Energy from Biomass: Nature’s Power

This greenhouse study characterizes the interactions between nitrogen and calcium in the production of switchgrass, which could be converted to ethanol fuel. (Photo courtesy of USDA-ARS Northern Great Plans Research Laboratory, Mandan, ND)

One way to reduce U.S. reliance on imported oil and environmentally unfriendly coal is to increase our use of renewable energy sources, which tap naturally occurring flows of energy to produce electricity, fuel, and heat. Only about 3% of our nation’s energy is produced from biomass, as the result of burning wood and wood residues to produce electricity or converting grains and agricultural wastes to liquid fuels such as ethanol. Thus, the U.S. government is trying to make biomass more attractive economically as a replacement for oil and coal in the production of electricity and liquid fuels.

The President’s National Energy Policy Development Group (NEPDG) has recommended, for example, that the President direct the Secretary of the Treasury to work with Congress on legislation to extend and expand tax credits for electricity produced using renewable technology, such as wind and biomass. The NEPDG report notes that, “The President’s budget request extends the present 1.7 cents per kilowatt hour tax credit for electricity produced from wind and biomass; expands eligible biomass sources to include forest-related sources, agricultural sources, and certain urban sources; and allows a credit for electricity produced from biomass co-fired with coal.”

Making biomass energy cost competitive with that of fossil fuels and making production of biomass for energy a profitable agricultural activity are goals of the Department of Energy’s Bioenergy Feedstock Development Program, managed at ORNL. To track progress in these and other areas, the program supports economic analyses.

“Some 120,000 acres of U.S. land has been planted with hybrid poplar, eucalyptus, sweet gum, and sycamore trees as a result of the DOE program,” says ORNL’s Lynn Wright, a co-manager of the program. “Over a period of 20 years, DOE invested $48 million in the program, in which researchers learned how to raise fast-growing trees as crops. In one year fiber industry sales of paper products and wood for building construction and furniture produced from these trees equaled $48 million. The return on the government’s investment has been good. Jobs have been created in the timber and paper industry, even though restrictions were placed on harvesting trees in national forests.”

In the DOE program, researchers bred and cloned fast-growing varieties of hardwood trees. They developed new ways to grow them through the judicious cultivation of land and the use of weed-killing herbicides, fertilizer, and water to get a higher yield in less time. They domesticated this crop, controlled its characteristics, and found ways to harvest it more efficiently.

The key to increasing the production of biomass for energy, however, is the involvement of farmers. They could, for example, make money on bioenergy crops if there were an expanding market for ethanol to relieve the effects of a shortage of imported oil resulting from a war.

The U.S. government is looking at another possible incentive for farmers to grow more bioenergy crops. So, in 2000 the U.S. Department of Agriculture established a Bioenergy Pilot Program and proposed that owners of Conservation Reserved Program (CRP) land work with project managers to grow and harvest bioenergy crops on the land. To make this venture economical and worthy of government financial support, the CRP landowners must plant vegetation that controls erosion and promotes wildlife.

“One proposal is to loosen restrictions to allow harvesting of bioenergy crops such as switchgrass and hybrid poplar trees,” says ORNL’s Janet Cushman, co-manager of the Bioenergy Feedstock Development Program. “Our studies show that both types of plants control erosion and attract birds. Birds eat switchgrass seeds. Some species of birds that thrive in shrubs like hybrid poplar trees when they are young. When the trees grow taller, other bird species that prefer a forest-like habitat are attracted to the tree plantation.”

Ethanol today is produced from corn, grain, potato wastes, and other agricultural wastes that contain sugars or starches. DOE supports projects (including those led by ORNL’s Brian Davison) to demonstrate the production of ethanol by using enzymes to degrade cellulose to individual sugars for conversion by bacteria to ethanol.

At least one technology-development company and one waste-management company are interested in demonstrating the cellulose-to-sugar-to-ethanol technology by building commercial biomass-to-ethanol facilities. Other companies are considering building advanced systems to convert bio-mass into electricity (e.g., a wood waste gasifier and a deep-bed boiler to burn whole hybrid poplar trees). But the final decision on all these projects depends on whether the financial support is there.

For biomass energy proponents, it would help if money did grow on trees.

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Related Web sites

• Report of the National Energy Policy Development Group
• Bioenergy Feedstock Development Program

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