Posted: Aug 31, 2010

Bioenergy is a type of renewable energy made from biological sources.There are two main types of bioenergy: solid biomass such as wood, which can be burned to produce energy, and liquid biofuels such as bioethanol and biodiesel, which are derived from biological sources and can be used as automotive fuels.

Bioenergy is a type of renewable energy made from biological sources.There are two main types of bioenergy: solid biomass such as wood, which can be burned to produce energy, and liquid biofuels such as bioethanol and biodiesel, which are derived from biological sources and can be used as automotive fuels.
Biomass is the largest source of renewable energy in the U.S., accounting for 48 percent of the aggregate renewable energy in 2006.  Biomass is used for heating, transportation fuels (known as biofuels), cooking stoves, and electricity.  According to Section 932 of the Energy Policy Act of 2005, biomass is “any organic material grown for the purpose of being converted to energy.”  However, under different proposed and existing Renewable Portfolio Standards (RPS), definitions for qualifying biomass exclude certain sources.  For example, the definition of biomass under the Energy Independence and Security Act of 2007 (EISA) excluded wood harvested from federal lands, but the American Clean Energy and Security Act (ACES) that passed the House of Representatives in June of 2009 (but did not become law) included wood from federal lands. For a synopsis of biomass types that qualify for New York State’s RPS click here.  Qualifying biomass is usually required to be sustainably harvested.  That is, it must be able to regenerate in relatively short time periods, and the emissions released when biomass is combusted be stored by replacement biomass.  The major biomass sources are wood, waste, and crops.

Policies aimed at promoting biomass energy production provoke various responses from conservation groups and other observers. In May 2013, for example, a coalition of environmental groups launched a campaign to oppose the use of biomass for electricity generation, objecting in particular to the export to Europe of wood harvested through clearcutting in the Southern United States.

There are many pros and cons to bioenergy, varying by the type of biomass and fuel produced. Generally speaking, the major benefits are the following:

  • renewability and sustainability
  • greenhouse gas emission reductions
  • local availability
  • potentially cheaper than other fuels
  • wealth influx to rural economies

However, the potential pitfalls to biomass include its potential to:

  • increase consumer costs
  • displace other food sources
  • encourage farmers to plant on previously fallow lands, thus increasing greenhouse gas emissions
  • lead to forest mismanagement by overharvesting

In a report published in October 2011, the National Research Council cautioned that current federal biofuel mandates are not achievable without innovative new technologies or new policies. See story in the LA Times (10/4/11).

Key Concepts

Woody Biomass

Wood can produce energy as cords, chips, pellets, and “black liquor.” Burning logs of cord wood in the fireplace is the least efficient common form of bioenergy, and the cords must typically be dried for at least a year prior to burning. Wood chips are cheap ($15-$30 a ton – or even free from tree services), require little processing, and can be used immediately. However, wood chips generally require large combustion and feeding machinery and are most suitable for single buildings over 100,000 square feet or campuses. See Vermont Heat Research  for a small-scale experiment using wood chips to heat a home in Vermont. Wood pellets are another option. They are small pieces of uniformly compressed wood material – often sawmill byproducts – with low moisture content. Wood pellets serve well in small heating systems like high-efficiency stoves because they are easily stored and burned, and they release few emissions.  

Black liquor is a byproduct of paper pulping.  Pulp mills have used black liquor to produce electricity since the 1930s, which accounts for most of the electricity produced from biomass in the U.S.  Black liquor contains half the energy of the original wood, and can now be converted to syngas as well.

Waste of Energy

Waste from garbage, feces, and manufacturing byproducts can be converted to an energy source as anaerobic digestion generates methane.  Anaerobic digestion naturally occurs to organic materials in the absence of oxygen.  Methane is “natural gas” and serves as fuel for steam turbines to produce electricity.  An increasingly popular form of “waste to energy” is “poop to power,” a process of taking livestock waste, placing it in vats with anaerobic digesters and separating out the methane for energy production. 


Ethanol is grain alcohol, and it can be used to fuel automobile engines.  Ethanol contains about 2/3 the energy per gallon as gasoline, but is commonly blended with gasoline to produce a fuel that can run in standard automobile engines.  It can be produced by corn starch, sugarcane, cellulose or algae.  Cellulosic ethanol, also known as second generation ethanol, uses the entire plant to produce ethanol whereas normal corn ethanol only uses the kernels, making cellulosic ethanol more efficient although it remains more expensive to produce. A third generation of ethanol made from algae has also recently been developed.  While currently more expensive, ethanol made from algae is promising because it can be produced on much less land than is required for corn.  

