Research and innovation is showing that the uses of woody biomass are only limited by our imagination (Bozell and Landucci 1993, Kaminsky 2004, Pearl 1968, Zerbe 2006). For thousands of years, wood has been the key resource for the production of heat. In 2003, biomass was the leading source of renewable energy in the United States accounting for 4 percent of the total energy produced (EIA 2005). However, the direct combustion of woody biomass for heat and energy is but one use of the resources. With over 87 million hectares of forestland in the southern United States (Weir and Greis 2002), the South is primed to be a leader in the utilization of woody biomass, not only for energy production but as a substitute for petroleum-based products. In 2004, the United States consumed 104 quadrillion BTUs of energy, with 6 quadrillion produced from renewable resources (EIA 2005). Energy produced from woody biomass accounted for a third of the renewable sources (EIA 2005).

Energy Flow Diagram 2004

At the turn of the 20^th century, most non-fuel industrial products were derived from biomass sources. These included dyes, medicines, chemicals, synthetic fibers, and plastics (Committee of Biobased Industrial Products 2000). Yet by the 1970s, chemicals from petroleum derivatives had largely replaced those from biomass sources, gaining more than 95 percent of the market as petroleum began to account for more than 70 percent of our fuels (Morris and Ahmed 1992). Recently, environmental and energy security concerns have increased the interest and awareness in using biomass feedstocks to meet our growing energy and fuel demands. According to researchers at the starch-based biorefinery Roquette, we only discover one new barrel of oil for every six that we use. Demand for alternative sources of fuel, energy, and petroleum-based substitutes increase as our global population increases. We can expect the demand to continue to increase and prices to continue to rise as China, eastern European countires, India, and African nations continue to advance economically and technologically.

Currently there are technologies being developed among American industries to improve the efficiency of using wood for such purposes. Transportation fuels, bio-based plastics and chemicals, and small scale biomass based power plants are increasing yearly across the nation.

This section of the encyclopedia will examine the products such as energy, fuels, and bio-based materials that can be generated from woody biomass. Other sections of the Encyclopdia of Southern Bioenergy address the importance of resource management and sustainability. Production methods and specifications are also addressed in this module.

Sections for this entry:

• Woody Biomass
• Bioenergy
• Biomass Industrial Products
• Production Methods
• Worldwide Utilization
• Units of Energy

Biomass is any organic matter including forest and mill residues, agricultural crops and wastes, wood and wood wastes, animal wastes, livestock operation residues, aquatic plants, and municipal and industrial wastes (Bergman and Zerbe 2004). For the purpose of this encyclopedia, we will focus only on the biomass materials generated from forests and wood-processing wastes.

Annual Biomass Resource Potential
from Forest and Agricultural Resources

These woody materials can be forest residues such as thinnings or residual slash from harvest operations, wood wastes such as bark, sawdust, chips, or wood-processing wastes such as black liquor. It is estimated that nearly 5.6 million tonnes of unused wood residue is generated in U.S. sawmills yearly (Smith et al 1994).

Dry wood has roughly twice the caloric value of wet wood (Zerbe 2006) and with varying physical and chemical composition, it is useful to have an understanding of the different ways in which plant species, moisture and energy content, and ash affect biomass utilization.

This section is divided into:

• Wood Composition
• Properties of wood
• Forest Residues
• Wood-processing residues

Stack of Pine

Understanding the structure and composition of woody biomass is vital to efficient utilization. Wood is one of the most abundant resources in the bio-based industry and yet it is also one of the most complex materials, composed of polymers of lignin and carbohydrates that are physically and chemically bound together. Considerable amounts of energy are required to separate the polymers from each other (Committee on Biobased Industrial Products 2000). Deconstructing the hundreds of components that constitute woody material is the key to producing a substitute for petrochemicals. These components can be classified as:

• Cellulose
• Hemicelluloses
• Lignin
• Mineral Elements

Comprising nearly half of woody plant composition by weight, cellulose is a carbohydrate polymer composed of glucose chains (Miller 1999). Cellulose, comprised of carbon, hydrogen, and oxygen in the form of starches, proteins, and sugars, is the most abundant organic material on earth. It is isolated during the pulping process and processed to yield ethanol, cellophane, and cellulose ethers such as acetate, rayon, and nitrates. Due to the relatively high manufacturing cost compared to that of petrochemical polymers, many of these derivatives have only specialty applications.

The primary source of wood cellulose pulp comes from conifer species (Smith et al 1994) but over the last twenty years, hardwood utilization has increased. Processing biomass feedstocks always requires attention to cellulose due to its proportion of total volume and weight.

Cellulose

Starch being Applied to a Plywood Veneer

Starch is the principal carbohydrate reserve of plants. Corn starch currently is a primary feedstock for starch-based ethanol, plastics, loose-fill packing material, adhesives, and other industrial products. Approximately 600 million bushels of corn were used for the production of industrial products during the marketing year 1995 to 1996; of that total, 395 million bushels were used to produce fuel ethanol (ERS, 1996b). While the supply of corn starch has been sufficient to meet current demands, primarily anhydrous motor fuel grade and industrial ethanol, other supplies of sugar feedstocks are being evaluated to meet anticipated increases in demand for oxygenated fuels and chemicals.

Proteins are the primary means of expressing the genetic information coded in DNA. These polymers are based on building blocks of amino acid monomers whose sequence is predetermined by a genetic template. The sequence diversity of proteins is responsible for the wide array of functions performed by proteins in living organisms (OTA, 1993). A variety of plant proteins might one day be commercially exploited as materials, but current understanding of the structural properties of most plant proteins is limited.

Zein is perhaps the best understood plant protein. It has been given the most interest due to its ability to form fibers and films that are tough, glossy, and resistant to grease and scuffing. The Virginia-Carolina Corporation once produced 5 million pounds of Zein fiber before shifting to comparable synthetic fibers. Today Zein is used as a water-impermeable coating for pharmaceutical tablets, binding for bottle-cap liners, and a shellac substitute. The industrial usefulness and merits of Zein have stimulated continual examination of proteins (Wall and Paulis, 1978).

Fermentable sugars are the largest feedstock available to support a bio-based chemicals industry in the United States. A wide range of fermentable sugars can be found in crops and wastes from agriculture and forestry. Major feedstocks include corn, wheat, sorghum, potato, sugarbeet, and sugarcane; other sources include potato-processing residues, sugarbeet and cane molasses, and apple pomace (Polman 1994). Sugars can be produced directly or derived from polysaccharides such as cellulose and starch and then, via microbial fermentation, used to produce a wide range of commodity and specialty chemicals. Existing commercial fermentation primarily utilizes glucose to produce ethanol, acetic acid, amino acids, antibiotics, and other chemicals. Over the long term, new sources of glucose will be required to meet the demands of a bio-based industry. Growth of a bio-based chemicals industry will depend on production of cellulose-rich crops, including those currently under production such as corn and alfalfa and others that presently are not grown commercially, such as switchgrass and hybrid poplar.

