Biopower

Quick Facts

  • In 2011, biopower provided 5.7 percent of total U.S. renewable electricity generation at 27.7 billion kilowatt hours. This is greater than the contribution of solar power but considerably less electricity than wind or hydropower.[1]
  • The United States led biopower capacity globally with 11.5 gigawatts (GW) of generating capacity in 2011, a 1.6 percent increase from 2010. More rapid increases in biopower occurred in developing countries including India with an 8 percent increase in 2010[2] and China with a 25 percent increase in 2011.[3]
  • Globally, an estimated 72 GW of biomass power capacity was in operation at the end of 2011, a 9 percent increase from 2010.[4]
  • In 2011, the electric power sector produced 51 percent of biopower capacity and 49 percent of biopower generation while commercial and industrial biopower made up the remaining percentage.[5]
  • The International Energy Agency found that biopower produced through gasification with carbon capture and storage (BECCS) could result in GHG emission reductions of more than 6.5 gigatons (Gt) per year by 2050.[6]

Background

Before fossil fuels like coal and petroleum transformed the world’s energy landscape, biomass, especially wood, was a primary source of energy for most of human history. Today, biomass provides 10.2 percent of global primary energy consumption, with 61 percent attributed to traditional uses of biomass – primarily domestic cooking, lighting, and heating in the developing world.[7] Additional applications of biomass include combined heat and power (CHP) and in transportation fuels. Biopower, the production of electricity from biomass, holds significant potential as a major renewable energy source in a low-carbon energy future.

Biopower uses biogenic fuels to create electricity through various technologies and fuels including woody biomass, biogenic municipal solid wastes, agriculture wastes, and black liquor burned for industrial sector CHP. Globally, an estimated 72 GW of biopower capacity was in operation at the end of 2011, a 9 percent increase from 2010.[8] In 2011, the United States generated 57 terawatt hours (tWh) of biopower, a 1.6 percent increase from 56.1 in 2010 (see Figure 1).[9]

Figure 1: Biopower Capacity and Generation in the United States, 1980-2011

Source: EIA 2012.[10]

If grown in a sustainable manner, biomass is considered a carbon-neutral energy source – meaning that the greenhouse gas (GHG) emissions, namely carbon dioxide (CO2), released from converting biomass to energy are equivalent to the amount of CO2 absorbed by the biomass plants during their growing cycles. If coupled with future carbon capture and storage (CCS) technology (see Climate TechBook: CCS), biopower could even be a net carbon-negative energy source by permanently removing carbon from the atmosphere.[11]

If grown in a sustainable manner, biomass is considered a carbon-neutral energy source – meaning that the greenhouse gas (GHG) emissions, namely carbon dioxide (CO2), released from converting biomass to energy are equivalent to the amount of CO2 absorbed by the biomass plants during their growing cycles. If coupled with future carbon capture and storage (CCS) technology (see Climate TechBook: CCS), biopower could even be a net carbon-negative energy source by permanently removing carbon from the atmosphere.[12]

Description

Biopower uses biogenic materials to produce electricity for industrial and commercial consumption. In the United States, woody biomass produces 67 percent of electrical power while biogenic municipal solid waste (MSW), landfill gas, and agricultural and other byproducts produce the remaining 33 percent (see Figure 2).[13] Regional fuel sources, ecologic variation, and productivity levels strongly influence biomass production and markets, such as with agricultural waste biopower production development closest to areas with strong agriculture markets (see Figure 3).[14] Recent improvements in biomass collection and storage, and in the development of feedstock markets, have reduced the economic and logistical constraints that limited biomass growth in the past.[15] Increased production, sales, and shipments of wood pellets is one example of a growing biomass market. Overall, biopower is widely distributed across the United States with power plants in all regions, though primary fuel sources vary regionally.[16]

Figure 2: U.S. Biopower Generation by Fuel (2010)[17]

Source: EIA 2011.

A recent projection from the U.S. Department of Energy (DOE) National Renewable Energy Laboratory (NREL) found that United States use of biomass for dedicated biopower as well as co-firing (the burning of biomass alongside other fuels such as coal or natural gas) would require an estimated 259.8 million dry metric tons of biomass by 2035.[18] NREL recently estimated the short-term United States biomass supply range between 270 to 460 million dry metric tons while the long-term potential is more than 1,200 million dry metric tons.[19]

Biopower is primarily produced through combustion from either biomass alone (referred to as direct combustion) --- or co-firing (with other fuels such as coal or natural gas) of solid biomass, biogas, renewable municipal solid waste (MSW), or liquid biomass (pyrolysis). Approximately 300 commercial-scale power plants around the world have undergone conversions to incorporate biomass to diversify fuel sources and lower carbon emissions.[20] New markets for biomass, particularly through wood pellets, have allowed for an increase in average generation capability of biopower facilities. The world’s largest biomass power plant, located in the United Kingdom, is 750 megawatts (MW) and fueled largely with imported pellets. [21]

Biomass for biopower is typically sourced from six categories: mill residues, urban wood waste, forest harvesting residues, agricultural waste material, dedicated herbaceous crops, and specified woody crops.[22] Woody biomass, the primary feedstock for commercial-scale electricity and heat generation, consists mainly of residuals from timber harvesting, sawmilling, and pulp and paper production. Future supply may come from increasingly specific “dedicated” energy crops such as hybrid poplar or willow trees.

