Biomass Cofiring: A Transition to a Low-Carbon Future

This fact sheet from the Environmental and Energy Study Institute describes biomass cofiring—the simultaneous combustion of biomass and a base fuel, typically coal—as a low-cost transition tool to reduce greenhouse gas emissions and fossil fuel reliance in the electric sector.

• Biomass cofiring involves burning a biomass fuel alongside a base fuel, most commonly coal, to generate electrical power. The process typically uses a mixture containing less than 20 percent biomass by energy content. Feedstocks include municipal waste, construction debris, crop residues, low-value wood from forestry, and dedicated energy crops like hybrid poplar, willow, and switchgrass. Systems are categorized as either separate feed systems or blended delivery systems, with the latter requiring fewer power plant modifications.
• Cofiring reduces air pollutants and greenhouse gases. CO2 and sulfur dioxide (SO2) emissions decline linearly as biomass replaces coal. While nitrogen oxides (NOx) are produced during biomass combustion, using wood at 7 percent of total heat input can reduce NOx emissions by up to 15 percent compared to coal-only operations. These reductions mitigate health risks associated with urban smog and acid deposition.
• The technology supports sustainable land management by creating markets for hazardous fuels reduction in fire-prone forests. In the western United States, 28 million acres of forest require thinning. Cofiring can make these treatments affordable by providing a market for small-diameter logs. Additionally, cultivating perennial crops like willow or switchgrass on agricultural lands can conserve soil and reduce the need for nutrients and water.
• Cofiring is presented as an economically viable option due to low capital costs, primarily limited to boiler retrofits. Annual fuel costs for an average-sized boiler at a federal facility can be between $60,000 and $100,000 lower than pure coal plants, with production costs reduced by 0.02 to 0.22 ¢/kWh and payback periods often under 10 years. A 2006 experiment in Iowa known as the Chariton Valley Project used switchgrass to produce 19.6 million KWh of electricity, reducing carbon emissions by 50,800 tons and generating 19,600 renewable energy credits over six months.
• Several barriers hinder the adoption of cofiring. Retrofitting costs range from $50 to $300 per kW of biomass energy output, with separate feed systems costing up to four times more than blended systems. Additionally, current ASTM standard (C618) restricts the use of fly ash in cement manufacture to pure "coal fly ash," meaning biomass-cofired fly ash cannot be marketed and becomes valueless waste.
• Cofiring is viewed as a "bridge-technology" that could reduce total U.S. emissions by 1.5 percent if 5% of coal in power production were replaced by biomass, a goal achievable within 5-10 years. It is noted as more cost-effective for carbon mitigation than cellulosic ethanol, which may cost over $1/gallon (equivalent to a carbon price of $200/ton or more).

APA

Caputo, J., & Hacker, J. (2009). Biomass Cofiring: A Transition to a Low-Carbon Future. Environmental and Energy Study Institute. https://www.eesi.org/files/cofiring_factsheet_030409.pdf

Chicago

Caputo, Jesse, and James Hacker. Biomass Cofiring: A Transition to a Low-Carbon Future. Environmental and Energy Study Institute, 2009. https://www.eesi.org/files/cofiring_factsheet_030409.pdf.

Wikipedia

{{cite report |last1=Caputo |first1=Jesse |last2=Hacker |first2=James |title=Biomass Cofiring: A Transition to a Low-Carbon Future |publisher=Environmental and Energy Study Institute |date=March 2009 |url=https://www.eesi.org/files/cofiring_factsheet_030409.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{caputo2009biomass, author = {Caputo, Jesse and Hacker, James}, title = {{Biomass Cofiring: A Transition to a Low-Carbon Future}}, institution = {Environmental and Energy Study Institute}, year = {2009}, month = mar, url = {https://www.eesi.org/files/cofiring_factsheet_030409.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }