Biomass Feedstocks for Biopower in the United States

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Growing willows for wood chips in Uppland, Sweden. Source: Vilseskogen/Flickr

Biopower—a form of renewable energy—is the generation of electric power from biomass feedstocks. Biopower, which comprised about 1% of electricity generation in the United States 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.

Note: This article was derived from the Congressional Research Service Report R41440 by Kelsi Bracmort, January 20, 2011

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.

U.S. 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 U.S. Environmental Protection Agency has not exempted biomass combustion emissions from the Prevention of Significant Deterioration (PSD) and Title V Greenhouse Gas Tailoring Rule, although it announced plans to defer for three years GHG permitting requirements for carbon dioxide emissions from biomass-fired and other biogenic sources (those produced by living organisms). In the PSD and Title V Permitting Guidance for Greenhouse Gases issued in 2010, EPA noted that biomass could be considered a best available control technology (BACT)—a pollution control standard mandated by the U.S. Clean Air Act.


The production of bioenergy—renewable energy derived from biomass—could potentially increase U.S. national energy security, reduce greenhouse gas emissions, and contribute to rural economic growth. Legislative, research, and industrial attention have focused on the production of bioenergy in the form of liquid transportation fuels (e.g., corn-based ethanol).1 Biopower—the production of electricity from biomass feedstocks—may require new national policies or incentives if Congress decides to encourage its development.

Biopower, or biomass power, comprised about 1% of electricity generation in the United States in 2008.2 It was the third-largest renewable energy source for electricity generation in that year, after conventional hydroelectric power and wind.3 The Department of Energy’s (DOE’s) Energy Information Administration (EIA) projects that electricity generation from biomass will grow from 0.9% of total generation in 2008 to 5.5% in 2035.4 The DOE reference case for this projection assumes extension of federal tax credits, state requirements for renewable electricity generation, and the loan guarantee program in the Energy Policy Act of 2005 (EPAct05; P.L. 109-58) and the American Recovery and Reinvestment Act of 2009 (ARRA; P.L. 111-5).

Current concerns for accelerating biopower growth include the need for a continuously available feedstock supply, a commercial-scale facility to generate the biopower, and market certainty for investors and purchasers alike. Improved feedstock availability, technological advancements, and new forms of economic support could increase the relative contribution of biopower to meeting U.S. energy demand.

One reason for the projected growth of biopower is the fuel’s ability to be used in a baseload power plant. Baseload power is the minimum amount of electric power delivered or required over a given period of time at a steady rate. If a plant operates as a baseload plant, the plant can run continually except for maintenance and outages. With sufficient feedstock supplies, a biopower plant could provide “firm” power for baseload needs (and long-term contracts would reduce risk). In contrast, wind and solar energy require either a form of power storage, such as batteries, or a backup power source, such as natural gas turbines, in order to provide firm power.

Power generation from biomass is not limited to a specific feedstock and therefore is relatively flexible in terms of fuel suppliers. Each region of the country can pursue biomass feedstocks that are native and readily available (e.g., corn stover in the Midwest, hybrid poplar in the Northwest, switchgrass in the Southeast). The economic climate for biopower dictates that biopower plants should be located in close proximity to feedstocks to reduce transportation costs, which can be significant.5 Furthermore, existing combustion plants can be retrofitted for biopower production; power from these plants could use existing transmission infrastructure. Financing and siting of new transmission infrastructure could add uncertainty to a proposed project.

The availability and cost of biomass feedstocks determine the amount of biopower that can be produced nationally. An overarching concern is maintaining a sustainable biomass feedstock supply.6 If feedstocks are collected without regard to replenishment, or in an otherwise unsustainable manner, biopower enterprises may lead to natural resource deterioration such as soil erosion or the depletion of forested land. The Renewable Fuel Standard (RFS), expanded under the Energy Independence and Security Act of 2007 (EISA; P.L. 110-140), mandates a minimum volume of biofuels to be used in the national transportation fuel supply each year. Under the RFS, biomass used for renewable fuel for transportation purposes cannot be removed from federal lands, and the law excludes crops from forested lands.7 Thus far, biomass used for biopower is not subject to the same constraints as biomass used for liquid transportation fuels under the RFS. Additionally, feedstock diversity is a formidable challenge to biopower growth, because cultivation, harvest, storage, and transport vary according to the feedstock type. Another challenge is accounting for the amount of feedstock available for biopower production due to market fluctuations and weather variability.

This article provides analyses of commonly discussed biomass feedstocks and their relative potential for power generation.

Additional biopower issues—feedstock accessibility, the biomass power plant carbon-neutrality debate, and unintended consequences of legislative activities to promote bioenergy—are also discussed.

What Kind of Biomass Is Available for Biopower?

The type, amount, and costs of biomass feedstocks available for biopower will largely determine whether biopower can thrive as a major renewable energy alternative. There is limited comprehensive data on the amount of biomass feedstocks available to meet current and future biopower needs at a national level. The supply data available is generally evaluated in terms of meeting biofuel demand. Some may argue that feedstock assessments for biofuels are adequate for biopower purposes, as the same feedstock may be used to meet both biofuel and biopower demands. Information that identifies which feedstocks exhibit the most potential for power generation in the near and long term is also scarce.8 Furthermore, ideal or feasible locations where feedstocks may be grown are not well assessed. The potential inclusion of genetically modified dedicated energy crops or selective breeding for bioenergy purposes may alter the amount of biomass feedstock available for biopower production (and may alter land use).

Additional legislative action concerning financial support of biopower may depend on better data to estimate the economic viability of biopower plants nationwide.9 Costs associated with biomass storage and transportation to a biopower plant, as well as other economic and environmental considerations, are among the factors assessed in individual biopower plant feasibility studies. These factors are key to determining which biomass feedstocks can be used.

In addition to economics, biological characteristics play a large role in determining the suitability of any type of biomass. Biomass is organic matter that can be converted into energy. Plants use photosynthesis to store energy (carbon-based molecules) within cell walls, and that energy is released when the biomass undergoes a biological process such as anaerobic digestion, or a chemical process such as combustion. Biomass can include land- and water-based vegetation (e.g., trees, algae), as well as other organic wastes (see Table 1).