Municipal waste produces biopower by utilizing landfill gas as fuel or by incinerating solid, nonhazardous, biogenic waste in waste-to-energy facilities. In the United States, there is approximately 3.7 GW of biogenic municipal waste capacity producing 16.4 billion kWhs of electricity – 60 percent of the total electricity produced by biomass materials. [23] Landfill gas produced 14.3 billion kWhs of electricity in 2011.[24] Because opportunities exist to utilize a greater percentage of municipal solid and gas wastes, this has the potential to increase to 9.88 GW by 2030.[25] In 2010, only 12 percent of solid biogenic U.S. trash was diverted from the waste stream and combusted for energy.[26]

When coupled with plug-in electric vehicles PEVs, which include hybrid electric or electric vehicles, or PEVs, biopower can complement biofuels and even serve as an alternative to liquid transport fuels derived from biomass. For example, a study comparing the use of biopower to charge PEVs and the use of cellulosic ethanol to fuel vehicles with internal combustion engines estimated that the biopower/PEV scenario allows for 81 percent more miles driven and 108 percent more emission reductions per unit of land devoted to growing biomass.[27]

Figure 3: Biomass Resources in the United States by County

Source: National Renewable Energy Laboratory (NREL), Biomass Maps, 2009.[28]

Biopower Methods

Conversion Processes convert biomass into biogenic fuels. There are four predominant processes:

  • Gasification, which processes feedstock in a hot, oxygen-starved environment to produce a synthesis gas, or syngas, composed mostly of carbon monoxide and hydrogen. This gas then fuels a gas turbine to produce electricity. In biomass-integrated combined cycle plants (BIGCC), the exhaust from the first cycle runs through a steam turbine in a second cycle, similar to a natural gas combined cycle power plant. While still a developing technology, BIGCC plants are expected to attain efficiencies of up to 60 percent.[29] A study by the International Energy Agency found that the cost of incorporating CCS into BIGCC was lower than for other biopower technologies.[30]
  • Torrefaction is a process in which the feedstock is dried and heated in a special process, allowing it to become pelletized. This process improves the energy density, grindability, and the storage life of the fuel.[31]
  • Pyrolysis, in which biomass is converted into a liquid product by thermal decomposition through processing without oxygen. This is the first step for most biomass processing. Depending whether this process is slow or fast, typically a thirty second difference, the resulting products have different compositions for use in different capacities. Following a rapid heating in fast pyrolysis, the main resulting product is a biomass-derived crude bio-oil. This bio-oil is then substituted for fuel oil or diesel in furnaces, turbines, and engines for electricity production.[32]
  • Anaerobic digestion, in which bacteria decompose organic matter from waste processing methane-rich biogas, landfills, or a dedicated system, which is then purified and used for electricity generation (see Climate TechBook: Anaerobic Digesters). This process does not use traditional biomass feedstocks; rather, it typically captures and utilizes the biogas emitted from the plentiful waste found at landfills (landfill gas) and farms.

Combustion is the processes of creating energy from the biogenic fuels, which then creates electricity for consumer consumption.

  • Direct-firing. In direct-firing, biomass is the only fuel used in a power plant. These plants have efficiencies up to 40 percent, though the norm is often much lower.[33] The feedstock is burned in a boiler to create steam, which is then used to power a steam turbine and produce electricity, similar to a traditional coal power plant. In producing only electricity, the steam remains in the turbine cycle while in a CHP system it used for heat production after extraction.[34] Direct firing power generators include various stoker boilers and fluidized bed boilers.[35]
    • Repowering. An existing fossil fuel power plant can undergo extensive retrofitting, known as repowering, and function as a direct firing facility by fully substituting biomass for fossil fuel. This is a relatively expensive option because it requires substantial modifications.
  • Co-firing. In a co-fired system, biomass substitutes a portion of the fossil fuel source used in a power plant. This technology is readily available and at commercial scale today. In general, a coal plant can be modified to accommodate biomass constituting up to 20 percent of its fuel.[36] Because biomass has much lower sulfur content than coal, this allows coal-fired plants to dramatically lower sulfur dioxide emissions.[37] The feedstock is blended with coal either before entering the boiler through a blended delivery system, or within in the boiler through a separate feed system, a process that requires more extensive plant retrofitting. Biomass co-firing attains efficiencies of 33 to 37 percent, equivalent to that of the average coal plant and typically greater than direct firing biopower plants.[38] Most plants that co-fire are older and smaller (<25 megawatts of electricity capacity, MWe) than the average coal plant.[39]
  • Combined heat and power (CHP, or cogeneration). CHP is a system that produces both electricity and useful heat from various fuels (see Climate TechBook: Combined Heat and Power). CHP combusts fuel to produce steam that powers a turbine generator and the exhaust is used onsite for another electricity generation cycle or directly for industrial uses, such as heat for district heating.[40] CHP plants have efficiencies as high as 75 to 90 percent by reducing energy losses typical in conventional separate heat and power generation by nearly half.[41] Biomass CHP makes up a third of the existing U.S. biopower generating capacity.[42]