Significant increases in glucose reserves are available from lignocellulosic substances found in most plants, crop residues, and waste paper. Cellulose can be hydrolyzed by acid to glucose, although much of the glucose is destroyed during this process. The second most abundant sugar found in hardwood and agricultural residues is xylose, which is derived from xylan hemicelluloses. Xylose is relatively easily recovered by acid or enzymatic hydrolysis and can be fermented to ethanol by naturally occurring organisms or recombinant microbes. The practical sugar yield from lignocellulosics would increase significantly if commercial fermentations could utilize xylose, a 5-carbon sugar or pentose, as well as glucose, a 6-carbon sugar or hexose. Novel genetically engineered microorganisms will play a key role in the direct conversion of cellulose oligomers and 5- and 6-carbon sugars to ethanol.

Enxymatic hydrolysis using mixtures of enzymes, such as cellulase and hemicellulaces, is used to avoid the destruction of sugars associated with acid treatments (hydrolysis) of lignocellulosic material. These enzymes, when combined with effective pretreatment of lignocellulosics, provide high yields of glucose, xylose, and other fermentable sugars with minimal sugar losses. However, these enzymes are currently too costly to use in large-scale conversion of lignocellulosic materials to fermentation substrates.

Hemicellulose is composed of carbohydrates based on pentose sugars, mainly xylose, as well as hexose sugars, such as glucose and mannose. Hemicellulose comprises 25 to 35 percent of the dry weight of wood residues; they are second only to cellulose in abundance among carbohydrates. While use of hemicellulose is currently limited, quantities of hemicelluloses, pectins, and various other plant polymers are abundant in crop residues and have great potential in the production of chemicals and materials. During the pulping process, hemicellulose is pooled with lignin to become the wood-processing residue, black liquor.

Hemicellulose

Lignin Monomer

Lignin is a phenylpropane polymer that holds together cellulose and hemicellulose components of woody biomass. Lignin constitutes about 15 to 25 percent of the weight of woody biomass. Lignin has not yet been used as a raw material for industrial purposes in large quantities. Concerted attempts by pulp and paper research laboratories to develop new markets for by-product lignins have had only limited success (Bozell and Landucci, 1993). Production of low-molecular-weight compounds from kraft lignin, phenols in particular, has also not yet proved to be commercially competitive. This reflects the chemical complexity of lignin and its resistance to depolymerization. Nevertheless, a recent Department of Energy study concluded that pyrolysis of lignocellulosics could make production of phenolics and anthraquinone from lignin competitive, and the potential also exists to produce benzene, toluene, and xylenes from lignin via pyrolysis (Bozell and Landucci, 1993). Lignocellulose pretreatment will be a key step for realizing the presently untapped potential of abundant lignocellulosic materials found in wood (Malherbe and Cloete 2002). Until these higher value products emerge, lignin will continue to be burned to produce energy.

In addition to oxygen, hydrogen, nitrogen, and carbon, trees are composed of many other mineral elements. While these elements do not produce energy during combustion they do affect the energy content of woody biomass. On average, hardwoods have a higher concentration of these mineral elements than softwoods; but the presence of these minerals is more affected by the site where they are grown than their age, species, or size.

Nitrogen is a component of all fuel systems and during the combustion process it is oxidized into NOx. When emitted from combustion facilities at relatively low levels, NOx may have a useful fertilizing effect on forests, however as emission levels increase, NOx produces adverse health effects and increases the acidification of water and soils. Nitrogen concentrations in wood are typically less than that in coal and oil (BROKEN-LINK Alakangas et al. 1987), thus NOx emissions from wood-based fuels are lower and more environmentally friendly than fossil fuels.

Calcium and potassium are the most abundant mineral elements found in woody biomass but other trace elements such as sulfur, chlorine, and heavy metals are also present. Sulfur emissions from combustion of fuels cause extensive damage to ecosystems and buildings, so fossil fuels are often graded by the amount of sulfur present. As occurs for nitrogen, sulfur is oxidized during combustion to form SOx. This compound can have serious environmental effects and causes the acidification of soils and water. The sulfur content in woody biomass resources is much lower than fossil fuels (Richardson et al. 2002). Equipment to remove sulfur during or resulting from the combustion of fossil fuels is expensive. As emission standards become more stringent, woody biomass is considered a viable alternative fuel for reducing SOx emissions associated with fossil fuel sources.

Most chlorine in trees is found in the foilage as an essential component in chlorophyll. Although only present in trace amounts, its ability to form alkali compounds with potassium and sodium can create serious problems for boiler equipment during combustion as a result of oxidation and corrosion (Riedl and Obernberger 1996). Eliminating foilage from woody biomass feedstocks has been shown to reduce corrosion problems, as has co-firing biomass resources with higher sulfur content fuels such as peat or coal (Orjala et al. 2000).

Heavy metals may vaporize during combustion. The remainder contributes to ash formation. Should levels of heavy metals be high, recycling of ash as fertilizer is restricted by environmental legislation, since the metals may leach into ground water or be absorbed by crops. More modern furnaces are often equipped with filters to reduce heavy metal emmisions but it is best that painted or treated wood waste be avoided as a fuel source considering the higher heavy metal concentrations found in these sources.

The properties of wood vary between species and have a direct impact on moisture content which in turn influences the potential energy that is produced from the material.

Properties that influence woody biomass utilization include:

• Plant Species
• Moisture Content
• Energy Content
• Ash Content

The moisture content of biomass material varies greatly. This has a significant effect on many of the energy conversion processes. As an example, when biogas is obtained from an anaerobic digestion process the percentage of solids present in the digestate affects the gas yields. For dry biomass fuels such as wood, the amount of water present has a considerable effect on the proportion of the total heat content of the material that is able to be recovered during combustion.

For wood, the moisture content depends on a combination of climatic conditions, time of year when harvesting takes place, and the duration and method of storage (Simpson and TenWolde 1999). The following simple formulas can be used to calculate the moisture content of biomass:

moisture content (wet basis) = (total weight of wet wood ? oven dry weight)/total weight of wet wood * 100

moisture content (dry basis) = (total weight of wet wood ? oven dry weight)/oven dry weight * 100.

Energy yields are often expressed as net caloric values. These values increase as wood moisture content is reduced. Thus, the drier the wood, the greater the amount of energy that can be produced. The percent moisture content of the biomass utilized has a large impact upon the design and selection of technologies ideal for energy production.

Net calorific value of waste wood (Pinus radiata)
as a function of moisture content.

The potential energy value of biomass materials is determined by its chemical composition and is measured as Joules of energy in 1 g of fuel (J/g). For convenience this measure is usually expressed as MJ/kg or GJ/t. However, for practical matters the volume-related energy density is a much more important parameter considering the packaging of energy materials, ie. chips vs. sawdust vs. logs.

While the energy value of solid biomass has relatively low variation, the volume of a single unit of fuel equivalent can easily vary by a factor of ten, depending on the method of harvesting or processing. In the case of chipped forest and agricultural biomass, the application of densification technologies can considerably reduce the volume of space required for storage, thus increasing the energy density of the materials.

The total amount of energy released from fuel is called the heating value. Due to differences in chemical composition, softwoods have higher heating values than hardwoods, branches have higher heating values than stemwood, and bark and foilage have higher heating values than wood in general despite the higher ash and heavy metal content (Nurmi 1993). The approximate heating values of wood and various wood residues are shown in the table below (Corder 1976).