Several types of feedstocks can be used as a fuel source for electric power generation. Primary biomass feedstocks are materials harvested or collected directly where they are grown (e.g., grains). Secondary biomass feedstocks are by-products of the processing of primary feedstocks (e.g., corn stover). Tertiary biomass feedstocks include post-consumer residues and wastes (e.g., construction and demolition waste). Appendix A shows the energy value, crop yield, advantages, disadvantages, and general comments for selected biomass feedstocks and fossil fuels for comparison.

Biomass would have to be grown in enormous quantities if it is to be used as a power source to satisfy a significant portion of national energy demand. For example, approximately 31 million acres—roughly the amount of land in farms in Iowa—of managed crops with a yield of 6 dry tons per acre per year would be needed to supply enough biomass feedstock to satisfy 6% of total 2008 U.S. electricity retail sales.10 Quintessential biomass crops grown specifically for energy generation (i.e., dedicated energy crops) are being considered to meet energy demand. Dedicated energy crops may possess several desirable characteristics: high yield, low energy input to produce, low cost, low nutrient requirements, low contaminant level, pest resistance, and low fertilizer input.11

Table 1. General Classification of Biomass


Biomass groups

Biomass sub-groups, varieties and species

Wood and woody biomass

Coniferous or deciduous (gymnosperm or angiosperm); stems, branches, foliage, bark, chips, lumps, pellets, briquettes, sawdust, sawmill and other wastes from various woody species

Herbaceous and agricultural biomass

Annual or perennial and field-based or process-based such as:

  • grasses and flowers (alfalfa, arundo, bamboo, bana, brassica,cane, miscanthus, switchgrass, timothy, others);

  • straws (barley, bean, flax, corn, mint, oat, rape, rice, rye, sesame, sunflower, wheat, others);

  • other residues (fruits, shells, husks, hulls, pits, pips, grains, seeds, coir, stalks, cobs, kernels, bagasse, food, fodder, pulps, cakes, others)

Aquatic biomass

Marine or freshwater algae and microalgae; macroalgae (blue, green, blue-green, brown, red); seaweed, kelp, lake weed, water hyacinth, others

Animal and human biomass wastes

Bones, meat-bone meal, chicken litter, various manures, others

Contaminated biomass and industrial biomass wastes (semi-biomass)

Municipal solid waste, demolition wood, refuse-derived fuel, sewage sludge, hospital waste, paper-pulp sludge and liquors, waste papers, paperboard waste, chipboard, fibreboard, plywood, wood pallets and boxes, railway sleepers, tannery waste, others

Biomass mixtures

Blends from the above varieties

 Source: Stanislav V. Vassilev, David Baxter, and Lars K. Andersen, et al., “An Overview of the Chemical Composition of Biomass,” Fuel, vol. 89 (2010), pp. 913-933. Adapted by CRS.

From Biomass to Biopower

Biomass can be converted to biopower via thermo-chemical and bio-chemical conversion processes. These processes include combustion (or firing), pyrolysis, gasification, and anaerobic digestion (see box, below, and Figure 1). The technologies are at varying stages of maturity (see Figure 2). The choice of conversion technique selected for a specific biomass feedstock results in differing amounts of useful energy recovered and forms for that energy.12 The systems can range substantially in scale. Small-scale systems (or modular units) may be an optimal choice for rural areas with limited electricity demand. Large-scale systems may be more economically suitable in more urbanized areas or near grid connections if feedstocks are ample.

caption Figure 1. Biopower Conversion Processes. Source: Peter McKendry, “Energy Production from Biomass (Part 2): Conversion Technologies,” Bioresource Technology, vol. 83 (2002), pp. 47-54. Adapted by CRS.

Selected Biopower Conversion Processes Defined

Combustion is the burning of biomass in a power plant. The biomass is burned to heat a boiler and create steam. The steam powers a turbine, which is connected to a generator to produce electricity. Existing plant efficiencies are in the low 20% range, although methods are available to advance efficiency to upwards of 40%. (“Efficiency” describes which percentage of the feedstock processed is actually converted to electricity.) Approximately 180 combustion units for biomass are in operationin the United States using wood and agricultural residues as the feedstock.

Co-firing, the simultaneous firing of biomass with coal in an existing power plant, is the most cost-effective biopower technology. Co-firing with biomass using existing equipment is less expensive than constructing a new biopower plant. The existing plant does require retrofitting to accept the biomass entering the plant. Certain air particulates associated with coal combustion are reduced with co-firing, as less coal is being burned. Co-firing has a generation efficiency in the 33%-37% range; coal-fired plants have efficiencies in the 33%-45% range. Approximately 78 co-firing units for biomass are in operation using wood and agricultural residues as the feedstock.

B. Gasification is the heating of biomass into synthesis gas (syngas, a mixture of hydrogen and carbon monoxide) in an environment with limited oxygen. The flammable syngas can be used in a combined gas and steam turbine to generate electricity. Generation efficiencies range from 40% to 50%. One challenge for gasification is feedstock logistics (e.g., cost to ship or transport the feedstock to the power plant). A wide variety of feedstocks could undergo gasification, including wood chips, sawdust, bark, agricultural residues, and waste. There are currently no gasification systems for biomass at any scale.

C. Pyrolysis is the chemical breakdown of a substance under extremely high temperatures (400°C -500°C) in the absence of oxygen. There are fast and slow pyrolysis technologies. Fast pyrolysis technologies could be used to generate electricity. Fast pyrolysis of biomass produces a liquid product, pyrolysis oil or bio-oil, that can be readily stored and transported. The bio-oils produced from these technologies would be suitable for use in boilers for electricity generation. One of the challenges with pyrolysis is that the bio-oil produced tends to be low-quality relative to what is needed for power production. Commonly used feedstock types for pyrolysis include a variety of wood and agricultural resources. There are currently no commercial-scale pyrolysis facilities for biomass.

