A

v

Woody Biomass for 

Bioenergy and Biofuels 

in the United States—

A Briefing Paper

Eric M. White

United States 

Department of 

Agriculture

Forest Service

Pacific Northwest 

Research Station

General Technical Report

PNW-GTR-825

July 2010

DEPAR TMENT OF AGRICULT URE
B

Authors

Eric M. White is a research associate, Department of Forest Engineering, 

Resources and Management, College of Forestry, Oregon State University, 

Corvallis, OR 97331.

Published with joint venture agreement between the USDA Forest Service, 

Pacific Northwest Research Station, Forest Products Laboratory, and Oregon 

State University.

Cover photo by Dave Nicholls.

The Forest Service of the U.S. Department of Agriculture is dedicated to the principle of 

multiple use management of the Nation’s forest resources for sustained yields of wood, 

water, forage, wildlife, and recreation. Through forestry research, cooperation with the 

States and private forest owners, and management of the National Forests and National 

Grasslands, it strives—as directed by Congress—to provide increasingly greater service 

to a growing Nation.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and 

activities on the basis of race, color, national origin, age, disability, and where applicable, 

sex, marital status, familial status, parental status, religion, sexual orientation, genetic 

information, political beliefs, reprisal, or because all or part of an individual’s income 

is derived from any public assistance program. (Not all prohibited bases apply to all 

programs.) Persons with disabilities who require alternative means for communication of 

program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET 

Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write 

USDA, Director, Office of Civil Rights, 1400 Independence Avenue, SW, Washington, DC 

20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal 

opportunity provider and employer.
i

Abstract

White, Eric M. 2010. Woody biomass for bioenergy and biofuels in the United 

States—a briefing paper. Gen. Tech. Rep. PNW-GTR-825. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

45 p.

Woody biomass can be used for the generation of heat, electricity, and biofuels. In 

many cases, the technology for converting woody biomass into energy has been 

established for decades, but because the price of woody biomass energy has not 

been competitive with traditional fossil fuels, bioenergy production from woody 

biomass has not been widely adopted. However, current projections of future energy 

use and renewable energy and climate change legislation under consideration 

suggest increased use of both forest and agriculture biomass energy in the coming 

decades. This report provides a summary of some of the existing knowledge and 

literature related to the production of woody biomass from bioenergy with a particular focus on the economic perspective. The most commonly discussed woody 

biomass feedstocks are described along with results of existing economic modeling 

studies related to the provision of biomass from short-rotation woody crops, harvest 

residues, and hazardous-fuel reduction efforts. Additionally, the existing social 

science literature is used to highlight some challenges to widespread production of 

biomass energy. 

Keywords: Forest bioenergy, climate change, forest resources.
ii

Summary

Forests are expected to have an important role in climate change mitigation under 

future climate change policy. Currently, much of the interest in forests centers on 

the opportunity to sequester carbon as part of a cap and trade policy. In addition to 

sequestering emitted carbon, forest resources reduce carbon emissions at the source 

when substituted for the fossil fuels currently used to generate heat, electricity, 

and transportation fuels. Woody biomass can be used to generate heat or electricity solely or in a combined heat and power (CHP) plant. As an energy feedstock, 

woody biomass can be used alone or in combination with other energy sources, 

such as coal. The technology to convert woody biomass to ethanol is established, 

but no commercial-scale cellulosic ethanol plants are currently in operation. 

About 2 percent of the energy consumed annually in the United States is 

generated from wood and wood-derived fuels. Of the renewable energy consumed 

(including that from hydroelectric dams), 27 percent is generated from wood and 

wood-derived fuels. The majority of bioenergy produced from woody biomass is 

consumed by the industrial sector—mostly at pulp and paper mills using heat or 

electricity produced onsite from mill residues. U.S. Department of Energy baseline 

projections indicate that wood and wood-derived fuels will account for 9 percent 

of the energy consumed in 2030. Climate change policies that promote bioenergy 

production could lead to greater future woody biomass energy consumption. 

The woody biomass feedstocks most likely to be supplied at low prices (e.g., 

$10 to $20/ton) are those that are low cost to procure, such as wood in municipal 

solid waste, milling residues, and some timber harvesting residues. As biomass 

feedstock prices increase (e.g., $25 to $40/ton), it is likely that more milling residues 

would become available for energy production (drawn away from existing production uses) along with more timber harvest residues. From the most recent estimates 

available for the United States, there are approximately 14 million dry tons of wood 

in municipal solid waste and construction debris, 87 million dry tons of woody 

milling residues, and 64 million dry tons of forest harvest residues produced annually. Biomass from short-rotation woody crops (SRWC) (and other energy crops) 

and agriculture residues (e.g., corn stover and husks) would likely be utilized for 

bioenergy at moderate feedstock prices. At the highest feedstock prices (e.g., above 

$50), it is likely that energy crops (e.g., SRWC) and agriculture residues will provide the greatest amounts of bioenergy feedstock. At moderate and high feedstock 

prices, some small-diameter material, generated either from hazard-fuel reduction 

or precommercial thinning could become available for bioenergy. Recent studies 

have estimated that about 210 million oven dry tons of small-diameter and harvest 

residue material could be removed through hazard-fuel treatments in the West. 
iii

There are regional disparities in the potential supplies of woody biomass. 

Urban wood waste availability generally follows the population distribution with 

some local differences related to construction and waste generation rates. Mill and 

harvest residues follow the regional distribution of harvesting and timber processing with most activity in the South Central and Southeast regions. The potential 

supply of energy crops largely mirrors the distribution of existing cropland, with 

significant potential plantation areas in the Corn Belt, Lake States, and South 

Central regions. Hazard-fuel volumes that could be used for bioenergy are located 

primarily in the West, with some of the greatest volumes in the Pacific Coast States, 

Idaho, and Montana. Across all woody biomass feedstocks, the Intermountain and 

Great Plains regions have the least potential supplies. 

Increased use of woody biomass for bioenergy is expected to have some ripple 

effects in the forest and agriculture sectors. Increased use of mill residues for bioenergy will likely decrease their availability for their current use (e.g., oriented strand 

board, bark mulch, and pellet fuel). Forest residues are currently left in the woods 

both because they have little product value and, in some management systems, they 

recycle soil nutrients and improve micro-climate site conditions. There is some 

evidence that for some sites, removal of harvest residues can reduce soil nutrients, 

potentially impacting future forest yields. Widespread planting of SRWC for bioenergy feedstock or traditional forest products (e.g., pulpwood) is expected to lead 

to some reductions in cropland availability for traditional agriculture production. If 

agriculture yields do not increase as expected in the coming years, this may result 

in some land transfers from forest to agriculture to increase agriculture production. 

There are a number of challenges to increasing the use of woody biomass for 

bioenergy. Perhaps foremost, woody biomass is not cost competitive with existing 

fossil fuels, except when generated in large quantities as a waste product. This 

cost gap may narrow under climate policies where carbon emissions have a market 

value or the use of woody biomass for bioenergy is promoted. In addition to the 

economic constraints, there are organizational, infrastructure, and social challenges to widespread implementation of woody biomass for bioenergy. The existing 

frameworks for energy plant approval and permitting do not always apply well to 

approval of woody biomass plants. This can make it difficult to establish plants 

within the energy sector to use woody biomass. There are some concerns that the 

existing infrastructure (e.g., equipment and transportation systems) is not sufficient 

to support widespread generation of woody biomass, particularly for a significant 

expansion in the harvesting of small material from hazard-fuel reduction. Finally, 

it remains unclear to what extent the public will support significant increases in 

woody biomass bioenergy production. Opposition by some groups to using biomass 
iv

for bioenergy is often centered on the belief that energy from wood is outdated 

technology, the generated energy is inconvenient for use, the feedstock is unreliable 

and difficult to obtain, and forest resources are better used in the production of 

other forest products or services. 

Additional research is necessary to develop a better understanding of the 

responses in the energy, agriculture, and forest sectors to policies that would impact 

bioenergy usage. More comprehensive measurements of both the land suitable 

for and the willingness to plant SRWC and other energy crops, will help to better 

identify the potential volumes that could be expected from that resource. Better 

identification of the locations of current and potential bioenergy production facilities will help to identify those woody biomass resource stocks that may be in the 

best position for increased use. Similarly, a better understanding of how feedstock 

(woody and otherwise) supply curves differ by region and subregion will be useful in identifying the locations where woody biomass is most likely to be used for 

bioenergy. 
v

Glossary of Select Terms

In the text, we have been careful to define important terms and new concepts. 

However, in this glossary, we provide some definitions of particularly important 

measurement units and general concepts. 

bioenergy—Renewable energy derived from biological sources, to be used for 

heat, electricity, or vehicle fuel (USDA ERS 2009).

biofuel—Liquid fuels and blending components produced from biomass feedstocks, used primarily for transportation (US EIA, n.d.).

biomass—Organic nonfossil material of biological origin constituting a renewable 

energy source (US EIA, n.d.).

British thermal unit (BTU)—Standard unit of measure of the quantity of heat 

required to raise the temperature of 1 lb of liquid water by 1 degree Fahrenheit at 

the temperature at which water has its greatest density (approximately 39 degrees 

Fahrenheit) (US EIA, n.d.). One kilowatt-hour of electricity is equivalent to 3,412 

BTUs. 

cubic foot of wood—Amount of wood equivalent to a solid cube measuring 12 by 

12 by 12 inches (Avery and Burkhart 1994). In this paper, we assume that there are 

27.8 dry pounds of woody material in 1 ft3

. 

gigawatt hour (GWh)—One billion watt-hours. Often expressed as 1 million 

kWh. 

kilowatt-hour (kWh)—One thousand watt-hours. 

megawatt-hour (MWh)—One million watt-hours. 

oven dry ton (ODT)—A U.S. ton (2,000 lb, also called a short ton) of biomass 

material with moisture removed. In this paper, we assume that 1 odt of wood can 

generate 17.2 million BTUs. A metric ton is equivalent to 1.102 U.S. (or short) tons. 

terawatt-hour (TWh)—One trillion watt-hours. Often expressed as 1 billion kWh. 

watt—Generally used within the context of capacity of generation or consumption. 

A unit of electrical power equal to 1 ampere under a pressure of 1 volt. A watt is 

equal to 1/746 horsepower (US EIA, n.d.).

watt-hour—Electrical energy unit of measure equal to 1 watt of power supplied 

to, or taken from, an electric circuit steadily for 1 hour (US EIA, n.d.). Typically 

used in consideration of the amount of electricity generated or consumed. Often 

expressed in units of 1,000 (i.e., 1 kWh). 
vi

Contents

1 Introduction

2 Context for Considering Bioenergy From Woody Biomass

6 General Projections of Bioenergy Production

7 Bioenergy Production and Carbon Policies

9 Woody Biomass Feedstocks

10 Short-Rotation Woody Crops

12 Biomass From Harvest Residues

15 Biomass From Milling Residues

16 Municipal and Construction/Demolition Wastes

17 Biomass From Hazard-Fuel Reduction

23 Biomass Feedstock Supply Curves

25 Modeling Studies for Specific Biomass Resources

25 Short-Rotation Woody Crops

30 Harvest and Milling Residues

32 Challenges to Biomass Utilization

35 Conclusions

38 Acknowledgments

38 Metric Equivalents

38 Literature Cited
1

Woody Biomass for Bioenergy and Biofuels in the United States

Introduction

A transition from energy based largely on fossil fuels to a greater reliance on 

renewable energy has been a central focus of many of the current discussions on climate policy. Woody biomass is an important provider of renewable energy currently 

and is anticipated to be an important component of any future renewable energy 

portfolio. The current discussion of using woody biomass continues a long history 

of relying on wood for energy production, both in the United States and in the 

world. Many technologies currently being discussed for utilizing woody biomass 

for bioenergy are based on processes established decades ago. 

Reflecting the interests of many groups for using woody biomass, the scientific literature, peer-reviewed and grey, on bioenergy from biomass is extensive. 