Environmental Considerations/Emission Reduction Potential

Biomass can be an effective option to address long-term climate change goals and to meet related regulatory emissions targets. Biopower mitigates greenhouse gas emissions by replacing some or all of the fossil fuels in power production. Because biomass feedstock has lower sulfur content than coal, replacing coal with biomass also reduces sulfur dioxide emissions, the cause of acid rain and health problems.[43] One DOE study found that co-firing reduces CO2 and SO2 emissions by about one to one – 10 percent co-firing with coal reducing CO2 and SO2 emissions each by about 10 percent.[44] A different study found that 15 percent co-firing urban waste biomass with coal could reduce the overall greenhouses gas emissions by 19 percent, due the diversion of methane that would be released had the waste organic matter decomposed naturally.[45] Despite improvements relative to coal systems, biopower still emits particulate matter, carbon monoxide, volatile organic compounds, and nitrogen oxide emissions.[46] Additionally, land-use changes (LUC) from biomass crops and fossil fuel use in biomass harvesting, transporting, and processing all have an effect on total emissions.[47]

Biopower also emits CO2 directly, but one of the most compelling aspects of biopower is the possibility of zero, or even negative, life cycle emissions of CO2. Energy activities that release carbon into the atmosphere are carbon-positive (like burning coal) while energy activities that remove carbon from atmosphere are carbon-negative (like CCS). Biopower’s carbon neutrality is under scrutiny because of questions about how policymakers should address the timing of emissions vs. sequestration and because of concerns about biomass sustainability. However, studies have shown that biopower can boast lower carbon emissions over the long term than traditional fossil fuels, even when fossil fuel systems use carbon sequestration.[48]

Sustainable biopower sources refer to electricity from biomass that limits LUC, limits pollution, prioritizes waste materials, and regrows quickly. Without actions to ensure sustainability, an increase in dedicated crops could result in undesirable impacts in natural settings, such as LUC and pesticide use.[49] Moreover, biomass results in a ‘carbon debt’ by releasing existing carbon accumulated in forests and natural settings. Recovering the released carbon is equivalent to the time required to regrow the biomass, referred to as a ‘payback’ period.

The Manomet Biomass Sustainability and Carbon Policy Study found that when using harvested forest biomass in electricity generation, the payback period ranges from 21 years when replacing coal to more than 90 years when replacing natural gas.[50] Instead, using logging and forest waste residues – tops and limbs – requires a 10-year payback period for coal and 30-year payback period for natural gas.[51] Dedicated grassland crops replacing coal repay the carbon debt in as little as one year.[52] Using biogenic MSW and landfill gas systems do not have a payback period because of the difference in fuel source. They can even be considered to avoid methane emissions that would have otherwise occurred, has the gas been allowed to escape. Besides changes in CO2, removing biomass can also temporarily disturb surface reflectivity, or albedo, which can impact the local climate and biophysical balance. This is particularly true when sourcing biomass from forested areas that typically experience seasonal snow cover.[53] ­

Life cycle emissions from biopower depend on a range of factors including the type of biomass, technology used, feedstock production (cultivating and harvesting), transportation, and power plant operating standards.[54] An in-depth greenhouse gas life-cycle analysis (LCA) for biopower incorporates a broad scope of important characteristics including the fossil fuels replaced, the impact on global LUC, and the sustainability of the biomass sources.[55] Importantly, meta-analysis of existing LCAs by NREL found GHG emissions per kWh were lower for biopower when compared with fossil-based systems (LUC was not included due to inconsistencies in accounting and a lack of information) (see Table 1).

