The term fluidized bed is used to describe the fluid-like characteristics created in a container of sand-like particles that are suspended by an upward flowing stream of air (see Figure 1). The air injected into the bottom of the FBC creates a buoyant force that lifts and suspends the particles in the bed. If enough air is injected, the bed of sand begins to bubble, hence the term "bubbling fluid bed (BFB)." If still more air is injected into the sand, at some point the sand particles will be carried out of the bed chamber where they can be captured and returned (recirculated) to the bed. This type of FBC is called a circulating fluid bed (CFB).

FBCs have several advantages over other types of combustors. The refractory and bed material provide significant mass that can store heat and facilitate the burning of very moist materials. This thermal mass also can allow the FBC to idle for long periods of time without the addition of fuel, while still retaining enough heat to ignite fuel when the unit needs to start back up.

Patrick Travis, Division Manager with EPI, notes that FBC technology has been evolving since the mid-1960’s and has become "...the recognized ‘best available’ technology for handling many of the non-standard solid fuel and/or waste materials currently being combusted." This ability is partially because the intense turbulence of the bed scours off ash that forms on the surface of burning particles, thus facilitating air getting to the particle. Suspension also facilitates air reaching the entire surface of the particle.

One other important feature is that fuel is very rapidly consumed, making the amount of fuel in the combustor minimal. This feature allows the BFB to follow load demands by varying the rate at which fuel is fed into the system.

EPI has constructed FBC units that burn paper, de-inking, and sewage sludges; cardboard, municipal wastes, RDF, paunch manure (the manure in the stomachs of slaughtered cattle), hog fuel, wood processing wastes, Medium Density Fiberboard waste including sanderdust and board trim, petroleum tanker sludge, urban wood wastes, agricultural wastes (including cotton seeds, olive pits, wheat and rice straw), coal, bark, and plastics. EPI is one of the few companies that have systems operating using CCA treated wood for fuel.

Additionally, EPI has tested over 200 feedstocks in their FBCs including a wide variety of biomass feedstocks. Many of the feedstocks tested have been kept confidential at their clients’ request.

The EPI study on applying their FBC technology to animal manure notes that the US is currently producing nearly 8 billion chickens, 300 million turkeys, 100 million hogs, and 60 million cattle annually. The solid wastes from poultry production alone is estimated at nearly 100 million dry tons per year and manure from hog production is estimated to produce another 110 million dry tons per year.

The waste streams created by these industries represent nearly 2,000 trillion Btu’s of energy, roughly equivalent to 300 million barrels of oil. At $25 per barrel, this would represent an energy reserve for the US equivalent to approximately $7.5 billion per year.

EPI conducted its first tests with 110 tons of poultry litter in 1983 using poultry litter based on rice hull bedding. Table 1 is a comparison of the fuel analysis for poultry litter with coal and wood. The amounts of moisture and ash in poultry litter can vary widely due to the method of removing the litter and other factors. Both poultry litter and wood have high volatile contents, ranging up to 75 percent on a dry weight basis.

Table 2 is a comparison analysis of poultry litter ash and aspen wood ash—a wood ash with some of the higher levels of potassium and sodium. The high levels of potassium (K2O) and sodium (Na2O) in both ashes indicate the high probability of fouling or slagging of combustion surfaces. However, typical operating temperatures in the EPI FBC are below 1750 ºF and no slagging or fouling was observed in tests at these temperatures. Although these preliminary results were positive, additional tests need to be conducted to verify that slagging does not occur under long-term operations.

To verify that low temperatures were at least partially responsible for the absence of fouling or slagging during the tests with poultry litter, the furnace was operated at 1800-2000 ºF for a one-day run. Operation at these temperatures resulted in measurable slagging and ash buildup on the furnace walls.

EPI also conducted emission tests with poultry litter. By adding limestone to the FBC bed, they were able to capture 100 percent of the sulfur. And by using their SNCR technology to inject ammonia into the upper region of the FBC, an 89 percent reduction of NOx was achieved, bringing NOx levels down to 25 ppm, equivalent to 0.08 lb/MBtu.

As shown in Table II, poultry litter has a high chlorine content. Of greatest concern among all potential emissions was chloride, because of its ability to form hydrochloric acid (HCl). However, using various techniques, technicians at EPI were able to achieve a chlorine capture efficiency of 84 percent.

