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27 Overview A number of existing technologies can convert biomass feedstocks, such as wood, starchy grains, and oilseeds, into heat, electricity (biopower), or transportation fuels (biofuels). Over the past decade, biomass energy consumption in the United States has increased more than seven fold. A number of states have explored the potential to utilize highway ROWs to grow biomass feedstocks. These pilot projects have focused primarily on the potential to grow oilseed crops to produce biodiesel, though a few have also experimented with growing switchgrass (Panicum virgatum) or harvesting existing grassy biomass. Notably, the focus of all these efforts has been limited to identifying the technical constraints of growing feedstocks in the ROW. Little attention has been paid trying to understand the business model or market development issues required to move up from pilot to commercial scale. While it is technically possible to implement biomass feedstock projects in the highway ROW, under current conditions, the practical opportunity for such projects to produce marketable bioenergy feedstocks is limited by a number of factors. First, there are considerable challenges in ensuring that feedstocks grown in the ROW would ultimately serve a bioenergy end use. Second, management considerations about motorist safetyâincluding fixed-object hazards in the clear zone, risk of vehicleâwildlife collisions and potential for sightline obstructionâpresent additional complications for potential bioenergy feedstock projects. While many of these issues can be managed through careful site selection, the effect is to substantially restrict the areas within the ROW where feedstocks can be grown. Third, the soil conditions, geography, and land configuration of highway ROW make farming in the ROW more difficult, and therefore more expensive than normal agricultural conditions. Fourth, the prevailing prices for bioenergy feedstocks are not currently sufficient to recover production costs, even assuming yields comparable to normal agricultural conditions. Conditions to Monitor As noted above, the limits to produce marketable bioenergy feedstocks in the highway ROW are largely market constraints, not technical constraints. Some of these constraints may not hold in the future. The conditions to monitor that might alter project viability include the deploy- ment of new technologies, the development of higher yielding crop varieties, and increases in electricity and fossil fuel prices. There are a number of next generation technologies in varying phases of development that offer great promise for future energy generation and market expansion. Some of these technolo- gies have been successfully demonstrated on a pilot scale and are in the early stages of commer- cial deployment, while others remain in the research and development phase. Technologies to C H A P T E R 3 The Biomass Energy Market: A Primer for DOTs
28 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation watch include dry anaerobic digestion, cellulosic bioethanol, torrefaction, pyrolysis, and gas- ification. Opportunities for bioenergy feedstock crops will increase as these technologies are further developed and achieve commercial scale. Similarly, researchers continue to investigate opportunities to enhance bioenergy feedstock crop yields through traditional plant breeding and selection as well as genetic engineering. Yields can also be enhanced and production costs reduced through improvements in agronomic prac- tices, which can significantly improve project economics. Finally, rising electricity and fossil fuel prices would improve the financial viability of projects by increasing the competitiveness of bioenergy technologies, thereby increasing the value of feed- stocks. The minimum feedstock price for woody biomass must generally exceed $60 per dry ton for projects in the ROW to be viable. Rising fossil fuel prices also make decentralized bio energy conversion technologies, like small-scale integrated seed crushing and biodiesel production, eco- nomically possible. These small-scale, decentralized systems are generally better suited to the volumes of bioenergy feedstocks that can be efficiently grown in highway ROWs. Direct Combustion for Heat and Power Direct combustion, the burning of a bioenergy feedstock in the presence of oxygen from the air, is the most common technology used to release the energy stored in biomass. Wood and wood-derived fuels are the primary bioenergy feedstocks for direct combustion technologies. While dedicated woody energy crops, like poplar and willow, could potentially serve as a suitable feedstock for some direct combustion technologies, they are not currently widely utilized for this purpose. Grassy biomass feedstocks, like switchgrass, are not widely utilized because high mineral silica content causes increased slagging of combustion equipment. The energy released from direct combustion is either used directly as heat or indirectly to produce steam that can be used for process energy or to generate electricity. Most biomass com- bustion occurs in the residential (25% of U.S. wood energy consumption) and industrial sectors (62% of U.S. wood energy consumption). The electric power sector (9% of U.S. wood energy consumption) and the commercial and institutional sector (4% of U.S. wood energy consump- tion) comprise the rest of the market (Energy Information Administration, 2012a). Residential scale biomass combustion systems include fireplaces, wood stoves, pellet stoves, and centralized wood and pellet boilers and furnaces. The primary feedstocks in the residential sector are local, self-sourced cordwood and wood pellets that are manufactured from fine mill residues (e.g., sawdust) from wood product manufacturers or high-quality wood chips. Industrial-scale biomass combustion systems primarily produce thermal energy, typically in the form of steam, for use in the manufacturing process. Systems can also be configured to generate electricity in addition to thermal energy, a so-called combined heat and power (CHP) application. Industrial combustion systems typically feature fuel handling and preprocessing equipment, a combustion chamber and heat exchanger (i.e., a boiler) and, where designed to generate electricity, a steam turbine. On the industrial scale, the primary feedstocks are manufacturing by-products, often self- sourced, from the paper and wood products industries like pulping liquors and hog fuel. Hog fuel, named for the type of grinder used to produce it, is a mixture of wood product mill wastes, most often ground bark and trim mixed with fine mill residues. Hog fuel can also be derived from small-diameter whole trees (e.g., forest thinnings), logging residues (e.g., slash), and urban wood waste (e.g., tree trimmings). Most electric power sector combustion systems are located at dedicated biomass electric power plants, where wood and wood waste are the only fuel sources. Some electric power plants