D. Anaerobic digestion (not shown in Figure 1) is a biological conversion process that breaks down a feedstock (e.g., manure, landfill waste) in the absence of oxygen to produce methane, among other outputs, that can be captured and used as an energy source to generate electricity. Anaerobic digestion systems have historically been used for comparatively smaller-scale energy generation in rural areas. Feedstocks suitable for digestion include brewery waste, cheese whey, manure, grass clippings, restaurant wastes, and the organic fraction of municipal solid waste, among others. Generation efficiency is roughly 20%-30%. Approximately 150 anaerobic digesters are in operation using manure as the feedstock.

Sources: Oak Ridge National Laboratory, Biomass Energy Data Book: Edition 2, ORNL/Tm-2009/098, December 2009. International Energy Agency, Biomass for Power Generation and CHP, ETE03, January 2007. National Association of State Foresters, A Strategy for Increasing the Use of Woody Biomass for Energy, Portland, ME, September 2008. Sally Brown, "Putting the Landfill Energy Myth to Rest," BioCycle, May 2010. John Balsam and Dave Ryan, Anaerobic Digestion of Animal Wastes: Factors to Consider, ATTRA—National Sustainable Agriculture Information Service, IP219, 2006. Jennifer Beddoes, Kelsi Bracmort, and Robert Burns et al., An Analysis of Energy Production Costs from Anaerobic Digestion Systems on U.S. Livestock Production Facilities, USDA Natural Resources Conservation Service, October 2007. Personal communication with Robert Baldwin, National Renewable Energy Laboratory, 2010. Personal communication with Lynn Wright, biomass consultant working with Oak Ridge National Laboratory. For more information on anaerobic digestion, see CRS Report R40667, Anaerobic Digestion: Greenhouse Gas Emission Reduction and Energy Generation, by Kelsi Bracmort.

caption Figure 2. Biopower and Biofuel Technology Pipeline. Source: Electric Power Research Institute, Biopower Generation: Biomass Issues, Fuels, Technologies, and Research, Development, Demonstration, and Deployment Opportunities, February 2010.

The volume of biomass feedstock supply necessary to run a biopower plant depends on the feedstock’s energy content—the less the energy value, the more volume is needed. The growing area needed to produce the biomass that will supply a biopower plant is contingent not only on the energy value of the feedstock, but also on the power plant capacity, the power plant efficiency, and the feedstock yield (see Table 2). Power plant capacity is the maximum output of power, commonly expressed in millions of watts (megawatts, MW), that generating equipment can supply over a certain time period. Power plant efficiency is the amount of electric energy produced per unit of feedstock input. In general, the higher the yield of the biomass feedstock, the less growing area is required to produce a MW of power. Also, less biomass is needed to support power plants with high efficiency rates.

caption Source: Department of Energy, Relationship Between Power Plant Efficiency and Capacity and Tons Biomass Required and Acres Required, Lynn Wright,

Notes (from original source): Raw numbers have been used in the above table. Calculations assume dry biomass at 8500 btu/lb = 19.75 Gj/MG and 3413 btu/kWH = 0.0036 Gj/kWh.

Rule of thumb relationship of 1000 acres and 5000 dry tons per MW is based on 80% capacity, 30% efficiency, and 5 dry ton/acre/year yield. A program goal would be to have a relationship of 500 acres and 4200 dry tons per MW at 90% capacity, 40% efficiency, and 8 dry ton/acre/year yield.

Yields of 1-2 dry ton/acre/year are common for natural forests but could also represent residue levels available from high yield plantations. Yields of 3-4 dry ton/acre/year are common for pulpwood pine plantations. Yields of 4-7 dry ton/acre/year are being observed in woody crop and herbaceous crop plantings without irrigation, 5dt/ac/yr still best average estimate. Yields of 7-10 dry ton/acre/year are being observed in some energy crop plantings with best clones or varieties and/or with irrigation or high water tables.

Total planted area or growing area required to supply a biomass facility should be used rather than area actually being harvested in any given year. While these are the same for a herbaceous crop harvested annually, they differ significantly for a woody crop harvested once every few years. Calculation of the annual harvested area for a wood crop requires knowing both the yield (dry ton/acre/year) and the harvest age of the woody crop. This varies from project to project.

Carbon Balance

Certain sources of biomass (e.g., forestry products, dedicated energy crops) are deemed by some to be carbon-neutral because they absorb enough CO2 during their growth period to balance the release of CO2 when they are burned for energy (see Figure 3). The term carbon-neutral is generally defined as the combustion or oxidation of matter which causes no net increase in GHG emissions on a lifecycle basis.13 One controversial aspect of the carbon neutrality debate, and what requires further study, is the magnitude in which these plant-derived feedstocks will be used for energy production and thus whether the feedstock supply can be sustained (or replenished) without environmental impairment. Some examples of environmental impairment involve disrupting forest ecosystems by cutting down large amounts of trees, or affecting the climate by not capturing GHGs emitted during bioenergy production. If the feedstocks are not replenished so that they can absorb CO2, or GHG emissions are not captured from a biopower plant, the resulting GHG releases can be akin to that of carbon-positive fossil fuels.

caption Figure 3. Carbon Balance of Energy. Source: John A. Matthews, “Carbon-Negative Biofuels,” Energy Policy, vol. 36 (2008), pp. 940-945; Biopact, “The Strange World of Carbon-Negative Bioenergy: The More You Drive Your Car, the More You Tackle Climate Change,” 2007, Adapted by CRS.

Notes: Carbon-positive fuels are burned, releasing CO2 into the atmosphere. Carbon-neutral fuels absorb CO2 as they grow and release the same carbon back into the atmosphere when burnt. Carbon-negative fuels absorb CO2 as they grow and release less than this  amount into the atmosphere when used as fuel, either through directing part of the biomass as biochar back into the soil or through carbon capture and sequestration.

