and light trucks consume three quarters of U.S. highway transportation fuel, mostly as gasoline. Our strategy for the passenger vehicle sector is two-pronged: 1) demonstrate cost-competitive, production-ready vehicles with advanced gasoline engines that are at least 25% more efficient than conventional engines by 2014; 2) demonstrate cost-competitive, production-ready diesel passenger vehicle engines based on high-efficiency clean combustion technologies that are at least 40% more efficient than current gasoline engines by 2014.

Although they account for fewer than 5% of highway vehicles, medium-duty and commercial vehicles account for a quarter of the fuel used. These vehicles are big, and they are driven constantly. We aim to build on these results by demonstrating a 50%-efficient commercial engine in 2014, which represents a 20% improvement over today's engines and a 55% efficient engine by 2017.

Strategies for Developing Higher-Efficiency, Cleaner-Burning Engines

Our strategies for achieving higher engine efficiencies focus on three complementary technology pathways involving collaborative partnerships with vehicle and engine manufacturers, suppliers, national laboratories, and universities:

  1. Improve the fuel economy of traditional spark-ignited gasoline engines by more than 25% using advanced technologies such as downsizing, variable compression ratio, and lean-burn engine operation.
  2. Develop new combustion approaches that are more efficient than diesel combustion, but with near-zero emissions, which could enable engines to meet emissions regulations without the complicated and expensive equipment that is currently required.
  3. Recover energy from the engine's exhaust to achieve a 10% or greater efficiency improvement using turbocompounding/turbocharging, bottoming cycles, and thermoelectric devices that convert heat to electricity for powering the vehicle and auxiliary loads.

Research and development (R&D) efforts focus on improving engine efficiency while meeting future federal and state emissions regulations through a combination of: combustion technologies that minimize in-cylinder formation of emissions; aftertreatment technologies that further reduce exhaust emissions; and understanding fuel property impacts on combustion and emissions. Technologies that improve the overall engine performance are also pursued. Activities include: Combustion and Emission Control R&D, and Solid State Energy Conversion R&D.

Sandia National Laboratories advanced laser diagnostics. Sandia National Laboratories advanced laser diagnostics.

Sandia National Laboratories Engine Combustion Research. Data from multiple advanced laser diagnstics have substantially improved understanding of engine combustion and emissions formation.

Benefits

Research and development would enable advanced high-efficiency, low-emission internal combustion engines to be commercially viable and available for passenger vehicles (cars and light trucks) and commercial vehicles (medium and heavy trucks). Over the past five years, commercial engine research and development (R&D) funded by VTP has saved more than 2 billion gallons of petroleum-based fuel, resulting in fuel cost savings many times greater than the federal investment. Commercialization of these technologies would lead to an improved vehicle fuel economy and, therefore, a dramatic overall reduction in transportation petroleum use.

Current Annual Progress Reports