A focus on renewable fuels could bring energy independence, spur economic development, and improve environmental quality.

By Jay Wrolstad

In an unassuming lab tucked behind Riley-Robb Hall sits a round bale of cut grass. It looks just like hay harvested from the fields surrounding Ithaca, but this grass wasn’t grown to feed livestock; it was grown to feed the global economy’s insatiable appetite for energy.

This is switchgrass.  With roughly the same energy content as wood, it has great potential as a source of sustainable fuel. Professor Larry P. Walker is conducting experiments on this and other common perennial grasses to perfect a process in which certain enzymes convert carbohydrates like cellulose into sugars that can be transformed into ethanol fuel.

Switchgrass can also be converted to industrial chemicals such as surfactants, organic acids, and biopolymers. It’s a favorite of President George W. Bush, who touted the tall plant in a State of the Union address as an alternative fuel source. And it is just one of the “biomass” materials being tested by Walker and others at Cornell.

Biomass is any organic material containing carbon, nitrogen, and oxygen. That includes most plant life, organic waste, and solid waste. “Looking ahead, we need these resources in place to support sustainable human development,” says Walker.

Walker is among those leading a broad-based charge to change the way we think about and produce the power needed to light and heat our homes, and run our cars. “Biomass is the only direct replacement liquid fuel that is imminent,” says Walker, a professor of biological and environmental engineering. “It will play a large role in shaping our future, with agriculture becoming a major supplier of energy and industrial chemicals.”

Walker initially delved into the fundamental processes of creating energy from biomass during the oil embargo-induced shortages of the 1970s, but when the long lines at the pumps dwindled, so did funding for renewable energy research. Today, however, increasingly fierce global competition for energy, alarm over global warming, and concern for agricultural communities have combined to rekindle interest in biomass.

Making biomass commercially feasible, Walker contends, requires new tools and methods to process organic material more efficiently, and on a massive scale. The corn-to-ethanol conversion process has been the most successful effort to date, he notes, but corn may not be the best option. It requires major inputs of water for irrigation, and of fertilizers and pesticides, which, ironically, are derived from oil. The focus on corn diverts attention from other potential energy crops that are more sustainable in different ecosystems across the country. Also, farmers worry that using corn for ethanol production may cause feed shortages and higher costs.

In 2002, the Biomass Research and Development Technical Advisory Committee, a panel established by Congress to guide the future direction of federally funded biomass R&D, proposed replacing 30 percent of the petroleum currently used by the United States with biofuels by 2030. That vision includes a 20 percent replacement of transportation fuels, which translates to 60 to 65 billion gallons of ethanol each year. Reaching that 30 percent target will require more than one billion dry tons of biomass annually.

To help meet those ambitious goals, Walker hopes to use a process similar to making moonshine.

“One approach is to use molecular biology to engineer microorganisms that can achieve both cellulose hydrolysis and fermentation of the six- and five-carbon sugars that are derived from plant carbohydrates. Another approach is to do what nature tends to do and use a mixture of ‘bugs’ to process the sugars—and this is an alternative paradigm that biofuels researchers need to develop,” Walker says.

In the Riley-Robb labs, researchers are developing enzymatic and microbial processes to speed the sugar-to-ethanol conversion. They are isolating bacteria from compost reactors and using DNA analysis and high throughput screening to identify those that show the most promise as biocatalysts.

Before the fermentable sugars in perennial grasses can be converted to ethanol, they must first be extracted. A key component of this step is chemical and physical pretreatment, which involves size reduction of the biomass and subsequent treatment using acids or alkalis at various concentrations, temperatures, and pressures. Professor James Gossett, director of the School of Civil and Environmental Engineering, and his graduate student Deborah Sills are investigating this piece of the cellulosic ethanol system.

Another biomass material being studied at Cornell is organic waste. Again using enzymes, scientists can produce hydrogen, biogas, and organic acids from such material. Norman Scott, professor of biological and environmental engineering, explains: “Our work complements that being done by Professor Walker by studying the anaerobic digestion of waste, such as food scraps and animal manure, to create biogas.”

Scott envisions community-based biogas plants relying on a steady supply of manure from farms and other organic wastes from the community. “With the participation of five to 10 farms, and their 20,000 cows, we could convert enough gas to significantly supplement the public natural gas supply,” Scott says.

Before such biorefineries are built to process organic waste on a large scale, there are issues to clarify, such as how the waste will be transported to the refinery, whether the farmer or the fuel producer owns the raw product, and how carbon and emission credits might be awarded. The decisions made on these points will help to identify incentives for farmers to participate in a sustainable energy strategy.

Ruth Richardson, an assistant professor of civil and environmental engineering who is collaborating with Scott in harnessing energy from dairy waste, is confident that microbial fuel cells can be developed using bacteria to process the material and turn it into electricity. “Using a diversity of processes will help optimize the amount of energy obtained from biomass material, and that will involve working with soil experts, farmers, and the agriculture industry,” she says.