Table 1: Life Cycle GHG Emissions of Electricity Generation Technologies (g CO2e/kWh)

Energy source

Emissions

 

Lowest 25% of plants

Plant average

Highest 25% of plants

Coal

883

1001

1141

Natural gas

427

477

543

Biopower (average)

-3

52

69

Co-firing*

9

49

65

Direct combustion

7

56

84

Gasification

16

49

63

Gasification Engine

85

81

100

Source: Avoided GHG are primarily from using methane from landfill and biomass wastes NREL 2012. [56] *Note: NREL is only reporting the biomass portion for co-firing estimates.

Reducing CO2 emissions from biopower with CCS (BECCS) can create a carbon-negative cycle by removing atmospheric carbon (see Climate TechBook: CCS). BECCS can be applied in direct-firing or in co-firing with natural gas or coal. However, using unsustainable biomass sources with a long payback period, such as with forest removal as described above, could counterbalance the benefits of BECCS, at least in the short-term, making sustainable biomass essential for maximizing climate benefits of GHG emission reductions. [57] The International Energy Agency found that BECCS via gasification has the potential to reduce GHG global emissions by more than 2.5 Gt per year by 2050.[58]

Overall, biopower is a promising option to meet future energy needs from a renewable energy source and with reduced greenhouse gas emissions. Large-scale deployment of biopower will likely require an increase in energy crops to meet fuel demands. these crops will need to be carefully selected and in order to avoid negative externalities such as LUC, high water demand, pollution, degraded natural places, and food crop displacement.[59] With sustainable biomass and by utilizing new technology such as CCS and landfill methane capture, biopower can act as a carbon-negative energy source.

Cost

Biopower costs depend on several factors including feedstock type and source, boiler technology, plant generating capacity, and services provided (heat and/or electricity). Because of the wide range of fuel sources and technologies available, there is a significant range of costs and system flexibility.

Fuel Costs

Biomass fuel prices depend on moisture content, processing level, transportation expense, and acquisition difficulty of the material. Compared with fossil fuels, biomass has lower energy density, meaning that each ton of biomass produces less energy. This leads to significant transportation costs, up to 50 percent of the feedstock cost, making proximity an important factor of cost-effectiveness.[60] Agriculture residues are typically the least expensive biomass source for biopower followed by mill residues and foresting wastes. The most expensive feedstock is dedicated energy crops.[61] In 2011 in the United States, coal averaged $2.39 per million Btu, [62] natural gas averaged $3.98 per million Btu,[63] and biopower had a high cost estimate of $5.00 per million Btu, based on the availability of 473 million dry tons at $60 per dry ton or less.[64]

Power Plant Costs

As with many large power projects, high capital costs can be a limitation to implementing biopower technology solutions. However, because of the range of technologies available, including incorporation into existing systems, biomass configurations may be more readily available than other types of renewables that require independent infrastructure. For example, capital costs for co-feed, a type of co-firing plant that mixes biomass with coal prior to grinding, are the least expensive of all biopower options.[65] ­To more accurately compare costs of various technologies and fuel sources, the levelized cost of electricity (LCOE) takes into account equipment costs, discount rate, economic life, feedstock costs, operating and maintenance, and efficiency. Recent LCOE analyses performed by the U.S. Energy Information Administration found that when comparing levelized biopower to traditional fuel sources, biomass costs are competitive (see Table 2 for a comparison between biopower and traditional fossil fuels).

Table 2: Comparison of New Power Plants Entering Service in 2017 (USD/MWh)

 

Levelized Capital Cost

Variable O&M (including fuel)

System Levelized Cost

Coal

 

Conventional Coal

64.9

27.5

97.7

Advanced Coal (IGCC)

74.1

29.1

110.9

Advanced Coal with CCS

91.8

36.4

138.8

Natural Gas

 

Natural Gas Combined Cycle (NGCC)

17.2

45.8

66.1

Advanced NGCC

17.5

42.4

63.1

Advanced NGCC with CCS

34.3

50.6

90.1

Biopower

 

Biomass

56

44.3

115.4

Source: USD Annual Energy Information Administration of the Department of Energy 2012.[66] Note: Because many biomass technologies are combined to produce this number, a high degree of variability is hidden. See Table 3 for more information on specific technologies.

While average total system costs are higher, it is important to note that there is variation between biopower systems (see Table 3). Moreover, clean energy incentives may encourage investment. In the near term, biomass co-firing is likely to remain the most economically feasible technology for biopower today. Other biopower technologies also have great potential to meet energy and climate goals in the medium and long term. For example, the most advanced gasification technology is still in an early commercialization stage of development in the United States, though it is in operation in European countries.[67]

Table 3: Capital and Operating Costs of Select Biopower Technologies

 

Overnight Capital Cost (2010 $/kW)

System Levelized Cost (2010 $/MWh)

Co-firing, co-feed

559

47

Co-firing, separate feed

1000

47

Landfill Gas (MSW)*

1917 – 2436

90 – 120

CHP

3859

67

Stoker Combustion

3657

59

Source: National Renewable Energy Laboratory 2012IRENA, 2012.