EPI officials calculate that the fuel required to power a 20 MW plant would range from 150,000 to 200,000 dry tons per year. If each bird produces 0.1 pound of dry manure per bird per day, a 20-MW plant could utilize the wastes from 11 million birds annually.

EPI officials not only see opportunities for providing process heat to the meat and poultry industries, they also see tremendous opportunities for utilities to meet their renewable energy and green power requirements by installing companion combustion systems. These systems consist of a new fluid bed combustor or gasifier installed adjacent to a fossil fuel boiler with the energy output from the FBC fed directly into the existing boiler. Another successful option has been to retrofit an existing boiler with FBC technology. In both the latter two cases, the fluidized bed system can be operated either as a combustor or gasifier.

In addition to creating "green power" from the manure, or any of hundreds of other biomass materials, EPI’s FBC systems reduce air pollution by displacing the amount of fossil fuels used, thereby reducing greenhouse gases. The use of manure and biomass waste as a fuel also reduces its contribution to excessive nutrient loadings of land, groundwater, and streams.

For additional information on EPI and their products, or to obtain a copy of their study entitled Fluidized Bed Technology Solution to Animal Waste Disposal, contact Patrick Travis at Energy Products of Idaho, 4006 Industrial Avenue, Coeur d’Alene, Idaho 83814-8926, phone +1 208 765 1611, fax +1 208 765 0503, or email epi@energyproducts.com

However, a plant producing ethanol as a sole product is not economic based on this technology and an ethanol price of $1.25 per gallon. This result implies that a way of making ethanol economically viable—without federal subsidy—is to co-produce it with other higher value products in a "biomass refinery plant".

An important objective of the study was to estimate the optimum size processing plant, given the LCF resource base in Missouri. Of particular importance was evaluating the economies-of-size of larger plants versus increasing feedstock costs, an unavoidable consequence of hauling feedstocks over greater distances. Size economies were identified as being the dominant economic factor, thus feedstocks were assumed to be hauled rather long distances in the base case scenario. The optimum size plant processed an estimated 4,360 tons of feedstocks daily, producing an estimated 47.5 million gallons of ethanol and 323 thousand tons of furfural annually.

The optimum size processing plant would have an estimated investment cost of $455 million, generate annual income of $281 million, and have an annual pre-tax net profit of $108 million. After providing a 15 percent return on investment annually "off the top" to the original investors, it still would provide a 22.5 percent return on investment over the 15 year project lifetime. The net present value of the estimated lifetime income stream would be $177 million after repaying the original construction cost of $455 million.

Crop residues (corn stover, wheat straw and milo stover) were the feedstocks of choice because of higher levels of hemi-cellulose—used in producing the higher value furfural—and low levels of lignin relative to other feedstocks considered. In addition, some woody residues were used in the optimum base case solution. However, no dedicated energy crops were used, primarily because: 1) they were assumed to be more expensive than both crop residues and woody biomass, and 2) their composition, compared to other feedstocks, would include higher levels of cellulose, which is a feedstock for ethanol, and lignin, which is used as process energy. Both of these have lower value uses and less valuable products than the furfural produced from hemi-cellulose.

The optimum location, based on the use of a GAMS mathematical optimization model, was in Carroll County, MO, a major crop production area in west central Missouri.

Plant operations would provide significant employment opportunities and a large stimulus to economic activity in the west central Missouri region. Up to 6,000 additional jobs might be created as the result of operating this processing plant. Only about 2,700 of those would be in Missouri, although many of the Missouri jobs would be seasonal and involve feedstocks harvest. The largest number of jobs would be in the chemicals industry and located elsewhere in the U.S.

Operation of an ethanol/furfural plant in Missouri should not result in offsetting job losses in the state because all ethanol and liquid fuels are currently imported. Thus, any offsetting job losses should be in other states that produce ethanol and/or produce and refine petroleum, however both of these industries are capital—not labor—intensive.

Personal income would also increase as the result of plant operations. Up to $155 million might be expected annually, again with much of the increase realized by personnel in the chemicals industry.