A federal program under the Energy Independence and Security Act of 2007 (EISA) requires 36 billion gallons of biofuels be produced in the U.S. by 2022.  In 2008, corn ethanol composed almost all of the 9 billion gallons of biofuels.  All ethanol is subsidized at 45 cents/gallon to make it competitive with gasoline, but imported ethanol is taxed at 54 cents per gallon plus 2.5% ad valorem. See Controversies: Ethanol for comments on the subsidy, the tariff, and ethanol’s environmental impact.


Biodiesel is a diesel fuel made from vegetable oil and animal fat.  It can be used in standard diesel engines, but engine modifications may be required.  Biodiesel can be blended with petrodiesel and contains almost as much energy as petrodiesel.  Another advantage of biodiesel is that it is biodegrable and non-toxic, meaning a spill would not damage the environment like a petrodiesel spill would.  See Title II of EISA for its definition of biodiesel, required quantities of biodiesel production (1 billion gallons by 2012), and research funding.  Section 230 provides for $50 million in research funding for cellulosic ethanol and biofuels.

Combined Heat and Power (CHP)

CHP (also known as cogeneration) systems capture the heat created as a byproduct of electricity generation that is normally emitted into the atmosphere in traditional power plants.  The heat is then used for local domestic or industrial steam heating or for hot water.  The heat generation makes CHP systems far more efficient than separate electricity and heating systems.  Biomass is well-suited for CHP because it generates a lot of heat while being processed for electricity.  Usually the power systems are fueled by an engine or turbine and the heat recovery systems use a boiler.


Biomass can be gasified by heating the inputs with a controlled amount of oxygen, thereby producing synthesis gas (syngas).  Syngas is a combination of H2 and CO, and is usually an intermediate step in producing other fuels like synthetic natural gas, methanol, and synthetic petroleum.


Biogas refers to gases produced by the breakdown of organic material, usually in the absence of oxygen, which can be used as fuel similar to natural gas.  Depending whether the biogas is produced from landfill gas, manure, or woody biomass, the compound can be significantly different but functions in the same basic way as combustible fuel.


Biochar is a type of charcoal produced by heating biomass to between 400 and 500 degrees in the absence of oxygen. The resulting high-carbon solid can be mixed into the soil to sequester carbon for hundreds to thousands of years. Biochar also increases the soils fertility, and the gasses released during its creation can be used to produce biofuels. For more on carbon sequestration see Climate Change: Carbon Capture and Storage (CCS).

Process Essentials: Federal Subsidies

Research and Development

Several federal and state policies provide funding for biomass R & D with a focus on making biomass competitive with fossil fuels. Section 231 of EISA provides yearly budgets ($398 million for 2009) for “research, development, demonstration and commercial application for bioenergy.”   

The American Recovery and Reinvestment Act of 2009 (ARRA) added more funding to provide $786.5 million for research, development, and biorefinery demonstration projects.  $85 million from the ARRA has been set aside especially for advanced biofuel production.  The DOE is concentrating first on making algae biofuels competitive with petroleum products.  Algae has strong potential as a biofuel because it grows in water instead of displacing arable land, it consumes CO2 from the atmosphere, and an acre of algae ponds can produce 15,000 gallons of biofuel whereas an acre of soybean produces only 50 gallons of biofuel.  The DOE’s second priority with the earmarked money is promoting the cost-effective conversion of woody biomass, including plant stalks and wood chips, to biodiesel and biogasoline.

The federal government also provides financing for biomass technologies through programs such as the Biobased Products and Bioenergy Program.  A similar program, the Biorefinery Grant and Loan Guarantee Program provides grants for up to 30% of the cost of a biorefinery, and loans of up to 80% of the project costs.  Eligible biorefineries must produce advanced biofuels and be commercially viable. 

Click here for a suite of federal and state bioenergy tax credits, grants, and loans or  here for federal and Colorado-specific bioenergy policies.  Policies include grants to universities for studies, subsidies for mixing ethanol and gasoline, and loans for pilot biorefineries.

Renewable Fuel Standard (RFS)

biomass_chart.pngEISA contains a RFS with required quantities of biofuels to be used in automobiles.  See the chart below for the requirements by year.  Total renewable fuels refer to all biofuels, and advanced renewable fuels are biofuels not made from cornstarch that achieve a 50% greenhouse gas emission reduction (including cellulosic biofuel and biodiesel).  In 2008, almost all of the 9 billion gallons of biofuels produced in the U.S. were made from cornstarch while the U.S. requires almost 2/3 of the biofuels in 2022 to be non-cornstarch based. 

