Beyond ethanol
Though ethanol has drawn most of the recent spotlight, a large number of other biofuel alternatives exist. One that is being actively researched at Penn State is biodiesel.
A renewable version of standard petroleum diesel, biodiesel can be made from vegetable oils, animal fats, even kitchen grease. In the U.S. it's made mostly from soybeans. Blended in with standard diesel at a ratio of up to 20 percent (known as "B20"), it burns well in existing diesel engines.
Five years ago, to demonstrate that fact, Glen Cauffman, manager of farms and facilities in the College of Agricultural Sciences, began a program to convert the college's farm equipment to biodiesel fuel. Cauffman also worked with Joe Perez and Wally Lloyd, emeritus faculty members in chemical engineering, who developed a program that has undergraduate students making biodiesel from leftover fryer grease donated by campus food services. By 2006, Penn State had converted all of its diesel equipment to run on B20 biodiesel.
For the past year, in collaboration with Pennsylvania-based tractor manufacturer Case New Holland, Cauffman and his staff have extended the experiment even further, running two unmodified New Holland tractors entirely on pure B100 biodiesel. "Thus far," Cauffman reports, "we have experienced no negative effects."
Andre Boehman Credit James Collins
Though biodiesel (mostly from rapeseed or canola oil) is used widely in Europe, research continues into its combustion properties, emissions, and its effects on diesel engines. Fuel scientist Andre Boehman has studied the impact of using biodiesel on what he calls the two "classic problems" of diesel engines: soot and nitrogen oxides, or NOx.
"Biodiesel tends to lower soot emissions," Boehman reports. "It also tends to make the particulate less carcinogenic. We've been able to postulate an oxidation mechanism for biodiesel soot that's very different from other diesel soots."
The effect on NOx (pronounced "knocks") is a trickier problem. NOx, Boehman explains, is a major contributor to smog and ground-level ozone. "What's been seen with B20 blends is a consistent two to four percent NOx increase," he says. "At high loads it can be significantly higher." Last year Boehman spent a sabbatical at Sandia National Lab trying to get a better handle on "the NOx effect." For older, hydraulic-line fuel systems, he says, "We've showed how it happens and how to get around it." Ironically, for newer electronically timed diesel engines, he says, "we still don't know."
Boehman sees clean diesel technology as a critical component in a sustainable energy future. "Diesel engines are inherently more efficient than gasoline engines," he explains. "And we won't benefit much by moving to biofuels if we don't improve the efficiency of the vehicles that use them."
One emerging problem, he says, is the uneven quality of today's biodiesel fuels. "Too much of what's being made is not in compliance with government specifications." In part, he says, this is a result of rapid expansion of the U.S. biodiesel market, from a total of 75 million gallons sold in 2005 to 225 million in 2006. "When you have that kind of explosive growth, you're going to have growing pains." But as emission standards grow more strict and engine systems more sophisticated, Boehman adds, the importance of fuel quality only increases.
Higher standards for fuel economy will "almost certainly" favor additional diesel vehicle options for U.S. consumers, Boehman predicts. He's less sure about the role of today's biodiesel in fueling those vehicles. So-called "green diesel" takes a different approach to making fuel from soybean oil, one that may be even cleaner burning, he notes. "We can also make various synthetic fuels from renewable feedstocks."
"There's no single fuel that's going to solve all our problems," Boehman concludes. "It's much more likely that we'll have a variety of fuels, each used in the context where it works best."
Rural electric
Jay Regan's research skips the off-site fuel part altogether. Regan, an assistant professor of environmental engineering, is interested in converting biomass directly to electricity. Since he arrived at Penn State in 2002, Regan has worked with colleague Bruce Logan on improving designs for microbial fuel cells, which exploit the energy-producing activity of microbes feeding on organic matter.
"Most living things oxidize organic matter," Logan explains. "They eat stuff and their bodies burn it to make energy." That "burning" frees up electrons, which microbial fuel cells convert into electric current. Over the last few years, Logan has attracted worldwide attention with his attempts to perfect a fuel cell that runs on wastewater, potentially taking an energy-intensive activity—sewage treatment—and turning it into an energy producer.
"More recently," Regan says, "my students have been looking at using cellulosic materials—not just wastewater, but biomass—as the substrate for running a microbial fuel cell. We're talking about farm waste materials—corn stover, or manures mixed up with their bedding materials." He and graduate student Zhiyong Ren are studying different combinations of microbes, trying to optimize the necessary reactions. "The main constraint we have right now is the kinetics of the process," he reports. "How fast can the organism degrade cellulose?"