The premise that biomass energy is carbon neutral is under scrutiny.14 Some argue that biomass combustion could increase GHG emissions if biomass feedstock is handled in an unsustainable manner, among other concerns. Others contend that biopower plant emissions add no new carbon to the atmosphere because biopower plants use only materials that would decay (e.g., residuals, byproducts, and thinnings). Under the final Prevention of Significant Deterioration (PSD) and Title V Greenhouse Gas Tailoring Rule, PSD requirements apply to projects that increase net GHG emissions by at least 75,000 tons per year CO2 equivalent.15 The rule grants exemptions based on tonnage amounts, not emissions based on source category (e.g., biomass combustion). The Tailoring Rule does not exempt emissions from biomass combustion.16 EPA has decided to defer for three years permitting requirements for CO2 emissions from biomass-fired and other biogenic sources.17 Moreover, EPA decided that certain types of biomass could be regarded as a best available control technology (BACT).18 Further guidance will be issued by EPA in early 2011 on how to include biomass in the BACT selection process. PSD permits require that facilities apply the BACT. BACT is determined by individual states with EPA guidance on a case-by-case basis.19

There are other aspects associated with the designation of biomass energy as carbon neutral, many of which are beyond the scope of this report.

Implications for Legislation

Biopower straddles at least three legislative areas: agriculture, energy, and environment. The main benefits that agricultural legislation could provide, as argued by proponents for biopower, are to ensure an adequate feedstock supply, maintain productive field conditions during biomass growth and harvest, and assist farmers who participate in the bioenergy market. Energy objectives, as stated by supporters, involve establishing a robust biopower technology platform and providing financial and technical assistance for biopower technology pioneers. Protecting the environment throughout the biomass-to-biopower conversion is the major environmental objective, including monitoring GHG emissions released during energy production.

As a candidate for large-scale energy use, the biopower industry may challenge the U.S. Congress to address its evolving needs on a frequent basis until biopower is a seasoned energy alternative. One frequent topic of discussion for renewable energy is the “uneven” playing field for certain feedstocks. Supporters of pre-selected feedstocks for biopower production argue that resources can be targeted to that handful of feedstocks that display the most potential for bioenergy production. Opponents contend that pre-selecting certain feedstocks makes it difficult for other feedstocks to obtain the support needed to show their competitiveness as a biopower source. Congress currently supports biopower with the Renewable Energy Production Tax Credit (PTC) and the Investment Tax Credit (ITC). The PTC is an incentive to business developers of renewable energy projects producing electricity, whereby a developer can apply for a credit against taxes for each kilowatt-hour of renewable energy produced.20 The ITC is an incentive for domestic investment in renewable energy plants and equipment.21 In lieu of tax credits, biopower administrators may apply for payments from the Department of the Treasury under the Section 1603 Program for having placed in service a specified energy property.22 Qualifying projects are those that are placed in service or under construction before the end of 2011. Moving forward, there may be unintended consequences of legislation that supports biopower. For example, initial USDA regulations for implementing the Biomass Crop Assistance Program (BCAP) led to shifting sawmill residues from products (especially particleboard) to energy rather than increasing utilization of forest waste or planting biomass feedstocks for bioenergy.23

Legislative efforts are under way to further support the biopower industry. One relevant legislative effort is the creation of a renewable electricity standard (RES) to encourage renewable energy use, and thus production of renewable energy such as biopower. One energy policy bill, introduced during the 111th Congress, that included a federal RES was the American Clean Energy Leadership Act of 2009 (ACELA, S. 1462).24 The RES would have required utilities that sell electricity to consumers to obtain a percentage of their annual electricity supply from renewable energy sources or energy efficiency, starting at 3% in 2011 and rising incrementally to 15% by 2021. S. 1462 identified biomass as an eligible renewable source. H.R. 2454, H.R. 890, S. 433, and S. 3021 were other bills introduced during the 111th Congress that would have created a federal RES. H.R. 2454, the American Clean Energy and Security Act, contained provisions that would have supported biopower, such as transmission planning and net metering, along with an RES.25


While there remain significant challenges to its future development, biopower production could increase in the coming years to satisfy U.S. renewable energy demand (e.g., state renewable portfolio standards). Generation of electricity from biopower plants has advantages over other renewable sources such as wind and solar. Biopower plants are considered baseload plants. Also, multiple biomass feedstocks can be used to generate electricity. Some disadvantages of using biomass for electricity generation include the cost to transport the biomass to the biopower plant, less biomass to be used for other purposes, and environmental tensions such as whether biomass combustion is carbon-neutral. A sustainable supply of biomass feedstocks could be favorable to biopower growth.

Questions remain about what would be needed to increase biopower production and simultaneously address technological, environmental, and agricultural concerns. Because market and regulatory uncertainties exist for biopower, the agricultural community may be hesitant to grow the amount of biomass feedstocks needed to support large-scale biopower production. Moreover, most biopower technologies, with the exception of combustion and co-firing systems, have yet to reach commercial status. Improvements to the remaining biopower conversion technologies may arise when there is a solid market for biopower. Furthermore, regulatory uncertainty has contributed to the reluctance to develop biopower. There is no federal mandate requiring the production of biopower, although more than 25 states have implemented state renewable portfolio standards or goals that include biopower. Additional assurances of federal support, whether technical, economic, or through renewable mandates, could spur commitments by investors, the technology community, and others.