Plant operations also would bring increased tax revenues to the local area, to Missouri and to the U.S. treasuries. Local and state tax benefits (income, sales, excise tax on liquid fuels, and property taxes) could increase by an estimated $10.8 million per year, excluding increased taxes that might accrue to other states. Also, in order to attract the plant, concessions might be made by local governments in the level of real and personal property taxes to be collected, thus reducing these estimated revenues.

The conversion of municipal solid waste (MSW) into ethanol was not as economically attractive as when using crop residue feedstocks because: 1) the primary product produced would be ethanol, not as profitable as furfural, and 2) tipping fees of $30 per ton are not high enough to pay for the necessary additional equipment and labor used in sorting the feedstock prior to processing. In comparison, tipping fees approximately twice that level are quite economically attractive for an MSW-to-ethanol project under construction in Orange County, New York.

Development of an LCF-to-ethanol industry would be highly complementary to the existing grain-to-ethanol industry. It would simultaneously help to provide much larger volumes of high quality ethanol than can be provided from grain to augment the approximately 155 billion gallons of gasoline used in the U.S. annually.

Finally, an LCF-to-ethanol project in Missouri should provide significant incentives for agglomeration in attracting other plants and businesses opportunities.

For more information or to receive a copy of the report entitled The Economic Feasibility of Converting Ligno-Cellulosic Feedstocks to Ethanol and Higher Value Chemicals, contact Dr. Donald L. Van Dyne, University of Missouri, Department of Agricultural Economics, 200 Mumford Hall, Columbia, Missouri 65211, phone (573) 882-0141, fax (573) 882-3958, or email VanDyneD@missouri.edu

Most bamboo species grow in the tropics; however, some varieties occur naturally in subtropical and temperate zones of all continents except Europe. The growing zone ranges from latitudes 46 °N to 47 °S and from sea level to over 13,000 feet (4,000 m) in elevation. Asia alone has over 1000 species, most of it in natural stands. Current major bamboo-producing-and-using countries include China, India, Bangladesh, Indonesia, and Thailand.

Approximately 1,500 commercial applications of bamboo have been identified. These applications may be divided into the following broad categories:

• Construction and reinforcing fibers—agricultural and fishing tools, handicrafts, musical instruments, furniture, civil engineering (bridges, scaffolding), and buildings (house frames, walls, window frames, roofs, interior dividers).

• Paper, textiles, and boards—this also includes rayon, plywood, oriented strand board, and laminated flooring.

• Food—bamboo shoots are widely used in Chinese and other Asian cuisine.

• Bioenergy feedstocks—no references were found in the literature concerning the use of bamboo as an energy feedstock.

A mature planting of bamboo forms a dense stand with little light penetration. Bamboo is semi-deciduous, with leaves shed at the end of the growing season or for species on a two-year cycle, during the following growing season. Plants that have a biennial pattern of leaf emergence typically also exhibit strong shoot production in the year when leaves are not shed.

One of the more interesting aspects about bamboo is its rapid growth. The plant will send out rhizomes (underground horizontal plant stems) tens of meters in all directions that are 12 to 20 inches (30 to 50 cm) beneath the surface. Shoot buds appear on the sides of these rhizomes, and with the onset of warm spring weather, the buds lengthen and form a compact upright shoot that penetrates the ground’s surface. The plant now concentrates on growing the culm, without branches, as fast as possible. Tall species of bamboo have been observed to grow as much as 20 inches (0.5 m) per week. After the shoot reaches the same height as other culms, leafy branches appear near the top of the culm. Growth over the following years consists of thickening the walls of the culm and increasing the wood density.

Another interesting phenomenon about bamboo is its flowering patterns. A few species are known to flower frequently, even annually, and a few species flower a few culms at a time.

However, for the majority of bamboo species, the entire clump at a location will produce flowers and then die back over the next two to three years. For most of the latter species, flowering happens every 30 to 40 years although for some species the period is over 60 years. This infrequency of flowering makes bamboo hard to study and partially accounts for the lack of knowledge about bamboo.

Since bamboo is propagated vegetatively by planting rhizomes, it may not be known where the plant is in its flowering cycle. This uncertainty of when flowering and die-back may occur has long been a concern with bamboo growers. However, the ORNL report states that "…the threat of catastrophic flowering need not pose an economic problem for bamboo growers, as long as uneven-aged propagation material is maintained, and entire stands are replaced before they approach flowering age."

