More Sustainable Feedstock for Ethanol

A six-year Great Lakes Bioenergy Research Center (GLBRC) study on the viability of different bioenergy feedstocks recently demonstrated that perennial cropping systems such as switchgrass, giant miscanthus, poplar, native grasses and prairie can yield as much biomass as corn stover.

The study is significant for addressing one of the biofuel industry’s biggest questions: Can environmentally beneficial crops produce enough biomass to make their conversion to ethanol efficient and economical?

Since 2008, research scientists Gregg Sanford and Gary Oates, based in the lab of CALS agronomy professor Randy Jackson, have worked with colleagues at Michigan State University (MSU) to cultivate more than 80 acres of crops with the potential to become feedstocks for so-called “second-generation” biofuels, that is, biofuels derived from non-food crops or the nonfood portion of plants. They’ve grown these crops at the CALS-based Arlington Agricultural Research Station and at MSU’s Kellogg Biological Station.

“We understand annual systems really well, but little research has been done on the yield of perennial cropping systems as they get established and begin to produce, or after farmland has been converted to a perennial system,” says Oates.

To find out basic information about how well certain crops produce biomass, Sanford and Oates tested the crops across two criteria: diversity of species, and whether a crop grows perennially (continuously, year after year) or annually (needing to be replanted each year).

Highly productive corn stover has thus far been the main feedstock for second-generation biofuels. And yet perennial cropping systems, which are better equipped to build soil quality, reduce runoff, and minimize greenhouse gas release into the atmosphere, confer more environmental benefits.

Corn, when grain is included, proved to be most productive over the first six-year period of the study at the Wisconsin site, but giant miscanthus, switchgrass, poplar and native grasses were not far behind. At the MSU site, where soil is less fertile, miscanthus actually produced the same amount of biomass as corn (grain included) in the experiment, with poplar and switchgrass within range.

“All of this means that, at large scales and on various soils, these crops are competitive with corn, the current dominant feedstock for ethanol,” Sanford says.

Now in the midst of the study’s eighth year, Sanford says the study will continue for the foreseeable future.

“We know that perennial systems can prevent negative impacts such as soil erosion and nitrate leaching, and that they also provide habitat for native species that provide beneficial ecosystem services,” Sanford says. “But there are still a lot of questions we want to answer about soil processes and properties— questions that take many years to answer.”

Researcher Gregg Sanford stands before a plot of giant miscanthus at Arlington.

Photo credit – Matthew Wisniewski

Give: Hands-On Fieldwork

Before last summer, Vera Swanson’s only exposure to plant sciences had been through classes in introductory biology. That changed big-time when Swanson, a junior majoring in environmental sciences and Russian, signed on to intern at the CALS-based Arlington Agricultural Research Station as a crop scout.

Crop scouts are used in agricultural management to diagnose stress factors in a field—such elements as potentially negative soil and climate conditions, the presence of pests, and threatened crop performance—and determine which management practices are appropriate for the goals of a specific plot. As part of her training, Swanson spent copious hours learning to identify weeds by walking through the fields and the Weed Garden, which displays dozens of invasive plants accompanied by their names.

Swanson paired her internship, which was run through the Department of Agronomy, with an independent research project involving biofuel crops being tested at Arlington. For that work Swanson drew on her growing knowledge of weeds to test the effect of three biofuel crop systems—native prairie, switchgrass and continuous corn—on the soil’s weed seed bank, or the viable seeds present in the soil and its surface. The project involved working one-on-one with research scientists in Randy Jackson’s grassland ecology lab. Jackson is running the crop trials through his affiliation with the UW’s Great Lakes Bioenergy Research Center, housed in the Wisconsin Energy Institute.

The intense focus on plants got Swanson thinking a lot more about soil. “It is such a finite resource, yet so much of what we depend on comes from it—our food, clothing and the materials that we build with,” says Swanson.