Although much of this information is useful, the volume of material available 

makes a synthesis of the current state of knowledge desirable. Some (e.g., BRDB 

2008, Milbrandt 2005, Perlack et al. 2005) have completed syntheses with estimates 

of available or demanded quantities of woody biomass and agriculture residues. 

This synthesis differs from those by its economic perspective and reliance on 

economic models to quantify demands for and supplies of woody biomass. This 

report also differs from the others by, when possible, considering woody biomass 

within the context of production quantities and land use changes involving both the 

agriculture and forest sectors. 

The primary goal of this briefing paper is to describe woody biomass feedstocks and examine their potential use in bioenergy production in the context of 

climate change policy. Specifically, we aim to describe the anticipated uses of 

biomass for energy production, detail the woody biomass feedstocks and their 

potential availability, describe general projections of biomass use for bioenergy in 

the coming decades, and report the results of several economic modeling studies 

related to the use of woody biomass feedstocks. 

In the next section, we discuss some past, current, and expected future uses of 

woody biomass for bioenergy. We then identify the bioenergy woody biomass feedstocks and provide general estimates of their potential quantities based on the existing literature. Following that general description, we examine a number of studies 

that modeled the supply and consumption of biomass feedstocks for bioenergy and 

traditional forest products. We close by describing some of the noneconomic and 

nontechnical challenges to the increased use of woody biomass for bioenergy.

Woody biomass is 

anticipated to be an 

important component 

of any future renewable 

energy portfolio.
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GENERAL TECHNICAL REPORT PNW-GTR-825

Context for Considering Bioenergy From Woody 

Biomass

In the United States in 2008, slightly more than 2.1 quadrillion (1015) BTUs of 

energy from wood and wood-derived fuels (including black liquor from pulp production) was consumed in all sectors—approximately 8.7 billion cubic feet equivalents of woody material (US EIA 2009a).1

 For comparison, 1.4 quadrillion BTUs 

of corn and other material was used to produce ethanol in 2008. The component of 

renewable energy consumption associated with wood and wood-derived fuels has 

remained fairly constant since 1989 at slightly more than 2 quadrillion BTUs (fig. 

1). Over the same period, the amount of energy consumed from wind and biofuels 

has increased, particularly in the years since 2000. 

Within the context of climate change policies, woody biomass is primarily 

being considered as inputs into three processes: the production of heat, electricity, 

and biofuels. Woody biomass can also be used to create chemicals not directly used 

for bioenergy. In the United States in recent decades, the use of woody biomass for 

the production of heat, electricity, or biofuels has been undertaken as a secondary 

process to utilize wood residues created in the course of creating other products. 

1 Assuming 17.2 million BTUs per oven dry short ton of wood and 27.8 oven dry pounds 

per cubic foot. 

Figure 1—United States energy consumption from renewable sources between 1989 and 2007. Data 

sources: US EIA 2009b, 2009c.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Year

1989199119931995199719992001200320052007

Wind

Solar

Hydroelectric conventional

Geothermal

Wood and derived fuels

Waste

Biofuels

Renewable energy consumption

(quadrillion BTUs)
3

Woody Biomass for Bioenergy and Biofuels in the United States

However, the current expectation is that woody biomass will increasingly be the 

focus of stand-alone processes where at least some of the biomass is obtained 

directly from natural resource stocks with the primary intent of generating bioenergy. 

Woody biomass has been used to produce either electricity or heat independently as well as in combined heat and power (CHP) systems, also referred to as 

cogeneration plants. Woody-biomass-fired heat-only operations are often found in 

Europe, where centralized plants produce heat and hot water that is distributed via 

piping to local heating districts (see Nicholls et al. 2009 for examples). Small-scale 

heat-only woody biomass plants have historically been used in the United States 

to provide heat for drying cut lumber at sawmills and more recently for producing 

heat for schools (Nicholls et al. 2008). The former operation often relies on milling 

residues and dirty wood chips, whereas the latter relies on milling residues (e.g., 

in Vermont) or woody stems harvested as part of hazard-fuel reduction operations 

(e.g., in Montana) (Nicholls et al. 2008). There is much interest in the United States 

in taking advantage of significant improvement in efficiency through the use of 

CHP plants to generate energy from woody biomass. Woody-biomass-fired CHP 

systems have been implemented in the United States in some institutional settings. 

However, a challenge to widespread adoption by the electrical sector of CHP plants 

fired by woody biomass is the general lack in the United States of centralized heating districts (e.g., Maker, n.d.). Space heating using woody biomass in residential 

and small commercial buildings is typically completed via heat-only wood-burning 

stoves operating on fuelwood harvested from standing timber or wood pellets made 

from wood residues. 

Electricity-only operations involving woody biomass can rely solely on woody 

biomass or cofire with another fuel source. If cofired, wood is often combined 

with coal. Cofiring woody biomass with fuels such as coal can be completed using 

existing plant technologies with only minor burner tuning and offers an opportunity 

to directly substitute a renewable fuel for a fossil fuel (Bain and Overend 2002). 

Additionally, plants originally designed to be fired with coal can be converted to 

burn woody biomass exclusively, as is being done with two units of the R.E. Berger 

powerplant in Ohio (FirstEnergy Corporation 2009). Bioelectricity plants using 

modern technologies were first operated during the 1940s in Oregon using mill 

residues. More recently, in the 1980s, a number of stand-alone woody-biomass-fired 

electricity plants came into operation in California. Although there are a number 

of stand-alone plants where the electricity generated is solely input to the grid, 

electricity plants operating in association with timber industry are more common. 

Of the approximately 1,000 wood-fired electricity plants in the United States today, 

Woody biomass has 

been used to produce 

either electricity or 

heat independently as 

well as in combined 

heat and power 

systems.
4

GENERAL TECHNICAL REPORT PNW-GTR-825

nearly two-thirds are owned and operated by the wood products industry (Nicholls 

et al. 2008). Much of the electricity generated by industry-owned plants is used 

onsite rather than contributed to the electrical grid. 

In the United States in 2008, 38.8 billion kilowatt-hours (kWh) (38.8 terawatthours [TWh]) of electricity were generated using woody biomass. This production 

represented about 10 percent of the electricity produced from renewable sources 

(behind hydropower [67 percent of renewable electricity] and wind [14 percent of 

renewable electricity]) and about 1 percent of all electricity produced (US DOE 

2009b). The industrial sector accounted for 27.9 billion kWh of all woody-biomass 

electricity production—primarily from the wood products sector (US DOE 2009d). 

Of the 10.9 billion kWh of electricity produced by the electricity-production sector, 

2.1 billion kWh were produced from CHP plants (US DOE 2009c)—representing 

the relative newness of that technology and the scarcity of district heating systems 

in the United States. 

Bioethanol is perhaps the best known biofuel. Methanol and liquid fuels processed from vegetable oils (e.g., biodiesel) are also biofuels that can be produced 

using current technology. Bioethanol is desirable because it reduces the need to 

add octane-enhancers to gasoline, reduces the production of carbon monoxide and 

hydrocarbons from automobiles by increasing oxygenation of fuel, and offsets the 

consumption of gasoline produced from fossil fuels (Galbe and Zachhi 2002). One 

well-documented drawback to producing bioethanol from corn is the creation of 

competition in demand for corn for food versus energy. In 2007, approximately 24 

percent of the corn acreage planted in the United States was used for corn ethanol 

production (BRDB 2008). In addition to the competition for food production, some 

have argued that corn ethanol is not a sustainable renewable resource and requires 

more energy to produce than is contained in ethanol (e.g., Pimentel et al. 2002), 

although others (e.g., Farrell et al. 2006) have argued against that conclusion. 

Corn-based ethanol is considered a first-generation biofuel, whereas commercialscale cellulosic ethanol production is considered a second-generation technology. 

Producing ethanol from corn or sugar cane (or other sugar/starch crops) is less 

technically challenging (and thus currently less costly) than producing ethanol from 

lignocellulose in woody materials (Galbe and Zachhi 2002, Zerbe 2006). Current 

ethanol refining capacity in the United States is about 8.5 billion gallons per year 

with the majority of production achieved from dry milling corn (BRDB 2008). 

In 2007, the United States produced about 6.5 billion gallons (US DOE, n.d.) and 

imported about 440 million gallons of ethanol. Cellulosic ethanol can be produced 

from lignocellulose under several alternative techniques that differ primarily in 

their approach to hydrolysis (i.e., concentrated acid, diluted acid, or enzymes) of the 
5

Woody Biomass for Bioenergy and Biofuels in the United States

cellulose to monomer sugars (Galbe and Zachhi 2002). Acid hydrolysis has been 

used since the 19th century, whereas enzymatic approaches are often the focus of 

recently developed technologies adopted in new plants (see AE Biofuels Inc. 2008). 

Contrary to the perception of some that current efforts to produce automotive fuels 

from wood are novel, liquid fuels were produced from wood in the United States 

during World War I and in Germany and Switzerland during World War II (Zerbe 

2006).

Currently, no commercial-scale cellulosic ethanol plants are operating in 

the United States; however, several commercial demonstration plants are under 

construction or have recently begun initial startup. Many of the demonstration 

plants are supported through funding from the U.S. Department of Energy (DOE) 

and rely on a variety of feedstocks, including woody biomass. In 2007, DOE 

provided grants to support a number of commercial-scale cellulosic ethanol plants, 

having a combined planned capacity of about 130 million gallons of cellulosic 

ethanol per year (US DOE 2007). Most of these plants are expected to begin startup 

production in the next couple of years. Only one of the 2007 demonstration plants 

will solely use woody biomass as a feedstock (40 million gallons/year capacity), 

and two others (33 million gallons/year capacity in total) will use wood wastes in 

combination with other feedstocks. One ton of dry woody biomass will produce 

approximately 89.5 gal of cellulosic ethanol (BRDB 2008). At that conversion rate, 

producing 20 million gallons of cellulosic ethanol would require about 223,000 

oven dry tons (odt) of woody biomass. 

Although ethanol receives much of the attention, the production of methanol 

from wood has also been considered (e.g., Hokanson and Rowell 1977, Zerbe 1991). 

In recent years, others have promoted producing liquid chemicals (including liquid 

fuels) and synthetic gas for energy production from black liquor—a byproduct of 

kraft pulp production (Landalv 2009). Despite long-term interest, the production 

of methanol from woody biomass has been found to not be economically efficient 

(e.g., Hokanson and Rowell 1977, Zerbe 1991) and natural gas is currently used to 

produce most methanol. Much of the black liquor byproduct is currently used to 

produce heat and electricity for pulp and paper plant operations, and it is yet to be 

seen if pulp and paper mills will make the capital investments to put biorefinery 

facilities in place. Although it is technically possible to produce biodiesel from 

woody biomass, it is generally produced from soybean oil. 

In addition to the production of energy, woody biomass from residues or traditionally nonmerchantable material have been used in a variety of products, from 

visitor information signs (http://altree.com/), to building materials (http://www.fpl.

fs.fed.us/documnts/fplgtr/fplgtr110.pdf), to pedestrian bridges (http://www.hdrinc.
6

GENERAL TECHNICAL REPORT PNW-GTR-825

com/13/38/1/default.aspx?projectID=582). Woody biomass use for these materials 

is generally considered in the context of creating value-added products, reducing 

waste, and creating markets for currently nonmerchantable timber, rather than in 

consideration of climate change, and we do not consider these products here. 

General Projections of Bioenergy Production

The DOE provides estimates of current energy use from renewable sources as well 

as reference projections to year 2030. In 2008, about 6 percent (6.1 quadrillion 

BTUs) of the energy consumed in the United States came from renewable sources 

(excluding ethanol) (US DOE 2009f). For the years 2004 to 2008, about 2.1 quadrillion BTUs of this renewable energy was supplied from woody biomass. Energy 

consumed from woody biomass accounted for about 30 percent of the renewable 

energy consumed annually, but just about 2 percent of annual energy consumption 

from all sources (US DOE 2009a). Renewable energy consumption (excluding 

ethanol) is projected to increase to 8.4 quadrillion BTUs (8 percent of energy 

consumption) by 2015 and to 9.7 quadrillion BTUs (9 percent) by 2030. Assuming 

the current share of renewable energy coming from woody biomass remains static, 

woody biomass would be the source of about 2.5 quadrillion BTUs of energy in 

2015 and 2.9 quadrillion BTUs of energy in 2030. At present, wood energy consumption requires about 122 million odt of woody material annually (assuming 

17.2 million BTUs per odt of wood). Under the reference projection from the DOE, 

approximately 145 million odt of wood will be used for energy in 2015 and 168 

million odt will be used in 2030.