Appendix A.  Biomass Feedstock Characteristics for Biopower Generation

Feedstock Type Energy Value Btu/lb (dry)a Feedstock Yieldb Selected Advantages Selected Disadvantages Commentsc
Woody Biomass          
Willow (example of a wood crop grown as a bush type or “coppice” crop in high density plantings as dedicated bioenergy crop) 7,983-8,497 4-8 dry tons/acre/year harvested on 2-4 year cycle
  • High yield potential
  • Grown for several cycles before replanting
  • Select varieties easily replicated by cloning
  • Easy to automate planting and harvest as a row crop
  • Short harvest cycle for wood
  • Farmers can grow and harvest
  • Low ash content
  • Requires specialized harvesting equipment
  • High density plantings are costly to establish
  • U.S. experience and varieties of willow currently limited to Northeast
  • Must be harvested in winter to obtain regrowth for several cycles
  • Agricultural site preparation needed for successful establishment
  • Susceptibility of some willow varieties to insects and diseases may require occasional chemical applications
  • Very high future yield potential with genetic selection
  • Innovative harvest equipment  is available
  • Many woody hardwood crops can be grown as bush type crops
  • Economic yields obtained on marginal to good cropland
  • Less fertilization required than agricultural crops
Hybrid poplar (example of a fast growing hardwood grown as a row crop for bioenergy or multiple purposes) 8,183-8,491 3-7 dry tons/acre/year; harvested on 5-15 year cycles
  • High yield potential
  • Select varieties easily replicated by cloning
  • Easy to automate planting and harvest as a row crop
  • Can be stored on stump until needed
  • Relatively low-maintenance crop
  • Improvements for bioenergy will also likely benefit the pulp and paper industry
  • No immediate return on investment
  • Susceptibility of some hybrid poplar varieties to insects and diseases may require occasional chemical applications
  • Agriculture-type site preparation needed for successful establishment
  • Regrowth after harvest is possible but replanting with superior clones is recommend
  • Very high future yield potential with genetic selection
  • Innovative harvest equipment is under development
  • Economic yields obtained on marginal to good cropland
 Loblolly pine (example of fast-growing softwood grown as a row crop for bioenergy or multiple purposes )  8,000-9,120  3-7 dry tons/acre/year; harvested every 20-40 years
  • 30 million acres of southern pines already are being managed in southern U.S.
  • Somewhat higher energy value than poplars and willows
  • Grows better than poplars and other hardwoods on marginal coastal plains and flatwoods soils
  • Valuable to landowners as a low-intensity crop with multiple markets
  • Pines cannot currently be cloned; standard breeding and family selection techniques must be used to improve yield
  • Pines are mostly hand planted, since planted as rooted seedlings; Limited automation is possible
  • Agricultural type site preparation needed for rapid early growth
  •  Well suited for thermal technologies to generate electricity and ethanol
  • Conversion to liquid fuels is possible with acid hydrolysis and as a co-product of pulp fiber production
  • Less fertilization required than for agricultural crops
Pine chips (example of forest residues from timber and fiber harvests)  8,000-9,120  10-20 dry tons/acre of on-site residues following logging; harvested every 20-40 years
  • Relatively inexpensive if chips produced at the roadside as a byproduct of wood processing
  • Infrastructure to handle forest residues exists
  • High retrieval cost when tops and branches collected in forest due to labor-intensive collection and transportation
  • Tops and branches may not be accessible or environmentally sustainable to remove for chipping, depending on location and soil type
  •  An expanded ethanol industry using wood can also be an additional source of biopower as a co-product
 Mill residue (from both sawmills and pulp mills)  7,000-10,000  Highly variable depending on operating size of the mill
  • Easily available and accessible
  • Inexpensive
  • Infrastructure to handle feedstock exists
  •  Nearly all mill residues are currently being used in wood products such as particleboard and paper, as fuel for heat or biopower, or to make mulch
  •  Most mill residues will continue to be used at or near the site where wood is processed though at higher energy costs, more might shift to on-site bioenergy production
 Herbaceous Biomass          
 Miscanthus (highly productive grass in Europe)  7,781-8,417  4-7 dry tons/acre/year current U.S. average 4-12 dry tons/acre/year has been observed for delayed harvest yields in Europe
  • Once established, can be harvested annually for 15-20 years before having to replant
  • Low fertilizer requirements
  • Drought-tolerant
  • Very high yield potential with adequate water
  • Long growth season in mid-U.S.
  • Giant miscanthus is sterile, thus not invasive
  • No immediate harvest; takes one to three years to be established
  • Not a native species
  • Testing as a bioenergy feedstock limited to the last 10 years (most research conducted in Europe)
  • Thick-stem and moisture content of 30 to 50% in late fall requires specialized harvesting equipment
  • Planting of rhizomes requires specialized equipment
  • Perennial grass
  • Established vegetatively by planting divided rhizome pieces
  • Higher yields are likely to occur on well-drained soils suitable for annual row crops
  • Suitable for thermochemical conversion processes, such as combustion, if harvest is delayed until late winter
 Switchgrass (example of several possible perennial warm-season grasses)  7,754-8,233  4-9 dry tons/acre/year range in research trials
  • Suitable for growth on marginal land
  • Relatively high, reliable productivity across a wide geographical range
  • Low water and nutrient requirements
  • Provides wildlife cover and erosion control
  • Can be grown and harvested with existing farm equipment
  • Planted by seeding
  • Low moisture content if harvested in late fall (15% to 20%)
  • Few major insect or disease pests
  • No immediate harvest; takes two to three years to be established
  • May require annual fertilization to optimize yields, but at relatively low levels
  • Annual harvest must occur over a relatively short window of time each fall
  • Year-round storage is needed if switchgrass is only feedstock for a bioenergy facility
  • Energy content diminishes over year if not kept dry
  • Ash content can be high
  • Native perennial grass