The Food, Conservation, and Energy Act of 2008 contains a provision requiring the Secretary of Agriculture to ensure expanding production of advanced biofuels.  It also continued the subsidies on domestic ethanol and the tariffs on imported ethanol.  Click here for details.

Tax Credits

The Biodiesel Income Tax Credit provides taxpayers a $1.00 tax credit per gallon for delivering unblended biodiesel (B100) into a customer’s vehicle tank or using B100 in their trade or business.  (The Credit expires on December 31, 2009 if not renewed.)  26 U.S.C. 40A. 

Individual states also give credits for alternative fuel vehicles as well as hybrids.  For example, Colorado gives a tax credit up for up 100% of the incremental or conversion cost for the purchase of an alternative fuel vehicle. 

Oregon offers a 35% tax credit for projects that produce renewable energy or use alternative fuel vehicles as well as a 50% property tax exemption for qualifying ethanol producers.  

Process Essentials: Opening a Biofuels Facility

A publication issued by the state of Missouri outlines the necessary steps to open a biofuels production facility. It sketches the timeline (two to five years) and recommends the following steps: 

  • investigating the market potential
  • forming a steering committee
  • hiring a legal team
  • securing financing
  • obtaining permits
  • selecting a site with adequate access to transportation

Biofuel production facilities are subject to the same environmental regulations as other industrial facilities, and obtaining air and water permits is a major part of the process. The chart below shows what permits must be obtained in the state of Missouri in order to open a biofuels facility. Anyone looking to open a biofuels facility should begin by investigating the local, state, and federal permitting processes. 


One issue on which the report does not go into detail is the availability of subsidies from the federal and state governments.  For example, the Biorefinery Grant and Loan Guarantee Program provides grants for up to 30% of the cost of a biorefinery, and loans for up to 80% of the project costs.

Click here for the full report.

Click here for federal and Colorado-specific bioenergy policies.

Pending Legislation


Controversies: Ethanol

Ethanol, particularly corn ethanol, has been a point of contention for farmers, environmentalists, and politicians on both sides of the aisle. 

Competing Studies

Part of the disagreement over ethanol regards its impact on greenhouse gas emissions. The Rocky Mountain Farmers Union supports the proposition to increase ethanol contents in regular gasoline from 10% to 15% by citing a study from the Journal of Industrial Ecology claiming the direct greenhouse gas emissions from corn ethanol are 50% less than from gasoline. However, a study by Duke University contends that corn ethanol actually produces more greenhouse gas emissions than petroleum over the first forty years of production if grown on previously fallow land. Further, the study says, corn ethanol only reduces greenhouse gas emissions by 20% in good scenarios, after considering the production costs and comparative energy content of the two fuels, whereas setting aside land for native vegetation is a better greenhouse gas control project. In order to produce the 36 billion gallons of ethanol as mandated by EISA, previously set aside land will likely be used to produce corn for ethanol. Thus, the policy could produce some negative impacts on greenhouse gas emissions. 

All studies agree that cellulosic ethanol reduces greenhouse gases to a much greater degree than corn ethanol.


“Farmers who grow corn both for food and for ethanol are pressing the federal government to allow them to plant corn on protected wetlands, grasslands and swamps. These lands, protected for 30 years under the Conservation Reserve Program, prevent 400 million tons of erosion every year. This is soil, pesticides, and herbicides that would otherwise drain into the Mississippi River watershed, impacting water quality in the rivers and streams — not to mention the quality of drinking water. Much of this gunk would then make its way to the Gulf of Mexico and contribute to an ever-expanding dead zone that is making vast areas of marine ecosystems unfit for life and fishing.”

Another aspect of contention is the cost of U.S. ethanol policy. Using corn for ethanol drives up food prices directly as well as indirectly because of greater demand for corn increasing its cost. Furthermore, cornmeal is the food of choice for livestock, and corn is displacing other crops. Many sources have blamed ethanol for the large increases in food prices since 2000, but the Congressional Budget Office released a report in 2009 saying that ethanol was only responsible for 10 to 15% of the 5% increase in overall food prices from April 2007 to April 2008. 

In addition to the food costs is the 45 cents/gallon subsidy to ethanol blenders paid for by American taxpayers. That subsidy is spread out by market forces to corn growers, ethanol refiners, and the price at the pump, but it still costs the average American money and raises questions about the economic validity of corn-based ethanol.

On the other hand, the Rocky Mountain Farmers Union claims that ethanol will generate $24.4 billion dollars for the U.S. economy, could create more than 136,000 “green-collar” jobs, and will reduce dependency on foreign petroleum. 