Approximate heating values of wood and various wood residues

The energy density of a fuel is the heating value per unit volume. Energy density has been found to be highest in chips from high-density species such as oaks. The southern scrub oak forest type has been shown to be an important component of southern fuelwood resources for industrial heat generation in South Carolina (Harris et al. 2004).

Energy density is relatively low in biomass chips. The space required for transporting and storing chips is 11 to 15 times greater than the space needed for oil, and 3 to 4 times greater than that required for coal (Young 1980). These differences result in higher utilization costs and the biomass material being utilized closer to the source. A commonly used conversion factor shows that a solid cubic meter of wood will produce roughly 2.5 cubic meters of loose chips (Standish et al. 1985).

Factors that influence the solid content of chips include:

1. Particle shape: Reduced ratio between diagonal length and thickness increases solid content (Edberg et al. 1973).
2. Size distribution: Heterogeneous size distribution increases solid content.
3. Tree species: Brittle, low-density materials have a higher solid content.
4. Branch content: Fresh branches and twigs reduce the solid content value.
5. Loading: Compaction from blowing increases solid content versus free-fall loading systems.
6. Storage: Stored materials tend to contain more fine materials and slightly higher solid content.

Comparisons of fuel sources often examine the energy balance ratio or the output energy versus the input to create energy. The energy balance ratio of chips from logging residues and thinnings has been shown to be high compared with other energy crops such as alfalfa, rapeseed, canary reed, and potato (Richardson et al. 2002). Thus, as long as forest fuel is a by-product of other operations and transportation is kept to a minimum, forest residuals make an excellent energy source.

Ash from biomass comes from the minerals present in the structure of the plant and any soil contamination. Characterization of ash by elemental analysis and fusion temperatures is important when selecting biomass fuels because it provides information on how much ash will be generated requiring disposal and indicates the potential for slagging and fouling of burners and boilers (Riedl and Obernberger 1996). When wood is combusted as the only fuel, ash fusion is not usually a problem since the combustion temperatures are likely to be low. However, when biomass is co-fired with coal, combustion temperatures are considerably higher and may reach a level where slagging could occur (Misra et al. 1993).

Ash management presents both a problem and an opportunity. Removal of ash from the furnace and disposal in landfill areas incurs costs for power plants. However, if ash is recycled in the forest or agricultural ecosystems or used to reclaim mine spoils, depletion of plant nutrients, other than nitrogen, and acidification associated with intensive biomass removal is radically reduced.

Sugar and Ash Composition of Feedstocks

All plant species that store primarily carbohydrates or oils are suitable for producing liquid energy sources. Cellulose, starch, sugar and inulin (Ohta et al. 1993) can be used to produce ethanol, and vegetable oils can be used as fuels. Parts of plants containing lignocellulose can provide energy directly as solid fuels or indirectly after conversion (Wright and Berg 1996). Oak Ridge National Lab and Washington State University have conducted research into the utilization of hybrid poplars for bioenergy while the State University of New York has examined other species for utilization.

Populus spp., Salix spp., Eucalyptus spp., and other fast growing species make excellent choices for energy plantations. Various other hardwoods and some softwoods would make better choices for other biobased products due to various differences in sugar composition. Just like making forest management decisions, deciding which species is best for your objectives will depend greatly upon site and economic conditions (Bouton 2002).

To learn about a specific plant species and its role in bioenergy and biobased product utilization, Phyllis has been created. Sponsored by Shell Global Solutions, Agrotechnology and Food Innovations, and maintained by the Energy Research Center of the Netherlands, this site provides analysis and composition data for over 2000 various biomass and waste materials. Biomass materials are group by untreated and treated wood, grasses, agricultural waste, animal waste, and other organic residues. The system also provides comparisons to fossil fuel sources including peat. Phyllis will provide users with information regarding ash and water content, calorific values, and biochemical composition of the material.

Nearly 20 billion cubic feet of wood is removed on an annual basis from lands in the United States. Of that volume, 16 percent is classified as logging residues (Smith et al. 2004). This material is mainly tree tops and small branches that have been considered uneconomical to harvest. The USDA Forest Service Inventory and Analysis program estimates that 61 million dry tons of residuals are available annually from harvesting and fuel reduction activities. A recovery system, that would follow behind a conventional logging operation, could recover 60 percent or 40 million dry tons of this residue for potential bioenergy and biobased product markets (Stokes 1992). To maintain soil properties and nutrients, not all available forest residuals should be recovered during operations (Perlack et al. 2005).

Current Availablity of Logging Residues and Other Removals

Post-logging operations typically result in two categories of waste:

• Harvesting Wastes
• Bark

The outer part of woody stems and branches is comprised of bark and typically comprises 9 to 15 percent of a log's volume (Chang 1954). There are large differences in the types and amounts of various chemical components that comprise bark, even within a single species which depends on growing conditions, age, and various disturbances (Harkin and Rowe 1971). The volume of bark and coarse materials that are available annually in the United States approaches 83 million dry tonnes. Historically, this bark has been used to produce tannins, dyes, resins, flavorings, and medicinal products. As utilization techniques have improved, more and more chemical extracts have become commercially available for utilization. However, bark can be difficult to utilize due to soil contamination during harvesting (Harkin and Rowe 1971).

Bark Pile

The most common use of bark is in mulching or soil amendment (Mater 1969). When worked directly into the soil, bark?s decomposition rate is considerably slower than wood, thus lasting longer; its lower consumption of nitrogen also results in less nitrogen-availability related stress affecting planted vegetation (Allison 1965).

Bark has also been commonly used as a fuel source. On average, 9 tonnes of completely dry bark is the equivalent of nearly 6 tonnes of coal with an effective heating value of 2.34 to 2.93 kWh per pound of bone dry material (Harkin and Rowe 1971). However, these values dynamically decrease as percent moisture content rises. Bark can be processed to create a higher value fuel by manufacturing briquettes but still is limited due to its higher moisture values (Dingwall 1969).

Discarded bark has found an outlet in building materials such as fiber and particleboard (Murphey 1969) and because bark conducts heat less readily than wood, it is a component of insulation board (Martin 1970).

The chemical utilization of bark is still in its infancy, mainly due to the economic expense of transportation, storage, and volume of the material. Very few pure organic compounds have been isolated on a grand scale, such as Salicin from aspen bark but, with advanced fractionation techniques emerging, more compounds are on the horizon (Pearl 1968). More crude fractions such as tannins have been used in larger quantities in the fields of tanning leather, development of drilling muds, adhesives for plywood and particleboard, and taxol for research into cancer treatments (Hathway 1962, Hergert et.al 1965, MacLean and Gardner 1952, Minore and Weatherly 1996).

Forest residues typically refer to those parts of trees unsuitable for sawlogs – treetops, branches, small-diameter wood, stumps, leaves, dead wood and even poorly-formed whole trees – as well as undergrowth and low-value species. While applications may exist for any individual constituent, the difficulty is determining whether there are sufficiently large quantities to warrant separation and harvesting.

If harvested, these residues are sometimes used for combustion or chipping for production of other usable feedstocks. Please see the harvesting section in this encyclopedia for more information.

Primary processing mill residues are very desirable for energy and other bio-based products because they are often clean, uniform, on-site, and have low moisture contents. Because of these desirable traits, very few mill residues are not currently being utilized by industries. Beyond using the residuals for energy and heat, mills are becoming more adept at incorporating them into products such as OSB, acoustic panels, and particleboard.