The Renewable Fuels Standard (RFS) of the Energy Independence and Security Act of 2007 requires increased production of ethanol, including significant 

expansion of advanced biofuel production. By 2022, the RFS targets that 36 billion gallons of ethanol be used, with 21 billion gallons of that coming in the form 

of advanced biofuels, including at least 16 billion gallons of cellulosic ethanol. 

Although no commercial-scale production facilities for cellulosic ethanol are 

currently in place, several should begin initial production in the next several years. 

At least one of these plants (the Range Fuels plant in Soperton, Georgia) is focused 

solely on the production of cellulosic ethanol and methanol from woody biomass. 

Any wood biomass demanded to support the RFS is in addition to that identified 

above in the baseline DOE projections. 

In examining increased cellulosic ethanol production, the Biomass Research 

and Development Board (BRDB) (2008) assumed conservatively that 4 billion 

gallons of cellulosic ethanol would come from woody material in support of meeting the RFS in 2022. At 89.5 gallons of ethanol per odt of wood using expected 

In 2008, about 6 

percent of the energy 

consumed in the 

United States came 

from renewable 

sources.
7

Woody Biomass for Bioenergy and Biofuels in the United States

technologies, this production would require about 45 million odt of wood. At a price 

of $44/odt, approximately 45 percent (20 million odt) of the forest resource feedstock is expected to come from logging residues, 25 percent (11 million odt) from 

thinnings for hazard-fuel reduction, and 14 percent (6 million odt) from other forest 

resource removals for such things as land clearing. The remainder is expected to 

come from mill residues (3 percent), municipal wood waste (5 percent), and material 

that might otherwise be used for conventional wood production (8 percent). The 

projected use of 45 million dry tons of woody material for cellulosic ethanol production serves as a useful baseline for expected future demand for woody material 

for biofuels. 

Congress is currently considering a renewable electricity standard (RES) to 

increase the production of electricity generated from renewable sources. Although 

the proposed legislation has yet to be formally presented, it is reasonable to expect 

the RES would lead to at least some increase in electricity generation from woody 

biomass over any baseline increases. The DOE reference projections for electricity 

(which do not include an RES) can provide a projection of the baseline expectations 

for future renewable electricity generation from biomass. In 2008, approximately 43 

billion kWh (43 TWh) of electricity was generated from wood and other biomass, 

most of which was woody biomass (US DOE 2009e). The current level of electricity production is estimated to require about 30 million odt of woody material.2

Because the majority of the woody biomass electricity is generated by the forest 

products sector, much of the material currently used to generate electricity likely 

comes from mill residues, both woody and black liquor. The DOE projects that 

electricity generation from wood and other biomass will increase to 81 billion 

kWh by 2105 and 218 billion kWh by 2030 (fig. 2). These projected figures include 

expected expansion of the biomass supply from energy crops—including perennial grasses and energy cane—grown on agriculture lands. Assuming the share 

of woody biomass contribution to renewable electricity and electricity generation 

efficiency from woody biomass remains constant, approximately 57 million odt of 

woody biomass will be demanded in 2015 and 154 million odt of woody material in 

2030 for electricity generation. Efficiency improvements would reduce the volume 

of material required. The establishment of an RES would likely lead to an increase 

over this baseline. 

Bioenergy Production and Carbon Policies

The reference projections from the DOE indicate a general increase in the extent of 

energy created from biomass in the decades ahead. Policies aimed at reducing carbon 

2 Assuming approximately 0.7 oven dry tons of woody biomass per megawatt hour.
8

GENERAL TECHNICAL REPORT PNW-GTR-825

emissions are expected to increase use of woody biomass for energy generation 

because it results in less carbon emissions than using coal (although greater than 

natural gas). Johansson and Azar (2007) examined the impact of a carbon tax or 

cap and trade system on U.S. bioenergy and agricultural production. In the Johansson and Azar model, bioenergy feedstock was available from energy crops grown 

on cropland and grazing land and from agriculture and forestry residues. Under a 

policy where carbon is highly valued at $50/ton in 2010 and increasing linearly to 

$800/ton in 2100 and with no carbon offset opportunities, biomass is expected to 

be the source of about 16 percent of the energy generated in the United States in 

2030—approximately a fourfold increase over modeled use in the current period. 

Johansson and Azar (2007) projected that by 2050, biomass would be the source of 

about 30 percent of the energy generated—approximately a sevenfold increase from 

the modeled use in the current period. In both future years, the projected biomass 

use levels are approximately double those projected by the DOE in their reference 

case. In the Johansson and Azar model, where carbon has a high value, coal use 

begins to decline dramatically in 2020 and falls out of energy production by 2070. It 

is important to note that Johansson and Azar did not include carbon offsets, which 

are likely to be an important tool for coal powerplants to meet carbon caps under 

the legislation currently being considered in the U.S. Congress. 

Figure 2—Projected baseline electricity generation from renewable fuel sources, 2010 to 2030. Data 

source: US DOE 2009e. Renewable electricity generation (TWh) 

0

100

200

300

400

500

600

700

800

900

2010 2015 2020 2025 2030

Year

Wind

Solar

Wood and other biomass

Municipal solid waste

Geothermal

Conventional hydropower
9

Woody Biomass for Bioenergy and Biofuels in the United States

Changes in crop mix and agricultural land uses are expected under a carbon 

policy. The Johansson and Azar model does not include a forest sector, so land use 

change between forests and agriculture was not modeled. For the agriculture sector, 

a carbon policy that creates a carbon price of between $20 and $40/ton leads to a 

conversion of up to 24 million acres of cropland to produce biomass for bioenergy 

(Johansson and Azar 2007, estimated from sensitivity analysis results). At carbon 

prices higher than $40/ton, high-quality grazing land begins to be used for energy 

crop production. At a $50/ton carbon price, about 24 million acres of cropland and 

49 million acres of high-quality grazing lands would be devoted to energy crop 

production. At carbon prices above $150/ton, low-quality grazing land begins to 

be converted to energy crop production. Despite having fewer acres in energy crop 

production, cropland provided most of the energy crop volume from agriculture 

lands because of higher yields. Under the simulated carbon policy, farm prices for 

energy crops are projected to increase to more than $30/ton in 2020 and to about 

$50/ton in 2040 (Johansson and Azar 2007). 

Woody Biomass Feedstocks

Woody biomass for use in bioenergy and biofuel production is generally considered 

from the following sources: short-rotation woody crops (SRWC), residues from timber harvests that would typically be left onsite (either dispersed or in piles), residues 

from the milling process that may or may not already be used in other processes, 

waste wood and yard debris collected via municipal solid waste systems, timber 

resources that could be harvested for other products (e.g., saw logs or pulpwood), 

and stems that are currently considered nonmerchantable (including those that 

could be harvested in the course of forest management activities). 

Some woody biomass materials are available to the bioenergy production 

process cost free or at very low cost. In the case of a few woody biomass feedstocks, their use for bioenergy may avoid disposal costs (e.g., avoided waste hauling 

costs). Other biomass materials are available to the bioenergy production processes 

only if procured and transported. Those biomass products that are low-cost or 

no-cost to procure (e.g., milling residues, black liquor) are already widely used for 

the production of energy (including through wood pellets) or other wood products 

(e.g., oriented strand board, bark mulch). Other forms of woody biomass expensive 

to procure (e.g., nonmerchantable stems) or that are currently not widely produced 

(e.g., SRWC) might become widely used only after additional investment in their 

production (e.g., extensive planting of SRWC), increased yields, increased prices of 

fossil fuels, and/or increased support for bioenergy production. 

Biomass products that 

are low-cost or no-cost 

to procure are already 

widely used for the 

production of energy or 

other wood products.
10

GENERAL TECHNICAL REPORT PNW-GTR-825

Four “types” of availability have typically been reported in woody biomass 

studies completed to date. Some studies (e.g., Milbrandt 2005) report all or nearly 

all of the quantity of woody biomass as “potentially available.” Other studies (e.g., 

Perlack et al. 2005), report the amount of biomass that is “technically available” 

and could be used. This has generally been accomplished by applying a percentage factor, representing the amount of biomass that is expected to be recoverable 

using current or expected technology, to the potentially available quantity of woody 

biomass. A smaller number of studies have quantified the amount of woody biomass 

that could be available at a given market price (e.g., BRDB 2008, Walsh et al. 2003). 

Finally, a few studies have estimated a supply curve, a schedule of supplied quantities over a range of prices, for woody biomass (e.g., Gan 2007, Walsh et al. 2000). 

In various places in this report, we rely on each type of “availability” and make an 

effort to differentiate these types for the reader. 

Short-Rotation Woody Crops

Short-rotation woody crops are tree crops grown on short rotations, typically with 

more intensive management than timber plantations. All of the studies described 

here considered SRWC grown strictly on agriculture land. However, it is possible 

that SRWC could be planted on land currently in forest plantations or naturally 

regenerated forests. The tree species most commonly considered as SRWC are 

hybrid poplars (Populus spp.) and willow (Salix spp.)—although sycamore (Platanus spp.) and silver maple (Acer saccharinum L.) have also been considered (Tuskan 

1998). Short-rotation woody crops are one component of a larger group of plantings 

known as energy crops, which also include the perennials switchgrass (Panicum 

virgatum L.) and energy cane (high-sugar varieties of sugar cane [Saccharum L.])—

both of which are also typically planted on agriculture land. In addition to their 

potential use for bioenergy and biofuel, SRWC can also be used for pulp and paper 

production and sawtimber (Rinebolt 1996, Stanton et al. 2002). In the 1970s oil 

embargo, SRWC were considered as a potential biofuel source (Stanton et al. 2002). 

During most of the period since then and until recent years, the primary interest in 

SRWC has been as a quick-growing high-yield timber supply (Tuskan 1998). 

Rotation lengths for SRWC range from about 6 to 12 years, although they can 

be shorter (3 years, e.g., Adegbidi et al. 2001) if the material is sold for bioenergy 

feedstock or longer (up to 15 years, e.g., Stanton et al. 2002) if sold for sawtimber. 

As with timber harvests on forest land, multiple products can be derived from 

harvested SRWC stands, with stems being used for clean chips for pulp and paper 

and limbs and other residues being sold for energy (Schmidt 2006). Some studies 
11

Woody Biomass for Bioenergy and Biofuels in the United States

have assumed that 25 percent of the material harvested from SRWC stands (mostly 

bark and small limbs) can be sold for energy with the remainder going to higher 

valued products (e.g., McCarl et al. 2000). Harvested SRWC stands can be regenerated via stump coppicing or planting of new cuttings. Stump coppicing reduces 

the cost of regeneration, but coppicing can add to labor costs when thinning of the 

coppice sprouts is required. Regeneration through stump coppicing also requires 

alternate harvest timing and can result in missed opportunities to take advantage 

of genetic improvements in new planting stock (Stanton et al. 2002, Tuskan 1998). 

Coppice regeneration is more common when the stand will be harvested for bioenergy production (e.g., Adegbidi et al. 2001). Coppiced willow may ultimately be the 

most popular crop for bioenergy production under low-price bioenergy feedstock 

scenarios (Ince and Moiseyev 2002). 

SRWC acreage—

The number of acres currently planted in SRWC is not definitively known, although 

the total acreage is not extensive (Tuskan 1998). Ince (2009) estimated that less than 

0.1 percent of the privately owned agriculture and forest land base is currently dedicated to SRWC poplar plantations. Zalesny (2008), citing the work of Eaton (2007), 

reports approximately 132,000 ac of hybrid poplar currently planted in the United 

States. Hybrid poplar is planted on approximately 50,000 ac in the Pacific Northwest—for pulpwood and sawtimber production—(Stanton et al. 2002) and on about 

6,000 ac in Minnesota for both pulpwood and energy production. Short-rotation 

woody crops have also been planted in the South (Tuskan 1998) and the Northeast 

(including willow for bioelectricity production) (Adegbidi et al. 2001). It is expected 

that expansion of the market for bioenergy feedstocks would support significant 

expansion of SRWC acreage on marginal to good agriculture lands (Wright et al. 

