Biomass
Biomass is the burning of biological products, such as wood and plants to produce energy. Biomass currently supplies 1-2% of the U.S.’s electricity. Biomass is a broad term and generally refers to the burning of wastes (agriculture waste, logging residues, paper industry wastes, building wastes, and trash), forests (pre-commercial thinnings, imperfect commercial trees, and dead or dying trees), energy crops (corn, soybeans, and fast growing trees and grasses, such as miscanthus and switchgrass), and wood pellets.
Photo Credit: Steve Roe
Most biomass technology involves direct burning of the biomass. Other technologies include cofiring (biomass is burned with a traditional fuel source, such as coal), burning of landfill gases (methane and carbon dioxide) or gas from wastewater treatment plants, biomass gasification (oxygen free heating of biomass to produce synthetic gas), liquid pyrolysis (oxygen free liquefaction of biomass), or cogeneration.
Fact Sheet
Interested in using biomass at Harvard? Our fact sheet goes through the basics of what you need to know.
Biomass Cogeneration
Biomass used for the co-generation of heat and electricity is 70-80% efficient as compared to just electricity generation, which is only 25%.
Biomass Gasification
When biomass is heated in the absence of oxygen, a mixture of carbon monoxide and hydrogen, called syngas, is released. Syngas burns cleanly into water vapor and carbon dioxide. Inorganic components, such as metals and minerals, are trapped in an inert and environmentally safe form as char, which can be used as a fertilizer. Gasification is almost carbon neutral, because the growing of the biomass feedstock removes CO2 from the atmosphere (additional processing and other inputs can add excess CO2 to the atmosphere). Syngas inherently burns more efficiently and cleanly than the solid biomass from which it was made
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Wood Pellets
Wood pellets are made from low grade waste wood (sawdust shavings) and have a consistent size, shape, and weight. They are efficient because all of the moisture has been removed. The manufacturing process may make it less carbon neutral than the burning of unprocessed wood.
Carbon Neutrality
Plants capture solar energy and use carbon dioxide via photosynthesis to create stored energy. Burning the biomass returns the CO2 that was absorbed as the plants grew to the atmosphere and releases the energy. Biomass is commonly stated as having no net release of CO2 if the cycle of growth and harvest is sustained (called carbon neutral). This is not always true as it takes some energy (and therefore a discharge of CO2) to grow, harvest, and/or transport the biomass.
Emissions
Compared to oil and coal, the burning of biomass releases less harmful air pollutants at the stack including, NOx and SOx. Biomass gasification releases even less NOx, SOx, carbon monoxide, and particulate matter.
Other Benefits
Biomass is locally available and is continuously available and does not contribute to national security issues. Using biomass supports local industries and the local economy. Biomass can be used continuously, as opposed to solar and wind which are intermittent.
Supply
New England’s biomass supply generally comes from chipped wood leftovers from sawmills, excess harvested wood, waste from manufacturing, or wood pellets. Massachusetts' state forests are Forest Stewardship Council certified and currently underutilized.
Costs
Biomass costs less than other fuel options (in the Northeast, oil and gas cost 2 to 2.5 times as much as wood chips and wood is 8-10 times cheaper than electricity). Biomass costs have stayed stable over the past 20 year, in part because they are not linked to global instability or corporate monopolies. Future energy taxes are less likely to impact biomass than other fuels. For information on the feasibility of switching to biomass, use the Wood Fueled Boiler Financial Feasibility.
LEED
Buildings can obtain LEED points for using renewable energy on-site. More information is available on our Renewable Energy and LEED page.
Sources/Additional Information:
Massachusetts Technology Collaborative: Biomass Benefits & Barriers
Massachusetts Sustainable Forest Bioenergy Initiative
Securing a Place for Biomass in the Northeast
Bioenergy Feedstock Characteristics
Natural Resources Defense Council: Biomass
Northeast Regional Biomass Program
Guidebook to Wood Pellet Heating
The Woody Biomass Supply in Massachusetts
Biomass Energy Resource Center
Michael Brower, Cool Energy, MIT Press, Cambridge, MA, 1992.
Roy Nersesian, Energy for the 21st Century, M.E. Sharpe, New York, 2007.
Biomass Symposium at Harvard
The Harvard Green Campus Initiative sponsored a symposium about using biomass in boilers on October 5, 2007.
Agenda: 
Introduction: Opportunities at Harvard
Leith Sharp: Director, Harvard Green Campus Initiative
Overview of Biomass
Ben Urquhart: Biomass Specialist, MA Division of Conservation & Recreation
Central Plant Biomass Case Studies
Rob Rizzo: Director of Facilities Administration, Mt. Wachusett Community College
Mike Moser: Central Heating Plant Manager, Middlebury College
Building-Scale Boilers Biomass Case Studies
Kamalesh Doshi: Project Director, Biomass Energy Resource Center
For more information:
Download the invitation.
Download powerpoints by clicking on the presenter's name.
Download the symposium proceedings.