  • Can be used for gasification, combustion or pyrolysis technologies to generate electricity or for biochemical conversion to ethanol
  • Research for bioenergy feedstock began in the 1980s
 Sorghum—varieties selected for biomass production (similar to a tall thin stalked forage sorghum crop)  7,476-8,184  4-10 dry tons/acre/year Higher yields observed
  • Suitable for warm and dry growing regions
  • Seed production delayed, thus produces more biomass
  • Annual crop, thus immediate return on investment
  • Grows across most of eastern and central U.S., not frost limited
  • Yields more variable than switchgrass, with rainfall differences
  • Requires > 20 inches of rainfall annually
  • Annual crop, thus more expense and work to replant each year
  • Sweet, grain, and silage sorghums are more suitable for ethanol production with higher sugar content
  • Susceptibility to anthracnose disease of some genotypes
 Sugarcane/Energycane  7,450-8,349  Yields exceeding 10 dry tons/acre common
  • Takes approximately one year to become established
  • Has very high yield potential in tropical, semitropical and subtropical regions of world
  • A multi-purpose crop-producing sugar (or ethanol) and biopower feedstock
  • Drought-adapted
  • Planting locations limited to a few states in the South and Hawaii
  • Must be replanted every 4 to 5 years
  • Planting is vegetative (stalks are laid down) rather than by seed
  • Vulnerable to bacterial, fungal, viral, and insect pests
  • Crop must be harvested green and dewatered or stored like silage
  •  Literature mostly centers on its use for ethanol
  • The bagasse (residue once juice is extracted from the sugarcane) may be used for biopower e.g., frequently used in Brazil
  • Research ongoing to hybridize to achieve cold tolerance
 Aquatic Biomass          
 Algae  8,000-10,000 for algal mass; 16,000 for algal oil and lipids  Estimates not available for biopower
  •  Cultivation strategies can minimize or avoid competition with arable land and nutrients used for conventional agriculture
  • Can use waste water, produced water, and saline water, reducing competition for limited freshwater supplies
  • Can recycle carbon from CO2-rich flue emissions from stationary sources including power plants and other industrial emitters
  • Relatively little R&D investment regarding feedstock, biopower conversion, and infrastructure
  •  Considered a third-generation bioenergy source
  • Mainly considered for biofuel purposes; however, some scientists are studying its biopower potential, both directly or via methane productiond
 Agricultural Biomass and Animal Wastes          
 Corn stover  7,587-7,967  Stover amounts could range from 3-4.5 dry tons/acre/year in fields producing 100-150 bushels of grain/acre
  • Cultivation techniques are established
  • Using a resource that has previously gone unused
  • Stover conversion process could be added to grain-toethanol facilities
  • Harvesting and transportation infrastructure not yet established
  • Excessive removal may lead to soil erosion and nutrient runoff
  • Requires high level of nutrients and fertile soils
  • Corn grain and stover use has reinvigorated the food-fuel debate
  • Can be used for gasification, combustion, or pyrolysis technologies for electricity or biochemical processes for biofuels
 Wheat straw  6,964-8,148  2.6 tons dry tons/acre
  • Cultivation techniques are established
  • Using a resource that has previously gone unused
  • Harvesting and transportation infrastructure not yet established
  • Excessive removal may lead to soil erosion and nutrient runoff
  • Can be used for gasification, combustion or pyrolysis technologies to generate electricity or biochemical processes to biofuels
 Sugarcane bagasse (residue once juice is extracted from the sugar cane; see above for sugarcane  7,450-8,349  14%-30% of total sugarcane yield
  • Sugarcane takes approximately one year to become established
  • Bagasse is collected as part of the main crop
  • Bagasse availability limited to a few states in the South and Hawaii
  • Ash content can be high
  • Literature mostly centers on its use for ethanol
  • The bagasse is used to power sugarcane mills in many parts of the world.
 Cattle manure  8,500  Based on manure excretion rate of cow
  • Using a resource that is generally regarded as a waste product with little to no value
  • Using a resource that has undesirable environmental impacts if improperly managed
  • Collection systems established for dairy manure
  • Water and air quality improvement
  • Technology to convert manure to electricity is expensive 
  • Difficult for some agricultural producers to sell power to utilities due to economics and utility company collaboration
  • Well suited for anaerobic digestion to generate electricity
 Industrial Biomass          
 Municipal solid waste (MSW)  5,100 (on an as arrived basis)  1,643 lbs/person/year
  • A resource available in abundant supply
  • Diverts MSW from landfill disposal
  • Well commercialized technology (wasteto- energy plants)
  • Could serve as a disincentive to separate and recycle certain waste
  • Air emissions are strictly regulated to control the release of toxic materials often in MSW; toxins removed from air emissions will be transferred to waste ash, which may require disposal as hazardous waste
  • Costs are substantially higher than landfill in most areas
  • Not considered by some as a renewable energy feedstock because some of the waste materials are made using fossil fuels
  • Well suited for combustion (waste to energy plants), gasification, pyrolysis, or anaerobic digestion technologies to generate electricity
 Fossil Fuels          
Coal (low rank; lignite/sub-bituminous) 6,437-8,154 Not applicable
  • Established infrastructure
  • Reliable
  • Relatively inexpensive
  • Limited resource
  • Major source of mercury, SO2, and NOx emissions
  • Main source of U.S. greenhouse gas emissions
  • Generates a tremendous amount of waste ash that likely contains a host of hazardous constituents
Coal (high rank; bituminous) 11,587-12,875 Not applicable
  • Established infrastructure
  • Reliable
  • Relatively inexpensive
  • Limited resource
  • Major source of mercury, SO2, and NOx emissions
  • Main source of U.S. greenhouse gas emissions
  • Generates a tremendous amount of waste ash that likely contains a host of hazardous constituents
Oil (typical distillate) 18,025-19,313 Not applicable
  • Established infrastructure • Reliable
  • Limited resource
  • Major source of SO2 and NOx emissions
  • Purchased in large quantities from foreign sources