1992). Alig et al. (2000) assumed that about 170 million acres of cropland was 

physically suitable for planting SRWC, mostly in the Corn Belt, Lake States, and 

South Central states (table 1). 

Table 1—Cropland suitable for 

short-rotation woody crop planting

Region Area

Thousand acres

Pacific Northwest 1,274

Lake States 33,190

Corn Belt 85,040

Southeast 14,022

South Central 36,816

Source: Alig et al. 2000.
12

GENERAL TECHNICAL REPORT PNW-GTR-825

SRWC yields—

Current estimates of expected yields from SRWC come from limited numbers of 

stands planted on a variety of sites in different regions of the country using different planting stocks. However, general yield figures for SRWC using contemporary 

planting stock under current management systems range from 5 to 12 dry tons 

per acre per year of woody material (Adegbidi et al. 2001, BRDB 2008, Volk et al. 

2006). Under 6-year rotations with 900 trees per acre, Stanton et al. (2002) reported 

yields from hybrid poplar planted for bioenergy of 37 to 55 dry tons per acre at 

the time of harvest. Under a management regime aimed primarily at using SRWC 

for pulpwood production, stem densities of 600 trees per acre yielded 28 to 45 dry 

tons per acre of clean chips for pulpwood and an additional 10 to 15 dry tons of 

dirty chips for bioenergy production. In the Pacific Northwest, hybrid poplar grown 

for saw-log production is estimated to yield up to 12 dry tons per acre of chips for 

energy production at the time of harvest (Stanton et al. 2002). 

Biomass From Harvest Residues

Harvest residues are the unused portions of growing-stock trees (e.g., tops, limbs, 

stems, and stumps) that are cut or killed by harvesting operations and currently 

left onsite (Smith et al. 2009). Harvest residues may be left distributed across the 

harvesting site or may be piled. In some management systems, harvest residues 

are mulched (e.g., in the South and on gentle slopes in the West) or burned (e.g., in 

the Pacific Northwest), whereas in other systems the residues are left distributed 

throughout the harvest site to naturally decay. In 2006, approximately 4.6 billion 

cubic feet of harvest residues were generated (Smith et al. 2009). The reported 

volume of harvest residues has been increasing since the 1950s (Smith et al. 2009); 

however, this increase is influenced to at least some extent by changes in reporting and sampling systems. In addition to the residues from harvesting operations, 

some studies (e.g., Perlack et al. 2005) also consider the residue generated in “other 

removals,” which include forest harvests conducted for activities like land clearing 

and precommercial thinnings. In 2006, there was approximately 1.6 billion cubic 

feet of woody material in “other removals” (Smith et al. 2009). 

Assuming 27.8 dry pounds of material per cubic foot, the harvest residues in 

2006 amount to about 64 million dry tons of cut or killed material left on harvest 

sites. Only a portion of this material would be available for use in the production of 

bioenergy or biofuel given current technology and costs of handling and transport. 

In their report, Perlack et al. (2005) assumed that it was technically feasible to 

remove about 65 percent of harvest residue, equating to about 42 million dry tons 

of residue in 2006. The spatial distribution of harvest residues in the United States 

In 2006, approximately 

4.6 billion cubic feet of 

harvest residues were 

generated.
13

Woody Biomass for Bioenergy and Biofuels in the United States

generally follows the spatial distribution of harvests, with the South (2.3 billion 

cubic feet) and the North (1.3 billion cubic feet) accounting for the majority of the 

residue generated (fig. 3). 

Harvest residues, regional availability—

The amount of harvest residues that are economically available is less than the 

amount technically available (measured in Perlack et al. 2005). With the goal of producing 4 billion gallons of cellulosic ethanol from a combination of woody biomass 

feedstocks, BRDB (2008) estimated that about 20 million dry tons of forest residues 

would be supplied annually from nonfederal timberlands at a roadside price of $44 

per dry ton. Counties in the southern Delta region, the Northeast, along the Pacific 

Coast, and in the northern Lake States were projected to have the greatest quantities 

of forest biomass supplied (BRDB 2008). Counties in the Mountain West would 

have the least forest residue supplied. 

Regionally, the Northeast and the hardwood producing areas of the upper 

Midwest would seem to have the greatest opportunity for increased use of timber 

Figure 3—Harvest residues generated in the United States by region, 1962 to 2006. Data source: Smith et 

al. 2009. 

0

500

1,000

1,500

2,000

2,500

Region

H

arvest residu

e

s

(million

cubic feet)

2006

1996

1986

1976

1962

North South Rocky

Mountains

Pacific

Coast
14

GENERAL TECHNICAL REPORT PNW-GTR-825

harvest residues given the current volume generated per harvest acre, all else being 

equal. However, the South generates the greatest volumes of residue owing to high 

harvesting rates. The predominance of coal-fired powerplants in the East may offer 

opportunities to cofire harvest residue woody biomass. The existing infrastructure 

for producing corn ethanol and the nascent infrastructure for cellulosic ethanol in 

some parts of the Midwest may be a catalyst for establishment of harvest residue 

feedstock use in that region. 

One uncertainty for the Northeast and Midwest in regard to expanding harvest 

residue use for bioenergy is any significant shifts in forest species composition in 

response to climate change. There is the potential that climate change may result 

in the movement north to Canada of hardwood species and a northward progression of Southern U.S. softwood species. Timber harvests involving softwoods tend 

to generate fewer residues than harvests involving hardwoods (Smith et al. 2009). 

Furthermore, the amount of residues generated and left onsite in softwood harvesting operations has declined over the last several decades (Smith et al. 2009). The 

increased utilization of harvested softwood reflects both technological improvements in softwood harvesting systems as well as additional markets for softwood 

biomass. At the same time, the volume of softwood harvested nationally has been 

declining since about 1976. Hardwood harvests have declined in recent periods but 

are still greater than 1976 and 1986 volumes (Smith et al. 2009). 

Harvest residues, harvest site implications—

In management systems where harvest residues have traditionally been left onsite, 

removing all harvest residues can have implications for soil nutrients and soil 

carbon. This can lead to reductions in tree growth in subsequent rotations (e.g., 

Walmsley et al. 2009). However, the impact of whole-tree harvest on soil nutrients 

and growth in the second rotation is highly variable and likely site specific (Carter 

et al. 2006, Walmsley et al. 2009). If removal of logging residues led to widespread 

reductions in future timber yields, timber supplies could decline, leading to 

increased stumpage prices and timberland values, all else being equal. Alternately, 

managers may choose to use fertilizer to augment available soil nutrients on areas 

where logging residues have been removed. This may lead to increased fertilizer 

use, which might have implications for greenhouse gas emissions and water quality. Ultimately, the widespread impact, if any, of a general shift to removing logging residues from harvesting operations is not known and would require careful 

monitoring in the future. One potential benefit from whole-tree harvesting is that it 

can reduce site preparation costs for subsequent timber rotations (Westbrook et al. 

2007). 
15

Woody Biomass for Bioenergy and Biofuels in the United States

Biomass From Milling Residues

Milling residues include wastes from sawdust, slabs and edgings, bark, veneer clippings, and black liquor (Rinebolt 1996). In 2006, woody biomass milling residues 

from primary wood processing mills amounted to approximately 87 million dry 

tons of material (Smith et al. 2009). This is up slightly from the 83 million dry tons 

of milling residue generated in 2001 (Smith et al. 2003). Black liquor production 

is not considered here. Reflecting their low cost of procurement (or avoided cost 

of disposal) nearly all milling residues—about 86 million dry tons—are currently 

used in production of other products or bioenergy. This pattern of use continues a 

practice in place since about 1986 (Rinebolt 1996). In 2006, nearly equal amounts 

of residues (36 million dry tons) were used for energy production and fiber products 

with an additional 13 million dry tons used for other products (Smith et al. 2009). 

Some (e.g., Perlack et al. 2005, Rinebolt 1996) suggested there may be increased 

availability of milling residues in the future, assuming increased timber mill 

production (e.g., in response to hazard-fuel thinning). However, this seems to ignore 

the pattern of increasing efficiency in timber mill production practices over past 

decades, which has been projected to continue in the future (Skog 2007). If robust 

markets for woody biomass for bioenergy and biofuel develop in the future, the 

delivered prices for woody biomass could draw some milling residues from the 

production of other products to bioenergy and biofuel production. This would likely 

then lead to at least short-term increases in the costs of products currently produced 

from milling residues. 

Mill residues, regional availability—

The South Central and Northeast regions have the greatest volume of milling 

residues not currently used (fig. 4). Most of this unused residue is in the form of 

slabs, edgings, and trimmings (i.e., coarse material). This could be fortuitous, as the 

Northeast generates a significant amount of electricity from coal and would likely 

have an opportunity to expand cofiring of woody residues with coal. However, even 

in the South Central and Northeast regions, the amount of unused residue is small. 

Woody biomass supplied from SRWC may offer a greater long-term opportunity for 

cofiring woody biomass with coal than do milling residues.

Mill residues, secondary wood product facilities—

Mill residues created at secondary wood product manufacturing facilities (e.g., cabinet production, furniture makers) are another mill residue source. Unfortunately, 

the amount of woody material available from secondary wood processing industries 

is difficult to ascertain. Milbrandt (2005) estimated approximately 3 million tons 

of woody residues are generated annually from secondary wood product firms. In 

Reflecting their low 

cost of procurement, 

nearly all millling 

residues are currently 

used in production 

of other products or 

bioenergy.
16

GENERAL TECHNICAL REPORT PNW-GTR-825

Figure 4—Woody biomass mill residues generated in the United States, 2006. Data source: 

Smith et al. 2009.

a previous study completed in the late 1990s, approximately 1 million dry tons of 

secondary mill residues were estimated to be available annually for feedstock use 

at approximately $20 per ton (1996 dollars) (Rooney 1998). Although potentially 

available residues from secondary mills are distributed throughout the forested 

regions of the country, they represent a fraction of the other potentially available 

woody material. Further, as the secondary wood products manufacturing industry 

continues to contract (Quesada and Gazo 2006), the amount of residue available 

will likely also decline. Ultimately, secondary wood product residue is perhaps best 

characterized as a niche source of woody biomass for bioenergy and biofuel production in some locales. 

Municipal and Construction/Demolition Wastes

Wood and paperboard in a variety of consumer products are discarded as municipal 

solid waste (MSW). A portion of that waste is recovered for recycling or other uses, 

and the remainder is generally discarded into landfills. In MSW, woody biomass 

can be found in paperboard and paper waste, discarded wood products such as 

furniture, durable goods, crates and packaging, and in yard trimmings. In 2007, 

the United States generated approximately 83 million tons of paper and paperboard—54.5 percent (45 million tons) of this was recovered for recycling or other 

0

5

10

15

20

25

30

35

N

ortheast

N

orth Central

Southeast

South Central

Great Plains

Intermountain

P

acific N

orthw

est

P

acific Southw

est

Region

Mill residues

(million

dry ton

s)

Not used

Currently used
17

Woody Biomass for Bioenergy and Biofuels in the United States

uses (US EPA 2008). Corrugated boxes make up the greatest single component of 

the paper and paperboard waste stream and, after newspapers, the highest rate of 

product recovery. The generation of paper and paperboard waste has flattened in 

recent years after a decades-long increase. Over the same period, the rate of recovery of this waste has continued to increase (US EPA 2008). Discarded wood in furniture, durable goods, and wood packaging amounted to 14.2 million tons in 2007. 

An estimated 1.3 million tons of discarded wood from pallets was recovered for 

such things as mulch and animal bedding. Yard wastes are difficult to measure, but 

disposal is believed to have declined from highs in the early 1990s in response to 

legislation limiting yard waste disposal in landfills (US EPA 2008). In 2007, about 6 

million tons of brush and leaves were generated but not recovered from yard debris. 

