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RCA Issue Brief #2 September 1995

What are biofuels?
What are energy crops, and where can they grow?
What about farmers?
Do biomass crops help control erosion? Hold carbon? Withstand flooding?
Estimated net carbon savings from substituting biofuels for conventional energy sources
Who is using biofuels?
Why aren't more people using biofuels now?
How can we make the transition?
How about jobs?

Did you know ...

...that in the 1920s, 25 percent of America's farmland was used to produce energy (the fuel for horses and mules, among other things)?

...that the United States spent $51 billion for imported oil and petroleum products in 1992?

...that about 150 electric power plants are currently fueled by energy from biofuels only and another 365 plants use a combination of biomass and fossil fuels?

...that grassy crops (switchgrass, bluestem) and fast-growing trees (willow, cottonwood) can be used for biofuels?

...that such perennial crops can conserve, protect, and enhance highly erodible lands and water quality?

...that energy and other crops can "sequester" carbon, thus reducing atmospheric carbon dioxide, the major greenhouse gas contributing to climate change?

What are biofuels

Woody and herbaceous plant tissue and animal wastes can be burned directly or converted into liquid or gaseous fuels. They can be used instead of, or together with, fossil fuels (coal, oil, and natural gas) to produce energy for electricity and for transportation and industrial uses. A billion gallons of ethanol from corn were produced in 1993, primarily for use as a gasoline additive to provide cleaner transportation fuel. Some farmers are converting manure--through "biodigestion"--into methane as an on-farm energy source. As they become commercially viable, biofuels and other renewable energy resources can reduce the Nation's dependence on imported oil and the expense of purchasing it.

What are energy crops, and where can they grow?

Crops for energy can grow anywhere plant life can survive, even in the arid Southwest, though energy value varies greatly depending on crop, climate, topography, soil quality, availability of water, and yield.

Among trees suitable for energy crops are cottonwood, hybrid poplar, silver maple, black locust, sweetgum, eucalyptus, sycamore, and willow. Perennial herbaceous crops might include bluestem, switchgrass, reed canarygrass, wheatgrass, some tropical grasses, and a few legumes; these can be harvested like hay.

Annual crops such as corn, sorghum, and soybeans already are being grown and processed for biofuels in some areas.

Some people believe it important to grow crops similar to original native species in their regions, and many species are being hybridized to improve yield and resistance to stresses. There is general agreement that biomass crops should be grown in ways that ensure environmental and economic sustainability, with minimal or no adverse effects on natural ecosystems and biodiversity and minimal reliance on any single crop.

What about farmers?

As demand and the infrastructure for biofuels develop, farmers will have assured markets for their energy crops. In some places they could use land not currently used for crop production. About 35 million acres of sensitive and highly erodible lands have been set aside under the Conservation Reserve Program (CRP), at a cost of about $1.8 billion a year. Perennial biomass crops do not require annual tillage and could, with appropriate production and harvest practices, enable farmers to meet conservation needs and improve wildlife habitat. Some of the lands in the CRP and other lands under conservation plans could potentially be used for biomass production, while protecting ecosystem stability. Moreover, this could provide farmers with an income-generating alternative use of these lands.

Do biomass crops help control erosion? Hold carbon? Withstand flooding?

Some biomass crops have very deep and strong root systems; switchgrass roots, for example, weigh as much as the crops themselves. Such crops would not only hold soil and reduce erosion, but also could sequester up to a ton of carbon per acre per year more than conventional crops-for up to 5 years, varying according to crop.

Additionally, the burning of biomass releases less carbon into the atmosphere than does the burning of fossil fuels. The net carbon savings shown in the table below reflect the decrease in carbon emissions through substituting biofuels crops for coal in electric power generation, and substituting ethanol for gasoline in transportation.

Some crops now grown primarily for pulp and paper could be utilized for biofuels. One Mississippi plantation, for example, grows Eastern cottonwoods on 30,000 acres between levees and the Mississippi River. With the exception of the first year after planting, these cottonwoods generally easily withstand annual flooding.

photo of cottonwoods Cottonwoods, Fettler Managed Forest, Mississippi River area.
Photo credit: C. Jeffrey Portwood, James River Timber Corp.

