But Are They Compatible?
New biofuels must be compatible with
America's existing transportation infrastructure.
The ultimate goal of ORNL's BioEnergy Science Center is, naturally, to produce biofuel—but not just any biofuel. To achieve the center's goal of helping to reverse the nation's dependence on oil imports, a successful biofuel will need to be a stepping stone that fits neatly into America's current fuel infrastructure as part of a path to a transportation system that rests far less heavily on petroleum products.
The research performed by Distinguished Scientist Bruce Bunting and his colleagues at ORNL's Fuels, Engines and Emissions Research Center (FEERC) focuses on ensuring that new biofuels meet both requirements. The research, funded in large measure by the Department of Energy's Office of Energy Efficiency and Renewable Energy through the Vehicle Technologies Program, is coordinated with the Office of Biomass Programs. The studies include the evaluation of biofuels for compatibility with existing cars and trucks, as well as with fuel production and delivery systems. Bunting explains that the transportation fuel infrastructure in the U.S. is made up of refineries, product pipelines, terminals that store fuel locally and trucks that transport fuel to service stations and trucking depots. "That system," he says, "has evolved over much of the last century to handle petroleum products, and does an excellent job of providing high-quality, reliable fuels. The easiest way to adapt biofuels to this system is to make them as similar as possible to the existing petroleum- based fuels."
FEERC scientists evaluate new fuels from a variety of sources, including those made by the BioEnergy Science Center, to determine whether they meet industry standards and to evaluate their impact on engine performance. They also provide feedback on chemical factors that improve engine performance and the compatibility of new biofuels with existing fuels. The process of testing new biofuels usually follows a similar pattern. Once the biofuel is blended with standard gasoline or diesel fuel, FEERC researchers analyze the mix to ensure that the blend meets industry standards for fuel quality. The fuel is then run in a highly instrumented laboratory engine to determine whether it meets performance expectations. Finally, the new fuel may be
The majority of biofuel currently being produced is ethanol. Unlike gasoline, ethanol mixes easily with water, which can cause problems if it enters a vehicle's fuel system. Because water is present at various points in the fuel distribution infrastructure, fuel companies keep ethanol and water separated by transporting ethanol to fuel terminals and blending it with gasoline late in the distribution process, literally as fuel trucks are loaded at the terminals. One potential alternative to using ethanol as a biofuel would be to make ethanol and then chemically convert it to hydrocarbons. Not only would this process help avoid water-related problems, but the hydrocarbons could be blended with gasoline or diesel fuel directly at the refinery. Because both gasoline and diesel fuel are blended from a variety of components, Bunting expects that successful biofuels will mimic one or more of these components and be blended into the fuel in a similar way. He notes that producing biofuels with higher octane (for gasoline) or cetane (for diesel) values might be the most effective approach because the components are worth more per gallon, making them more attractive to fuel producers. "Our goal," Bunting says, "is to use this process to replace about 20 percent of the nation's petroleum-based fuel consumption over the next ten years."
While Bunting discourages the idea of an undiscovered magic bullet that would revolutionize transportation fuel production, he does identify potential improvements that he views as realistic. "New fuels have to meet a number of requirements," he says. "Most importantly, they must be compatible with existing vehicles. They also need to be compatible with the distribution system. And of course, biofuels must attract enough interest from the investment community to make them commercially viable." Improvements seen by the consumer, he suggests, are likely to be gradual, making it easier to meet regulatory requirements and allowing a skeptical public to gain confidence in the new fuels.
Bunting expects the development of improved biofuels to be accompanied by improvements in engine technology. "We are working with DOE, other national labs, universities and industry to explore engine designs that could couple the advantages of biofuels with technologies designed to optimize their performance. Our team is examining advanced combustion technologies that could produce improved fuel economy and lower emissions. Studies like these enable us to work in parallel to improve both engines and fuel at the same time."
At first glance, the applied research conducted by Bunting and other fuels researchers at FEERC appears very different from that taking place in the bioenergy laboratories. The reality, however, is that these studies are just another step in the biofuels development process that spans disciplines ranging from land-use planning and agronomy to molecular biology and materials science. More important, this particular step bridges the gap between the concept of sustainable biofuels and the goal of a marketable product that could contribute to greater domestic production in the transportation fuels sector. Bunting is optimistic about the potential of biofuels to reach this ambitious goal. "I like to say we are gathering data that will be used by others to make decisions about future fuels," he explains. "We cannot tell energy companies what to make, but we are providing solid research to help guide their decisions. I think that's the most positive benefit of this research—working with these companies to help shape the future."