Including paper and paperboard, approximately 57 million tons of woody biomass 

is currently discarded and not currently recovered. Excluding paper and paperboard, 

approximately 19 million tons of wood is not recovered from the MSW stream. In 

both instances, one could expect that only a portion of this material is recoverable 

for use in the production of bioenergy and biofuels. Perlack et al. (2005) estimated 

that approximately 7.7 million tons of solid wood was available from MSW. 

In addition to that contained in MSW, discarded solid wood is potentially available in the debris created from building construction and demolition. Between 20 

and 30 percent of construction and demolition debris is estimated to be solid wood 

products (e.g., dimension lumber, wood doors and flooring, wood shingles) (US 

EPA 2009). In 2003, approximately 164 million tons of debris material was created 

from construction and demolition (US EPA 2009). Assuming 25 percent of that 

material was wood, approximately 41 million tons of wood waste was created from 

construction and demolition in 2003. This is very similar to a previous estimate of 

39 million tons of debris wood in 2002 from McKeever (2004). McKeever (2004) 

has estimated that approximately 50 percent of construction and demolition wood 

waste is potentially recoverable or currently recovered. Assuming this percentage, 

almost 20 million tons of wood was available from construction and demolition 

debris in 2003. 

Biomass From Hazard-Fuel Reduction

Much of the material on public and private forests identified as overstocked or at 

high risk of fire because of stand conditions is small-diameter material for which 

there is not currently a market. With no market for this precommercial material, 

there is limited opportunity to offset the costs of thinning these forested stands. 

With renewed attention to bioenergy, there is much interest in using the precommercial material in hazard-fuel treatments as woody material feedstock for bioenergy and biofuel production (e.g., WGA 2006). The focus of hazard-fuel treatments 
18

GENERAL TECHNICAL REPORT PNW-GTR-825

is the Western United States, and Skog et al. (2006, 2008) identified approximately 

24 million acres in the 12 Western States on all ownership types as potential sites 

for treatment. This acreage figure compares well with the 28 million acres of timberland in 15 Western States likely to need mechanical fuel treatment as identified 

by Rummer et al. (2005). 

Hazard fuel reduction, potential biomass—

Skog et al. (2006, 2008) simulated both even-age and uneven-age thinning operations. The uneven-age scenarios included two aimed at achieving high structural 

diversity in the remaining stand and two aimed at achieving limited structural 

diversity in the remaining stand. In the uneven-age scenarios, stems in a variety 

of diameters were removed. In the even-age scenarios, larger diameter stems were 

removed only if all smaller diameter stems had been removed (thin from below). 

No diameter limits were included in the scenarios. Some scenarios had limits on 

the amount of basal area that could be removed in the thinning. In all cases, acres 

were deemed treatable only if they would provide 300 ft3

 of merchantable material 

per acre—a volume that is often considered the minimum necessary to yield net 

revenue (Skog et al. 2006, 2008). 

Scenarios that treat acres using an uneven-age management thinning regime 

aimed at maintaining high structural diversity and containing no limits on basal 

area removed yielded the greatest number of acres treatable—17.5 million acres—

and material removed—627 million odt (Skog et al. 2006, 2008). An even-age 

thinning from below with no basal area limits was estimated to be feasible on about 

7.3 million acres, yielding about 190 million odt of material. Fewer acres are treatable under the even-age regime because lesser amounts of merchantable material 

would be generated in the treatment, making this regime feasible only under limited 

conditions. In the uneven-age management regime, about 35 percent of the removed 

material would come from California timberlands (fig. 5). Oregon, Idaho, and 

Montana timberlands each would account for an additional 13 percent of removed 

material. The remaining approximately 25 percent of material would come mostly 

from Washington, Colorado, and New Mexico. 

Westwide across all scenarios, the majority (approximately 55 percent) of the 

simulated removed biomass material from hazard-fuel reduction is associated with 

timberland on national forests (Skog et al. 2006, 2008). Under an example unevenage thinning regime aimed at achieving limited structural diversity and with a basal 

area limit, privately owned lands would contribute approximately 32 percent of 

removed biomass (122 million odt of merchantable and nonmerchantable material) 

(table 2). Of the private timberland in Western States, those in California would contribute the greatest volume (50 million odt) of thinned material under this thinning 

The majority of the 

simulated removed 

biomass material from 

hazard-fuel reduction 

is associated with 

timberland on national 

forests.
19

Woody Biomass for Bioenergy and Biofuels in the United States

Figure 5—Material of all sizes removed from a simulated uneven-age thinning regime 

on public and private timberland in the Western States. Data source: Adapted from Skog 

et al. 2006.

regime. The contribution of material from private timberlands would be lowest (less 

than 4 million odt) in Arizona, Nevada, New Mexico, South Dakota, Utah, and 

Wyoming because of small areas of timberland in those states. 

An uneven-age thinning regime without basal area limits and promoting high 

structural diversity would yield about 9.5 odt per acre of material from stems less 

than 7 inches in diameter and from the branches and tops of stems used for higher 

value products (Skog et al. 2006). This material is most likely to be used for bioenergy production. Treatment on all 17.5 million acres where this uneven-age thinning 

regime is feasible would yield about 166 million odt of small woody material. The 

thinning-from-below even-age regime would yield approximately 11 odt per acre 

of material from stems less than 7 inches in diameter and the branches and tops of 

stems used for higher value products (Skog et al. 2006). If all 7.3 million even-age 

feasible acres were treated, about 80 million odt of small woody material could be 

generated. In both cases, it is unlikely that all of this material would be harvested at 

once. Assuming operations occur evenly over approximately 20 years (i.e., 2010 to 

2030) with no retreatment, about 8.3 million odt could be removed per year under 

the former scenario and 4 million odt per year under the latter scenario. This is a 

0

50

100

150

200

250

Arizon

a

C

alifornia

C

olorad

o

Idah

o

Montan

a

N

e

vad

a

N

e

w

M

e

xico

Oregon

South D

akota

Utah

W

ashington

W

y

o

ming

V

olu

m

e re

m

ove

d

(million

ove

n

dry ton

s)
20

GENERAL TECHNICAL REPORT PNW-GTR-825

slight simplification, as it ignores stand growth over that period, which may move 

some stems into higher valued uses and ignores the growth of new small-diameter 

material. 

Perlack et al. (2005) reported that 49 million dry tons of woody biomass could 

be generated from timberland through hazard-fuel harvests throughout the country 

annually. Perlack et al. estimated an additional 11 million dry tons available from 

forest lands (lands not productive enough to be classified as timberland) annually. The vast majority of this volume is expected to be generated in the Western 

States. The results of the two studies provide good sideboards on likely woody 

biomass availability. The study by Perlack et al. (2005) contains a fairly liberal 

set of assumptions on likely treatable acres and generated volume. Skog et al. 

(2006) adopted a fairly stringent set of assumptions on treatable acres, including 

the requirement of producing at least 300 ft3

 of merchantable material. The results 

of Skog et al. (2006) likely provide a more reasonable estimate of the potential 

production from hazard-fuel thinnings. This is particularly true in the short run 

where institutions are not in place to support widespread hazard-reduction thinning, markets currently support only low prices for bioenergy chips, and there are a 

number of social obstacles to thinning for bioenergy. 

The results reported in Skog et al. (2006, 2008) are consistent with the analysis 

(involving many of the same authors) reported by the Western Governors Association on forest biomass availability (WGA 2006). In that analysis, 10.6 million acres 

of western timberland is available for hazard fuel reduction yielding 270 million 

Table 2—Volume of material removed under a simulated uneven-age hazardfuel thinning regime by timberland ownership type 

National Other State and

State Private forest federal local Total

Million oven dry tons (odt)

Arizona 2.0 6.9 0.0 0.0 8.9

California 50.0 65.1 0.6 1.7 117.4

Colorado 5.9 8.9 2.4 0.2 17.4

Idaho 13.2 35.7 3.5 5.3 57.7

Montana 14.8 38.2 3.2 2.6 58.9

Nevada 0.2 0.0 0.0 0.0 0.2

New Mexico 3.3 10.7 0.0 1.1 15.0

Oregon 16.3 28.3 8.4 2.1 55.1

South Dakota 0.0 1.1 0.0 0.0 1.1

Utah 1.6 3.9 0.3 1.1 6.9

Washington 12.8 18.4 1.1 6.4 38.8

Wyoming 2.3 3.1 1.8 0.1 7.3

 Total 122.3 220.2 21.3 20.8 384.6

Source: Adapted from Skog et al. 2006.
21

Woody Biomass for Bioenergy and Biofuels in the United States

odt of biomass. Assuming these acres were treated over a 22-year period and that 

50 percent of the removed biomass could potentially be available for bioenergy and 

biofuel production, the annual volume of available woody biomass would be 6.2 

million odt. Again, this figure is well below that reported in Perlack et al. (2005). 

Hazard-fuel reduction, costs and revenues—

Mechanical treatment and removal to the roadside is an expensive approach to 

treating hazard fuels. In general, treating the fuels via prescribed burning is less 

expensive (Rummer et al. 2005), although the resulting reductions in fire hazard 

may not be similar to that achieved via mechanical thinning. Mechanical treatment 

and removal to the roadside is estimated to have an average cost of between $34/

odt and $86/odt for a variety of western forest types on a mix of site types (Rummer et al. 2005) (table 3). These treatment costs do not include the additional costs 

for hauling the removed material from the roadside to the mill. Treatment costs 

are strongly influenced by site conditions, and treatments on slopes greater than 

40 percent are estimated to cost at least double that of treatments on gentle slopes 

(Skog et al. 2006). 

The uncertainty around whether hazard-fuel reduction could generate net 

revenues per acre is a challenge to widespread implementation of hazard thinning. 

For a simulated uneven-age thinning regime, Skog et al. (2006) estimated treatment 

and removal to the roadside would cost on average about $27/odt on gentle slopes 

and $51/odt on slopes greater than 40 percent. A typical delivered value assumed 

for dirty chips for energy production is $30/odt. Based on those costs and values, 

and if all material is used for dirty chips, there is a net cost of about $21/odt at the 

roadside for treatment on slopes greater than 40 percent and a small net revenue

of about $3 at the roadside on gentle slopes (fig. 6). The $3 of net revenue on gentle 

Table 3—Treatment costs for removal and 

transportation to the roadside of hazard fuels 

Forest type Costs 

Dollars/odt

Southwest ponderosa pine 55.74

Intermountain ponderosa pine 55.26

Intermountain lodgepole pine 45.24

Sierras ponderosa pine 44.78

Sierras lodgepole pine 57.85

Rocky Mountain ponderosa pine 61.46

Rocky Mountain lodgepole pine 48.91

Great Basin ponderosa pine 86.96

Great Basin lodgepole pine 34.72

Note: odt = oven dry ton. 

Source: Adapted from Rummer et al. 2005. 

Mechanical treatment 

and removal to the 

roadside is estimated 

to have an average cost 

of between $34/odt and 

$86/odt for a variety of 

western forest types.
22

GENERAL TECHNICAL REPORT PNW-GTR-825

slopes is prior to incurring transport costs to the processing site. At an assumed 

transportation cost of 35 cents per mile, in this example roadside net revenues 

would be negated after an 8.5 mi transport to the processing facility. 

Based on the expected costs and delivered values, it is unlikely that hazardfuel treatment could widely be economically feasible if all removed material is 

required to be sold for energy chips. In their study, after accounting for expected 

transport costs, Skog et al. (2006) found that no simulated hazard-fuel thinning 

regime yielded net revenue per acre if all woody material was required to be sold 

for chips at $30/odt (table 4). However, if some of the thinned material could be sold 

for higher valued pulp and sawtimber products, some thinning regimes became 

economically feasible. When stems above 7 inches in diameter can be sold for 

higher valued products, uneven-age thinning regimes conducted on gentle slopes 

yield net revenue (table 4). However, even-age thinning regimes and any thinning 

regime conducted on steep slopes did not yield net revenue even if material was 

sold for higher valued products (table 4). Under a scenario where energy chip value 

increased by $20 (e.g., through a subsidy or as a reflection of increased demand), all 

Figure 6—Simulated costs of treatment and roadside removal of hazard fuel compared to anticipated 

delivered values of energy chips. Data source: Adapted from Skog et al. 2006. 