Estimated net carbon savings from substituting biofuels for conventional energy sources
Substitution Net carbon savings
Conversion to electricity:  
Short-rotation woody crops 4.66 tons/acre/year
Herbaceous 3.40 tons/acre/year
Conversion to ethanol:  
Wood 2.11 tons/acre/year
Corn crop:  
with current mix of electrical power for processing 0.48 tons/acre/year
with all electrical power for processing derived from biomass energy 1.16 tons/acre/year

NOTE: These estimates of sequestered carbon include the energy inputs needed to produce the crops, including the differences in harvesting and transportation losses, differences in crop management (e.g, fertilizer and pesticide use, and tillage) and the reductions in greenhouse gases that occur as a result of substituting biofuels for fossil energy.

Source: Oak Ridge National Laboratory.

Who is using biofuels?

Six major electric utility companies and a number of independent power producers are already using biofuels, while others are experimenting with crop types, fuel mixes, and conversion and combustion technologies. There are currently about 150 electric power plants fueled exclusively by energy from biofuels and another 365 plants that use a combination of biomass and fossil fuels. The forest products industry is the largest producer/user of biofuels, drawing on the residue from forest harvesting and wood processing. About 55 to 60 percent of power used by the pulp and paper industry is self-generated; this is not insignificant: the industry is the fourth largest consumer of electricity nationwide.

Why aren't more people using biofuels now?

Technologies for producing, processing, and using biofuels are coming into the commercial mainstream. Still, achieving commercial viability and developing environmentally benign products and processes will take time, especially in light of the continuing low prices of traditional energy resources. The "chicken-and-egg" problem is timing: utilities and other potential biofuel users need a secure, reliable supply, while the farmers who might produce such fuels need a secure, reliable market. It takes 2 years to get grasses started, and 5 to 8 years to produce short-rotation woody crops or build a new power plant.

Other questions to answer include:

  • How much biomass is required to operate a power plant?
  • How big should a power plant be to meet electric load demands?
  • What is the projected availability of nearby energy crop feedstocks?
  • How much flexibility is there to convert existing facilities from traditional to biomass fuels?
  • What is the best form (e.g, liquid, gaseous, solid) in which to use the biofuels?
  • Should energy crops be converted into transportable fuels? If so, how can the delivered biofuels be used safely, consistent with environmental needs?
  • What residues or wastes may be generated during processing or use? How can they be treated to produce, process, and use biofuels in an environmentally sustainable way? What are the appropriate scales of production and conversion?
  • What crop types are right for what regions of the country?

All these questions are being addressed by laboratory and university energy and agriculture researchers, electric utilities, and other energy processors and users.


How can we make the transition?

In the near term, it may make sense to adapt existing power plants to "co-fire" biofuels with their current fuels. The Electric Power Research Institute (EPRI) has found* that a significant number of coal-fired power plants could be retrofitted for co-firing with energy crops for up to 10 or even 15 percent of their capacity. Research and development are underway for power plants designed to run 100 percent on energy crops; such plants would use high-efficiency, advanced technologies, such as gas turbines and fuel cells.

*EPRI and the National Audubon Society cosponsored the National Biofuels Roundtable beginning in 1992. The diverse group reached consensus on many issues and published Principles and Guidelines for the Development of Biomass Energy Systems in May 1994; copies are available from EPRI, P.O. Box 10412, Palo Alto, CA 94303.

Energy crops could be produced on lands set aside under such programs as the Conservation Reserve, or on other lands unsuitable for conventional row crops. Until farmers are producing an assured supply of energy crops, forest and crop residues might serve as a bridge to dedicated fuel sources--if this can be done without depriving the soil of the nutrient and anti-erosion benefits of residues.

How about jobs?

Energy crops can create and maintain jobs in rural America. Production of woody biomass crops (quick-growing hybrid poplars, sweetgum, cottonwoods) can be labor-intensive because of the need for hand-planting on slopes, manual cultivation, and trimming. According to the Tennessee Valley Authority, "In 1987, activities associated with the use of industrial wood energy resulted in the production of over 71,000 jobs and $1 billion in personal income for the Southeast region. In addition, a total of $237 million in state and federal tax revenues were generated through wood energy-related economic activity." The 71,000 jobs and $1 billion represent net figures after subtracting income losses and job displacement, primarily in the oil, coal, natural gas, and electricity sectors.

Many other potential benefits could spring from a viable biomass energy industry:

  • Reduced local and regional air pollution;
  • Sequestration of carbon;
  • Job creation in rural America;
  • Economically sustainable family farms;
  • Erosion prevention and soil stability;
  • Wildlife habitat protection;
  • Increased cropping diversity;
  • A broadened "mix" of energy sources and less reliance on imported oil; and
  • Use as energy resources of substances now burned or discarded as "waste."


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