Other microbes feed on organic matter and produce hydrogen. “To make biological hydrogen production economically feasible, we have to increase the yield of hydrogen from feedstocks, such as agricultural and food production wastes,” says Sarah Munro, a graduate student in Walker’s lab whose objective is to alter bacterial metabolic activity to increase hydrogen yields.

“We are approaching a point where industrial plants or public facilities could be powered by fuel cells utilizing hydrogen generated from these systems,” Munro says. “And these fermentations can also produce other useful co-products such as polymers for bioplastics.”

Colleen McGrath, meanwhile, is manipulating bacteria that can hydrolyze plant cell walls and create the sugars to be fermented into liquid fuel. She’s looking for specific enzymes that can quickly process biomass and can produce the most sugars.

“This research is long overdue; we have been dependent on petroleum for too long,” says McGrath, a graduate student in the Department of Molecular Biology and Genetics. “We can do a better job of producing energy by using biomass resources and cleaner production techniques for making fuel. But it requires government investment in research.”

The good news is that our elected officials have responded by funding the establishment of regional hubs for research collaboration under the federal Sun Grant Initiative. Cornell is one of five centers of excellence set up across the United States through the initiative, with the charge to leverage agriculture resources as a supply of both energy and industrial chemicals.

As the lead university for the Northeast Sun Grant Institute of Excellence, Cornell received a four-year, $6-million grant from the U.S. Department of Transportation, with the money spread among research projects from Maine to Michigan.

“We need a regional response to the opportunities biomass presents,” says Walker, director of the Northeast Sun Grant Institute of Excellence. “Land grant institutions like Cornell have always played a role in addressing rural development challenges, and we are set up with strong life sciences, agricultural, and engineering capacities. For biofuels to take off, you need a strong linkage between those sectors.”

Each center controls 25 percent of its funding, Walker explains, while the rest pays for competitive grants that support renewable energy projects. At Cornell, the grants program launched this fall was designed by a steering committee comprising agriculture experiment stations directors, extension directors, and stakeholders like farmers and non-profit groups.

 “We are bringing other land grants in our region to the table to think strategically about developing biofuel,” Walker says. He plans to devote most of his attention to agriculture and industrial biotechnology, two areas of strength at Cornell, with engineers who understand the industrial ecology concept.

Engineers are designing bioreactors to process organic material and developing new ways to pre-treat it. Nanobiotechnology can help scientists understand basic biological processes, manipulate them more efficiently, and create new microorganisms. The biological sciences play a significant role as well, with protein engineering research. The challenge is to orchestrate these capabilities into an integrated approach to developing sustainable bio-based industries.

“This is a systems integration project,” says Walker. “At Cornell we have all of these components in place.”

Harold Craighead agrees. “Engineers can create new biological process monitoring devices and new chemical analytical capabilities, such as labs-on-chips, that will make biological material processing, including the production of fuels, more efficient and practical,” says Craighead, professor of applied and engineering physics and director of the Nanobiotechnology Center. “Professor Walker is one of the global leaders in adapting advanced technology, including nanobiotechnology, for increasing the efficiency of deriving fuels from biomass sources.”

The interdisciplinary collaboration that has marked Walker’s career is essential to the Sun Grant effort. For example, bringing plant breeders to the table is critical, Walker says, in creating sustainable crops. “How much perennial grass can we produce with the best yields and sustainable practices on farms in this part of the country?” he asks. “We need to change our mindset about agriculture. For most farmers it’s, ‘Tell me what to produce and I’ll produce it,’ but there are crop storage and handling issues associated with processing biomass. Also, any ethanol producer will want assurances of long-term availability and cost-competitive pricing for biomass feedstocks. Thus, a strategic partnership must evolve between feedstock and ethanol producers.”

Any comprehensive energy strategy must also include discussion of erecting massive biorefineries that pull in material from a large region in a centralized production system, or building multiple, smaller plants that serve local communities.

“We can’t leave it up to private industry,” says Walker, describing an effort along the lines of the Manhattan Project, in which the public and private sectors collaborated on nuclear research. “We can exploit the multidisciplinary research being done at Cornell and establish partnerships with state and local governments and businesses.”

He cites New York State’s $25-million biorefinery pilot-plant initiative. A consortium of private businesses and researchers, including Walker, was recently selected to build one of two plants and it will be a proving ground for technology developed at Cornell. Further state involvement can be seen in a facility for students evaluating industrial biotechnology systems, and the investment of $750,000 that the New York State Office of Science, Technology and Academic Research made in Walker’s biofuels/industrial biotechnology research program. Industry is taking notice, too, with oil giant British Petroleum earmarking $500 million for biomass energy centers. “Companies like BP and Chevron realize that we must diversify our energy system,” Walker says.

“The pleasure for me is that we can do exciting research through the Sun Grant Initiative and apply what we learn,” he adds. “We can play a leadership role in national and international research. We are training a new generation of scientists that will take sustainable energy to the next level.”