Despite the general subsidy for ethanol, there is a tariff of 54 cents/gallon imposed on imported ethanol. Critics argue that the policy is purely protectionist and drives up automobile fuel costs because it prevents Brazil’s much cheaper sugarcane ethanol from taking over the market share of domestic corn ethanol. Proponents of the tariff argue that Brazil’s sugarcane crops will displace other lowland crops which will then encroach on the Amazon rainforest. 

“As for the criticism that ethanol plants use fossil fuels in the manufacturing process, the “closed-loop” ethanol plant, like the e3 Biofuels Plant in Mead, Nebraska, attempts to address this criticism. In a closed-loop plant, the energy for the distillation comes from fermented manure, produced from cattle that have been fed the by-products from the distillation. The leftover manure is then used to fertilize the soil used to grow the grain. Such a process is expected to lower the fossil fuel consumption used during conversion to ethanol by 75%.”

Ethanol Subsidies

Because of its higher price, ethanol must be subsidized by the government to be cost competitive with gasoline. The government currently gives a 45-cent per gallon tax subsidy to ethanol producers. These subsidies currently total about 6 billion dollars annually, which comes from taxpayers. Congress is currently considering whether to renew the subsidies, and may instead decide to cut them by 9 cents per gallon, to 46 cents.
Critics of the ethanol subsidy say that this cut is not enough, and want the subsidy to be dropped entirely. Several prominent newspapers, such as theChicago TribuneThe Washington Post, and the Wall Street Journal, have recently published editorials calling for the end of ethanol subsidies. They claim that there are more cost effective ways to reduce oil use, and the subsidies and tariffs have propped up the biofuel industry for too long.
Critics of the subsidy also argue that they are unnecessary because Congress has already mandated a certain amount of ethanol use with the Renewable Fuel Standard, so no further encouragement isnecessary.

Indirect International Land-Use Changes

The controversy continues in ACES. The bill contains a provision eliminating emissions produced by biofuels on indirect international land-use changes from calculations for at least the next five years. Indirect international land-use changes are exemplified by the concerns regarding sugarcane discussed above. Using more sugarcane as fuel reduces the space for soybeans to grow on the Brazilian coasts. Therefore, farmers cut down patches of trees in the Amazon to grow soybeans, and the deforestation releases CO2. Using corn for fuel can have the same impact as the supply from American farmlands is replaced elsewhere.

They will only be recalculated if EPA and the Department of Agriculture agree to do so. The Department of Agriculture is generally perceived as favoring agriculture and therefore ethanol, and it appears unlikely that they will agree to reinstate the indirect emissions at any point. 

Controversies: Biomass


Some critics of using woody biomass as a source of fuel fear that without proper regulations to ensure sustainability, trees will be over harvested, leading to a decrease in forest health.  The Forest Guild, an organization interested in protecting forest health, recently released a set of biomass harvesting guidelinesto address this issue.  The guidelines are designed to encourage the use of biomass as a renewable energy source while ensuring the health of forests where it is harvested.  

Greenhouse Gas Reduction

recent study commissioned by Massachusetts state officials found that the use of biomass power plants would actually increase the state’s net greenhouse gas emissions by 3 percent through 2050.  Although the study found that biomass would reduce greenhouse gas emissions by 19 percent in 2100, the State is now rethinking its biomass policies, including its tax incentives for woodburning plants in order to reach its 2050 reduction goals.

A group of 90 of the nation's top scientists recently sent a letter to Congress asking them to ensure that the net change in greenhouse gas emissions from the use of biomass is properly accounted for.  Although many laws and bills treat bioenergy as causing a 100 percent reduction in greenhouse gasses, this is only true of certain types of bioenergy.  For example, if trees are cut down to be burned as bioenergy, this can actually increase the amount of greenhouse gas released because the carbon sequestered in the trees will be released into the atmosphere.  The scientists want bioenergy emissions to be differentiated based on the source of the biomass used, in order to truly account for the greenhouse gas emissions.

For a story describing this controversy, see "Burning questions about biomass: Of cane, coal, and carbon dioxide," High Country News, 11/8/10. For information on the Natural Resource Defense Council's environmental campaign to reduce biomass exports from clearcut Southern forests, see "Our Forests Aren't Fuel," launched in May 2013.

In an effort to encourage renewable energy development, the EPA announced in early 2011 that it would not regulate greenhouse gas emissions from biomass facilities for the next three years. The agency said it would use this delay to study the potential impacts of these emissions. Environmental groups filed a lawsuit challenging this policy in August 2011, arguing that it would encourage a rush to build biomass facilities without adequate consideration of their greenhouse gas emissions.

