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Tuesday, October 12, 2010

Biomass Feedstocks for Biopower: Background and Selected Issues

Kelsi Bracmort
Analyst in Agricultural Conservation and Natural Resources Policy

Biopower—a form of renewable energy—is the generation of electric power from biomass feedstocks. Biopower, which comprised about 1% of electricity generation in 2008, may reduce greenhouse gas emissions, provide energy security, and promote economic development. A large range of feedstocks can be used, from woody and herbaceous biomass to agricultural residues. Each feedstock has technical and economic advantages and challenges compared to fossil fuels.

Unlike wind or solar energy, a biopower plant is considered to be a baseload power source because some biomass feedstocks can be used for continuous power production. However, ensuring a sustainable supply of biomass feedstocks is a major challenge. Although there are multiple biopower technologies, few of them except combustion have been deployed at commercial scale nationwide.

Federal policymakers are supporting biopower through feedstock supply analysis and biopower technology assessments. However, there is limited comprehensive data about the type and amount of biomass feedstock available to meet U.S. biopower needs at a national level. If the use of dedicated biomass feedstocks to generate biopower were to develop into a sizeable industry, concerns would likely include the effect of the industry on land use (i.e., how much land would it take to grow the crops needed to fuel or co-fuel power plants) and the effect on the broader economy, including farm income and food prices. To date, these have not been issues: most existing biomass feedstocks have been waste products generated by the forest products industry or by farms, or municipal solid waste for which combustion served as both a disposal method and a source of energy.

Growing crops for use as a power source would be different from using waste. Under generally accepted assumptions regarding crop yields and energy content, approximately 31 million acres— roughly the amount of land in farms in Iowa—would be needed to supply enough biomass feedstock to satisfy 6% of total 2008 U.S. electricity retail sales. When added to the amount of land needed to meet the requirements of the Renewable Fuel Standard (RFS), a federally mandated transportation fuel requirement, the potential impacts could be significant: the RFS already consumes 35% of the nation’s corn crop, and its requirements will triple between 2010 and 2022 (although much of this fuel will come from feedstocks other than corn).

Beyond land use and economic impacts, others are concerned that the use of biomass feedstocks to generate biopower, particularly through combustion, could add to greenhouse gas (GHG) emission levels and exacerbate climate change concerns. They fear that certain areas may be unsustainably harvested to meet biomass feedstock demand, or that less biomass may be left for other purposes (e.g., wood and paper products). The concerns exist partly because biomass used for biopower does not face the same constraints as biomass used for liquid transportation fuels under the RFS. In addition, the idea that biomass combustion is carbon-neutral is under scrutiny. The Environmental Protection Agency has not exempted biomass combustion emissions from the Prevention of Significant Deterioration and Title V Greenhouse Gas Tailoring Rule. The rule sets thresholds for GHG emissions that define when permits are required for new and existing industrial facilities. It is unclear what the rule would mean for biomass combustion plants, since determinations of the best available control technologies (BACT)—a pollution control standard mandated by the Clean Air Act—will be provided in another rulemaking. Those who consider biomass combustion emissions to be biogenic (produced by living organisms), and thus carbonneutral over time, argue that these emissions should be exempted from the rule.

Date of Report: October 6, 2010
Number of Pages: 30
Order Number: R41440
Price: $29.95

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