It also got her more interested in food systems, to the point where she chose to make horticulture a disciplinary focus within her major and a possible new career direction. “I’d love to work for an organization where I would be able to complement my interests in agriculture, development and language within a global context,” she says.

Swanson’s path exemplifies the power of “beyond classroom” experiences to dramatically shape, and in many cases transform, a student’s education and career goals. These experiences—which include internships, research projects, study abroad, honors thesis stipends, field courses and more—are the hallmark of a CALS education.

“They’re a big part of what makes CALS CALS—and they offer our students a major advantage in both their personal and professional development,” says Sarah Pfatteicher, the college’s associate dean for academic affairs. “Our goal is to ensure that each student can participate in at least four of these important opportunities.”

To help support the CALS Student Experience Fund, visit: http://go.wisc.edu/student-experience

Field Notes: South Africa

In the fertile, rolling hills of the Eastern Cape province of South Africa, it’s hard to imagine a food shortage. But hunger is a serious threat there, espe- cially for children. The area also has high levels of poverty and HIV infection.

Researchers at the CALS-based Center for Integrated Agricultural Systems (CIAS) are teaming with local groups to try to improve those condi- tions. Together they have formed the Livelihood, Agroecology, Nutrition and Development project— LAND for short—to address the region’s complex, interrelated problems.

“Using a participatory approach, we have built strong ties with local villagers and their co-op, the Ncedisizwe Co-op, which means ‘helping the nation,’” says CIAS director Michael Bell, a professor of community and environmental sociology.  The Ncedisizwe Co-op encompasses 800 small- holder farmers in 26 villages.

Other local partners include the Indwe Trust, an NGO focusing on sustainable development, and Kidlinks World, a Madison-based charity dedicated to AIDS orphans and other vulnerable children.

The group’s goals are to provide sustainable livelihoods for smallholder farmers and their com- munities; to integrate health and nutrition with sus- tainable agricultural practices; to enhance ecosystem services such as crane habitat, erosion control and carbon sequestration; and to strengthen communi- ties through participatory decision-making.

Better use of grasslands will be key in those efforts, researchers say. “The people of this region are blessed with a wealth of grassland resources, but these resources are literally being eroded before their very eyes,” says agronomy professor Randy Jackson, who accompanied the LAND team on a recent visit. “Much of this is attributable to a governance system that treats most rangelands as unregulated commons, resulting in continuous grazing that promotes unde- sirable plants and exposure of bare ground.”

Rotational grazing, the group notes—which actually originated in Africa—will potentially double the level of animal production while also building soil quality, reducing erosion and promoting wildlife habitat. LAND has conducted workshops with farmers on rota- tional grazing and helped develop a supply chain connecting local grass-based meat to national and international markets.

Other activities have included helping form a women’s cooperative for vegetable production, working with community members on improving water supplies, and helping establish perennial home gardens to increase the quality and variety of local diets.

The LAND project has matured to the point where it can serve as the basis of a new global health certificate field course, “The Agroecology of Health,” that debuted this past winter. Bell and doctoral student Valerie Stull brought 10 undergraduate and two graduate students to the Eastern Cape for a 15-day visit that encompassed learning about agroecology and hydrology systems and working with community members to establish a one-acre vegetable garden at a school in the village of Kumanzimdaka.

The students planted herbs, tomatoes, onions, peppers, cabbage and radishes and plotted locations for future fruit trees.

“The experience left me feeling a tremendous amount of respect for the people in the community who continue to live off and use the land,” says Alexa Statz, a junior in life sciences communication. “I have high hopes that the garden we built together will be something that can stay with them for generations to come.”

Bell plans to continue having undergraduates participate. Learning about themselves and their place in the world, questioning and thinking critically were all objec- tives of the trip. “But the biggest objective was to provide students with the chance to discover what it means to lead a life of consequence,” Bell says. “Now that’s a pretty grand goal—and I think it happened in South Africa. It clicked.”