Forest Products Industry Processing Residues -2004

Wood-processing Residues:

• Black Liquor
• Chips
• Sawdust

Sawdust for Energy

Sawdust is a lignocellulosic biomass source that is the particulate residue of lumber production. Most sawdust is considered green, not dried, and is relatively uniform in size and shape. Sawdust is also refered to as "wood flour", a designation that indicates the particles can pass through a 20-mesh gauge screen.

Sawdust can be used in gasification, combustion, and pyrolysis processes as well as undergo fiber composite manufacturing to produce bedding, abrasives, insulation, and packaging. Sawdust is considered a secondary wood residue in addition to shavings and cut-offs from sawmill operations. Nearly 14.5 million tonnes of seconday wood residues are generated yearly, which sell for about $13 per dry tonne before delivery (Barber 2003).

Chips are described as virgin wood which has beem comminuted by mechanical chippers. Ideal chips are a uniform size and contain no bark or rot. Chip size is a function of wood density, moisture content and orientation in the chipper. Uniformly shaped chips contribute to improved energy production. Chips are often stored on-site for a few months after chipping and care must be taken to limit exposure to the elements. The traditional markets for wood chips have been the pulp and paper industry and landscaping companies.

Wood Chips

Since a load of chips contains much more open space than a solid block of wood, several factors must be considered to determine the tons of chips needed for a specific project. The greater the diagonal-to-thickness ratio of the chips, the lower the solid content (Edberg et al. 1973). More heterogenous chips contribute to reduced space between chips and increase the solid ratio in chip-loads. Chip-loads from whole-trees or logging residues contain more fine materials than uniform chips from pulpwood, and tend to have higher solid content rates. Chip quality also varies according to species, with fuel chips from brittle low-density material containing more fine particles with a higher solid content. The solid content proportion of a fuel chip-load varies from 38 to 44 percent (Nylinder and Tornmarck 1986). A solid cubic meter of wood would produce approximately 2.5 cubic meters of loose chips.

European nations in Scandinavia and the Baltic regions have long used wood chips as a source of energy. One of the newest wood chip suppliers in Europe is GFC, or the Groupe Cooperation Forestiere based in Paris, France.

Groupe Cooperation Forestiere

GCF is the first French forest wood chips producer for bioenergy and the first French group which obtained the long-term durable forest certification of its members. Their goals are to provide private forest owners with the necessary technical assistance to support long-term and durable management, to improve the forests economic competitiveness, and to act as an essential part for regional planning. Beyond providing professional forest management services, harvesting, and reforestation operations, GFC has assisted their landowners in entering the growing market for wood energy by entering into cooperatives with independant enterprises that have produced guaranteed long-term contracts for wood chips off private lands.

In 2004, GFC had 35 members in their wood energy cooperative. They marketed 5 million cubic meters of wood and produced a profit in excess of 230 million Euros, or nearly US $255 Million.

Black Liquor

White liquor is a solution of caustic chemicals, such as sodium hydroxide, that is added to wood chips in Kraft and sulfite pulping processes to dissolve lignin and release cellulose fibers from wood. The fibers are then washed, and the resulting slurry of water, caustic chemicals and dissolved lignin is called black liquor. Black liquor is recycled in a process that gives off heat energy, carbon dioxide, and recoverable chemicals. These chemicals need only a 10 percent supplement of additional caustic chemicals to become white liquor again (Larson and Raymond 1997).

Nearly 47 million dry tonnes of black liquor is produced annually and is typically recovered as part of the pulping process (BEES 2001). Since the liquor is created and consumed in recovery boilers on-site, it is not readily available for off-site utilization. The steam that is generated during the black liquor recovery process contributes significantly to the energy needs of pulp and paper mills. In addition, some chemicals can be recovered from the liquor and through recycling can reduce the pulping processs chemical needs by almost 90 percent.

Biomass was the leading source of renewable energy in the United States in 2003, for the fourth year in a row, providing 8.5(e11) kWh of the 2.05(e13) kWh of energy produced. Biomass was the source of nearly half the renewable energy produced and accounted for 4 percent of the total energy produced in the United States (DOE 2005). Wood, and in particular residues from paper mills, are the most common resource used for generating electricity and industrial process heat and steam.

Currently, consumption of biomass generated energy is dominated by industrial use. The pulp and paper industries, solely using black liquor, consumed 3.22(e11) kWh of biomass generated energy (DOE 2005). Schools, prisons, and hospitals have recently started utilizing wood to produce energy at the local level. The residential sector consumed 9.73(e8) kWh of energy in 2004 (DOE 2005) and many other institutions are utilizing bioenergy on a variety of scales from 996 kWh up to 15001 kWh per hour (Zerbe 2006).

Companies who have ready access to biomass resources, at relatively low costs, often choose to mix traditional fossil fuels with biomass to enhance their competitiveness in the marketplace. With new emissions standards and carbon credits on the horizon, as well as consumer demand for green energy, more companies are looking to use biomass powered systems. For a more complete understanding of how energy and heat is produced from biomass, explore this encyclopedias section on production methods.

Comparative heating values of various commercial fuels

Energy production from biomass is a promising option with the potential largest impact occuring in developing countries, where the current level of energy services are low or non-existant. Biomass currently accounts for about one-third of all energy consumed in developing countries as a whole, and nearly 90 percent in some of the least developed countries. Over 2 billion persons depend on biomass energy for cooking and heating (Kartha & Larson 2000).

The following chart shows the comparative heating values of various commercial fuels used today for energy production (Payne 1980, UNEC 1978).

Use of liquid transportation fuels such as ethanol, methanol, and biodiesel, derived from biomass resources, are increasing rapidly as oil prices exceed $70 per barrel. Currently most of the ethanol and biodiesel generated in the United States comes from agricultural crops, but technological advances may make wood feedstocks for transportation fuels more appealing. In 2003, 2.81 billion gallons of ethanol were produced from corn alone (RFA 2005).

Ethanol and biodiesel can be used directly or blended with gasoline and diesel. Toxic air emmisions, greenhouse gas emissions, and dependence on unstable foreign oil all can be reduced by using biobased fuels and at the same time support rural community development (Wyman 1996). While current production of biofuels can not meet the daily demand in the United States, research is ongoing to improve production processes.

Fuels from Biomass

• Ethanol
• Methanol
• Biodiesel

Large imports of foreign crude oil in the 1960s and 1970s stimulated interest in fuel ethanol (Harsch, 1992). In the United States the primary approach taken was the production of gasohol, a blend of ethanol and gasoline. Researchers found that ethanol and its derivative, ethyl tert-butyl ether, work as octane enhancers, which increase the efficiency of gasoline burned in an internal combustion engine. Similar interest in ethanol occurred in Brazil, and, with subsidies from the government, Brazil forged ahead with ethanol production. Until six years, ago nearly 95 percent of the cars produced in that country ran on ethanol. Lately, Brazil has converted to ethanol-gasoline blends for their fuels (Anderson, 1993).