-$60

-$50

-$40

-$30

-$20

-$10

$0

$10

$20

$30

$40

Gentle slopes Steep slopes

Slope

D

ollars/oven dry ton

Costs for treatment and

removal to roadside

Value of delivered

energy chips
23

Woody Biomass for Bioenergy and Biofuels in the United States

thinning regimes on gentle slopes and a limited number on steep slopes did yield 

a net revenue (Skog et al. 2006). In a study of hazard-fuel reduction of sawtimber 

material in eastern Oregon, Adams and Latta (2005) found that the form and application of the subsidy had important implications for the number of acres treated as 

well as the longevity of the milling capacity in local communities. A lack of milling capacity could make hazard-fuel reduction less feasible, particularly for lower 

valued material that is not worth transporting long distances.

Biomass Feedstock Supply Curves

Walsh et al. (2000) estimated state-level biomass supply curves that, although dated, 

provide a useful “data point” as one estimate of the potential biomass feedstocks 

available for bioenergy production at a schedule of feedstock prices. Results from 

a current research effort to complete county-level biomass supply curves (Dykstra 

et al. 2008) were unavailable for use in this report owing to the fact that portions of 

the research are still underway and others are restricted from distribution because 

of an extensive peer-review process. At the lowest delivered prices ($20/ton), 

Table 4—Net revenue (or cost) per acre for simulated thinning regimes on public and private timberland 

in the Western United States 

Merchantable volume to 

Merchantable volume to higher value, plus

higher value products Chips only $20 chip subsidy

Scenario < 40% slope > 40% slope < 40% slope > 40% slope < 40% slope > 40% slope

Dollars

Uneven-age, 50% basal area

 removal limit, high structural

 diversity 533 -319 -992 -1,910 912 79

Uneven-age, high structural

 diversity 686 -9 -1,161 -1,917 1,159 479

Uneven-age, 50% basal area

 removal limit, limited

 structural diversity 278 -490 -971 -1,862 669 -87

Uneven-age, limited 

 structural diversity 356 -120 -1,023 -1,909 798 114

Even-age, thin-from-below,

 50% basal area removal limit -112 -833 -973 -1,882 391 -368

Even-age, thin-from-below -86 -762 -1,024 -1,892 441 -255

WUI, even-age, spruce-fir

 and lodgepole pine, 50%

 basal area removal limit -144 -726 -766 -1,550 202 -478

WUI, even-age, spruce-fir

 and lodgepole pine, 25% 

 basal area removal limit -18 -266 -1,073 -1,615 421 36

WUI = wildland-urban interface.

Source: Adapted from Skog et al. 2006. 
24

GENERAL TECHNICAL REPORT PNW-GTR-825

residues are primarily drawn from urban waste with a small contribution of mill 

residues (Walsh et al. 2000) (fig. 7). In many cases, handlers of these products avoid 

a disposal cost by providing them to bioenergy users and thus are willing to do so 

at low delivered costs. At $30/ton delivered, some forest residues become available, 

and the supply of mill residues increases. Because most of the mill residues are 

currently used for other products (e.g., bark mulch), at least some of this supply will 

come from mill residues currently being used in other products. A small amount of 

agriculture residues become available at $30/ton delivered. Energy crops and the 

amount of agriculture residues available increase substantially as delivered prices 

increase. These two sources become the primary supply of biomass residue at high 

delivered prices. In the Walsh et al. (2000) analysis, SRWCs were not included as a 

bioenergy source. 

Based on the estimated supply curves, the North Central and South Central 

regions have the greatest supplies of biomass available (Walsh et al. 2000) (figs. 8 

and 9). In those regions, the majority of the supply is associated with agriculture 

land (energy crops plus agriculture residues). The Southeast and Northeast regions 

Figure 7—Estimated biomass for bioenergy supply from the contiguous United States at a range 

of delivered prices. Note: Short-rotation woody crops are not included. Data source: Adapted from 

Walsh et al. (2000). 

0

100

200

300

400

500

600

20 30 40 50

Delivered price (dollars)

Bio

mass

supply

(million

dry ton

s)

Ag residues

Energy crops

Forest residues

Mill wastes

Urban wastes
25

Woody Biomass for Bioenergy and Biofuels in the United States

Figure 8—Estimated biomass for bioenergy by region at $40/ton delivered. Data source: Adapted from 

Walsh et al. (2000). 

produce a moderate amount of forest residues. As the biomass price rises to $50/

ton delivered, the supply of biomass from energy crops increases in both the North 

Central and Great Plains States (fig. 9). At the same time, there is a drop in crop 

residue from those regions, reflecting a change in planting mix to support energy 

crops. 

Modeling Studies for Specific Biomass Resources

Short-Rotation Woody Crops

Short-rotation woody crops have been proposed as an energy crop, to provide 

chips for pulp and paper production, and, in the Pacific Northwest, to provide 

sawtimber. Current markets for products and existing yields from SRWC have not 

been sufficient to spur widespread SRWC planting. However, it is anticipated that 

climate change policies that result in a carbon price or otherwise incentivize energy 

generated from biomass will result in some expansion of SRWC. This expansion 

may come in response to SRWC being used directly to address the climate policy 

(e.g., energy chips to reduce carbon emissions from powerplants and tree planting 

to sequester carbon) or in response to changes in the forestry sector (e.g., decreased 

Supply at $40/ton, delivered

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

Northeast

Southeast

South Central

North Central

Great Plains

Intermountain

Pacific Coast

Region

Bio

mass supp

y

(dry tons)

Ag residues

Energy crops

Forest residues

Mill wastes

Urban wastes

Short-rotation woody 

crops have been 

proposed as an energy 

crop, to provide chips 

for pulp and paper 

production, and to 

provide sawtimber.
26

GENERAL TECHNICAL REPORT PNW-GTR-825

supply of pulp chips from traditional forestry sources because of increased carbon 

sequestration efforts). 

Several studies have considered the use of SRWC for energy or pulp production. Walsh et al. (2003) considered bioenergy crop production using the POLYSYS 

model of the agriculture sector. The authors considered three energy crops: switchgrass, hybrid poplar, and willow. The authors assumed switchgrass could grow 

from the Intermountain region eastward and that hybrid poplar could be grown 

from approximately the Corn Belt eastward and in the Pacific Coast states. Willow 

was constrained to being grown in the Northern States. Two scenarios that differed 

in the farm price for biomass (for hybrid poplar, $32.90/dry ton and $43.87/dry ton) 

were considered. In the first scenario, Conservation Reserve Program (CRP) acres 

were treated as being managed primarily to support wildlife diversity, and in the 

second, CRP acres were treated as being managed primarily for bioenergy crop 

production. In both scenarios, landowners received only 75 percent of their CRP 

payment in exchange for being able to sell bioenergy crops. 

In the Walsh et al. (2003) study, about 20 million acres of agriculture land were 

planted to bioenergy crops under the lower price scenario, and 42 million acres 

were planted under the high-price scenario. In both scenarios, cropland contributed 

Figure 9—Estimated biomass for bioenergy by region at $50/ton delivered. Data source: Adapted 

from Walsh et al. (2000). 

Supply at $50/ton, delivered

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

200,000

Northeast

Southeast

South Central

North Central

Great Plains

Intermountain

Pacific Coast

Region

Bio

mass supply

(dry tons)

Ag residues

Energy crops

Forest residues

Mill wastes

Urban wastes
27

Woody Biomass for Bioenergy and Biofuels in the United States

more than half the acres planted to energy crops; CRP contributed most of the other 

acres. Hybrid poplar was planted only in the first scenario and then only on CRP 

lands (which were being managed with lower cost wildlife management practices). 

Although willow was one of the scenario options for bioenergy, it was not selected 

by the model. Under the first scenario, hybrid poplar plantations contributed 35.5 

million dry tons of biomass for bioenergy annually. Simulated hybrid poplar 

bioenergy supplies were focused in the Corn Belt region, from Ohio west through 

Iowa, and from southern Missouri to northern Minnesota. Hybrid poplar was also 

planted in some areas of the Delta Region, the Pacific Northwest, and limited areas 

of the Northeast. The bioenergy crop choices in the results of Walsh et al. (2003) 

reflected the assumed comparative yields of the three crops. Model results were 

fairly responsive to across-the-board increases and decreases in yields. Changes in 

yields among the bioenergy crops were not tested. 

Ince and Moiseyev (2002) extended the model reported in Walsh et al. (2003) 

by combining the agriculture sector model with the North American Pulp and Paper 

(NAPAP) model to examine the impact that hybrid poplar planted as SRWC might 

have on the pulp and paper sector. Although the focus of Ince and Moiseyev (2002) 

(and the paper discussed next—Alig et al.2000) is on SRWC production for pulp, 

it provides a useful reference for the amount and location of SRWC that might be 

planted on agriculture lands. Under current market conditions, the use of SRWC 

for pulp and paper production seems more likely than use in bioenergy production 

(Ince and Moiseyev 2002). 

Under their baseline scenario, Ince and Moiseyev (2002) projected little pulpwood production from hybrid poplar planted on agriculture lands. However, under a 

scenario where planting of hybrid poplar by farmers was incentivized (represented 

by lowering the model discount rate from 6 percent to 3 percent), the pulp production from hybrid poplar plantations increased more than threefold. The production 

from hybrid poplar was about 13 times the baseline in simulations where availability from the traditional pulp supply declined and the planting of hybrid poplar 

by farmers was incentivized. Pulp supply from traditional forestry sources could 

decline for a number of reasons, including forest ownership change or a change in 

timber management goals. In the Ince and Moiseyev model, the focus is on hybrid 

poplar for pulp and paper production, so most of the simulated agriculture acres 

planted to hybrid poplar are located in the South near existing pulp and paper 

manufacturing facilities. Under “high demand” scenarios, simulated hybrid poplar 

plantations on agriculture lands are also found in the Lake States and in the Northeast—other regions with strong pulp and paper sectors. 
28

GENERAL TECHNICAL REPORT PNW-GTR-825

Both of the previous studies relied on modeling efforts built on a model of the 

agriculture sector. Alig et al. (2000) differed from those studies by relying on a spatial optimization model (the Forestry and Agriculture Sector Optimization Model—

FASOM) that captures both the agriculture and forest sectors. One significant 

advantage of this approach is the ability to accommodate land transfers between 

forestry and agriculture as well as to capture the substitutability of product flows 

from agriculture and forest lands (e.g., pulp production from SRWC on agriculture 

lands vs. traditional pulp production from forest lands). Model results indicate 

hybrid poplar for pulp production would be planted on at most 2.8 million acres 

of agriculture land in the coming decades. The Pacific Northwest and Lake State 

regions showed the greatest land areas planted to hybrid poplar. Reflecting the high 

opportunity costs of converting cropland to another use and the lack of pulp manufacturing facilities, relatively little hybrid poplar was planted for pulp in the Corn 

Belt states in the Alig et al. model. The South had relatively few acres planted to 

hybrid poplar for pulp until the last decades of the model run. This pattern reflects 

the quantity of available pulp from traditional forest resources within that region.

Despite the relatively small land area devoted to hybrid poplar in the Alig et al. 

(2000) model, the pulp material harvested from these acres represented about 40 

percent of the pulpwood material harvested in the United States in the late 1990s. 

The ability of high SRWC yields to offset such large volumes of pulp material could 

“free up” many traditional forest sector acres to be managed on longer rotations for 

other products (e.g., sawtimber) or for other management goals (e.g., carbon sequestration). It is possible that under a climate policy where longer forest rotations are 

desirable, SRWCs have the capacity to offset some of the chip material that would 

have otherwise gone to the pulp and paper industry. 