The Biomass Energy Market: A Primer for DOTs 29 also combust woody biomass in combination with a fossil fuel, usually coal, in what is called a co-firing plant. Dedicated biomass electric power plants feature many of the same system com- ponents as industrial-scale systems except that electric power systems always include a steam turbine to generate electricity. Co-fired plants typically are retrofits of preexisting plants to which biomass feedstock preprocessing and fuel handling have been added. Dedicated biomass electric power plants accept a wide variety of woody biomass feedstocks, including hog fuel, wood chips, logging residue, urban wood waste, and whole logs. The type of feedstock accepted by a given facility depends on the capabilities of its preprocessing equipment, with some facilities only capable of accepting previously chipped or ground fuels, while others can accept whole logs up to six feet in diameter. Co-firing facilities tend to have more stringent feedstock requirements and generally prefer fine mill residues and wood chips. Commercial- and institutional-sector biomass combustion systems primarily produce ther- mal energy as steam to heat buildings. While this sector is small relative to others, interest in these types of systems is strong, particularly in rural and historically timber-dependent com- munities. For these communities, the deployment of biomass heating systems is seen as a boon for local economic development since feedstocks are generally sourced from local firms. Several states have developed programs specifically designed to encourage rural school districts to evalu- ate the feasibility of implementing biomass combustion projects. These systems are similar in design to industrial systems, with a fuel handling system and steam boiler, though at a much smaller scale. The primary difference is that commercial and institutional systems typically lack preprocessing equipment and therefore have stricter feedstock requirements. Most commercial and institutional biomass heating systems prefer paper-grade woodchips, so called because they are the primary feedstock for the pulp and paper industry, because of the uni- formity and low ash content. Paper-grade chips are a by-product of sawmill operations or a primary product of chip mills, facilities that debark and chip small-diameter logs. Lower grade woodchips, like those made from logging residue or urban wood waste, are generally not suitable for commer- cial and institutional systems because their irregular size, bark content, and the presence of debris can interfere with safe and efficient equipment operation. Some commercial and institutional sys- tems utilize high-quality wood pellets. Table 5 summarizes the direct combustion market. Sector Technology Feedstock Requirements and Availability Market Characteristics Drivers Residential wood and pellet heating Fireplaces, wood pellet stoves Cordwood, wood pellets 25% of U.S. wood energy consumption Socioeconomics, proximity to fuel source Commercial and institutional wood, wood chip, and pellet heating Centralized boiler for hot water and steam Paper-grade and bole chips, pellets 4% of U.S. wood energy consumption, schools, hospitals Proximity to fuel source, local value-add Industrial biomass combustion for thermal energy and electric power Fixed or fluidized bed boiler, CHP Pulping liquor, hog fuel, sawdust, shavings, chips; primarily self- consumption of manufacturing by- products 62% of U.S. wood energy consumption, concentrated in the pulp and wood products industry Proximity to fuel, avoid landfill tipping, natural gas substitution Electric power sector direct combustion Dedicated, co-fire Hog fuel, logging residue, urban wood waste 9% of U.S. wood energy consumption; competing with natural gas Proximity to fuel, renewable power mandates Table 5. Commercialized biomass conversion technologiesâdirect combustion.
30 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation Direct Combustion Feedstocks Potentially Applicable to Highway ROWs Fast-growing woody biomass species, such as poplar and willow, could potentially be grown in highway ROWs to serve some direct combustion biomass systems, specifically in industrial- and utility-scale direct combustion facilities. Advances in harvesting techniques that improve chip quality may also create opportunities to serve commercial and institutional scale biomass combustion systems. While perennial grassy biomass species, like switchgrass, have been extensively investigated as a potential bioenergy feedstock, concerns about high mineral contents potentially damaging combustion equipment have created resistance among potential end users, and markets for these feedstocks do not currently exist. Widespread commercialization of next generation bioenergy technologies, like cellulosic ethanol, thermochemical conversion, and dry anaerobic digesters, may create new opportunities for grassy biomass. Table 6 provides a summary of these potential feedstocks. Hybrid Poplar The genus Populus is composed of almost 30 species and is a well-established component of the native North American landscape. Intentionally cultivated poplars are usually hybridized varieties that have been selected to maximize productivity. While poplar has the ability to be coppiced and is often mentioned as a potential bioenergy feedstock, it is primarily managed as feedstock for paper or grown to mitigate runoff from land-applied wastewater biosolids. While various Populus species are adapted to every state in the continental U.S., the inten- tional planting of hybrid poplars is concentrated in the Pacific Northwest, lower Mississippi River Valley, and Upper Midwest. Hybrid poplars prefer sites with deep, medium-textured, moist, and nutrient-rich soils. Sites with slopes greater than 8%, highly alkaline or acidic soils, and those with a hardpan in the root zone are less productive and should be avoided. Hybrid poplar is established by mechanically planting dormant stem cuttings in weed-free seedbeds. As a bioenergy feedstock, it is recommended that poplar be planted at a density of about 700 trees per acre (just under eight foot by eight foot spacing). Stands are usually estab- lished in minimum blocks of 25 acres in order to simplify planting, maintenance, and harvest operations. Once planted, it is necessary to eliminate weed competition until the tree canopy closes, which is usually by the end of the second or third year after planting. Harvest can occur between years six and eight. While poplar can be coppiced, the practice of cutting a plant to just above ground level and allowing new growth to emerge from the stump, there is little research Crop Agronomics Market Potential ROW Considerations Poplar Plantation; 2â6 dry tons/acre/year; 8 yr. harvest & rotation cycle Industrial and electric power sector; bioenergy use is secondary to pulp and lumber use Limited maintenance; >4â diameter at maturity; >40â tall at maturity; requires >20 acre blocks Shrub willow Coppiced; 20â25 yr. rotation, 3-4 yr. harvest cycle; 2â6 dry tons/acre/year Industrial & electric power sector; no active buyers Low maintenance, small diameter, potential co- benefits; requires >20 acre blocks; potential sightline obstruction; potential wildlife attractant Switchgrass Widely adapted, low input, perennial, 2â10 tons/acre/year Co-fired in electric power; cellulosic bioethanol; no active buyers Low maintenance; >8â tall at maturity Table 6. Woody and herbaceous energy crops summary.
