Computer-based simulation of molecule assemblies can estimate important properties of bioderived compounds such as vapor pressure and density.

Engineering the biofuels of the future

The United States burns approximately 377 million gallons of gasoline and 121 million gallons of diesel fuel every day, according to the U.S. Energy Information Administration. Those eye-popping numbers are driving the quest for more biorenewable fuels. Michigan State University AgBioResearch scientist Carl Lira is helping with that effort by designing and testing bioderived chemicals and additives.

“We are not going to flip a switch and one day go off of fossil fuels and onto biofuels,” said Lira, an associate professor in the Department of Chemical Engineering and Materials Science in the MSU College of Engineering. “We will transition to biofuels. As we go along that path, we have to look at the properties of components as well as how the additives and fuels will be made and delivered. We also have to have vehicles that will work with them.”

Most of the media buzz is about ethanol/gasoline fuels, but Lira works primarily with diesel fuels. He collaborates with other researchers on the synthesis of alternative fuels, computer simulations of possible additives, blending and characterizing properties, combustion characteristics and engine tests.

“There has been more work with ethanol and biobased gasoline fuels than diesel fuels, but bioderived diesel will be an important aspect in the future,” said Lira, who has been working on thermodynamic properties of chemicals for almost 25 years. He began working with bioderived chemicals about 10 years ago and with bioderived fuels about four years ago.

One aspect of his research includes cold flow properties. A problem with traditional biodiesel fuels is their behavior at low temperatures: they tend to gel and turn solid. This means that traditional biodiesel fuels cannot be used in Michigan or much of North America during a large portion of the year.

“We are trying to understand how to determine a minimum temperature of a blend as well as to synthesize blends that will function at low temperatures,” Lira said. “As a multicomponent liquid begins to cool, before it solidifies there is an intermediate point where the solution begins to look cloudy — the cloud point. That’s where small crystals are coming out of the solution. The cloud point is something we can measure. We want to know how the cloud point changes with different additives.

“The long-range goal is to know if an arbitrary petroleum fuel and an arbitrary additive are put together how the resulting fuel will work in the vehicle,” he continued. “Are you going to have trouble with how it behaves when it’s stored and delivered? Will the fuel lines in the vehicle plug up? Testing the cloud point tells us the trends that we would see.”

Another project uses computer simulations to predict vapor pressures and densities of various biocompounds.

“Vapor pressure and density are important at engine startup,” Lira explained. “We hope to develop a method to understand how to predict both of these factors in any given compound.”

In addition to collaborations with other faculty members, Lira has worked with Ford Motor Company engineers on determining the properties of bioderived diesel fuels and making some for testing.

“So far it’s just two or three different fuels, but if the engine is tuned properly, the fuels work just fine,” he said.

Lira has also done work for the Defense Logistics Agency, the U.S. Department of Defense’s largest logistics combat support agency. He said the military is interested in biofuels, but their strategic plan calls for using only one type of fuel in all vehicles from planes to trucks. Lira and his research group are looking at how bioderived products might be blended into the standard military fuel.

“We are taking a series of additives that we create or that could be created and are looking at the molecules and then asking, ‘What chemistry could be performed on these materials in a simple, inexpensive way to make a biobased blend?’,” he said.

The use of biofuels will increase, and Lira sees the importance of research to create optimum fuels.

“Our understanding of structural relationships is going to be a fundamental thing that’s needed as we move into the future,” he said. “New pathways and molecules will be the core that we need for the development of the best biofuels.”