In the United States, ethanol occupies a niche in the transportation fuel market as an oxygenate in urban areas that do not meet the U.S. Environmental Protection Agencys air quality standards for carbon monoxide. Gasoline is blended with an oxygenate fuel such as ethanol or methyl tert-butyl ether (MTBE) to increase the combustion efficiency of gasoline and decrease carbon monoxide emissions in cold weather. Due to its lower cost in comparison with ethanol, MTBE has been the primary oxygenate used, and its use ranges from 63 to 81 percent of the total demand for oxygenates (EIA, 1997). Total estimated U.S. production of MTBE in 1995 was 8 billion kilograms; estimated ethanol production for 1994 was 4.3 billion kilograms (Committee on Environment and Natural Resources, 1997).

An interagency panel assessed the air quality, groundwater and drinking water quality, fuel economy and engine performance, and the potential health effects of MTBE and other oxygenates (Committee on Environment and Natural Resources, 1997). In its review of the draft federal report, the National Research Council concluded that the cold-weather air pollution effects of oxygenated fuels were unclear. While data on the occurrence of MTBE in groundwater and drinking water are scarce, MTBE has been detected in groundwater (Squillace et al., 1996), stormwater (Delzer et al., 1996), and drinking water (Committee on Environment and Natural Resources, 1997). Because MTBE is very soluble in water, is not readily absorbed by soil and aquifer materials, and generally resists degradation in groundwater, the interagency group recommended that there be an effort to obtain more complete monitoring data, behavior and fate studies, and aquatic toxicity tests for wildlife and to establish, if warranted, a federal water quality criterion.

Specific well-targeted research will be needed to answer questions about potential tradeoffs in using these chemicals as additives to gasoline (NRC, 1996). Demand for starch-based ethanol is influenced by the commodity market price for corn. During the 1995 to 1996 marketing year, high demand for corn grain drove up corn prices to record levels, leading to high input costs and a downturn in ethanol fuel production. Many ethanol producers opted to suspend ethanol production and do maintenance on their manufacturing facilities. Other producers diverted ethanol fuel production to the alcoholic beverage market. The USDA expects that producers will need to reestablish long-term contracts with blenders to regain market share lost due to corn markets experiencing a period of high input pricing in 1995 to 1996 (ERS, 1997).

In the long term, large-scale production of fuel ethanol from lignocellulose materials could become technically feasible and economically favorable. A key will be demonstrating that recent and anticipated technical innovations work at larger scales with representative raw materials. The production cost of ethanol from woody biomass must drop significantly if it is to penetrate a much larger fraction of the transportation fuel market. This change will occur only if economical lignocellulose conversion technologies are developed?a long-sought achievement. Use of these alternative feedstocks with new conversion processes may reduce production costs sufficiently to allow access to the commodity fuel market, even without subsidies or tax incentives. Lignocellulose-ethanol processing may be one approach toward reducing the costs of ethanol production (Bergeron and Hinman 1989).

There is a multi-national project on-going to investigate the utilization of ethanol. For more information, please refer to the BEST project. In the United States, the National Ethanol Vehicle Coalition is the nations primary advocate for blended fuels that use 85 percent ethanol (E85).

Ethanol Production Plants in the United States

The ‘Bioethanol for Sustainable Transport’, or BEST project, is working to demonstrate an extensive substitution of petrol and diesel with bioethanol in various vehicles across the world. The project is hoping to initiate a lasting and accelerated development of bioethanol vehicles. In an effort to reduce dependency upon oil and promote a reduction in greenhouse gas emissions, BEST is assisting in a massive, but strategic introduction of vehicles and distribution stations in 10 chosen sites through an integrated public-private partnerships of cities, car manufacturers, fuel producers, fueling stations, and fleet owners. They hope that this initiative will clearly demonstrate how the Biofuel Directive and Kyoto Protocol can be met in a cost effective and sustainable way. The BEST project will validate the reliability, energy-effectiveness, environmental and social benefits of ethanol use. There are no research groups from the United States currently working with BEST.

La Spezia, Italy is a test site for the BEST project. One hundred vehicles in regional and private fleets as well as three city buses will run on various high-ethanol blended fuels. Three fueling stations will be installed in the city and educational programs will accompany them. Incentive factors and market choices will be examined and implemented to help with the acceptance of the fuel changes.

Bioethanol Buses

Other cooperators in the BEST program include:

• Sweden:
  • Stockholm Environment and Health Administration
  • Stockholm Public Transit Authority
  • BSR Svenska AB
  • Biofuel Region
  • BioAlcohol Fuel Foundation
  • Svensk Etanolkemi AB
  • Ford Sweden
  • Sabb Automobile AB
  • Umea University           
• Italy:
  • ETA- Renewable Energies
  • Comune La Spezia
  • Provincia della Spezia
  • ATC Spa
  • Universita di Pisa
• United Kingdom:
  • Somerset County Council
  • Wessex Grain
  • Imperial College of Science, Technology, and Medicine     
• Spain:
  • EVE- Ente Vasco de la Energia
  • The City of Madrid
  • Municipal Company of Transport
• Netherlands:
  • Rotterdam Department of Public Works
  • Royal Nedalco 
• China:
  • City of Nanyang
  • Tsinghua University 
• Brazil:
  • CENBIO
  • Institute of Electrotechnics and Energy           
• Germany:
  • WIP- Renewable Energies 
• Ireland:
  • Maxol & CB Biofuels

Biodiesel is a vegetable-based fuel that is appealing, in part, because it confers some potential environmental benefits. Production costs for soy-based diesel currently are extremely high and it faces stiff competition in most petroleum-based diesel fuel markets. For example, in Europe, biobased diesel is more popular because incentives are offered to encourage its use. Further research and development may increase the demand for biobased diesel fuel in the long term.

In the United States, biodiesel would be unlikely to completely replace petroleum-based diesel. Even if all of the vegetable oil currently produced in the United States, about 3.1 billion gallons per year, went into biodiesel production, plant-based diesel production could provide only 6.4 percent of the nations annual diesel consumption of 45 billion gallons (Harsch, 1992). Production of 3 billion gallons of biodiesel necessary for agricultural uses would require farmers to dedicate 40 million to 60 million acres to biodiesel crops (Harsch, 1992). Introduction of biodiesel as a blend with conventional diesel fuel is a more feasible goal in the United States and one that could have significant benefits in areas where the environment is sensitive to disruption by conventional diesel emissions or spills.

Biodiesel is made by transesterifying plant oils with methanol in the presence of a catalyst to produce fatty acid methyl esters. Methanol for the reaction is readily available from biomass, natural gas usage, or coal. Oils that can be processed into biodiesel include soybean, canola, and industrial rapeseed (Harsch, 1992). If the reacted oils have the correct carbon chain length, the fatty acid methyl esters will have chemical characteristics similar to those of conventional diesel fuel when they combust in modern diesel engines. Biodiesel is usually mixed with petroleum-based diesel fuel in a ratio of 20 percent biodiesel to 80 percent diesel fuel (B20). The U.S. Department of Energy has moved to the rule-making process for inclusion of B20 as an approved alternative fuel under the Energy Policy Act of 1992. If this commercial acceptance occurs in the private sector, fleets of small diesel engines will be able to meet more stringent alternative fuel guidelines with biodiesel.

