Biofuels from Trees: Renewable Energy Research Branches Out

On sites ranging from the Pacific Northwest to the Mississippi delta, Jud Isebrands envisions the architecture of a future solar-energy installation: Sprawling across a thousand acres, it bristles with a million solar collection towers, each stretching 50 feet sunward. Each tower bears thousands of thin, maintenance-free photochemical panels. ❧ By day, these panels look to the light of the sun, converting solar radiation into stored chemical energy that will fuel vehicles or illuminate homes; by night, the panels double as exhaust vents, releasing the installation’s airborne emissons: oxygen and water vapor. ❧ And every autumn, Isebrands knows, the panels will turn golden-brown and flutter to the ground. The architectural elements and expanding the potential of As one of the nation’s leading Isebrands envisions, in other trees to provide clean, sustainable centers of energy research, ORNL words, are stems, branches, and fuels. The program, sponsored by has decades of experience with leaves, and his solar towers are DOE’s Office of Energy Efficiency efficient, advanced energy systems. trees—hardy, fast-growing, air- and Renewable Energy, is called They’ve found one of the best cleansing hybrid poplars, the Bioenergy Feedstock systems to be the tree, says Gerald planted on surplus farmland Development Program. Managed Tuskan, an ORNL geneticist. and cultivated for the energy by Oak Ridge National Laboratory Transfered into ethanol (a form of they can yield. (ORNL), it’s tapping the expertise alcohol), biomass can fuel cars of Isebrands, a plant physiologist and trucks. After high-temperature Isebrand’s vision is closer to with the U.S. Forest Service—along gasification, biomass can yield an being realized than you might with dozens of other federal, array of products, including think. At research sites across university, and timber-industry methanol and diesel fuel and a the nation, a major research scientists—to increase the growth wide variety of chemical program of the U.S. Department rates and hardiness of trees grown feedstocks for industry. Mixed with of Energy (DOE) is exploring as energy crops, or biomass. coal and burned in a conventional power plant, biomass can extend conventional fuels for producing electricity and, at the same time, reduce pollution from carbon dioxide, sulfur, and nitrogen oxides. High-tech trees For biofuels to become mainstream fuels, they must become economically competitive with petroleum, the liquid that quenches most vehicles’ thirst fairly inexpensively. Farmers, therefore, must start with extremely hardy trees remarkably resistant to drought, insects, and diseases that can produce high yields on many kinds of cropland. Advanced techniques, including gene-mapping and cloning, allows researchers to That combination of attributes select and reproduce large numbers of hardy, fast-growing trees. isn’t normally found in nature, so researchers must find ways to nurture it in the laboratory.

It’s a job for cutting-edge science. Using the same gene-mapping tools developed to unlock the secrets of human DNA, plant geneticists in Oak Ridge and at the University of Washington are probing the genes of fast-growing poplars. By finding the genes responsible for traits such as height, drought tolerance, and pest resistance, researchers can identify individual trees with particular promise, cross them with other trees that excel in other traits, and then produce Planted in rows and cultivated as energy crops, hybrid poplars show particu- genetically identical copies by the lar promise for high yields under a wide range of growing conditions. handful or by the hundred. After screening dozens of species In a research plot at Oregon State research program to of trees for growth rates, University (OSU), a cloned hybrid complement his company’s adaptability, drought tolerance, poplar—a product of genetic tree-breeding program. In the and disease resistance, researchers engineering—matures and begins company’s stands, hybrid have found particular promise in to flower. Then, on the verge of the members of the genus reproduction, something Populus—which includes poplars unusual happens: the tree’s and cottonwoods—and in the flowers begins to shrivel, then poplar’s cousin, the willow. die. A failed experiment? The work of insects or disease? No: A And Isebrands’ interest in the genetically engineered safety architecture of trees is more than measure. Geneticist Steve Strauss just aesthetic, too. The shape of a and a team of other OSU tree’s crown—the geometry of researchers are working to branches, the size and spacing of implant the tree’s reproductive leaves—determines its efficiency system with a self-destruct as a solar array. And one of the mechanism that lets them test best solar arrays in the plant sterilized genetically engineered kingdom, Isebrands has found, is trees in the field. the crown of the hybrid poplar. University and government Biofuels researchers have found that a In the Pacific Northwest, by research plots allow initial tree’s “crown geometry” plays a key role crossing the eastern cottonwood screening and development of in efficiently converting sunlight into with the region’s indigenous black promising hybrids, but it’s the cellulose. cottonwood, scientists have big leagues—giant attained yields as high as 10 tons plantings like James of dry biomass per acre, per year. River Corp.’s 10,000 That’s about 5 to 10 times more acres in Oregon and than trees produce in the wild. Washington—where Now, taking the best individual the lab work can be hybrids and crossing them with put to the ultimate other superior specimens, they’re test. Brian Stanton, a seeking trees with even faster James River growth rates, as well as greater geneticist, draws on drought tolerance and insect the research tools and resistance. insights of DOE’s