Several implications of SRWC supply exist for the agriculture and forestry land 

bases. Although intensively managed, SRWCs require less cultivation, fertilizer, 

and other chemical treatments than many of the traditional agriculture crops and 

could play a key role in natural resource conservation and carbon sequestration on 

existing agriculture lands (e.g., Ince and Moiseyev 2002). The increased supply of 

hardwood pulp from SRWC lessens the demand for pulp from traditional hardwood 

forests, lessening the opportunity cost of converting hardwood forests to softwood 

plantations (Alig et al. 2000). Reflecting the linkages between the agriculture and 

forestry land bases, having increased pulp production from SRWC results in land 

transfers from forestry to agriculture (to meet crop demands) above those identified 

in a baseline run. This transfer from forestry to agriculture in response to SRWC 

production may be less significant under a climate change policy where carbon 

sequestration is valued.

It is possible that under 

a climate policy where 

longer forest rotations 

are desirable, SRWCs 

have the capacity to 

offset some of the chip 

material that would 

have otherwise gone 

to the pulp and paper 

industry.
29

Woody Biomass for Bioenergy and Biofuels in the United States

One of the values of FASOM’s combined modeling of the agriculture and forest 

sectors is the ability to estimate the combined welfare changes of consumers and 

producers in the forest and agriculture sectors. Because these two sectors are linked 

so strongly, examining welfare changes for only one sector could lead to inappropriate conclusions regarding welfare impacts to society from new policies or market 

changes. Across consumers and producers in both sectors and foreign exporters 

of agricultural and forestry products, the establishment of SRWC on agriculture 

lands (in this case for pulp production) leads to an increase in net welfare of about 

$6 billion. Because of a projected drop in timber prices with SRWC, forest product 

consumers accumulated most of the welfare gains. Those agriculture producers 

who planted SRWC also gain with SRWC plantations. Because timber prices are 

reduced in the presence of SRWC, traditional timberland owners were projected 

to experience a loss relative to the baseline. Because cropland values increase and 

short-term agriculture commodity production levels decrease when some cropland 

is planted to SRWC, agriculture producers, in aggregate, are projected to also suffer 

losses relative to the baseline case. Finally, agriculture consumers will suffer some 

losses because of higher prices—although these losses are relatively small. However, it is important to recall that consumers who may suffer welfare losses from 

consuming agriculture products are also projected to experience welfare gains from 

the consumption of forest sector products (e.g., paper and paperboard). 

Although willow tree species did not factor into the result of either SRWC modeling efforts described above, its potential use as a bioenergy crop in the Northeast 

has been examined in other studies (e.g., Tharakan et al. 2005, Volk et al. 2006). 

Willow is often considered for bioenergy use by cofiring it with coal in Northeastern United States coal-fired powerplants. In the context of a potential carbon 

emissions cap under a climate change policy, cofiring willow (or any other woody 

biomass) with coal would yield a reduction in carbon emissions because woody 

biomass currently is deemed carbon neutral. Cofiring willow also reduces emissions 

of nitrous oxides (NOx) and sulfur dioxide (SO2), both of which are covered under a 

cap and trade program in the Northeast (Tharakan et al. 2005). 

Currently, the delivered price for willow biomass is not competitive with the 

delivered price of coal, making widespread adoption of willow cofiring in the 

Northeast unlikely under the current market conditions (Volk et al. 2006). Using 

a systems simulation model, Tharakan et al. (2005) found that a 1 cent/kWh price 

premium for green energy paid by consumers or a 2.4 cent/kWh tax credit to 

electric producers for biomass energy would make willow production for cofiring 

economically feasible for electric producers, biomass aggregators, and willow producers. The modeled green price premium is consistent with “green energy” price 
30

GENERAL TECHNICAL REPORT PNW-GTR-825

premiums in place for electricity elsewhere in the country (Tharakan et al. 2005). 

An increase in willow yield of about 5 odt/ac per year, either through improved 

planting stock or management systems, reduced the necessary price premium 10 

percent (to 0.9 cents/kWh) and the tax credit 12 percent (to 2.1 cents/kWh). The 

modeled yield improvement alone was not enough to make willow production 

economically feasible. Allowing willow to be planted on CRP lands for bioenergy 

production in exchange for reduced CRP payment to the landowner in a harvest 

year reduced the necessary price premium 25 percent (to 0.75 cents/kWh) and the 

tax credit 25 percent (to 1.8 cent/kWh) with current yields. Tharakan et al. (2005) 

did not examine the impact of a carbon price on willow feasibility. The Renewable 

Portfolio Standards adopted by New York and some other Northeastern States 

requires increased use of renewable fuels in electricity generation and may make 

SRWC willow plantations more feasible in the Northeast (Volk et al. 2006). 

Harvest and Milling Residues

Residues from logging represent a potentially extensive source of currently unused 

woody biomass material for bioenergy production. However, there are technical limits to the amount of this material that can be accessed and removed, costs 

associated with collecting and transporting logging residues, and, in some silviculture systems, concerns about the potential impacts to soil nutrients when logging 

residues are removed. 

In the context of firing electrical plants using woody biomass, Gan and Smith 

(2006) have estimated the state-level availability of residues from logging operations and other removals using 1997 FIA data. They estimated about 36 million dry 

tons of logging and other removal residues were available in 1997. This is consistent 

with the national-level supply estimated to be available at $40/dry ton delivered by 

Walsh et al. (2000) and that estimated by Perlack et al. (2005). Based on Gan and 

Smith (2006), the South Central region has the greatest amount of logging residues 

available, with lesser amounts available in the Northeastern, North Central, and 

Southeastern regions (table 5). The 36 million dry tons of logging residues were 

estimated to be capable of producing 67.5 TWh of electricity (Gan and Smith 

2006).3

 If all of residue-generated electricity were to offset electricity generated by 

coal-fired plants, which is unlikely, 17.6 million tons of carbon emissions would be 

avoided (Gan and Smith 2006).

Extending the Gan and Smith (2006) study, Gan (2007) used 2002 state-level 

FIA data to estimate a national harvest residue supply curve. The estimated supply 

3 Gan and Smith used a conversion factor of approximately 1.9 megawatt-hours of electricity per 1 oven dry ton of wood based on a 35-percent plant efficiency. 

Residues from logging 

represent a potentially 

extensive source of 

currently unused 

woody biomass 

material for bioenergy 

production.
31

Woody Biomass for Bioenergy and Biofuels in the United States

curve is highly elastic for most prices. That means that small changes in feedstock 

price yield large changes in the amount of harvest residues supplied. For a feedstock 

price range of between $38 and $40/odt delivered, approximately 5 to 35 million odt 

of harvest residues are available, respectively. These prices assume that all the costs 

of whole-tree harvesting are applied to the delivered price of the biomass. If only 

the additional costs of collecting and transporting the biomass material is included, 

delivered prices decline by about $8/dry ton. A $0 stumpage price was assumed 

in the Gan (2007) study. The median cost for producing electricity from logging 

residues at an optimally sized powerplant, when only the additional costs of collecting and transporting biomass is paid by the plant, was estimated to be about $47/

MWh. This estimated cost is greater than the current cost of $36/MWh for producing electricity via coal firing. The places where logging residues may be sufficient 

to supply bioelectricity may be limited. Gan (2007) estimates that about two-thirds 

of the recoverable logging residues in the United States are located in just 15 states: 

Alabama, Arkansas, Georgia, Louisiana, Maine, Michigan, Minnesota, Mississippi, 

North Carolina, Pennsylvania, Tennessee, Texas, Virginia, West Virginia, and 

Wisconsin.

Despite its potential supply, the inclusion of logging residues in any potential 

future bioenergy production portfolio is not certain. This is in large part owing 

to the high cost of procuring residues from the woods relative to other biomass 

resources and traditional fossil fuel sources. Biomass sources with very low 

procurement costs (e.g., mill residues) may figure more prominently than harvest 

residues in future bioelectricity portfolios. Using FASOM to model bioelectricity 

production from forest sector residue sources and SRWC, McCarl et al. (2000) 

found that logging residues and chips from whole-tree harvesting were not used in 

Table 5—Harvest and other removal residues, electricity 

potential, and carbon emissions displaced by region, 

annually 

Recoverable Electricity Carbon

Region residues potential displaced 

1,000 odt GWh 1,000 tons

Northeast 7,551 14,088 3,577

North Central 6,982 13,026 3,694

Southeast 6,223 11,611 2,939

South Central 11,229 20,950 5,461

Great Plains 99 184 52

Intermountain 1,251 2,334 636

Pacific Northwest 1,403 2,618 716

Southwest 844 1,575 431

 Total 36,197 67,532 17,621

Note: odt = oven dry ton, GWh = gigawatt hour. 

Source: Adapted from Gan and Smith 2006.
32

GENERAL TECHNICAL REPORT PNW-GTR-825

the production of bioelectricity; rather, in baseline projections, mill residues were 

relied on almost exclusively for bioelectricity plant firing. Most of the modeled 

bioelectricity from milling residues was generated in the South. Limited amounts 

of willow and switchgrass were also incorporated under baseline scenarios. When 

FASOM was run with SRWC yield improvements, the primary biomass feedstock 

was willow and some hybrid poplar in the Lake States (McCarl et al. 2000). Bark 

from poplar harvested for pulp was also used under high-yield SRWC scenarios. 

In the high-yield scenario, milling residues and switchgrass were used only when 

more than 650 bioelectricity plants (each 100 MW) were in operation. McCarl et 

al. (2000) suggested that if the goal of a government subsidy program is to avoid 

drastic increases in costs or to reduce emissions, a bioelectricity program that relies 

on milling residues in the short term and SRWC in the long term may be the most 

advantageous. 

Challenges to Biomass Utilization

The economic challenges and some of the technical challenges to using woody 

biomass for energy have been highlighted in the previous sections. There are also 

a number of social, organizational, and infrastructure impediments to widespread 

adoption of bioenergy production from woody biomass, and we highlight some 

of those in this section. Rosch and Kaltschmitt (1999) identified five categories of 

challenges to bioenergy production: lack of knowledge; funding, financing, and 

insuring; administrative conditions; organizational difficulties; and perception and 

acceptance. The focus of the Rosch and Kaltschmitt paper is the European Union, 

but many of the points are applicable to the U.S. situation. 

Lack of knowledge is pervasive across all the challenges identified by Rosch 

and Kaltschmitt (1999) and is not discussed separately. Many of the funding, financing, and insuring challenges have already been discussed in this paper. The existing 

administrative conditions, typically developed without a focus on bioenergy production, can make the permitting process confusing and cumbersome with uncertainties about the preconditions and requirements for issues unique to bioenergy 

production (e.g., ash disposal). Additionally, existing plant approval frameworks 

may not be applicable to bioenergy, resulting in confusion about the process and 

expectations. Administrative or legislative rules that define what qualifies as woody 

biomass for contribution to renewable energy targets, tax relief, or other comprehensive climate policies could impact the magnitude of future woody biomass 

use and the parties involved in supplying woody biomass feedstocks. The studies 

included here have not explored these limited eligibility issues, but researchers are 

beginning efforts to use the FASOM model to do so. It is difficult to examine the 

There are also a 

number of social, 

organizational, 

and infrastructure 

impediments to 

widespread adoption of 

bioenergy production.
33

Woody Biomass for Bioenergy and Biofuels in the United States

impacts of legislative and administrative rules on feedstock supply because many 

of the rules have only been proposed at this time and the definitions of qualifying 

material are often unclear. 

In regard to organizational difficulties, numerous groups and organizations 

are needed for successful implementation of large biomass plants. One unique 

challenge is identifying an adequate network of biomass suppliers. This could be 

accomplished via a biomass aggregator (e.g., in Tharakan et al. 2005) or the energy 

producer can contract with many individual feedstock producers. The former situation is likely more attractive for the energy producer (Tharakan et al. 2005). There 

are also existing concerns about the lack of infrastructure for collecting, transporting, and storing biomass. 

One of the greatest stumbling blocks may be public perceptions of biomass 

use. Rosch and Kaltschmitt (1999) remarked that there is a disconnect between the 

general approval of society for renewable energy production and their skepticism 

of generating energy from solid biomass. Rosch and Kaltschmitt highlighted three 

critical attitudes that are a challenge to adoption of biomass energy production. 