Current Status of Biopower

Biopower crosses a wide range of policy arenas including agriculture, land management, air emissions, industrial processing, and power production. Policy discussions concerning biopower are likely to intensify as the United States continues to seek renewable and clean energy options, particularly with the possibility to classify biopower as carbon-negative. The definition of ‘sustainable’ biomass will shape this classification and influence biopower development in upcoming years.

A range of policies can affect biopower, such as renewable electricity standards, clean energy standards, or extension of the Farm Bill.[68] The proposed 2012 Clean Energy Standard considered electricity produced from biomass as a fully creditable clean energy source, alongside other traditionally recognized renewable energy sources.[69]

Of importance, the EPA has authority to regulate greenhouse emissions under the Clean Air Act (CAA) following the Supreme Court case Massachusetts v. EPA (2007).[70] In 2010, the EPA set out rules for permitting of new large stationary sources to regulate emissions – the Prevention of Significant Deterioration (PSD) and the Title V Operating Permit Programs – but did not exempt biopower emissions.[71] However, on July 1, 2011, the EPA announced it would defer permitting requirements for biomass-fired and biogenic-sourced energy facilities for three years.[72] This deferment allows time for the regulatory authority to analyze the issues surrounding biopower’s potential for carbon neutrality outlined in the environment section.[73] While relieving requirements for the time being, there is concern that regulatory uncertainty may deter biopower investment.[74]

Biopower also needs to overcome difficulties in acquiring a consistent feedstock, which could limit the ability to achieve economies of scale in biopower production.[75] Financing and siting for projects often require long-term fuel supply projections – still an undeveloped market in some geographic areas – and can limit project scale.[76] There is also potential increasing fuel competition between the power and fuel sectors and between geographic regions. To date, no policy encompasses both power and fuel production from biomass.[77]

Policy Options to Help Promote Biopower

Government support could significantly encourage biomass-fueled electricity and other low-carbon energy technologies. Much of the existing biopower capacity is a result of synergies between industrial waste disposal (forest, agriculture, and municipal) and energy needs. With appropriate climate and energy policies, biopower could be a primary renewable resource in a portfolio of low-carbon energy technologies.

  • Price on carbon emissions and sinks. Currently, fossil fuel power plants face no direct financial consequences for emitting CO2. Policies placing a price on carbon, such as cap-and-trade, would discourage traditional fossil-fuel use and spur investments in clean energy technologies, including biopower. A carbon pricing policy could also value carbon sinks that absorb emissions, like carbon sequestration in plants and geological formations.
  • Market and regulatory barriers. Removing or softening market barriers at the local, state, and federal levels can remove investment uncertainty, improve understanding, and reduce differentiation between policy and incentive programs among governmental entities and regions.[78]
  • Loan guarantees. Loan guarantees make funding large projects more feasible and relieve project developers from a degree of risk. Until a better understanding of the market risks and barriers is established, loan guarantees will allow for more demonstration projects and develop a better understanding of overall market behaviors.
  • Government funding for RD&D. Government funding or financial incentives for RD&D can advance biopower technology (e.g., BIGCC and BECCS). Additional scientific research can also improve understanding of net GHG impacts of large-scale biomass production and build consensus on the life cycle GHG emissions of biopower.
  • Production tax credit. The American Recovery and Reinvestment Act of 2009 extended the federal production tax credit (PTC) to generators for biomass electricity as well as other renewable electricity generation through 2013. This incentive makes investments in biopower more cost-competitive with traditional fossil fuel.
  • Renewable portfolio standard (RPS). Ensuring inclusion of biopower as a renewable energy source can ease implementation. Currently 30 states and the District of Columbia have renewable portfolio standards (RPSs), requiring a certain level of electricity production to come from renewable resources.[79] Many of these include biopower as a qualified renewable energy source.[80] Additionally, Congress has considered proposals for a national RPS.[81]
  • Development and adoption of Certifiable Standards for biomass production. An independently certifiable standard, focusing on supply chain and feedstock production, can provide information on biomass sources and support development of a sustainable biomass market. A certification system would monitor and guarantee biomass is sustainable by addressing undesirable LUC, pollution, and degradation. Sources that have smaller risk for LUC, such as waste materials or utilizing marginal or degraded land, could be identified and encouraged.[82]

Related Business Environmental Leadership Council (BELC) Company Activities

DTE

Duke Energy

Exelon

Johnson Controls, Inc.