Looking for “Hotspots”

In their quest to make cellulosic biofuel a viable energy option, many researchers are looking to marginal lands—those unsuitable for growing food—as potential real estate for bioenergy crops.

But what do farmers think of that? Brad Barham, a CALS/UW-Extension professor of agricultural and applied economics and a researcher with the Great Lakes Bioenergy Research Center (GLBRC), took the logical next step and asked them.

Fewer than 30 percent were willing to grow nonedible cellulosic biofuel feedstocks—such as perennial grasses and short-rotation trees—on their marginal lands for a range of prices, Barham and his team found after analyzing responses from 300 farmers in southwestern Wisconsin.

“Previous work in the area of marginal lands for bioenergy has been based primarily on the landscape’s suitability, without much research on its economic viability,” says Barham, who sent out the survey in 2011. “What’s in play is how much farmers are willing to change their land-use behavior.”

Barham’s results are a testament to the complex reality of implementing commercial cellulosic biofuel systems. Despite the minority of positive responses, researchers found that there were some clusters—or “hotspots”—of farmers who showed favorable attitudes toward use of marginal land for bioenergy.

These hotspots could be a window of opportunity for bioenergy researchers since they indicate areas where feedstocks could be grown more continuously.

“People envision bioenergy crops being blanketed across the landscape,” says Barham, “but if it’s five percent of the crops being harvested from this farm here, and 10 percent from that farm there, it’s going to be too costly to collect and aggregate the biomass relative to the value of the energy you get from it.

“If we want concentrated bioenergy production, that means looking for hotspots where people have favorable attitudes toward crops that can improve the environmental effects associated with energy decisions,” Barham notes.

CALS agronomy professor Randy Jackson is also interested in the idea of bioenergy hotspots. Jackson, who co-leads the GLBRC’s area of research focusing on sustainability, says that just because lands are too wet, too rocky or too eroded to farm traditionally doesn’t mean they aren’t valuable.

“The first thing we can say about marginal lands is that ‘marginal’ is a relative term,” says Jackson. Such lands have a social as well as a biophysical definition. “This land is where the owners like to hunt, for example.”

The goal of GLBRC researchers like Barham and Jackson is to integrate the environmental impacts of different cropping systems with economic forces and social drivers.

The environmental benefits of cellulosic biofuel feedstocks such as perennial grasses are significant. In addition to providing a versatile starting material for ethanol and other advanced biofuels, grasses do not compete with food crops and require little or no fertilizer or pesticides. Unlike annual crops like corn, which must be replanted each year, perennials can remain in the soil for more than a decade, conferring important ecosystem services like erosion protection and wildlife habitat.

The ecosystem services, bioenergy potential and social values that influence how we utilize and define marginal land make it difficult to predict the outcomes of planting one type of crop versus another. To tackle that problem, Jackson is working with other UW–Madison experts who are developing computer-based simulation tools in projects funded by the GLBRC and a Sun Grant from the U.S. Department of Energy.

Jackson hopes that these modeling tools will help researchers pinpoint where farmer willingness hotspots overlap with regions that could benefit disproportionately from the ecosystem services that perennial bioenergy feedstocks have to offer.

“These models will include data layers for geography, crop yield, land use, carbon sequestration and farmer willingness to participate,” says Jackson. “There could be as many as 40 data layers feeding into these models so that you can see what would happen to each variable if, say, you were to plant the entire landscape with switchgrass.”

Where Are We Now?

TIM DONOHUE HAS SPENT THE LAST FOUR YEARS BUILDING A PIPELINE—but not the kind that springs to mind when we think of fuel.

The professor of bacteriology heads the CALS-led Great Lakes Bioenergy Research Center (GLBRC), founded with $142 million from the U.S. Department of Energy and a groundbreaking charge—to create the next generation of biofuels by harnessing renewable energy from the nonfood plants that are so plentiful all around us: grasses, trees and crop residues.

