Maryland researchers turn poplar trees into biofuel

May 03, 2010|By Meredith Cohn, The Baltimore Sun

In response to a national call for homegrown, Earth-friendly fuels to fill Americans' gas tanks, a couple of University of Maryland researchers are planting trees.

Fuel derived from the hardy, fast-growing common poplar could eventually replace some of the billions of gallons of petroleum-based fuel now pumped a year, say biologist Gary Coleman and engineer Ganesh Sriram, who have partnered to help turn the woody plant into a widely used biofuel.

"Oil is a finite resource," said Coleman, a professor of plant science in the College of Agriculture and Natural Resources. "I don't think there is any doubt in 10 years people will be using advanced biofuels."

The Obama administration has made development of biofuels a priority, citing the national security and environmental concerns with petroleum-based fuel — a problem driven home by the devastating oil spill along the Gulf Coast. The president toured the Midwest last week to tout renewable energy development, and the U.S. government already has mandated that biofuel production reach 36 billion gallons by 2022, tripling current levels.

Most biofuel now comes from corn in the form of ethanol, which is added to gasoline to increase its octane and decrease its harmful emissions. But the government is moving away from corn kernels, a food source, and has called for at least 60 percent of new biofuel to be derived from other sources.

A portion will come from cellulosic, or fiber-based, biofuel — the kind that comes from trees. To that end, millions in federal funds have been dedicated to research and processing plant construction.

Globally, other crops such as sugar are used to make biofuel. And more, including willow trees, algae and switchgrass, are in the race with poplars to become the next viable crop. But the government and scientists see poplars as having an edge because they naturally grow to about 70 feet in five or six years and grow just about anywhere.

Sugar, used to make biofuel in Brazil, for example, is sensitive to the cold in much of the United States.

Poplars would use up land, too, but not as much as corn and not in place of food crops, said Sriram, a professor of chemical and biomolecular engineering in the A. James Clark School of Engineering. Poplars, also called cottonwood or aspen, already are farmed, but for paper and timber.

"The scientific community already decided that poplars would make a good biofuel," Sriram said. "It's been studied since the '70s."

But after the 1970s oil crisis ended and gas prices dropped, so did the sense of urgency and research dollars, he said. Enough technology developed to turn trees into ethanol for use as a gas additive, but there's a lack of infrastructure and the cost would be high.

New research aims to make a cheaper and more advanced biofuel that could replace gasoline. Making that possible is a $3.2 million grant the researchers recently won from the National Science Foundation's Plant Genome Research Project, which funds work on plants that have potential economic and agricultural importance.

Also helping is the recent completion of the tree's genome by the scientific community. The complete tree map allows the researchers to identify and manipulate thousands of specific genes in their quest to understand and improve poplars' use of nitrogen, a key factor in the life cycle of the tree.

The plants store nitrogen in their branches in winter and send it back to the leaves in the spring. If researchers can make a tree cycle the nitrogen more efficiently, it will grow faster and use less fertilizer, a major cost saving.

"The more efficient we make the process, the more economical this will be," Coleman said. "But we're not there yet."

The trees would also absorb carbon as they grow, offsetting emissions from poplar-based fuel, he said.

Once the researchers perfect the cycle, they will hand off the job of making fuel to others.

As this is happening over the next decade, officials at the Department of Energy will move forward on other fronts. They expect that in a couple of years, ethanol from nonfood sources such as trees, grasses, algae, and forestry and crop waste will replace much of the corn-based fuel and the amount added to gasoline will be increased.

Ethanol is not likely to replace petroleum because, unlike advanced biofuels, it would require its own delivery system and modified cars to run on it, said Valerie Sarisky-Reed, acting program manager for the Energy Department's Biomass Program.

But ethanol will remain important in the short term as an additive that helps the environment and expands the petroleum-based fuel supply, she said. And it will remain important in the long term because a recent government study predicted those advanced biofuels will only be able to replace about a third of the transportation fuel used in the United States in the coming decades.

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