The Biomass Energy Market: A Primer for DOTs 31 on the optimal management regime. Poplar biomass yield is generally between two and six dry tons per acre per year. Poplar is incompatible with many DOT management considerations, most notably limits on the size of fixed objects in the clear zone, since it reaches up to 15 inches in diameter in just seven years. While hybrid poplar could technically be grown outside of the clear zone, the irregularly shaped parcels found outside of the clear zone are likely not large enough to accommodate the preferred large rectangular planting blocks that facilitate ease of planting and harvest. Moreover, utilization of poplar as feedstock for direct combustion facilities is largely non- existent in the U.S. Where it does occur, it is limited to the collection of harvest residues from hybrid poplar grown for pulp or timber. The primary challenge to the utilization of poplar as a bioenergy feedstock is its cost of production, even in less constrained contexts than the highway ROW, relative to the price of equivalent bioenergy feedstocks and fossil fuel substitutes. Shrub Willow Shrub willow (Salix spp.) has several characteristics that make it an attractive feedstock, including its potential to produce high yields in a short amount of time, relative ease of estab- lishment, ability to be coppiced, and chemical and energy characteristics similar to hardwood tree species. Besides use as a bioenergy feedstock, shrub willow also has potential applications in the establishment of riparian buffers, brownfield remediation, and as a living snow fence. Shrub willow is best adapted to the colder climates of the Northeast and Upper Midwest. Willow can be grown in a range of soil conditions but grow best on sites with soils that are well- drained, nutrient rich, and moderately deepâat least 18 inches. Sites with slopes greater than 8% or with standing water should be avoided, as they conflict with the safe, efficient operation of planting and harvesting equipment. Shrub willow is established by mechanically planting dormant stem cuttings called âwhipsâ in weed-free seedbeds. Plants are typically placed every 20 inches in double rows spaced 2.5 feet apart with spacing between these double rows of six feet to achieve a density of about 6,000 plants per acre. Effective weed control, especially in the first years of establishment, is essential and typically accomplished through a combination of mechanical and chemical controls. After the initial growing season, plants are cut back close to the soil surface to force coppice regrowth. Once established, willow requires little to no annual crop maintenance. Harvest occurs in the third or fourth growing season and every three years thereafter. Well-managed stands can remain productive for more than 20 years and yield between two and six dry tons per acre per year. Shrub willow is largely compatible with the operating constraints of the highway ROW and under the right economic conditions could be a viable bioenergy feedstock option for DOTs looking to grow marketable biomass. While initial establishment requires intensive manage- ment, once established, shrub willow is relatively self-sustaining and requires little maintenance. The tri-annual coppicing rotation keeps stem diameter below four inches, making it potentially acceptable inside the clear zone. Existing cropping systems could be easily adapted to the nar- row linear confines of the longitudinal ROWs. Further, willow stands could serve other DOT interests, such as mitigating storm water runoff and controlling blowing snow. A DOT should keep in mind that shrub willow can reach heights greater than 20 feet, creat- ing a potential sightline obstruction. Willow is also a potential wildlife attractant, as the plantâs tender shoots are highly palatable to deer. Shrub willow stands also provide habitat for birds and small mammals, so special care should be given to the timing of maintenance and harvest activities so as not to harm these species.
32 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation While willow has been utilized as a feedstock for direct combustion facilities in Northern Europe for more than two decades, in the U.S. its utilization remains largely limited to research and development trials. The primary challenge to the widespread commercialization of willow is its high production costs, even in less constrained contexts, relative to prices of other feedstocks and fossil fuel substitutes. In order to be economically viable some combination of the following must occurâyields must increase, production costs must fall, bioenergy feedstock prices must rise, or emerging technologies must open new markets. Biomass for Transportation Fuels Technologies that transform bioenergy feedstocks into liquid fuels for use primarily in the transportation sector account for about 40% of U.S. bioenergy consumption (Energy Informa- tion Administration, 2012b). The primary biofuel technology in the U.S. is starch hydrolysis and fermentation to produce bioethanol (ethyl alcohol) and transesterification to produce biodiesel (fatty acid methyl ester). Starch-derived bioethanol accounts for about 90% of all U.S. biofuel energy consumption, with the balance consisting of biodiesel consumption. Bioethanol can be substituted for, or blended with, gasoline. The average bioethanol content of gasoline sold in the U.S. is approximately 10%. Likewise, biodiesel can be blended or substituted for petroleum diesel, and is commonly blended at 5% and up to 20% by volume. Starch-derived bioethanol is produced by fermenting sugars extracted from starchy grains, in a process similar to liquor production. The grain is first milled and then mixed with water and enzymes to convert the complex starches into simple sugars. The resulting mixture is then combined with yeast and allowed to ferment. During fermentation, the yeast converts the sugars into ethanol and carbon dioxide. The ethanol is then distilled and a denaturant is added to make it unfit for human consumption. The primary feedstock for bioethanol production in the U.S. is corn, though some other starchy grains, like grain sorghum (milo), are common in some parts of the country. Corn is pre- ferred because of its relatively high starch content and ready availability. Ethanol plants are often operated as a part of a vertically integrated supply chain where the producer controls feedstock sourcing, transportation, grain storage, manufacturing and marketing. Corn and other starch grains are typically sold into commodity markets where the grower has little or no control over its ultimate end use. Most biodiesel manufactured in the U.S. is produced using a process called transesterification, where vegetable oils or animal fats are reacted with methanol and a catalyst (e.g., potassium or sodium hydroxide) to yield biodiesel and a co-product, glycerin. The biodiesel is then separated from the glycerin and further refined to remove impurities. Feedstocks high in free fatty acids, like animal fats and recycled vegetable oils, are subjected to a preprocessing step called acid esterification. Virgin soybean oil is the leading feedstock for biodiesel production, followed by virgin animal fats, virgin canola oil, and used cooking oil. Feedstock sourcing is driven by tradeoffs between quality, price, and availability. Virgin vegetable oils are preferred because they are readily avail- able and do not require preprocessing; however, they are more expensive than other feedstocks. Virgin oils are typically sourced from large oilseed crushing facilities that use a capital-intensive chemical extraction technique and source oilseeds on a commodity basis from regional grain elevators. Notably, biodiesel is only one potential, and not the most common, end use for virgin vegetable oils. While some very large oilseed firms have co-located biodiesel production facilities adjacent to preexisting crushing facilities, it is an uncommon practice for biodiesel producers to have integrated crushing capabilities. Table 7 summarizes biofuel considerations.