For fuel analysis, nine bamboo samples representing three different species at three different ages were collected. The publication lists the proximate, ultimate, and elemental analyses for these nine samples. The typical moisture content for freshly field-harvested bamboo is approximately 15 percent. The ash content of all samples was one percent or less, with no correlation between ash content and bamboo sample or age of sample apparent. This ash content is similar to other woody biomass materials.

Volatiles in the samples ranged from 63 to 75 percent with the balance fixed carbon and, again, no correlation between volatiles and bamboo sample or sample age was determined. Heating values were comparable to wood at 16 million to 16.5 million Btu/ton (19.09 to 19.57 GJ/t) on a dry basis.

Three bamboo characteristics—low nitrogen content, low chlorine content, and low alkali indices—are particularly significant for combustion of bamboo. Alkali indices (defined as pounds of alkali oxide per million Btu of energy content) range from 0.23 to 0.7 (0.1 to 0.3 kg/GJ), generally below the limit of 0.4 to 0.8 lb/MMBtu (0.17 to 0.34 kg/GJ) known to cause adverse fouling and slagging in combustion systems. The presence of chlorine has been shown to increase the volatility of alkali metals during combustion. However, the low chlorine values present in bamboo samples suggest that the potassium that is present is unlikely to be volatile and therefore not a problem.

Bamboo must be grown vegetatively and 1-2 year old rhizome cuttings of 12 to 20 inches (30 to 50 cm) in length with nodes and buds present are sometimes used. Younger rhizomes provide the best results. Propagation with rhizome cuttings with at least a foot of culm attached also gave better results. Typically up to eight years are required to achieve a good stand and the final stand height may not be reached until 15-20 years have elapsed.

Harvesting of traditionally grown bamboo is un-mechanized and labor intensive, especially if only selected culms are to be harvested. Research in India suggests that clear-cutting does not significantly damage bamboo stands, so it may be possible to use machinery such as modified sugar-cane harvesters. The Western and Southeastern Regional Biomass Energy Programs sponsored bamboo harvesting tests in Alabama in the late 1990’s using a flail-cutter-head harvester developed at Texas A&M Kingsville and obtained acceptable harvesting results for bamboo approximately 30 feet tall.

Bamboo has frequently been characterized as having a high productivity; however, the ORNL study did not substantiate this characterization. Values for productivity in the literature range from 1 ton/acre/year (2.2 t/ha/year) in Northern India to 7 tons/acre/year (15.5 t/ha/year) in Central Japan. Data from the United States is very limited. Data from stands in South Alabama that were aged 14 to 20 years averaged 2.7 to 3.9 tons/acre/year (6.1 to 8.6 t/ha/year). These figures exclude branches and leaves, which accounted for 14 percent of the above-ground biomass. The ORNL report speculates that based on figures available from overseas, as well as the limited trials conducted in the US, intensively managed bamboo stands with fertilization may be capable of producing over 4.5 tons/acre/year (10 t/ha/year) under Southeast US conditions.

For additional information, contact the American Bamboo Society, c/o Michael Bartholomew, 750 Krumkill Road, Albany, NY 12203-5976, http://www.bamboo.org/abs/index.shtml. A U.S. supplier of bamboo technology is West Wind Technology, John Woods, 5 South Hill Street, Athens, TN 37303, +1 (423) 745-5087, fax +1 (423) 744-8689, email jewwwt@usit.net, or http://esi.athenstn.com/wwt/wwt.html.

For a copy of the report Bamboo: An Overlooked Biomass Resource?, (ORNL/TM-1999/264) contact Anne Ehrenshaft at ORNL, Biomass Feedstock Development Program, P.O. Box 2008, Oak Ridge, Tennessee 37831-6422, Phone +1 (865) 576-5132, Fax +1 (865) 576-8143, email are@ornl.gov; or contact the US Dept. of Commerce, NTIS, 5285 Port Royal Road, Springfield, VA 22161, 1-800-553-6847, fax +1 (703) 605-6900, email orders@ntis.fedworld.gov, or website www.ntis.gov/ordering.htm. DOE employees may obtain copies from OSTI, PO Box 62, Oak Ridge, TN 37831, (865) 576-8401, fax (865) 576-5728, email reports@adonis.osti.gov, or website http://www.osti.gov/products/sources.html.