PG&E

Weyerhaeuser

Related C2ES Resources

C2ES Renewable Energy Resource Page

Climate Change 101: Technological Solutions

State Renewable Portfolio Standards Resource Map

C2ES A Performance Standards Approach to Reducing CO2 Emissions from Electric Power Plants, 2009

C2ES TechBook: Agriculture Overview

C2ES TechBook: Carbon Capture and Storage

Further Reading / Additional Resources

International Energy Agency (IEA) / Global Bioenergy Partnership (GBEP)

U.S. Department of Energy / National Renewable Energy Laboratory

Combined Heat and Power Resources

Manomet Center for Conservation Sciences

Renewable Energy Policy Network

U.S. Environmental Protection Agency

Intergovernmental Panel on Climate Change (IPCC)

Endnotes

 


[1] .U.S. Energy Information Association (EIA AER), Annual Energy Review 2011, (U.S. Department of Energy, 2012), http://www.eia.gov/totalenergy/data/annual/pdf/aer.pdf

[2] NREL, Indian Renewable Energy Status Report, NREL/TP-6A20-48948 (2010) http://www.nrel.gov/docs/fy11osti/48948.pdf

[3] Renewable Energy Power Network (REN21), Renewables 2011: Global Status Report, (Paris: United Nations Environment Program, 2012), http://www.ren21.net/REN21Activities/Publications/GlobalStatusReport/GSR...

[4] In 2010, worldwide biopower capacity was estimated to be 66 GW. REN21 2012.

[5] National Renewable Energy Laboratory (NREL), “Chapter 6: Biopower Technologies,” Renewable Electricity Futures Study: Renewable Electricity Generation and Storage Technologies, Vol 2., (2012), http://www.nrel.gov/docs/fy12osti/52409-2.pdf

[6] Refers to the technical and economic potential of BECCS. IEAGHG, Potential for Biomass and Carbon Dioxide Capture and Storage (2011), http://www.eenews.net/assets/2011/08/04/document_cw_01.pdf

[7] Chum, H., et al, Bioenergy. In IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation Cambridge University Press, (2011), http://srren.ipcc-wg3.de/report/IPCC_SRREN_Ch02.pdf

[8] In 2010, worldwide biopower capacity was estimated to be 66 GW. REN21 2012.

[9] EIA AER 2012.

[10] EIA, "Annual Energy Review" (2012), http://www.eia.gov/totalenergy/data/annual/#electricity

[11] OECD/IEA, Combining Bioenergy with CCS: Reporting and Accounting of Negative Emissions under UNFCC and Kyoto Protocol, (2011), http://www.iea.org/publications/freepublications/publication/bioenergy_c...

[12] OECD/IEA, Combining Bioenergy with CCS: Reporting and Accounting of Negative Emissions under UNFCC and Kyoto Protocol, (2011), http://www.iea.org/publications/freepublications/publication/bioenergy_c...

[13] EIA, Renewable Energy Consumption and Electricity Preliminary Statistics 2010, (2011), http://www.eia.gov/ftproot/renewables/pretrends10.pdf

[14] REN21 2012.

[15] REN21 2012.

[16] NREL 2012.

[17] Note: MSW biogenic is that portion of municipal solid waste consisting of paper and paper board, wood, food, leather, textiles and yard trimmings. Wood residuals and derived fuels include black liquor and mill byproducts in solid and liquid form. Other biomass includes agriculture byproducts/crops, sludge waste, and other biomass solids, liquids and gases. EIA 2011.

[18] NREL 2012.

[19] NREL 2012.

[20] REN21 2012.

[21] A decade ago, plants averaged around 20 MW, but today these are steadily increasing. REN21 2012.

[22] NREL 2012.

[23] Prior to 2000, the EIA included all solid waste in calculations of biopower. However, since that year, non-biogenic waste was no longer included. This document is also intends to cover only MSW biogenic in nature. EIA, Annual Energy Review - Total Energy. (2012), http://www.eia.gov/totalenergy/data/annual/showtext.cfm?t=ptb0802b; NREL 2012.

[24] REN21 2012.

[25] NREL 2012.

[26] US EPA. Municipal Solid Waste Generation, Recycling, and Disposal in the United States: Facts and Figure for 2010s, (2011), http://www.epa.gov/epawaste/nonhaz/municipal/pubs/msw_2010_rev_factsheet.pdf

[27] Campbell, J., Lobell, D., Field, C. “Greater Transportation Energy and GHG Offsets from Bioelectricity than Ethanol,” Science (324) 22 May (2009), 1055-1057.

[28] NREL, Total Biomass by County (2009) http://www.nrel.gov/gis/images/map_biomass_total_us.jpg

[29] Wright et al. 2006; Krister Ståhl, Lars Waldheim, Michael Morris, Ulf Johnsson, and Lennart Gårdmark, “Biomass IGCC at Värnamo, Sweden – Past and Future,” Global Climate and Energy Project: The Global Climate and Energy Project Energy Workshop. Stanford, CA. (2004). It must be noted, however, that the only BIGCC demonstration plant in the world operated at half of the 60 percent potential efficiency.