The Biomass Energy Market: A Primer for DOTs 33 Biofuel Feedstocks Potentially Applicable to Highway ROWs A number of common biofuel feedstocks, including starchy cereal grains, such as corn or grain sorghum, and vegetable oils from annual oilseed crops, such as soybeans or canola, could poten- tially be grown in the highway ROW. However, the primary markets for these crops are regional grain elevators where the ultimate end use is not discernable, making it a challenge to purposefully grow these crops for biofuels. If local small- to medium-scale biofuel producers exist, delivery contracts for feedstocks may be possible; these opportunities are very limited at this time. A number of non-food crops, including camelina (Camelina sativa) and switchgrass, have received considerable attention as potential biofuel feedstocks, but markets for these feedstocks have yet to mature as of the time of writing this Guidebook. Table 8 summarizes key character- istics of biofuel feedstock crops. Corn Corn (Zea mays) is the preferred feedstock for bioethanol production in the U.S. because of its abundance and high starch content. Because of high nutrient demands, corn is typically grown in rotation with a nitrogen-fixing crop such as soybeans or alfalfa. Sector Technology Feedstock Requirements and Availability Market Characteristics Drivers Biodiesel Transesterification Soybean oil, animal fats, canola oil, recycled cooking oil and grease 6% of U.S. biofuel energy consumption; few producers crush own oilseeds Blending mandates, biodiesel tax credit, renewable and low-carbon fuel standards Bioethanol Dry mill and wet mill fermentation Corn 94% of U.S. biofuel energy consumption Renewable fuel standard Table 7. Commercialized biomass conversion technologiesâbiomass for transportation fuels. Table 8. Biofuel feedstock crops summary. Crop Agronomics Market Potential ROW Considerations Starchy Cereal Grains and Sugar Crops (bioethanol feedstock) Corn High input, intensive production system; part of multi-year crop rotation; prefers deep fertile soils; yield 3.4â4.6 tons/acre; widely adapted 1st generation bioethanol producers; commodity value chain Potential sightline obstruction; potential wildlife attractant; requires high rates of fertilizer and pesticides; GMO Grain sorghum Dry-land farmed in multi- year rotation; yield 11â16 tons/acre (50â70 bushels/acre) 1st generation bioethanol producers Potential sightline obstruction; potential wildlife attractant Oilseed Crops (biodiesel feedstock) Soybeans Bi-annual rotation; 1â1.3 tons per acre (34â44 bushels /acre); widely adapted Biodiesel producers; commodity value chain (grown primarily for protein content, not oil production) Potential wildlife attractant; requires modest rates of fertilizer and pesticides; GMO Canola (Rapeseed) Spring/winter cultivars; part of multi-year crop rotation; rotated with cereal or grass crops; 1,200â1,800 pounds/acre Biodiesel; commodity value chain; competes in food oil market; limited market opportunity (less than 2% of canola oil serves biodiesel) Technically feasible
34 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation Corn is a warm season, annual grain grown throughout the continental U.S. in areas receiving 20 or more inches of annual precipitation, though its production is concentrated in the Mid- west. Most of the corn grown in the U.S. has been genetically modified to tolerate a number of herbicides and has pesticidal properties that provide insect protection. Corn prefers deep, fertile, well-drained, medium- to coarse-textured soils. Sites with steep slopes and droughty soils should be avoided. Dry-land farmed (i.e., without irrigation) corn requires 18 to 20 inches of available precipitation during the growing season. Corn can be established either with conventional or conservation tillage, if soils are not com- pacted. Corn is typically planted in rows with 15- to 38-inch spacing at seeding rates between 20,000 and 50,000 seeds per acre. Corn is intensely managed in order to provide supplemental fertilization and to control weeds, pests, and disease. At maturity, corn can reach heights in excess of 15 feet. Harvest is conducted with a combine that separates the kernel from the cob in the field. Yields vary depending on growing conditions, but on average, U.S. corn yields over the last decade have ranged between 122 and 164 bushels (3.4 to 4.6 tons) per acre. A number of challenges make growing corn in the highway ROW an unlikely fit for wide- spread adoption. First, the irregularly shaped and fragmented parcels found in the ROW are inefficient to farm. Corn demands intensive management that requires frequent field access, and it is not practical to have to frequently load and unload farm equipment to farm such small areas. Second, the intensive use of synthetic fertilizers, pesticides, and herbicides could imperil water quality. Third, corn can pose a sightline obstruction; encroachment of corn fields on the ROW, especially along rural roads, is a frequently mentioned management concern among state DOTs and local public works departments. Fourth, the suboptimal soil conditions of the ROW may not be suited to corn cultivation. A final factor disfavoring corn production in the ROW is its potential as a wildlife attractant. Grain Sorghum Sorghum (Sorghum bicolor) is a semi-tropical grass that can be cultivated for grain production (i.e., grain sorghum or milo). A small number of U.S. bioethanol producers currently use grain sorghum as a feedstock for bioethanol production. Grain sorghum production is concentrated in areas considered too dry for corn. Most grain sorghum is grown in the Great Plains states of Kansas, Texas, Oklahoma, Colorado, and South Dakota, where it is dry-land farmed in rotation with soybeans and cotton or wheat. While grain sorghum prefers deep, moist, fertile soils, it is resistant to drought and can still produce respect- able yields on more marginal lands. Sorghum has the highest water use efficiencyâhighest yield per inch of available waterâof commonly grown crops. A variety of tillage systems can be used to prepare a seedbed for sorghum planting, though conservation tillage is common in the erosion prone Great Plains states where production is concentrated. Grain sorghum is typically planted in rows 30 inches apart and, depending on annual rainfall, at a density of 37,000 to 153,000 seeds per acre. Similar to corn, grain sorghum is intensely managed in order to provide supplemental fertilization and to control weeds, pests, and disease. At maturity, grain sorghum reaches a maximum height of six feet, but there is con- siderable variation among modern hybrids. Grain sorghum is harvested with a combine that cuts the plant and separates the grain from the seed head. Yields for grain sorghum over the last decade have ranged between 11.4 and 16 tons per acre (50 and 70 bushels per acre). Growing grain sorghum in the highway ROW faces many of the same challenges as growing corn, including inefficient farming, encroachment that causes a sightline obstruction, and its potential as a wildlife attractant. However, grain sorghumâs ability to tolerate adverse growing conditions makes ROW soil conditions less of a concern.