First, is the belief by some that solid biomass energy is old technology, low efficiency, and limited only to heat and steam production. This perception probably 

traces to past experiences with smoky, low-efficiency, residential wood stoves. 

Second, is the perception by individuals that energy produced from biomass is not 

convenient for use (e.g., inability to change heat output). Finally, many perceive that 

the biomass feedstock supply is difficult to obtain and may not provide a regular, 

reliable supply because of such things as constraints on harvest timing. 

A recent case in Eugene, Oregon, may be illustrative of the productive capacity 

of bioenergy from biomass as well as the some of the unease regarding bioenergy production from woody biomass. In early 2009, Seneca Sawmill Company 

announced plans to install at a cost of $45 million an 18-MW CHP plant at their 

existing sawmill located outside the city of Eugene, Oregon. The expected feedstocks for the CHP plant are milling and forest harvest residues—including some 

residue currently sold for other products (including as pulp feedstock to a nearby 

mill that recently announced it will be ceasing operations). The heat produced by 

the CHP plant will be used for kiln drying on the mill site, and the electricity produced will be sold entirely to the power grid. The power generated would support 

the energy needs of about 13,000 housing units (Seneca Sawmill Company 2009). 

The project announcement has garnered local media attention and considerable 

back and forth on the local editorial page. Opponents of the plant most frequently 

voiced concerns about the expected pollutant emissions. Others have expressed 

concerns regarding the potential negative impacts to forest productivity as a result 
34

GENERAL TECHNICAL REPORT PNW-GTR-825

of logging residue removal and the distributional equity of where the plant (and 

expected emissions) are located (Eugene Register Guard 2009a, 2009b). Some 

opponents have stated a preference for using solar and wind energy, rather than 

woody biomass, to meet renewable energy portfolio requirements. In early October, 

2009, Seneca Sawmill was granted an air contaminant discharge permit from the 

Lane Regional Air Protection Agency, allowing for construction of the CHP plant 

(LRAPA 2009). The CHP plant is expected to become operational by the end of 

2010. 

Although energy crops, e.g., switchgrass or SRWC, have great potential for use 

in bioenergy, the revenue to a producer from energy crops would be delayed for 

several years after planting while the crop matures. This results in a situation where 

producers are reluctant to plant energy crops because of uncertainties and delays in 

any potential revenues, and the consumers of energy crops (e.g., powerplants) are 

unwilling to invest in the infrastructure (e.g., adjustments to coal burners) necessary to utilize biomass. Volk et al. (2006) characterized the situation by stating that 

the large-scale deployment of willow for biomass “remains challenging because 

there is currently not enough willow biomass established to initiate large-scale use 

of the material, while at the same time there are currently no long-term commitments assuring producers of a stable market in the future.” Because of this, in part, 

model results from FASOM (McCarl et al. 2000) indicate a short-term reliance on 

easily accessed feedstocks (e.g., milling residues) for bioenergy production, even 

though they may already be used in other products. This reliance would then shift 

over the long term as energy crops matured and more acres were planted to SRWC 

(McCarl et al. 2000). 

The use of residues from forest thinning, either from hazard reduction or from 

other management purposes, to produce bioenergy has been extensively discussed 

and promoted. In addition to the economic and technical constraints discussed 

above, there remain a number of other challenges to the use of small-diameter 

thinned material from forests for bioenergy production or other products (Hjerpe 

et al. 2009). First, infrastructure may be limited for harvesting, transporting, and 

processing small-diameter material. This has resulted in part from dismantling of 

some harvesting infrastructure following reductions in timber harvest from federal 

lands. Furthermore, the remaining infrastructure capacity may not be well suited 

to handling small-diameter material efficiently. Second, the supply of wood may 

be erratic depending on market conditions and, particularly if from federal lands, 

harvesting policies and regulations. Finally, some individuals and organizations 

have concerns about hazard thinning activities that include the removal of large 

trees. The concern over including large stems has important implications for the 
35

Woody Biomass for Bioenergy and Biofuels in the United States

effectiveness and economic feasibility of hazard-fuel thinning programs. Skog 

et al. (2006, 2008) have shown that hazard thinning programs that include the 

harvest of at least some larger stems are better able to meet targets for reducing 

the susceptibility of forest stands to wildfire crowning and torching. Further, those 

authors found that hazard-fuel reduction treatments become at least revenue neutral 

only if larger stems can be harvested and sold for sawtimber and pulp. On public 

lands, the concern over removal of large stems often manifests in an upper diameter 

limit on any thinning operations. Even on private lands, some individuals and 

groups may become concerned if they perceive that large trees are being harvested 

for traditional timber production under the guise of hazard mitigation or renewable 

energy production. 

To date, many have treated bioenergy from woody biomass (and other biomass 

resources) as carbon neutral; biomass was treated as such under the Kyoto protocol. 

However, very recently some have suggested that the use of woody biomass for 

bioenergy may not be carbon neutral if carbon emissions from the land use change 

and other activities in generating the woody biomass are included in carbon emissions accounting (e.g., Searchinger et al. 2009). As an example of carbon emissions 

unaccounted for in biomass generation, Searchinger et al. described a scenario in 

which mature forest is cleared to plant energy crops. Although this example makes 

a useful point in fully accounting for carbon emissions in energy generation, none 

of the studies reported here have involved such extreme land use changes to generate biomass for energy. Much of the forest woody biomass will likely come from 

residues generated from harvests that would have occurred anyway or through 

hazard-fuel thinning operations that could reasonably be expected to increase forest 

growth and perhaps reduce the intensity of wildfire. The energy crop plantings 

included in models discussed here are primarily considered on agriculture land, 

much of it marginal or fallow land. In some cases (e.g., no long-term increase in 

crop productivity), increased energy crop planting could result in some shifts of 

land from forest to agriculture. Although their discussion of land use change is 

important, Searchinger et al. seem to ignore the land use change (e.g., mountaintop 

removal) that would occur under the business-as-usual use of fossil fuels relative 

to that land use change that might occur with biomass feedstocks. Regardless, 

accounting issues and carbon life-cycle emissions will be important considerations 

in examining policies that promote woody biomass bioenergy. 

Conclusions

Bioenergy production from woody biomass is likely to be an important component 

in comprehensive climate change policy. Future expanded use of woody biomass 
36

GENERAL TECHNICAL REPORT PNW-GTR-825

in energy production will build on the current contribution of woody biomass to 

renewable energy. Current estimates of the potential volumes of woody biomass 

available for bioenergy production differ widely, primarily because of different 

“types” of availability that were considered and differing assumptions that were 

adopted in the estimates. Milling residues and wood in MSW currently have the 

greatest volumes of material used in production of bioenergy and other products. 

Logging residues currently left onsite and biomass material that could be generated as part of a hazard-fuel thinning program may offer the greatest volumes of 

material available and not currently used. However, handling and transport of this 

material is costly, and there are a number of social concerns about the use of this 

biomass for energy production. The acres of SRWC in production are currently 

very limited, but this resource may offer the most reliable and productive long-term 

supply of biomass for bioenergy. 

The distribution of woody biomass resources is not uniform across the United 

States. The eastern half of the United States, and the South in particular, has the 

greatest quantities of timber harvest and milling residues potentially available for 

bioenergy. Although not shown in this report, the distribution of woody material 

in MSW is thought to follow the population distribution, with some adjustments 

for recycling rates and waste generation. The West, and specifically California, has 

the greatest volume of material that could be available from hazard-fuel reduction. 

The majority of hazard-fuel reduction woody biomass is located on national forest 

timberland. The greatest areas of cropland suitable for production of SRWC are in 

the Corn Belt, Lake States, and the South Central regions. If planted for pulp production, SRWC may be most common in the South and Lake States. If planted for 

energy, the Northeast and possibly the Corn Belt may be the areas of planting focus. 

If there is a rapid increase in the demand for biomass for bioenergy, it is likely 

that widely available residues (i.e., mill residues and harvest residues) will be the 

initial biomass feedstocks. The use of mill residues for bioenergy may reduce the 

supply of residue available for other products like bark mulch. As a future woody 

biomass bioenergy sector expands, biomass may increasingly be drawn from SRWC 

and thinned small-diameter material. Niche markets using woody biomass supplies 

unique to the local area (e.g., secondary mill residues, MSW streams) may develop 

in some locales. 

In the United States, the current price of fossil fuel energy feedstocks and 

consumer prices for energy have not supported expansion of woody biomass use 

for bioenergy. The wood products industry, with an extensive supply of low-cost 

material and a large potential for reducing production costs, is the greatest producer 

The distribution 

of woody biomass 

resources is not 

uniform across the 

United States.
37

Woody Biomass for Bioenergy and Biofuels in the United States

of energy from woody biomass in the United States. In the absence of policies that 

make bioenergy production more attractive relative to energy derived from fossil fuels or significant changes in the price of fossil fuels, it seems that bioenergy 

from woody biomass will continue to remain a small component of the overall U.S. 

energy portfolio. However, several regions and states have implemented renewable 

energy standards in recent years, and bioenergy production from biomass may 

increase in these areas. 

Additional research is needed for improved inventory and monitoring of woody 

biomass availability. This research should focus not only on the production volume 

of woody biomass (e.g., the volume generated in MSW) but also the supply that 

could be available at a range of feedstock prices. The lack of a reliable inventory 

of existing and possible supplies makes it difficult to develop an understanding 

of possible future outcomes. Because of recent concerns about bioenergy carbon 

emissions accounting, research is needed to fully consider the “additionality” and 

“leakage” implications for carbon emissions as a result of using woody biomass for 

bioenergy and comprehensive climate change policies. Research effort is also necessary to develop a better understanding of the responses in the energy, agriculture, 

and forest sectors to policies that would impact bioenergy usage. Few models are 

capable of simultaneously modeling the interactions of all three sectors. The results 

of previous studies using the FASOM model to examine SRWC production and 

increased use of biomass for bioenergy have shown the importance of examining 

the agriculture and forest sectors jointly. Because the forest and agriculture sectors 

are linked so closely, if one sector is considered in isolation, the outcomes from new 

climate change policies may not be properly understood. 

Periodic estimates of harvest and milling residues are currently available. Estimates of the volume of woody material in MSW and at secondary wood products 

manufacturing facilities are generated less frequently and via a system with many 

assumptions about production per capita or facility. If it is desirable to use those 

materials for bioenergy production, more regular and rigorous efforts to quantify 

their volumes are necessary. More comprehensive measurements of land planted 

in SRWC over time will help to better identify the potential volumes that could 

be expected from that resource. Transportation costs are a significant deterrent to 

increased use of woody biomass. Better identification of the locations of current and 

potential bioenergy production facilities will help to identify those woody biomass 

resource stocks that may be in the best position for increased use. Similarly, a 

better understanding of the spatial patterns in supply curves for different bioenergy 

feedstocks (woody and otherwise) will be useful in identifying the locations where 

woody biomass is most likely to be used for bioenergy. 
38

GENERAL TECHNICAL REPORT PNW-GTR-825

Acknowledgments

The support of Ralph Alig and the Pacific Northwest Research Station was instrumental in completing this research. The final report benefited from the helpful 

review comments of Darius Adams, Rob Doudrick, Dennis Dykstra, Jeremy Fried, 

Greg Latta, Roger Lord, Dave Nicholls, and Marcia Patton-Mallory. Thanks to Judy 

Mikowski for technical assistance in preparing the manuscript for publication. 

Metric Equivalents

When you know: Multiply by: To get:

Inches (in) 2.54 Centimeters

Acres (ac) 0.405 Hectares

Miles (mi) 1.609 Kilometers

Cubic feet (ft3

) 0.0283 Cubic meters

Gallons (gal) 3.78 Liters

Pounds (lb) 454 Grams

Tons (ton) 0.907 Tonnes

Degrees Fahrenheit 0.56(F-32) Degrees Celsius

British Thermal units (BTUs) 1,050 Joules

Tons per acre (tons/ac) 2.24 Tonnes per hectare

Cubic feet per acre (ft3/ac) 0.07 Cubic meters per hectare

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