Biodiesel does confer some environmental benefits. One advantage of biodiesel over petroleum-derived diesel is the virtual absence of sulfur and aromatic compounds (Abbe, 1994). Further, combustion of biodiesel produces lower emissions of carbon monoxide, unburned hydrocarbons, and particulate matter than combustion of petroleum-based diesel (Abbe, 1994). Consideration of emissions is particularly important in urban areas suffering from poor air quality. Biodiesel may be valuable in the future because the fuel can be used in todays diesel engines without modification and in various blends without negative impacts on engine performance (Hayes, 1995).

An increased focus on biodiesel largely results from its success in Europe. The crop of choice in Europe has been rapeseed, and the European Union has implemented subsidies for farmers growing oilseed crops to promote biodiesel production. European production of biodiesel and implementation of government policies to promote its use have progressed relative to the United States. A liter of biodiesel requires 3.3 kilograms of soybean oil and other inputs valued between $0.50 and $0.70. If soybean oil costs $0.25 per pound, biodiesel must cost at least $2.33 per gallon excluding taxes, or at least four times the cost of tax-free petroleum-based diesel (Hayes, 1995). The USDA estimated a hypothetical market price of $4.25 per gallon for biodiesel (ERS, 1996). As a result of these high costs, biodiesel may be used only where it is mandated, such as in urban transit fleets and government-owned diesel vehicles, which limits the ultimate market size and encourages vehicle owners to seek less expensive alternatives (Hayes, 1995). Some research on other plant-based diesel fuel alternatives may be warranted. Direct substitution of plant oils for diesel fuel would be cheaper than the manufacture of biodiesel because the transesterification process imposes significant additional costs. Unfortunately, the high viscosity of the oils causes poor atomization and creates flow characteristics that are generally incompatible with present-day diesel engines (Harsch, 1992).

"Wood alcohol" or methanol is another alternative fuel and has similar chemical properties to ethanol. Methanol is now predominantly produced from natural gas feedstocks after the 1960s advancements in technology and processes made wood a less economical pathway compared to methanol from coal and natural gas utilization. A promising economical pathway for wood would require gasification of a woody feedstock and producing a syngas that would then be processed into methanol (Zerbe 2006).  There are 10 operating methanol plants in the United States in 2006, employing 10,000 direct and indirect jobs, which produce 4.9 billion liters of the domestically demanded 10.6 billion liters. The remainder of the demand is met from imports from Chile, Venezuela, and Canada (MI 2006).

Methanol can be found in plastics and paints and is an ideal hydrogen carrier fuel for fuel cell technologies, but since it has a lower fuel density than ethanol, it has fallen out of favor as a focus of the alternative fuel markets (Zerbe 2006). Methanol is best known today as the official racing fuel used by the Indianapolis 500 since 1965.  SVZ Schwarze Pumpe, in Spreewitz Germany operates a facility that utilizes solid and liquid wastes to produce methanol that is utilized as MTBE for fuel oxygenation in gasoline. In the United States, the Methanol Institute is the leading promoter of this alternative fuel source.

At the turn of the century, most nonfuel industrial products—dyes, inks, paints, medicines, chemicals, clothing, synthetic fibers, and plastics—were made from trees, vegetables, or crops. By the 1970s, organic chemicals derived from petroleum had largely replaced those derived from plant matter, capturing more than 95 percent of the markets previously held by products made from biological resources, and petroleum accounted for more than 70 percent of our fuels (Morris and Ahmed, 1992). However, recent developments are raising the prospects that many petrochemically derived products can be replaced with industrial materials processed from renewable resources (Kaminsky 2004). Scientists and engineers continue to make progress in research and development of technologies that reduce the real cost of processing plant matter into value-added products. Simultaneously, environmental concerns and legislation are intensifying the interest in agricultural and forestry resources as alternative feedstocks. Sustained growth of this developing industry will depend on developing new markets and cost-competitive bio-based industrial products (Morris and Ahmed 1992).

Numerous opportunities are emerging to expand industrial needs through the production and processing of biological materials. Todays bio-based products include commodity and specialty chemicals, fuels, and materials. Some of these products result from the direct physical or chemical processing of biomass—cellulose, starch, oils, protein, lignin, and terpenes. Others are indirectly processed from carbohydrates by biotechnologies such as microbial and enzymatic processing. The gross annual sales of these biochemicals in 1994 exceeded $13 billion US (Datta, 1994). Analyses of historical and present market growth rates suggest that the worldwide market for specialty chemicals will grow 16 percent per year (Datta, 1994).

A wide range of bio-based industrial products and technologies will be introduced to diverse industrial markets. Ethanol and oxygenated chemicals derived from fermentable sugars will be key precursors to other industrial chemicals traditionally dependent on petroleum feedstocks. In the long term, with advances in genetic engineering and large-scale fuel production from lignocellulosic plant materials may become cost competitive with petroleum fuels(RBEP 2004). In other cases, bio-based technologies such as enzyme catalysts are promising replacements for more hazardous industrial chemical processes. Increasingly, niche markets will be sought for a wide array of custom-engineered plant polymers not available in petrochemical-based products(Stricker and Smith 2004).

KEY BIOBASED PRODUCT AREAS:

• Intermediate and Specialty Chemicals
• Bio-based Materials

Specialty chemical markets represent a wide range of high-value products. These chemicals generally sell for more than $2.00 per pound. Although the worldwide market for these chemicals is smaller than those for bulk and intermediate chemicals, the specialty chemicals market now exceeds $3 billion US and is growing 10 to 20 percent annually (Datta, 1994). Examples of bio-based specialty chemicals include bioherbicides and biopesticides; bulking and thickening agents for food and pharmaceutical products; flavors and fragrances; nutraceuticals (e.g., antioxidants, noncaloric fat replacements, cholesterol-lowering agents, and salt replacements); chiral chemicals; pharmaceuticals (e.g., Taxol); plant growth promoters; essential amino acids; vitamins; industrial biopolymers such as xanthan gum; and enzymes.

Specialty chemicals can be made using fermentation and enzymatic processes or directly extracted from plants. Genetic engineering has now made possible microbial fermentations that can convert glucose into many products and can yield an essentially unlimited diversity of new bio-chemicals (Zeikus, 1990). Likewise, one could engineer plants to produce some of these same chemicals. Furthermore, industrial researchers are discovering that plants can be altered to produce molecules with functionalities and properties not present in existing compounds such as chiral chemicals. It is anticipated that advances in biotechnologies will have significant impacts on the growth of the specialty chemicals market (CLS 2000).

• Bio-based Acids
• Bio-based Oils
• Specialty Chemicals

Acids are a vital component of industrial production. Used in everything from the production of food preservatives, plastics, and medical discoveries, increasing the feedstock for the production of acids is vital for the United States to stay economically competitive in the global market. As technology advances and the understanding of acid production becomes more clear, the use of woody biomass for the production of specific acids becomes a more economically attractive solution over the current petroleum and high energy costing methods.

These are some important bio-based acids that can be recovered from forest residues:

• Acetic Acid
• Fatty Acids
• Itaconic Acid
• Lactic Acid
• Succinic Acid

Itaconic acid can be fermented from starch derived glucose and sucrose but fermentation from xylose has so far offered the potentially best economically efficient route (Brown 2003). The acid is used in the production of synthetic latexes to improve emulsion stability and adhesion. Many paper-coating and carpet-backing industries are the primary user of the product but derivatives of the acid are used in medicine, cosmetics, lubricants, and herbicides. Currently, the high costs of production have limited the use of itaconic acid (EI 2003).

