Report calls for development of advanced combustion engines for success of biofuels

By Holly Jessen | August 27, 2010
Posted Sept. 20, 2010

Although it's frequently overlooked, research and development of next-generation fuels should be done in conjunction with development of engines, according to a Sandia National Laboratories report released Sept. 15. "The oil companies and the automobile and truck engine companies have engaged in a dialogue and collaboration on fuel and engine issues for almost 100 years," said Ron Stoltz, manager of Sandia's Advanced Energy Initiatives. "But the same cannot be said for the majority of biofuel start-up companies, especially those that are thinking beyond ethanol'. The report highlights how fragmented the biofuels industry is today and how, by putting serious thought behind some key issues like fuel chemistry linked to engine performance, great strides can be made."

The 40-page report was based on the results of a November 2009 workshop that was underwritten with help from Chevron. Participating were researchers from the U.S. DOE's Combustion Research Facility and Joint BioEnergy Institute, as well as representatives from biofuel developers, oil companies and engine manufactures. In addition, there were a variety of experts from universities, regulatory agencies and laboratory communities.

The goal of the workshop, Stoltz said, was to bring together researchers and experts in an effort to find ways to accelerate the transition to biofuels. The group came up with a list of key attributes to make next-generation fuels a reality. Biofuels must be:
Clean (at or below U.S. EPA-designated pollutants criteria);
Sustainable (a CO2 footprint below that of the petroleum-based fuels being displaced); and
Compatible (with current and future engine designs, and with current and future distribution infrastructure).

Among other things, the group agreed that a consolidated federally funded research program should focus on biofuels and advanced engines. Currently, there are two separate DOE program offices to fund research on these two topics. "A consolidated research program would accelerate the transition to biofuels for the transportation sector," the report said.

Workshop participants also came up with four key recommended actions:
1. Modernize the testing, specification, and certification of all fuels;
2. Plan and integrate the research and development of next-generation biofuels in conjunction with the development of advanced engines;
3. Develop specific guidelines, roadmaps, and objectives for co-development of next-generation biofuels and advanced engines; and
4. Convene an International Fuels and Engines Summit, sponsored by industry with government and university participation, to ratify a fuels/engine strategy and implementation framework.

Another suggestion by the group is that biofuels policy should shift from rural development to energy security. "This would change the incentive framework and the potential evolution of the U.S. fuels industry," the report said.

The report also contained a short article called "Designing Spark Injection Engines to Take Advantage of Ethanol" by Magnus Sjoberg of Sandia. "One effective technique for increasing the fuel mileage of vehicles powered by gasoline type spark ignition piston engines is to apply engine downsizing," Sjoberg wrote. "The reduction can be achieved by reducing the number of cylinders and/or by reducing the swept volume of each cylinder."

The article went on to say that if nothing else is done, the increased fuel mileage will come at the expense of peak torque and power. To maintain both power and torque intake, pressure boost can be applied by the use of a turbocharger or mechanical supercharger. The next hurdle, he said, is engine knock, about which auto-ignition data indicates that ethanol has superior resistance to knock for highly boosted operation. "In summary," Sjoberg said, "ethanol has a clear potential to enable increased engine efficiency through its good high pressure performance and true single- stage auto ignition characteristics, while simultaneously replacing petroleum by being a renewable fuel."

To view the entire report, see