[30] EIAGHG, Potential for Biomass and Carbon Dioxide Capture and Storage (2011), http://www.eenews.net/assets/2011/08/04/document_cw_01.pdf

[31] Levine, E. Utility-Scale Biomass: Co-Firing and Densification, Public Meeting of the Biomass R&D Technical Advisory Committee, US Department of Energy (2011), http://www.usbiomassboard.gov/pdfs/levine_btac_3-3-11.pdf

[32]Bridgwater, T.” Task 34: Biomass Pyrolysis,” IEA Bioenergy (2007), http://www.ieabioenergy.com/MediaItem.aspx?id=5416

[33] Wright et al, 2006.; Richter, D., “Wood Energy in America,” EESI briefing on 2 June. (2009).

[34] NREL 2012.

[35] EPA, Biomass Conversion Technologies, Combined Heat and Power Partnership (2010) http://www.epa.gov/chp/documents/biomass_chp_catalog_part5.pdf

[36] Comer, K., “Background and Policy Issues for Biomass Co-firing and Repowering,” EESI briefing on 21 August (2008).

[37] NREL 2012.

[38] Wright et al. 2006.

[39] Levine, E., “Utility-Scale Biomass: Co-Firing and Densification.” Public Meeting of the Biomass R&D Technical Advisory Committee. US Department of Energy (2011), http://www.usbiomassboard.gov/pdfs/levine_btac_3-3-11.pdf

[40] District heating refers to a network for distributing hot water or steam through insulated pipes to serve commercial, residential, institutional, or industrial demand for space heating and process heat.

[41] Low estimate from IEA, Combined Heat and Power: Evaluating the benefits of greater global investment (2008); High estimate from IEA, Energy Technology Perspectives (2008).

[42] Lemar, P., “CHP and Biopower: Market Drivers and Outlook,” Resource Dynamics Corporation, EPA CHP Partnership Partners Meeting (2008); EPA, Biomass Combined Heat and Power Catalog of Technologies (2007), http://www.epa.gov/chp/documents/biomass_chp_catalog.pdf

[43] Mann, M.K., Spath, P.L., “A life cycle assessment of biomass co-firing in a coal-fired power plant,” Clean Products and Processes, 3 (2) August, p. 81-91 (2001).

[44] DOE, Biomass Cofiring in Coal-Fired Boilers. Federal Energy Management Program: Federal Technology Alert. DOE/EE-0288 (2004). http://www.nrel.gov/docs/fy04osti/33811.pdf

[45] This figure is assuming the biomass is produced from urban waste sources that would have otherwise been allowed to break down and produce methane, Spath & Mann 2004.

[46] NREL 2012.

[47] Bracmort K., “Is Biopower Carbon Neutral?” Congressional Research Service: R41603 (2012), http://www.fas.org/sgp/crs/misc/R41603.pdf; Wirsenius, S., et al. How much land is needed for global food production under scenarios of dietary changes and livestock productivity increases in 2030? Agr. Syst. (2010), doi:10.1016/j.agsy.2010.07.005

[48] Spath, P. and Mann, M., Biomass Power and Conventional Fossil Systems with and without CO2 Sequestration—Comparing the Energy Balance, Greenhouse Gas Emissions and Economics, U.S. DOE NREL/TP-510-32575 (2004), http://www.nrel.gov/docs/fy04osti/32575.pdf.

[49] NREL 2012.

[50] This study relies on the use of whole trees from harvested forest stands. Manomet Center for Conservation Sciences, Massachusetts Biomass Sustainability and Carbon Policy Study: Report to the Commonwealth of Massachusetts Department of Energy Resource,. Walker, T. (Ed.). Contributors: Cardellichio, P., Colnes, A., Gunn, J., Kittler, B., Perschel, R., Recchia, C., Saah, D., and Walker, T. Natural Capital Initiative Report NCI-2010-03 (2010).

[51] Bracmort 2011.

[52] NREL 2012.

[53] Cherubini, F., Bright, R., Stromman, A., Site Specific global warming potentials of biogenic CO2 for bioenergy: contributions from carbon fluxes and albedo dynamics. Environmental Research Letters. (2012) http://iopscience.iop.org/1748-9326/7/4/045902/pdf/1748-9326_7_4_045902.pdf

[54] Bracmort 2012.

[55] Manomet Center for Conservation Sciences, Massachusetts Biomass Sustainability and Carbon Policy Study: Report to Massachusetts Department of Energy Resources, Walker, T. (Ed.). Contributors: Cardellichio, P., Colnes, A., Gunn, J., Kittler, B., Perschel, R., Recchia, C., Saah, D., and Walker, T. Natural Capital Initiative Report NCI-2010-03 (2010).