Research into lower-cost production processes could enable itaconic acid to compete economically with petroleum based methyl methacrylate (MMA) in the clear plastics and shatterproof replacements for glass, such as Plexiglass and Lucite, and in acrylic paints. MMA markets are roughly 680,272 tonnes per year at a market price of $0.50 US per pound in 2002 (EI 2003). Other itaconic acid derivatives could be competition for pressure-sensitive adhesives. The market for this product was 136,054 tonnes and sold for $3.00 per pound in 2002 (EI 2003).

The fermentation of glucose from plant starches produces lactic acid. In the United States, nearly 72 million pounds are used yearly, mainly in the food and beverage service. Chemical companies have invested substaintal capital in identifing potential derivatives of lactic acid that can serve as bio-based alternatives to chemicals currently produced from petroleum. Currently the largest source of lactic acid results from the fermentation of corn. Advances lowered 2002 production costs by half; enabling lactic acid to be sold for $0.25 US per pound (EI 2003).

Following the leads of Cargill, Dow, Genencor, and the National Renewable Energy Laboratory, federal researchers are seeking to expand lactic acid fermentation processes into lignocellulosic feedstocks. Using an enzyme system, Genencor and NREL are enabling a system that would show a 10-fold improvement in the production of lactic acid from woody plant material. Others at the Department of Energy are working with advanced hydrolysis and microorganisms to ferment lignocellulose components directly.

Five bio-based products have been commerically identified from derivatives of lactic acid. Polylactic Acid (PLA) is a themoplastic polymer commercialized by Cargill Dow. With a 136,054 tonne capacity plant in Blair, Nebraska the company sells it as NatureWorks PLA to be used for consumer goods and food packaging as well as fibers for apparel, bedding, and carpet. In 2000, over 9.5 million tonnes of thermoplastics were used in packaging. Cargill Dow is projecting a potential market of 3.6 million tonnes for their PLA product by 2020.

Ethyl lactate is an environmentally friendly solvent that has recently been commercialized by Vertec BioSolvents. Used mainly in industrial applications such as specialized coatings, inks, and cleaners, the product could displace 80 percent of the 4.5 million tonnes of solvents used per year. Selling prices for ethyl lactate were still nearly 30 percent higher than for competitve petroleum standards in 2002 (EI 2003) but work done at the Argonne Labs have helped lower production costs and should continue their advances in the next few years.

Acrylic acid can be used as an adhesive with nearly 907,029 tonnes produced yearly. Research is ongoing to find an economical process that would route lactic acid to acrylic acid. The target selling price is around $0.50 US per pound (EI 2003). The production of propylene glycol from lactic acid is also being examined to develop a conversion process that would enable more economical production of such chemicals as antifreeze, resins, and solvents. Propylene glycol could displace nearly 498,866 tonnes of competitive petroleum based standards yearly (Balkcom et al. 2002).

Pyruvic Acid can be derived from lactic acid as well. This small-volume chemical can be used in pharmaceuticals but has found a specialty market as a fungicide.

Succinic acid and its salts are formed naturally by plants, animals, and microorganisms but most of the commercial production in the United States has come from petroleum utilization. In recent years, nearly 13,605 tonnes of succinic acids and salts were produced per year (Brown 2003). The product can be used in a variety of fields from pharmaceutical products to clothing and solvents. Over the last decade, the Department of Energy has funded intense research to improve the bioproduction of succinic acid from bioorganisms in a more cost-efficient manner. Research advancement has reduced production costs from $2 US per pound in 1992 to nearly $0.50 US in 2002 (EI 2003). The domestic market is expected to grow as production costs decline; and the market is expected to be $1.3 US billion per year in the near future. These increases in productivity and switching to a bio-based platform from a petroleum platform will result in an energy savings of 2.87(e9) kWh per year when compared to current petroleum based pathways ( DOE 1999).

A wide array of products depend on succinic acid and its derivatives. Succinic salts are being introduced into herbicides to improve performance and effectiveness while also making the product safer to humans and the environment. The salts lower the freezing point of water, thus making it an excellent addition to coolants and an alternative to glycols. With the growing need to improve the performance of runway and wing deicing at state, federal, and military airports, succinic salts are being favored in light of stringent EPA regulations on current deicing chemicals due to environmental toxicity. Salts could replace 100 percent of the current market in the next few years. Airports use nearly 4,535 tonnes of deicers per year at a cost of $0.75 US per pound (EI 2003). Diversified Natural Products is the leader in succinic salt advances.

Tetrahydrofuran (THF) is a solvent derived from succinic acid. THF is a key ingredient in adhesives, printing inks, and magnetic tapes. In 2002, the US annual market for these uses was estimated at 115,646 tonnes and could potentially displace 22,676 tonnes or more at a selling point of $1.55 US per pound (EI 2003). BDO, or 1-4-Butanediol, is another succinic acid based compound that is used in solvents and coating resins. Bio-based BDO could displace 13,605 tonnes or more of the 308,390 tonnes that sold for $0.80 US per pound in 2002(EI 2003).

Succinate and disuccinate esters can be produced as well. Succinate esters are excellent fuel oxygenates and when used can result in a reduction of particulate emissions. Disuccinate ester is marketed as a green alternative to highly volatile or chlorinated solvents. Products in the personal care sector are also incorporating succinic acid into their mixture. Diversified Natural Products has produced a nail polish remover that is safe, biodegradable, and non-volatile so it lacks a "chemical" smell.

Acetic Acid

Acetic or Ethanoic acid is produced from lignocellulosic fermentation. It is currently manufactured mainly using the Monsanto process (Toreki 2003) where methanol from syngas reacts with carbon monoxide. In 1999, nearly 3,174,602 tonnes of acetic acid was produced in the United States and sold on average for $720 per ton (Brown 2003). It is used as a foodstuff, a solvent, and a fungicide as well as key in the production of pharmaceuticals like aspirin. Esters derived from the acid are used for the production of vinyl acetate used in paints, glues, and wallboard and cellulose acetate which is used mainly for rayon and photographic films. Vinegar is 4-8 percent acetic acid by volume. PET or polyethylene terephthalate, a thermoforming polymer commonly used for food and beverage containers, is also produced using acetic acid.

Fatty acids, readily available from plant oils, are used to make soaps, lubricants, and chemical intermediates such as esters, ethoxylates, and amides. These three important classes of intermediates are used in the manufacture of surfactants, cosmetics, alkyd resins, nylon-6, plasticizers, lubricants and greases, paper, and pharmaceuticals (Ahmed and Morris, 1994). Of the approximately 2, 267,573 tonnes of fatty acids produced in 1991, about  907,029 tonnes, or 40 percent, were derived from vegetable and natural oils. The remaining  1,360,544 tonnes were produced from petrochemical sources. Twenty-five percent of all plant-derived fatty acids used in the coatings industry comes from tall oil, a byproduct of kraft paper manufacture (Ahmed and Morris 1994).

Raw liquefaction oil is a free-flowing dark liquid produced through thermochemical liquefaction that can be stored and transported, thus allowing the decoupling of feedstock production, conversion process, and utilization. Comprised of oxygenated hydrocarbons and aromatic compounds, the various oil factions can be refined to produce oils with a heating value of approximately 36 MJ/kg or 4.54 kWh per pound with essentially no sulfur (BROKEN-LINK Duncan and White 2002).