New developments in agricultural biotechnology are being used to increase the productivity of crops, primarily by reducing the costs of production by decreasing the needs for inputs of pesticides, mostly in crops grown in temperate zones. The application of agricultural biotechnology can improve the quality of life by developing new strains of plants that give higher yields with fewer inputs, can be grown in a wider range of environments, give better rotations to conserve natural resources, provide more nutritious harvested products that keep much longer in storage and transport, and continue low cost food supplies to consumers.

After two decades of intensive and expensive research and development in agricultural biotechnology, the commercial cultivation of transgenic plant varieties has commenced over the past three years. In 1999 it was estimated that approximately 40 million hectares of land were planted with transgenic varieties of over 20 plant species, the most commercially important of which were cotton, corn, soybean, and rapeseed. The countries include several of the world’s major producers and exporters of agricultural commodities: Argentina, Australia, Canada, China, France, Mexico, South Africa, Spain, and the United States. Approximately 15% of the area is in emerging economies. The value of the global market in transgenic crops grew from US$75 million in 1995 to US$1.64 billion in 1998.

The traits these new varieties contain are most commonly insect resistance and delayed fruit ripening. The benefits of these initial transgenic crops are better weed and insect control, higher productivity, and more flexible crop management. These benefits accrue primarily to farmers and agribusinesses but there are also economic benefits accruing to consumers in terms of maintaining food production at low prices. The broader benefits to the environment and the community through reduced use of pesticides contribute to a more sustainable agriculture and better food security.

In assessing the benefits and risks involved in the use of modern biotechnology, there are a series of issues to be addressed so that informed decisions may be made as to the appropriateness of the use of modern biotechnology when seeking solutions to current problems in food, agriculture, and natural resources management. These issues include risk assessment and risk management within an effective regulatory system as well as the role of intellectual property management in rewarding local innovation and enabling access to technology developed by others. In terms of addressing any risks posed by the cultivation of plants in the environment, there are six safety issues proposed by the Organization for Economic Cooperation and Development (OECD) that need to be considered. These are gene transfer, weediness, trait effects, genetic and phenotypic variability, expression of genetic material from pathogens, and worker safety.

The issues of major concern in relation to the future applications of biotechnology to crop improvement include the evaluation of any risks to human health and the environment; the need for mandatory and/or voluntary labeling of genetically modified foods and/or agricultural commodities for international trade; the relationship between countries’ responsibilities under the World Trade Organization; and international environmental treaties. These include the international protocol on biosafety being negotiated under the Convention on Biological Diversity, and whether this will provide oversight on traits and/or processes of genetic modification.

Governments and other responsible parties should effectively communicate with the public about the nature of new crop types and new crop varieties, about the unity of life processes in all organisms, and about the risks and benefits of agricultural biotechnology in their own country and internationally. There also is a need to continually improve the transparency and broad participation in the decision-making processes in relation to biotechnology, the release of genetically modified organisms into the environment, and the approval of genetically modified foods for commercial use.

For a copy of this Council for Agricultural Science and Technology (CAST) Issue Paper, contact Kayleen A. Niyo, Ph.D., Managing Scientific Editor, www.cast-science.org, or contact CAST at 4420 West Lincoln Way, Ames, Iowa 50014-3447, (515) 292-2125, fax (515) 292-4512, email, cast@cast-science.org. Refer to Issue Paper Number 12, December 1999. Cost is $3.

Considerable concern was expressed in the discussions about land use implications of energy crops, especially since increasing land areas for this purpose could affect marginal and ecologically sensitive areas (wetlands, wildlife habitat) and Conservation Reserve Program (CRP) lands. The environmental impacts of developing/growing/harvesting biomass crops and the collection of residues and wastes for conversion were discussed as well as chemical inputs to crops, and impacts on soil, water, and air. Possible impacts upon national forests and use of forest residues drew much concern, as did use of municipal solid wastes.