The Biomass Energy Market: A Primer for DOTs 35 Soybeans Oil from soybeans (Glycine max) is the primary feedstock for biodiesel production in the U.S. Soybeans are most frequently grown as a part of an integrated cropping system where soybeans are planted in two-year rotation with corn or another grain crop (e.g., wheat). Soybeans are a warm season, leguminous crop grown throughout the U.S., though pro- duction is concentrated in the Midwest. More than 90% of the soybeans grown in the U.S. are genetically modified varieties developed for herbicide resistance. Soybeans prefer deep, well-drained, fertile soils. Sites with wet, poorly drained soils should be avoided because of increased risk of disease. While conventional tillage prior to planting continues as a common practice, it is no longer considered necessary to maximize crop yields, and no-till planting is now considered the best practice. Soybeans are typically planted in rows of less than 30 inches at a seeding rate between 125,000 and 140,000 seeds per acre. While soybeans do not generally require supplemental fertilization, they are intensely managed to control weeds, pests, and disease. Soybeans have a relatively low growing habit and at maturity reach a height of four feet or less. Most soybeans are harvested with a combine that separates the seed from the rest of the plant. U.S. soybean yields over the last decade have ranged between 1 and 1.3 tons per acre (34 and 44 bushels per acre). Several factors make growing soybeans in the highway ROW an unlikely fit for widespread adoption. As with other annual crops, the irregularly shaped and fragmented parcels found in the ROW are inefficient to farm. Likewise, the compacted soil conditions are generally not suit- able for growing soybeans without substantial improvement. Additionally, soybeans are highly palatable to deer and other wildlife. Unlike some other oilseed and grain crops, the low stature of soybeans does not present the same concerns for sightline obstruction. Canola (Rapeseed) Oil from canola is the second most common biodiesel feedstock in the U.S. canola is actually a type of rapeseed (Brassica napus Linnaeus or Brassica rapa) that has been bred to have qualities that make it suitable for both human and livestock consumption. There are two basic types of canola cultivars that can be grown in the U.S.: spring canola, planted in the spring and harvested in the late summer, and winter canola, planted in the fall and harvested in the following summer. Because of susceptibility to disease, canola is most often grown on three to four year rotations with other crops. Most canola grown in the U.S. is spring canola with production concentrated in the Northern Plains. Winter canola is grown in the Pacific Northwest, the Southeast, and parts of the Midwest. Most canola grown in the U.S. is genetically modified for herbicide resistance. Canola prefers well-drained silt loams that do not crust. Canola will not tolerate poorly drained, wet soils. Spring and winter canola can be planted into soils that have been prepared via conventional or conservation tillage. Canola is typically planted in rows with seven- to eight-inch spacing at a seeding rate of about five to eight pounds per acre. While growing canola is less intensive than other oilseed and grain crops, it still requires the application of herbicides and pesticides to man- age weeds, pests, and disease. At maturity, canola reaches a height of four to six feet. Most canola is harvested by first swathing (i.e., cutting down) and windrowing (i.e., piling up) the plant, allowing uniform drying for 10 to 14 days. Later, a combine is used to thresh the seed from the plants. Canola yields vary by growing conditions, region, and cultivar type, with winter canola often outperforming spring canola by 20 to 30%. On average, U.S. canola yields over the last decade have ranged between 1,200 and 1,800 pounds per acre.