Changing World Technologies has produced a light liquefaction oil that can be used as refined biodiesel known as TDP-40 through their Thermo Depolymerization Process. It can be used as a blended fuel or stand-alone to generate steam and power in a stationary diesel engine. With its refinement techniques, TDP-40 has shown improvements in combustion pollutant emissions reductions (BROKEN-LINK Duncan and White 2002).

Some factions of liquefaction oil can be used as solvents, such as Cyclohexane which is a paint remover and also used in making nylon. Methylethyl benzene is used in the production of rubber, waxes, and can be blended with gasoline as well. Toluene, alson derived from liquefaction oils, is used in the manufacturing of explosives and added to jet fuel to improve octane.

Pyrolytic bio-oil is a complex, combustible mixture of oxygenated hydrocarbons with chemical constituents that vary according to feedstock species. Whole bio-oil has a heating value of 2 to 2.2 kWh per pound; this heating value is roughly the same and may even increase after value-added chemicals have been extracted (BROKEN-LINK Sturzl 1997). To make the product as economical as possible, the Ensyn Group recommends extraction of secondary products prior to using the oil as fuel. Pyrolytic bio-oil fuel can be marketed as a free-flowing, dark brown liquid that can be stored and transported and thus gaining benefits associated with decoupling the feedstock source, chemical processing, and utilization.

Pyrolytic bio-oil has been used commercially for industrial heat since the early 1930s for firing boilers. It is currently being tested as a fuel for diesel transportation and stationary turbine and diesel power (BROKEN-LINK Diebold 2000). The wood industry relies on petroleum based phenol-formaldehyde resins in plywood, oriented strand board, and other wood composites. Resins from bio-oils could replace up to 50 percent of the phenol-formaldehyde. Ensyn is expecting to sell nearly 1.8 billion tonnes per year at $0.30 US a pound.

Red Arrow Food Products Company has taken bio-oil from fast pyrolysis processes and cornered the market on a niche product. Extracted additives from bio-oils can be used to infuse "smoked", "roasted", or "grilled" flavors in food.

Specialty chemicals play an integral role in the economy of the United States. Organic chemicals are primarily synthesized from a petroleum base and used for the production of paints, solvents, fibers, and plastics. These products allow the United States to maintain its lavish lifestyle. Increasing the feedstock for these chemicals or incorporating methods that allow industries to produce the needed organics from woody biomass can off-set the dependency on petroleum bases and the economic consequences that occur when supply is interrupted.

This is a selection of the various specialty chemicals that can be produced from using woody biomass:

• Ethylene
• Enzymes
• PDO
• 3-HP
• Bio-based Fuel gas and Syngas
• Butanol
• Glycerin

Ethylene

Ethylene is perhaps the most important petrochemical because of the value of its numerous derivatives such as polyethylene, ethylene dichloride, vinyl chloride, ethylene oxide, styrene, ethanol, vinyl acetate, and acetaldehyde (CLS 2000). Before lignocellulose conversion technology came on the horizon, the ethylene market was considered inaccessible to bio-based production (Lipinsky, 1981). Bio-based ethylene production based on ethanol derived from corn stover still is not cost competitive with petroethylene sources (Donaldson and Culbertson 1983). Ethylene based on lignocellulose fermentation could move into the margin of competitiveness against petrochemical sources when market price reaches $0.14 per pound; based on increasing cost projections for oil prices, using long-term projections developed by the World Bank (Gallagher and Johnson 1995). Ethylene can be produced in large-scale operations that already process ethanol, thus enabling manufacturers to manage the costs from sluggish marketing periods. With rising petroleum prices or further improvements in the bio-based ethylene production process, the cost advantage of petroethylene could erode.

Natural Essential Soap Co.

Glycerin is a sweet, viscous alcohol that is produced as a byproduct of the manufacturing of biodiesel. There are roughly 1 kg of glycerin for every 10 kg of biodiesel produced (De Guzman 2003). Selling for US$600 to US$900 per ton, glycerin is used in soaps, solvents, and industrial lubricants that perform on par with or better than petroleum-derived relatives (De Guzman 2003).

It is estimated that in 2006, 199,546 tonnes of glycerin will be utilized in the United States (De Guzman 2003). Natural Essential Soap Co. is just one of many small home-based soap and gylcerin-based companies. The market in the United States is currently for more "boutique" products, but glycerin is also used as a humectant, a food additive that has the effect of keeping foodstuff moist in packaging. Research questions do surround the potential of using anaerobic fermentation to produce methane from glycerin.

The primary source of current and future enzymes is the fermentation of biological materials (Ahmed 1993). Enzymes function as catalysts in industrial mechanisms to produce feed additives and chemicals as well as functioning as detergents, reagents, diagnostics, or health aids. In 1989, the worldwide sale of enzymes totaled US$650 million (Layman 1990) and topped US$1 billion by 1993 (Thayer 1994). Novo Nordisk currently supplies 40 - 50 percent of the worlds enzyme market, with other European companies controlling most of the remainder (Thayer 1994). Expectations are that enzyme sales will increase 10 percent annually until 2010 as new markets and needs emerge. In 1989, the market was divided into 40% detergent and soap, 25% starch conversion, and 15% dairy applications (Layman 1990). The remaining market included the leather, pulp and paper, and animal feed manufacturing sector needs. This remaining 20% is of particular interest due to the historical adverse environmental impacts that the industries have inflicted. The companies will have an incentive to use more benign processes such as those based on enzymes (CLS 2000).

Enzyme-derived products have replaced water-polluting phosphate detergents and allowed wash waters to be cooler, thus reducing energy consumption (Falch 1991). They are used to coagualte milk proteins for cheese production, as sweetners for sodas, and in lactose-free milk. Xylanase enzymes are starting to replace chlorine in the pulp and paper industry, cellulase in the textile industry, and protease has shown to reduce pollutants in leather manufacturing (Wrotonowski 1997).

Carpet from PDO

A lignocellulosic fermentation product, PDO is most commonly combined with terephthalic acid to produce polytrimethylene terephthalate (PTT). PTT is a high performance polyester polymer that is used in carpets, upholstery, and apparel for its softness, dyeability, ease of care, and remarkable stretch-recovery. Currently it is almost exclusively manufactured from petrochemical feedstocks by Shell Chemical and DuPont.

Although PTT has been used by companies for over 50 years, only recently has it been discovered as a possible product from biomass. DuPont has announced that it plans to construct a large-scale PDO fermentation plant in 2006 and produce PTT using non-petrochemical inputs.

In 2002, the size of the PTT market was 454 million tonnes per year and sold at US$0.25 per ton (EI 2003). Tests have shown that the durability and strength of bio-based PTT surpasses nylon and PET in fiber applications and such resin applications as sealable closures, connectors, and blister packaging (Hwo and Shiffler 2000).

Nitrile Rubber Rings from 3-HP

3-HP is the best known intermediate chemical produced by lignocellulosic fermentation behind lactic acid and succinic acid. Produced by Cargill, research has shown that the intermediate chemical can be produced at a theoretical yield of 100 percent from glucose (Zvosec 2003). With the addition of chemical processing, 3-