Conversion technologies, particularly burning of wood and cofiring of wood or residues with coal, drew great interest and questions. About half of the discussants "had no problem" with burning trees, while others expressed concerns about bad experiences with incineration.

Most discussants were full of questions about every aspect of bioenergy fuel cycles and asked for more information. The author found a highly variable information base about biomass and bioenergy, which affected the study design. Discussants asked for comparisons among biomass sources and between biomass and other fuels.

Issues raised most often within the discussion agenda included sustainable agriculture and forestry, sustainable energy systems, and biodiversity. More issues were volunteered outside of the discussion agenda: land for food vs. energy, subsidies for fossil and nuclear energy vs. equalizing the playing field for renewables, centralized vs. distributed energy systems, how bioenergy fits with utility restructuring, visions of bioenergy futures, who will benefit from biomass programs and subsidies, and scale and size issues.

Values and concerns driving these responses appear to be within the context of moving toward an energy future based upon renewable resources. Other driver issues included concern about global warming and the global carbon balance; developing sustainable energy, agricultural and forestry systems; and doing so in ways that enhance (or at least do not further damage) biodiversity.

Internal organizational issues and strategies are already impacting these stakeholders’ reactions to and interest in bioenergy. For instance, groups working on global warming policy and legislation support development of bioenergy. The Sierra Club’s campaign to end logging in the national forests and the several campaigns to upgrade or close old coal power plants probably raise obstacles or deflect policy away from biomass. Concern over effects of global warming on wildlife habitat may push toward acceptance of biomass programs.

Sensitive issues and those which raise intense concerns have the potential to slow or stop program development. These may include: municipal solid waste (MSW), genetically modified organisms (GMOs), forest and forest residue use, cofiring as incineration, cofiring which extends the life of old polluting coal plants, and certain aspects of land use involving marginal and CRP lands.

Most of these stakeholders can be described as waiting hopefully for the promise of bioenergy to be demonstrated, but a sizeable minority are (influential) skeptics about the prospects. All want to have more information and analysis of the status, progress and prospects of biomass and bioenergy. The window of receptivity to information and dialogue is open now, but probably not for long.

Recommendations propose research and analysis to produce balanced information on net benefits of bioenergy fuel cycles, tailored outreach to external stakeholders, extended dialogue and involvement of stakeholders including periodic bioenergy/biomass roundtables, and developing the vision of bioenergy futures and various scenarios for achieving these futures.

This report, Biomass Stakeholder Views and Concerns: Environmental Groups and Some Trade Associations, is available electronically from www.doe.gov/bridge. Hard copies are available to the public from U.S Dept. of Commerce, NTIS, 5285 Port Royal Road, Springfield, VA 22161, 1-800-553-6847, 703-487-4639, fax 703-605-6900, email orders@ntis.fedworld.gov. Copies are available to DOE employees, DOE contractors, Energy Technology Data Exchange (ETDE) representatives, and International Nuclear Information System (INIS) representatives from Office of Scientific and Technical Information, PO Box 62, Oak Ridge, TN 37831, 865-576-8401, fax 865-576-5728, email reports@adonis.osti.gov, web site http://www.osti.gov/products/sources.html. Refer to ORNL/TM-1999/271. Date of Issue of the publication is January 2000.

The inflation factor is calculated using GNP Implicit Price Deflator as computed and published by the Department of Commerce. During 1999, a comprehensive revision of the national income and product accounts by the Department of Commerce resulted in an Inflation Adjustment Factor that was lower than 1997 or 1998 amounts.

The §29 credit is an income tax credit for the production and sale of gases derived from biomass and synthetic fuels derived from coal. The credit allows a reduction in income tax for every BOE of these alternative fuels sold to an "unrelated party." The credit is generally available for gases derived from thermal air or oxygen gasifiers, landfill gas, or anaerobic digesters. The credit is calculated by multiplying the BOE’s of eligible fuel produced by the current year’s credit, subject to limitations under certain circumstances.

The full amount of the credit is available when the calendar-year "Reference Price" for oil is $23.50 or less per barrel (adjusted annually for inflation). The Reference Price is the average wellhead price per barrel for all unregulated domestic crude oil. The Reference Price for 1999 is $15.56. Thus, no phase-out of the credit occurred for qualified fuels in 1999.