Trees destined for conversion to biofuels can be harvested with In just six growing seasons, hybrid poplars can reach the same equipment as trees grown for timber, pulp, or fiber. sixty feet or more in height. poplars are reaching heights of 70 by spring rains. Four years from feet, with trunks nearly a foot in now, that twig could yield the diameter ... after just six short light by which a first-grader learns years. By working together, the to read, or the heat that browns a public and private sectors divide family’s Thanksgiving turkey. the cost of research—but double its value. That small twig is part of a big demonstration of the energy- producing potential of biomass. Think farming, Planted in a research plot at State University of New York (SUNY), the not logging twig—like thousands of others One surprising beneficiary of around it—is a live cutting from a biomass energy could be America’s willow that will root and grow, forests. Energy researchers hope to then help fire utility boilers. The protect natural forests by demonstration program, involving developing a new source of wood— researchers, farmers, and several tree crops. The crops could be power companies, aims to reduce grown on biomass farms, sited on the state’s fossil-fuel consumption, land that’s too erosion-prone for cut emissions of carbon dioxide Besides offering a promising and row crops, soil that’s been worked and other pollutants, and promote renewable energy source, trees also too hard for too long, acreage that renewable energy sources. lessen the greenhouse effect by crop surpluses have rendered removing carbon dioxide from the unprofitable for agriculture. According to Ed White, SUNY’s air. dean of research, the willow By displacing idle farmland, cuttings will grow for a single biomass crops could help revitalize season, then be lopped off near the NT O E F E America’s farm economy. By ground. The following spring, TM N R E A R Produced for stabilizing soil, reducing erosion three or four new stalks will P G

E Y D DOE's Office of and runoff, and restoring organic emerge from each set of roots. In

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A N Transportation C matter to depleted land, these just three more years, White says, I I T E R Technologies and D E crops could restore the land’s vigor. each of the thousands of stalks M ST A the Office of Utility ATES OF And by providing shelter for birds will measure up to three inches Technologies within and other wildlife, they could boost thick and 20 feet tall. the Office of Energy Efficiency and Renewable Energy. the environmental diversity of the farm belt. Then, come autumn, they’ll be harvested, chipped, and burned in And no matter where it’s grown or an electric utility boiler, mixed how it’s used, biomass offers with coal. The mixture—10% For more information, tremendous environmental biomass, 90% coal—will reduce contact: advantages compared with coal, emissions of nitrogen oxides and petroleum, and natural gas: It’s sulfur by about 10%, White renewable, and as it grows, figures. In addition, the willows Anne Ehrenshaft, biomass removes carbon dioxide will have begun to recycle carbon, Bioenergy Feedstock from the air, thus helping slow the removing several tons of carbon Development Program, buildup of “greenhouse gases” that dioxide from the air to feed their Oak Ridge National Laboratory, threaten to warm the globe and photosynthetic growth. P.O. Box 2008, alter Earth’s climate forever. Oak Ridge, TN 37831-6422, By the end of the decade, White 423-576-5132 (phone), hopes to see 2,000 acres planted in 423-576-8143 (fax), Stakeholders in boiler-bound willow. As it burns, email: [email protected] or visit the say White and other researchers Biofuels Information Network, the future who believe in the promise of http://www.esd.ornl.gov/bfdp/ In a former pasture in upstate New biomass, it will light the way to a on the Internet. York, a graduate student shoves a cleaner, greener energy future for pencil-sized twig into soil softened America. September 1998