Source: Compiled from various sources by CRS and Lynn Wright, biomass consultant working with Oak Ridge National Laboratory.

Notes: The information provided in this table are estimates for general use. Multiple factors including location, economics, and technical parameters will influence the data on a case-by-case basis. Lynn Wright, biomass consultant working with Oak Ridge National Laboratory, provided the following comments: The infrastructure to handle woody resources (both forest residues and plantation grown wood) already exists in the pulp and paper industry and can be easily used for the bioenergy industry. Most woody biomass resources (whether forest residues or plantation grown wood) will be delivered as chips similar to current pulp and paper industry practices. However, new equipment and harvest techniques may allow delivery as bundles or whole trees in some situations. Wood resources such as chipped pine (softwoods) and hardwoods and urban wood residues are already being used to generate electricity using direct combustion technologies, all woody feedstocks are well suited for all thermal conversion technologies including combustion, gasification and pryolysis to generate electricity. Biopower can also be produced from the black liquor by-product of both pulp and ethanol production. Clean wood chips from willow, hybrid poplar, and other hardwoods are also very suitable for conversion to liquid fuels using biochemical conversion technologies.

a. Energy values for the following feedstocks were obtained from Oak Ridge National Laboratory, Biomass Energy Data Book: Edition 2, ORNL/Tm-2009/098, December 2009,; Table A.2 “Heat Content Ranges for Various Biomass Fuels”; willow, hybrid poplar, pine = Forest Residues - softwoods, switchgrass, miscanthus (converted from kj/kg to Btu/lb) corn stover, sugarcane bagasse and wheat straw. Energy values for fossil fuels were obtained by converting the heating values (GJ/t) provided in Jonathan Scurlock, Bioenergy Feedstock Characteristics, Oak Ridge National Laboratory, 2002, papers/misc/biochar_factsheet.html to an energy value (Btu/lb). The energy value for sawmill residue was obtained from Nathan McClure, Georgia Forestry Commission, “Forest Biomass as a Feedstock for Energy Production,” oral presentation for Georgia Bioenergy Conference, August 2, 2006,—Forest%20Biomass%20as%20a%20Feedstock%20for%20Energy%20Production.pdf. The energy value for algae was obtained from Oilgae, “Answers to some Algae Oil FAQs—Heating Value, Yield ...,” February 2007, html. The energy value of manure on a dry ash-free basis was obtained from Texas Cooperative Extension, Manure to Energy: Understanding Processes, Principles and Jargon, E-428, 2006, The manure heating value may be reduced by the ash and moisture content of the manure given certain conditions. The energy value of municipal solid waste was obtained from C. Valkenburg, C.W. Walton, and B.L. Thompson, et al., Municipal Solid Waste (MSW) to Liquid Fuels Synthesis, Volume 1: Availability of Feedstock and Technology, Pacific Northwest National Laboratory, PNNL-18144, December 2008, main/publications/external/technical_reports/PNNL-18144.pdf. The energy value for sorghum was obtained using a value for sudan grass, a closely related crop, from the European PHYLLIS database

b. The harvest frequency is on an annual basis unless stated otherwise. Energy yield ranges for willows, poplars, pines, switchgrass, miscanthus, sugarcane, sugarcane bagasse and sorghum were provided by Lynn Wright, biomass consultant working with Oak Ridge National Laboratory. Energy yields for miscanthus. and switchgrass were also discussed with Jeffrey Steiner (USDA), August 2010. Energy yields for hybrid poplar were also obtained from Minnesota Department of Agriculture, Minnesota Energy from Biomass,; Energy yield for pine chips (forest residues) was obtained from calculations from data in David A. Hartman et al., Conversion Factors for the Pacific Northwest Forest Industry (Seattle, WA; Univ. of Washington, Institute of Forest Products, no date), pp. 6, 47. Energy yield for corn stover was obtained from R.L Nielsen, Questions Relative to Harvesting & Storing Corn Stover, Purdue University, AGRY-95-09, September 1995, Energy yield for wheat straw was obtained from Jim Morrison, Emerson Nafziger, and Lyle Paul, Predicting Wheat Straw Yields in Northern Illinois, University of Illinois at Urbana-Champaign, 2007, publications/2007/PredictingWheatStrawYieldsFinalReportToExtensionMay2007.pdf; In general, it is assumed a dairy cow excretes 150lbs of manure/day based on the American Society of Agricultural and Biological Engineers (ASABE) Manure Production and Characteristics Standard D384.2, March 2005. Energy yield for municipal solid waste was calculated based on data from U.S. Environmental Protection Agency Office of Solid Waste (In 2008, U.S. residents, businesses, and institutions produced about 250 million tons of MSW, which is approximately 4.5 pounds of waste per person per day). Energy yield for miscanthus in Europe was obtained from Clifton-Brown, J.C., Stampfl, P.A., and Jones, M.B., Miscanthus Biomass Production for Energy in Europe and Its Potential Contribution to Decreasing Fossil Fuel Carbon Emissions. Global Change Biology, 10, (2004) pp. 509-518; Energy yield for siwtchgrass was obtained from McLaughlin, S.B., and Kszos, L.A., “Development of Switchgrass (panicum virgatum) as a bioenergy feedstock in the United States.” Biomass and Bioenergy 28 (2005) pp. 515-535. Energy yield for sorghum was obtained from W.L. Rooney, et al, “Designing Sorghum as a Dedicated Bioenergy Feedstock.” Biofuels, Bioproducts, and Biorefining. 1, (2007) pp.147-157; Energy yield for sugarcane/energycane obtained from (a web-published abstract of a book chapter written by Bransby et. al. and submitted for publication in February 2010); Energy yield for sugarcane baggase was obtained from (an abstract of a book chapter prepared by R. Viator, P. White, and E. Richard, and entitled “ Sustainable Production of Energycane for Bio-energy in the Southeastern U.S.” submitted for publication by the Sugarcane Research Unit in Houma, LA in August 2010).

c. For more information on the state of combustion, pyrolysis, gasification, and anaerobic digestion technologies, see the shaded text box on page 5.

d. For more information, see Stanford University, “Stanford Researchers Find Electrical Current Stemming from Plants,” press release, April 13, 2010,; and John Ferrell and Valerie Sarisky-Reed, National Algal Biofuels Technology Roadmap, U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Office of the Biomass Program, May 2010, algal_biofuels_roadmap.pdf.