Collaboration in Action: Fuels for Schools

Fuels for Schools is a federal program that encourages burning under-utilized local woody biomass to heat schools. It gives communities a way of coping with many problems at once by reducing wildfire risks from fallen trees, productively utilizing local wood waste, and reducing hazardous fossil fuel emissions. Vermont began using local wood waste in the 1980s to provide reliable heat because electric heat prices were high. Now 20 percent of students in Vermont attend schools heated by local biomass. The program is a collaboration between schools that use the power, state and federal governments that provide funding, and local wood-reliant industries and the Forest Service that provide the fuel.

The Vermont system served as a model for other locales, including the town of Darby, Montana. In 2001, after forest fires blanketed large portions of western Montana, the Forest Service and the nonprofit organization Bitter Root Resource Conservation and Development Area, Inc. initialized a pilot project in Darby, Montana. They used funds provided by the National Fire Plan of 2001, which gave grants for pilot projects using smaller woody biomass. The Forest Service initially provided substantial funding to pilot biomass boiler systems in Darby and other Montana public schools. The schools were studied as bases for later biomass projects, and the percentage of funding has been gradually reduced as biomass boilers prove self-sufficient. The Forest Service's Fuels for Schools program has since spread to several states, and beyond just schools. The Northern Nevada Correctional Facility has installed a 1 MW biomass CHP facility.

There are several big advantages of woody biomass boilers. The fuel is usually found locally, lowering transportation costs. The boilers eliminate the need for transmission lines. Prices don’t fluctuate very much, unlike natural gas. Sustainable woody biomass is essentially carbon neutral because new trees sequester the emissions from the consumed ones; thus, schools can seek funding from state and Federal governments for renewable energy tax credits. 

School officials in Kalispell, Montana, estimate that burning woody biomass to heat Glacier High School will save the school district over $58,000 annually. See "School's biomass boiler is a budget boon," Daily Inter Lake, 1/15/10.

Collaboration in Action: Pine Beetle Control

Pine beetles in Colorado have infested large expanses of forests from the western slope to the eastern foothills. It is unclear whether the beetle outbreak is the result of global warming (pine beetles are more successful in warmer weather with fewer severe frosts) or forest management practices (large forest fires would be more common without forest thinning, meaning forests would be younger, and young trees are less susceptible to pine beetles than old ones) or a natural phenomenon. Regardless, the concentration of dead trees is enormous. When the trees are first killed, the red needles provide incendiary fuel for forest fires, thereby threatening nearby residents, homes, and resorts. However, some studies indicate that, once the red needles fall, beetle-killed trees provide no more of a forest fire threat than regular fallen trees.

Several facilities – including a recreation center in Fairplay, the Natural Renewable Energy Laboratory in Golden, and a school in Oak Creek – have made the switch to woody biomass from propane, natural gas, and coal respectively, each for the lower relative cost of local wood chips. If a cap-and-trade bill such asACES, passes the Senate, the price of fossil fuels will increase due to a carbon pricing scheme. Because sustainably harvested biomass is essentially carbon neutral, biomass could be the relatively cheaper heating option for many more facilities. Most biomass qualifies under the majority of current and proposed Renewable Electricity Standards.

One option to discourage the large-scale wildfires which are likely to result from the pine beetle outbreak, is the removal of dead and dying trees – which entomologists calculate will include 95% of Colorado’s lodgepole pines by 2013. Such a task is unfeasible across all the infested forests, but it might be feasible in local areas adjacent to housing and other developments. Moreover, it may be a bad idea to remove all the trees: when they fall and decompose, dead trees provide nutrients for new ones to grow. On the other hand, turning the pine beetle wood into biochar could enrich the forest soil while some is used to displace coal use. 

Despite the drawbacks, there are situations where tree removal makes sense, and removed trees make good fodder for biomass facilities. The city of Vail, Colorado, is cutting down trees surrounding the resort to create a defensible space for firefighters to stop flames from encroaching on the community. The project is already costly, and it is made more so by the need to transport the trees to distant lumber yards and chipping factories. For the cost-related reasons and to reduce greenhouse gas emissions, Vail has requested funding from the U.S. Department of Energy to build a 28 MW CHP biomass facility. John Deere has offered to help with the tree removal to showcase new machinery, and Hayden-Carry & King Co. has offered to build the facility planned to generate 6 MW of electricity and 22 MW of heating. The results may affect whether and how other ski resorts make use of beetle-kill wood. 

Collaboration in Action: California Biomass Collaborative

One group attempting to increase the use of biomass is the California Biomass Collaborative,a partnership of government, industry and environmental groups that is directedbuy the University of California, Davis. The group seeks to improve the sustainable management and development of biomass in California through research, collaboration and public outreach. Their website contains resources and tools to help government and industry advance their use of biomass.


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