“We need to create liquid transportation fuels that are more cost-effective, more sustainable and won’t compromise the Earth or our quality of life,” says Donohue. “We’re in the middle of developing ways to generate these new fuels that are essential for powering our daily lives.”

With Michigan State University (MSU) as UW–Madison’s major partner, Donohue has assembled a team that now includes more than 400 researchers and staff and an additional nine member institutions. The effort spans two countries, 11 states and more than 60 individual lab and field facilities.

That’s a lot of brainpower. But the magnitude of the effort is commensurate with the task at hand, Donohue notes.

“We need to be considering everything from roots in the ground to what’s coming out of the nozzle,” Donohue says. “Without such a holistic approach, we won’t be able to demonstrate that this technology is feasible or see the weak spots where we can make improvements.”

What GLBRC has built is a research pipeline, a process that considers all factors that go into developing and implementing cellulosic biofuels—from creating sustainable agricultural landscapes and building better bioenergy crops to innovations in plant biomass processing and converting plant sugars into fuels.

While the promise of creating sustainable plant-based fuels isn’t new, the level of public investment needed to tackle this challenge has only recently emerged. According to the International Energy Agency, the United States leads world spending on biofuels public research, development and demonstration projects, investing $189 million in 2010 alone.

“By relying on fossils fuels, we’re living on energy that arrived on Earth many millions of years ago,” says Steve Slater, GLBRC’s scientific programs manager. “In order to reach a sustainable energy economy, we need to learn to live on the energy that arrives from the sun today. There’s a lot of that solar energy held within plant biomass, if we can figure out how to sustainably convert it to liquid fuels.”

Four years into its five-year grant, GLBRC has made some significant breakthroughs along the research pipeline. Here are some major points of interest.

First Stop: PLANTS

At agricultural research stations in Wisconsin and Michigan, GLBRC researchers tend to tall stands of such biofuel crops as switchgrass and miscanthus, measuring above-ground traits like crop yield and digging down in the dirt to monitor soil microbes and water movement. Sophisticated instruments measure greenhouse gases such as carbon dioxide and nitrous oxide. Researchers count birds and insects to measure biodiversity and use satellite data to capture a watershed-level view of land use patterns.

It’s a lot of information, but each measurement plays a role in determining how these crop contenders would fare as large-scale bioenergy crops.

The leaves and stalks of these potential bioenergy plants are comprised of large quantities of cellulose, the most abundant organic compound on the planet. Cellulose is a polysaccharide, a long chain of tightly linked sugar subunits that must be broken down into simple sugars before they can be processed into biofuel. That alone is difficult—but to make the process even harder, much of a plant’s cellulose is locked within cell walls that form a tough, protective barrier. Breaking past the walls, using enzymes or chemicals to do so, is one of the biggest challenges in creating economically viable cellulosic biofuels.

Plant cell wall structures have evolved over time to fight off pests and disease. The more scientists understand about how the walls are created, the easier it will be to break them apart. DNA sequencing capacity provided by the Department of Energy (DOE) Joint Genome Institute allows plant breeders access to genetic and genomic data that provide clues about how those cell wall layers are built.

While determining the best genetic traits for bioenergy crops is a long-range goal, GLBRC plant researchers already have made important headway when it comes to tackling lignin, one of the toughest compounds that make up plant cell walls. Researchers hope to take it apart to get at the cellulose locked inside and convert small pieces of lignin into valuable co-products. CALS biochemistry professor John Ralph and his team have identified a gene that would allow easily breakable bonds to be incorporated into plant cell walls. They’re calling this new technology Zip-Lignin™ for its ability to break apart—or unzip—the lignin within. By getting lignin out of the way, biomass processing could be completed at lower temperatures. And lower temperatures mean lower overall costs.

And on another track, GLBRC researchers at MSU have located an enzyme that creates a plant oil with unique biodiesel-like properties. Now they’re working to encourage plants to produce more of that oil, which could be used directly as a “drop-in” or ready-to-use diesel replacement.