36 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation Growing canola in the ROW presents fewer complications than other common biofuel feed- stock crops. Canola is less intensively managed than other oilseed and grain crops and its low stature is unlikely to pose a sightline obstruction. Moreover, canolaâs root structure, which fea- tures a long, strong taproot, is capable of penetrating and breaking up compacted and hardpan soils, making it better suited to thrive in roadway conditions. While canola may be better suited than other oilseeds and grains to be grown in the ROW, challenges remain. First, as with other annual crops, the fragmented and irregularly shaped parcels in the ROW are inefficient to farm. Second, canola may act as a wildlife attractant. This is especially true of winter canola, whose leafy greens may stand out in contrast to other vegetation that goes dormant in the winter. Third, the widespread planting of genetically modified canola could increase the risk of genetic cross-contamination with brassica spe- cies, such as broccoli and cabbage, grown as cash crops, potentially creating conflict with neighboring agricultural producers. The risk of cross-contamination also extends to brassica species listed as noxious weeds, potentially creating management challenges in controlling those species. Emerging Technologies In addition to the commercialized biomass energy conversion technologies discussed above, there are a number of next generation technologies in varying phases of development. Some of these technologies have been successfully demonstrated at a pilot scale and are in the early stages of commercial deployment, while others remain in the research and development phase. Three of the most promising are dry-fermentation anaerobic digestion, cellulosic bioethanol, and thermochemical conversion. Anaerobic digestion is the biological process in which microorganisms decompose organic material in the absence of oxygen, producing biogas. Biogas is primarily composed of methane and can be combusted to generate electricity and heat, or cleaned and compressed to power vehicles. So-called âwetâ anaerobic digestion systems have long been utilized to treat municipal wastewater and livestock manure. More recently, dry-fermentation anaerobic digestion systems have been developed to process drier materials, such as yard waste and crop residues. Though there are only two dry-fermentation biogas plants currently operating in the U.S., more than 30 additional plants are in the planning stages. While it is anticipated that this technology will primarily be deployed as a way to manage organic material in municipal solid waste streams, widespread commercialization may create opportunities for other feedstocks, such as grassy biomass harvested from the highway ROW. Cellulosic bioethanol technologies seek to convert lignocellulosic biomass, like agricultural residues and grassy and woody biomass, into bioethanol. This is accomplished by first separating the feedstock into its constituent partsâcellulose, hemicellulose, and lignin. The cellulose and hemicellulose are then further treated to convert them into fermentable sugars that can be used to produce bioethanol. While widespread commercialization of the technology remains elusive, there is robust public policy support for the technology that may generate a substantial market for lignocellulosic feedstocks. Thermochemical conversion technologies transform lignocellulosic biomass into solid, liq- uid, or gaseous fuels through the manipulation of heat, oxygen, and pressure. There are three basic types of thermochemical conversion processes: torrefaction, pyrolysis, and gasification. These processes produce fuels that have higher energy densities and are more easily utilized in conventional energy systems than their original feedstocks. While these technologies have successfully been validated at demonstration and pilot scales, they have not gained widespread commercial adoption.
The Biomass Energy Market: A Primer for DOTs 37 Initial Feasibility Assessment Prior to developing a bioenergy feedstock project, a DOT should assess the technical and economic feasibility of the project concept. The purpose of this assessment is to take a critical and comprehensive look at a prospective project and make an objective determination of whether the project should move forward or be abandoned until conditions improve. The key elements of a feasibility assessment for a bioenergy feedstock project are the identification of a potential market buyer, the preliminary identification of proj- ect location, the evaluation of potential feedstock crops, and a preliminary financial analysis. The primary purpose of the Biomass Checklist in the Feasibility Toolkit described below is to guide a DOT through this type of feasibility analysis to determine if a project is worth pursu- ing further. If a decision is made to move forward with a project, it is advisable to consult with relevant agronomic experts to review the internal feasibility assessment before moving forward with formal project implementation. Identify a Potential Buyer The first step in assessing the feasibility of a bioenergy feedstock project is determining if there is an end-user interested in purchasing the feedstock and understanding the buyerâs quality specifications, pricing, and payment terms. Woody biomass feedstocksâPotential buyers of woody biomass feedstocks, like willow or poplar, might include industrial facilities with existing woody biomassâfired boilers, most likely in the wood products industry; dedicated or co-fired electric power generators; or commercial and institutional facilities with woody biomass combustion systems. Pellet producers may also be a potential buyer. There are a number of public and private databases listing existing biomass combustion facili- ties. Notably, there is no single source listing all such facilities and some of the databases overlap. Some of the leading databases are described below. The National Renewable Energy Labâs BioEnergy Atlas is a web-based interactive map that shows the location of all wood and wood wasteâfired industrial CHP and dedicated biomass electric power plants in the U.S. The site also shows the location of electric power plants co-fired with biomass. Notably, not all of the facilities listed have the capacity to accept woody biomass. See: http://maps.nrel.gov/biomass Biomass Magazine, a leading industry trade publication, maintains an online list of existing and proposed âbiomass plantsâ and pellet producers. The list of biomass plants includes both industrial and dedicated biomass electric power facilities and is sortable by feedstock type. See: http://biomassmagazine.com/plants/listplants/biomass/US/ http://biomassmagazine.com/plants/listplants/pellet/US/ The Biomass Energy Resource Center maintains a database of commercial- and institutional- scale facilities that use biomass energy for heating or CHP. The database is searchable by state and feedstock type used. See: http://www.biomasscenter.org/database.html The University of Tennessee Office of Bioenergy Programs also maintains a database, called Wood2Energy, of proposed and existing facilities that utilize woody biomass for heating or Key elements of feasibility assessment ⢠Identify a potential buyer ⢠Site selection ⢠Feedstock crops evaluation ⢠Financial analysis
38 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation electricity production. The list also includes wood pellet producers. The list is searchable by state and facility type. Notably, many of the listings are incomplete and do not specify the type of feedstocks utilized. See: http://www.wood2energy.org/Database%20Connection.htm Biofuel feedstock buyersâIdentifying buyers of biofuel feedstocks, like starchy grains and oilseeds, is complicated by the fact that many biofuel producers do not buy directly from grow- ers. Most often these crops are sold to regional grain elevators from where the ultimate end use is not discernable. This is especially true for oilseed feedstocks that require intermediate pro- cessing. However, there may be localized opportunities to contract directly with a bioethanol production facility or work creatively with an oilseed processor and biodiesel production facility. In the latter case, the objective would be to identify a small-scale biodiesel producer willing to work with a DOT and regional oilseed processor that would âtoll crushâ the crop. There are a number of databases listing existing biodiesel production facilities and oilseed processors. Notably, there is no single source listing all such facilities and many of the databases overlap or are out of date. The leading databases are described below. The Renewable Fuels Association, a national bioethanol industry trade association, maintains a list of operating and proposed bioethanol production facilities on its website. The list includes the plant location, production capacity, and primary feedstock. See: http://www.ethanolrfa.org/bio-refinery-locations/ Ethanol Producer Magazine, a leading industry trade publication, also maintains an online list of existing and proposed bioethanol facilities. The list is sortable by feedstock type, capacity, or location. The list also includes existing demonstration-scale cellulosic bioethanol plants and proposed full-scale facilities. State grain grower associations also often