Regan is also looking at improving anaerobic digesters, a related technology that holds potential for turning farm waste into energy. Digesters use anaerobic bacteria to break down manure, yielding methane that can be used to generate electricity or heat, enough to power a farm. During the energy crisis of the 1970s, Penn State researchers operated an experimental system at University Park, and several more were built around Pennsylvania, but the idea never really caught on. One problem, Regan says, is that digesters tend to be somewhat balky: the methane-producing organisms ("methanogens") that they run on are particularly sensitive to drops in pH. "They tend to crash if the pH decreases due to high organic loading rates," he says.
One of Regan's graduate students, Lisa Steinberg, recently found some hardier methanogens at Bear Meadows, an acidic bog in nearby Rothrock State Forest. "Lisa noticed that these bog methanogens thrive at very low pH levels," he says. "She's been working on characterizing and testing them, taking bog samples and feeding them municipal sludge in an engineered digester. So far, they seem to work well.
"If they hold up, we're hoping they will impart some needed stability to these systems."
The greatest challenge?
After all the talks he's given about the future of biomass energy, Tom Richard is used to ticking down the list of technical challenges. "Then," he says, "there's the big non-technical challenge: restructuring society to think and act differently.
"One thing for sure is we have to learn be more energy-efficient. This is particularly important in the mid-term, when we're going to have trouble filling the gaps between fossil fuels and renewables," he says. "Our biggest opportunity right now is in conservation, both at the policy level and at the level of individual decisionmaking. It's not sexy, but it's vital.
"In terms of production," he adds, "we need to develop cropping systems that provide food and fiber at levels at least equivalent to today, but also come up with energy-producing crop rotations such as cover crops to grow between food crops. We need to use land more intensively but in an environmentally sound way."
Clare Hinrichs Credit James Collins
Another important element in any large-scale transformation will be what Richard calls "buy-in" by key participants on the ground: first and foremost, farmers. "There's been an assumption that farmers are going to jump to it, planting these new energy crops," explains rural sociologist Clare Hinrichs. "It's not that simple.
"Growing corn for ethanol is no big leap for U.S. farmers," Hinrichs says. "But the shift to perennial grasses is a whole different thing. There's not much existing commercial market for it. So the issue of what are farmers thinking about it—would they want to do it, and under what conditions—is a really important one."
Last summer, Alissa Meyer, one of Hinrichs'graduate students, interviewed Iowa farmers who had participated in a switchgrass demonstration project. "These farmers have a very peculiar mix of hope and skepticism about what this transition would mean for them," Hinrichs says. "They see a huge rush of large-scale corporate actors into this arena, and they're not very sanguine that in the long run they're going to be able to retain much of the value."
This summer, Hinrichs began a similar ethnographic study in Pennsylvania. "It's a very different agricultural environment," she says, "a much more diverse agricultural economy. But you have some of the same restructuring going on, with farmers getting older, young people finding it difficult to get into farming, small farmers struggling to survive.
"There are lots of interrelated questions that will need to be answered in both places," she says. "What crops should be grown? What's the best way to grow them sustainably? How big will the refinery plants be? Where should they be located—closer to farms, or closer to consumers, in suburban areas? Who is going to be growing these energy feedstocks—will it be large-scale farmers? Small farmers? Retired farmers? Other landowners? It may be a whole different population, with a different relationship to the land, and different motivations.
"I think there's still a big disconnect here," Hinrichs adds at last. "People who are not associated with agriculture or with
rural communities tend to think that these decisions don't really affect them, but they do. We are more interdependent than we
realize. The answers to these questions will affect all of us."
RPS
Thomas L. Richard, Ph.D., is associate professor of agricultural and biological engineering in the College of
Agricultural Sciences and director of the Biomass Energy Center; tlr20@psu.edu.
Gregory W. Roth, Ph.D., is professor of agronomy in the College of Agricultural Sciences; gwr@psu.edu.
Charles Ray, Ph.D., is assistant professor of wood product operations in the College of Agricultural Sciences; cdr14@psu.edu.
Ming Tien, Ph.D., is professor of biochemistry and molecular biology in the Eberly College of Science; mxt3@psu.edu.
John E. Carlson, Ph.D., is associate professor of molecular genetics in the School of Forest Management and director of the Schatz Center for Tree Molecular Genetics; jec16@psu.edu.
Daniel L. Cosgrove, Ph.D., is Eberly professor of biology in the Eberly College of Science; fsl@psu.edu.
Donald A. Bryant, Ph.D., is Pollard professor of biotechnology and professor of
biochemistry and molecular biology in the Eberly College of Science; dab14@psu.edu.
Andre L. Boehman, Ph.D., is professor of fuel science and engineering in the College of Earth and Mineral Sciences; alb11@psu.edu.
John M. Regan, Ph.D., is assistant professor of civil and environmental engineering in the College of Engineering; jmr41@psu.edu.
Bruce E. Logan, Ph.D., is Kappe professor of environmental engineering in the College of Engineering; bel3@psu.edu.
Clare Hinrichs, Ph.D., is associate professor of rural sociology in the College of Agricultural Sciences; cch11@psu.edu.