[56] NREL, Life Cycle Assessment Harmonization Results and Findings (2012), http://www.nrel.gov/analysis/sustain_lca_results.html; Figures for specific biomass technologies from personal correspondence with NREL’s Ethan Warner.

[57] OECD/IEA 2011.

[58] The report refers to the realizable potential of IBCC and BIGCC and takes into account energy demand, capital turnover, and deployment rate. IEAGHG. Potential for Biomass and Carbon Dioxide Capture and Storage (2011), http://www.eenews.net/assets/2011/08/04/document_cw_01.pdf

[59] Beringer, T., Lucht, W. and Schaphoff, S. 2011. Bioenergy production potential of global biomass plantations under environmental and agricultural constraints. Global Change Biology Bioenergy 3: 299-312

[60] Biomass Research and Development Board, The Economics of Biomass Feedstocks in the United States: A Review of Literature. (2009), http://www.usbiomassboard.gov/pdfs/feedstocks_literature_review.pdf

[61] NREL 2012.

[62] EIA, Short-term Energy Outlook – Prices (2012), http://www.eia.gov/forecasts/steo/report/prices.cfm; Haq, Z., Biomass for Electricity Generation, EIA (2012), http://www.eia.gov/oiaf/analysispaper/biomass/

[63] IEA, Natural Gas Year in Review (2012), http://www.eia.gov/naturalgas/review/

[64] U.S. Department of Energy, U.S. Billion-Ton Update (2011) http://www1.eere.energy.gov/biomass/pdfs/billion_ton_update.pdf

[65] IRENA 2012.

[66] In this case, the assumed discount rate is 10 percent and the life of the biomass plants to be between 20 to 25 years. EIA AEO, Levelized Cost of New Generation Resources (2012), http://www.eia.gov/forecasts/aeo/pdf/electricity_generation.pdf

[67] Department of Energy, Energy Efficiency and Renewable Energy, Biopower Technical Strategy Workshop, (2010) http://www1.eere.energy.gov/biomass/pdfs/biopower_workshop_report_december_2010.pd f

[68] As of this writing, the updates to the 2008 Food, Conservation, and Energy Act of 2008, or the Farm Bill, that would have extended mandatory funding for rural energy programs failed to move by the last active legislative session. http://biomassmagazine.com/articles/8099/congress-fails-to-pass-farm-bil...

[69] C2ES, Bingaman Clean Energy Standard Act of 2012, (2012) http://www.c2es.org/federal/congress/112/summary-bingaman-clean-energy-standard-act-2012.

[70] Cornell University Law School, MASSACHUSETTS v. EPA (No. 05-1120), http://www.law.cornell.edu/supct/html/05-1120.ZS.html

[71] EPA, Clean Air Act Permitting for Greenhouse Gas Emissions – Final Rules (2012) http://www.epa.gov/nsr/ghgdocs/20101223factsheet.pdf; C2ES, BACT Guidance, http://www.c2es.org/federal/executive/epa/bact-guidance

[72] U.S. Environmental Protection Agency, “Biogenic Factsheet: Final Rule - Deferral for CO2 emissions from Bioenergy and Other Biogenic Sources under the Prevention of Significant Deterioration (PSD) and Title V Programs”(2011), http://www.epa.gov/nsr/documents/Biogenic_Fact_Sheet_June_2011.pdf

[73] Bracmort, K., Is Biopower Carbon Neutral? (2013), http://www.fas.org/sgp/crs/misc/R41603.pdf; See C2ES source on the EPA’s Tailoring Rule: http://www.c2es.org/federal/executive/epa-tailoring-rule

[74] Bracmort, K., “Biomass Feedstocks for Biopower: Background and Selected Issues,” Congressional Research Service R41440 (2010), http://www.fas.org/sgp/crs/misc/R41440.pdf

[75] IRENA 2012.

[76] Lemar 2008.

[77] NREL, 2012.

[78] NREL 2012.

[79] C2ES, Renewable and Alternative Energy Portfolio Standards Map, http://www.c2es.org/us-states-regions/policy-maps/renewable-energy-stand...

[80] Ashton, S. “Renewable and Energy Efficiency Portfolio Standards.” in Sustainable Forestry for Bioenergy and Bio-based Products: Trainers curriculum notebook, eds. Hubbard, W.; l. Biles; C. Mayfield; S. Ashton. (Athens, GA: Southern Forest Research Partnership, Inc., 2007).

[81] EIA, “Analysis of Clean Air Standard Act of 2012” (2012), http://www.eia.gov/analysis/requests/bces12/pdf/cesbing.pdf

[82] Council of Sustainable Body Mass, Developing Sustainability Standards for the Second Generation Cellulosic Bioenergy Industry (2012), http://www.csbp.org/