maintain a list of bio- ethanol plants operating in the respective state. While the aggregated plant lists do not specify if a facility accepts direct delivery from growers, the individual websites for the facilities often do. See: http://www.ethanolproducer.com/plants/listplants/US/Existing/All The National Biodiesel Board, a national biodiesel industry trade group, maintains a list of member biodiesel plants (http://www.biodiesel.org/production/plants/plants-listing). The list includes contact information for the plants but does not specify feedstock preference. Biodiesel Producer Magazine, a leading industry trade publication, also maintains a list of biodiesel pro- duction facilities. The list is sortable by location, capacity and preferred feedstock. See: http://www.biodieselmagazine.com/plants/listplants/USA/ The National Oilseed Processors Association, an industry trade group, maintains a list of its 13 membersâ plants on its website. The list provides the plant name, ownership, and location but does not specify the types of oilseeds processed or if the facilities accept direct delivery. See: http://www.nopa.org/content/oilseed/oilseed.html Another potential source to identify oilseed processors is the National Institute of Oilseed Products, a trade group that includes firms across the oilseed supply chain. See: http://www.oilseed.org/member_list.html Soyatech, an oilseed research and consulting firm, also maintains a list of U.S. oilseed crushing and processing plants. This list, organized by state, includes the plant owner as well as the seeds processed and production method. See: http://www.soyatech.com/oilseed_reference.htm
The Biomass Energy Market: A Primer for DOTs 39 Identify Feedstock Requirements, Pricing, and Level of Interest A DOT interested in developing a bioenergy feedstock project should compile a list of facilities in its state from these resources and seek to identify those facilities that directly accept external feedstocks, or in the case of oilseed biodiesel would be interested in developing a collaborative project. Calling on each facility directly and surveying it on its feedstock sourcing strategy can accomplish this. It may benefit a DOT to first call on experts in state agencies or other interested parties in the stateâs bioenergy industry who may be able to provide insight on the facilities most likely to accept these types of feedstocks. Potentially helpful agency resources include state departments of agriculture, forestry, energy, or commerce. Potentially helpful industry resources include trade associations, other biomass suppliers, and market intermediaries such as brokers or aggregators. If a facility does accept external feedstock supplies, then the DOT should inquire about the conditions of a potential supply agreement, including minimum quantities, quality specifica- tions, storage, handling, and pricing and payment terms. Moreover, the DOT should seek to gauge the potential buyerâs level of interest for the project concept. The prospect of growing bioenergy feedstocks in the highway ROW remains a novel concept and the commercializa- tion of the concept is untested. A successful project will require an enthusiastic partner to work through the inevitable challenges. The purpose at this point is to start establishing a relationship with the potential buyer and collect information to be used at latter stages of the feasibility assessment. Site Selection Once a potential buyer, or set of buyers, has been identified, the next step should be to identify those areas potentially available for project implementation. Site selection should consider prox- imity to potential buyer; field shape, size, and access; and compatibility with DOT management considerations. Transportation costs are an important variable component in determining the profitability of any agricultural enterprise. This is particularly true for woody biomass crops that have low bulk energy densities, the ratio of energy content to volume. These voluminous materials are expensive to transport because it generally takes more trips to deliver a given quantity of energy. Biomass combustion facilities typically source feedstocks from within 50 to 75 miles because transporting fuels beyond this distance is usually not economical. In addition to having higher bulk densities, the grain and oilseed crops also tend to have valuable co-products that increase the distance these crops can be economically transported. That said, most producers initially deliver their crop to market by truck to either a local elevator or value-added processor within a few hundred miles. Potential sites should also be able to accommodate the safe and efficient use of equipment for land preparation, vegetation establishment and maintenance activities, and crop harvest. In general, agricultural fields should be large, flat, rectangular, and contiguous. Larger fields are more efficient to farm than smaller fields with a given piece of equipment because on the larger field the equipment will spend more time operating in the field and less time in the headlands, the area at the end of the field used to turn around equipment. Flat fields are more efficient to farm than sloped fields because sloped fields require rows to be planted along the contours of the slope to prevent erosion, slowing equipment operation and increasing operating costs. Irregu- larly shaped fields are less efficient to farm than rectangular fields because they require farm equipment to pass over an area more than once in order to ensure full coverage. Not only does
40 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation this increase equipment operating time and expense but it also tends to result in greater inputs like seed, fertilizers, etc., because of more overlap areas needed to completely plant and harvest the field. Contiguous fields, or at least those in close proximity to one another, are more efficient to farm because moving and setting up equipment between fields takes time and expense. These issues are especially acute for intensely managed annual crops, like grains and oilseeds, which require access multiple times a year. In general, these types of crops will require fields at least 20 acres in size, though in many parts of the country, the typical field size is much larger. While these issues are less acute for longer standing woody biomass feedstocks like poplar and willow, they also benefit from the production efficiencies of large, rectangular, and contiguous fields. In general these types of crops will also require areas of at least 20 acres. Sites should be selected to avoid conflict with DOT management considerations (described in Chapter 1). A project should be located where it will not pose a risk to motorist safety or conflict with other current or planned highway uses. Potential sites should also avoid both direct and indirect impacts to sensitive environmental resources. As the list of candidate sites is finalized, they should be subjected to a context-sensitive evalu- ation that considers environmental, economic, and community attributes at each site; engages local stakeholders; and inventories potential issues and concerns. Utilizing such an approach helps ensure a project fits into its location and provides the opportunity to identify and resolve potential conflicts early on, thereby avoiding costly delays. Feedstock Crop Evaluation Once potential buyers and sites have been identified, the next step is to evaluate the type of feedstock that should be grown. This evaluation should consider both the requirements of a potential buyer and the growing conditions of candidate sites. The feedstock requirements of potential buyers will largely determine feedstock selection since the buyer is likely specialized for one feedstock typeâeither woody biomass, starchy grains, or oilseed. The buyer may also have a preference for a specific feedstock crop. In the event there are multiple buyers or more than one feedstock crop is acceptable, it is advisable to consider how each crop fits site growing conditions. The types of growing conditions to consider include macro-climatic and micro-climatic vari- ables, soil type and conditions, topography, and hydrology. Climatic variables that influence plant growth include seasonal temperature ranges, length of growing season, quantity and tim- ing of precipitation, and wind exposure. Soil characteristics that influence plant growth and sur- vival include type, texture, structure, compaction, drainage, toxic contamination, and available nutrients. Topographic features to consider include slope, aspect, and surrounding terrainâall of which influence sunlight exposure. Hydrological factors to consider include drainage and propensity to flooding, the presence of and relative location of ground water, and surface water features. Each of these factors will influence the ability of a plant species to grow and survive, with most species best adapted to a specific combination of conditions. Examine Economic Feasibility The purpose of the financial analysis is to determine if expected revenues will exceed expected production costs. Expected revenues are a function of crop yield and the price received for that crop. Expected production costs are a function of the type of site preparation, vegetation establishment and maintenance, harvest and transportation activities, and the unit cost of those activities.