  1. The Renewable Fuel Standard, a mandate to ensure that domestic transportation fuel contains a specified volume of biofuels, is one reason most legislative and administrative efforts have focused on development of biofuels for transportation. For more information, see CRS Report R40155, Renewable Fuel Standard (RFS): Overview and Issues, by Randy Schnepf and Brent D. Yacobucci.
  2. U.S. Energy Information Administration, Annual Energy Review 2009, DOE/EIA-0384(2009), August 2010.
  3. U.S. Energy Information Administration, Renewable Energy Annual 2008 Edition, August 2010. Biopower constituted roughly 14.4% of electricity generation from renewable energy sources in 2008, preceded by conventional hydroelectric power and wind, which constituted roughly 67% and 14.5%, respectively.
  4. U.S. Energy Information Administration, Annual Energy Outlook 2010, DOE/EIA-0383(2010), Washington, DC, April 2010. The bulk of this increase is expected to come from growth in co-firing operations. Co-firing is the combustion of a supplementary fuel (e.g., biomass) and coal concurrently.
  5. Pew Center on Global Climate Change , Biopower, December 2009. Certain analysis indicates that feedstock supply should be located within a 50- mile radius to avoid excessive transportation costs: Marie E. Walsh, Robert L. Perlack, and Anthony Turhollow et al., Biomass Feedstock Availability in the United States: 1999 State Level Analysis, Oak Ridge National Laboratory, January 2000.
  6. Executive Order 13514 defines sustainability as the creation and maintenance of conditions that allow humans and animals to exist in productive harmony, and that permit fulfilling the social, economic, and other requirements of present and future generations. For more information, see CRS Report R40974, Executive Order 13514: Sustainability and Greenhouse Gas Emissions Reduction , by Richard J. Campbell and Anthony Andrews.
  7. For more information on biomass definitions, see CRS Report R40529, Biomass: Comparison of Definitions in Legislation Through the 111th Congress, by Kelsi Bracmort and Ross W. Gorte.
  8. Some of this information may be provided in a forthcoming update to the frequently cited DOE/USDA Billion-Ton Study, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply, April 2005.
  9. In September 2010 the National Renewable Energy Laboratory released a comprehensive mapping application that may provide better data to compare biomass feedstock and biopower by location. National Renewable Energy Laboratory, “NREL Releases BioEnergy Atlas—A Comprehensive Biomass Mapping Application,” press release, September 28, 2010.
  10. CRS calculations based on 2008 total U.S. retail electricity sales. Power plant capacity factor was assumed to be 80% with 988 growing acres required per megawatt. The yield, six dry tons/acre, is similar to what may be achieved by switchgrass. Land in farms data for Iowa obtained from the 2007 Census of Agriculture.
  11. Peter McKendry, “Energy Production from Biomass (Part 1): Overview of Biomass,” Bioresource Technology, vol. 83 (2002), pp. 37-46.
  12. Peter McKendry, “Energy Production from Biomass (Part 1): Overview of Biomass,” Bioresource Technology, vol. 83 (2002), pp. 37-46.
  13. Section 201 of the Energy Independence and Security Act of 2007 (EISA; P.L. 110-140) defines lifecycle emissions as follows: “(H) LIFECYCLE GREENHOUSE GAS EMISSIONS.—The term ‘lifecycle greenhouse gas emissions’ means the aggregate quantity of greenhouse gas emissions (including direct emissions and significant indirect emissions such as significant emissions from land use changes), as determined by the Administrator, related to the full fuel lifecycle, including all stages of fuel and feedstock production and distribution, from feedstock generation or extraction through the distribution and delivery and use of the finished fuel to the ultimate consumer, where the mass values for all greenhouse gases are adjusted to account for their relative global warming potential.” 42 U.S.C. §7545(o)(1). For more information on lifecycle emissions, see CRS Report R40460, Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard (RFS), by Brent D. Yacobucci and Kelsi Bracmort.
  14. For more information on carbon neutrality of biomass energy, see CRS Report R41603, Is Biopower Carbon Neutral?, by Kelsi Bracmort.
  15. The rule sets thresholds for GHG emissions that define when permits are required for new and existing industrial facilities. For more information on the history of the Tailoring Rule, see CRS Report R41103, Federal Agency Actions Following the Supreme Court’s Climate Change Decision: A Chronology, by Robert Meltz..
  16. EPA’s decision on biomass combustion and biogenic activities is described in further detail on pages 419-422 of the final rule. For more information on the final rule, see CRS Report R41212, EPA Regulation of Greenhouse Gases: Congressional Responses and Options, by James E. McCarthy and Larry Parker.
  17. Environmental Protection Agency, “EPA to Defer GHG Permitting Requirements for Industries that Use Biomass/Three-year deferral allows for further examination of scientific and technical issues associated with counting these emissions,” press release, January 12, 2011. Biogenic includes facilities that emit CO2 from sources originating via a biological processes, such as landfills.
  18. BACT is an emissions limitation that is based on the maximum degree of control that can be achieved. It is a caseby- case decision that considers energy, environmental, and economic impact. BACT can be add-on control equipment or modification of the production processes or methods. BACT may be a design, equipment, work practice, or operational standard if imposition of an emissions standard is infeasible. Environmental Protection Agency, PSD and Title V Permitting Guidance For Greenhouse Gases, November 2010.
  19. Environmental Protection Agency, PSD and Title V Permitting Guidance For Greenhouse Gases, November 2010.
  20. 26 U.S.C. § 45.
  21. 26 U.S.C. § 48.
  22. U.S. Department of the Treasury, Payments for Specified Energy Property in Lieu of Tax Credits under the American Recovery and Reinvestment Act of 2009, January 2011.
  23. For more information on BCAP, see CRS Report R41296, Biomass Crop Assistance Program (BCAP): Status and Issues, by Megan Stubbs. BCAP provides financial assistance to producers or entities that deliver eligible biomass material to designated biomass conversion facilities for use as heat, power, biobased products, or biofuels.
  24. For more information on the proposed RES in S. 1462, see CRS Report R40837, Summary and Analysis of S. 1462: American Clean Energy Leadership Act of 2009, As Reported, coordinated by Mark Holt and Gene Whitney.
  25. For more information, see CRS Report R40890, Summary and Analysis of S. 1733 and Comparison with H.R. 2454: Electric Power and Natural Gas, by Stan Mark Kaplan.


Attached Files



Service, C. (2012). Biomass Feedstocks for Biopower in the United States. Retrieved from