The Biomass Energy Market: A Primer for DOTs 41 It is vital that initial estimates of costs and revenues in the analysis are conservative since at this point in the project analysis much uncertainty about the ultimate design of the project remains. Those projects that cannot demonstrate profitability or are only marginally viable are not likely to withstand additional scrutiny and should not be pursued further. Typical project costs and potential project revenues associated with the three different bio- energy feedstocks best suited to be grown in the highway ROW are discussed below. Addition- ally, the accompanying Feasibility Toolkit provides a spreadsheet that allows a user to calculate the net present value of a proposed projectâs cash flow over a 25-year period based on a proj- ectâs establishment, maintenance and harvest costs, expected yield, and commodity price. The 25-year period was selected in order to address various crop rotation lengths and be able to make like comparisons across bioenergy feedstock crops. The Feasibility Toolkit includes default val- ues for discount rate, production costs, expected yield, and commodity prices based on a review of the literature conducted for this research project. The Feasibility Toolkit is designed to allow the user to define alternative values or model other crops to develop a customized analysis. Project Costs Project costs include costs associated with project development, vegetation establishment and maintenance, harvest, and transportation. Some of these costs are one-time costs while others are ongoing costs. Site reconnaissanceâThe cost of onsite scouting of potential sites in order to identify poten- tial hazards or conflicts (e.g., trash, debris, culverts, wetlands, etc.) and for soil testing. The default value included in the Feasibility Toolkit is $60 per acre and is based on estimates from a Wisconsin study that considered the feasibility of harvesting existing grassy biomass from the highway ROW. SafetyâThe cost of mobilizing traffic and safety equipment. The default value included in the Feasibility Toolkit is $30 per acre for each incursion into the ROW and is based on the pilot project experience in North Carolina and Michigan. Labor and equipment costsâThe labor and equipment associated with site preparation, planting, maintenance, and harvest activities. Total labor and equipment costs are a function of a given feedstockâs management regime, a set of recommended activities, and the unit cost of a given activity. The Feasibility Toolkit includes default values for the type and frequency of recommended activities as well as for unit costs. The management regime for a given feedstock is based on best practice recommendations found in the literature and described in fuller detail in the final research report. The unit cost of a given activity is derived from recent state-level reports on custom farm rates, typical charges for contracted farm services, and other literature sources. InputsâThe cost of materials associated with site preparation, planting, and maintenance activities including seed or nursery stock, herbicides, fertilizers, other soil amendments, etc. Total input costs are a function of the feedstock management regime and the unit cost of a given input. The Feasibility Toolkit includes default values for the type and quantity of recom- mended inputs as well as the unit cost of those inputs. The recommended type and quantity of a given input is based on best practice recommendations found in the literature and described in fuller detail in the NCHRP Project 25-35 final research report. The unit costs of various inputs were also derived from the literature. TransportationâThe cost to deliver harvested crops from the field to a buyerâs gate. The default value in the Feasibility Toolkit is $0.25 per ton-mile. Total transportation costs are calcu- lated by multiplying the transportation rate by total yield by total distance traveled. The default value for distance traveled is 25 miles.
42 Guidebook for Designing and Managing Rights-of-Way for Carbon Sequestration and Biomass Generation Project Revenues Project revenues include both the value of the sale of the biomass feedstocks and potential savings from avoided or reduced maintenance costs that might be realized as a result of project implementation. Estimated yieldâThe quantity of harvested material per acre. Yield affects the cost of trans- portation, the cost of harvest, and the total project revenues. The analysis considers a range of yields for each feedstock based on historic U.S. averages and other published studies. Price paid to farmerâThe price received per unit for feedstock sold at the producerâs gate. The default values in the Feasibility Toolkit are based on recently reported prices for the same or similar commodities. Avoided costâIn some cases, the cultivation of a bioenergy feedstock may displace or reduce the need for traditional maintenance activities, like mowing, on the ROW, resulting in a cost savings to the agency. However, the default assumption in the Feasibility Toolkit is that no such savings will occur since project implementation is likely to occur in areas where DOTs have already reduced or eliminated routine mowing. Feasibility Toolkit A DOT interested in evaluating the specific opportunity for developing a bioenergy feedstock project in its state should use the accompanying Feasibility Toolkit (described in additional detail in Chapter 4) to determine if local conditions are favorable to project development.
