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Review of the Research Strategy for Biomass-Derived Transportation Fuels 3 Feedstock Development PROGRAM OBJECTIVES AND OVERVIEW The objective of feedstock research by OFD is to develop low-cost lignocellulosic biomass to be used for ethanol and coproduct conversion. This objective is to be achieved by (1) developing agricultural and silvicultural systems for the efficient production, harvesting, and handling of perennial crop biomass from different regions of the United States; (2) improving the yield and quality of biomass by traditional plant breeding and biotechnology; and (3) developing environmentally acceptable methods for collecting and handling biomass, including residues from agriculture and forestry and municipal wastes (OFD, 1998). In addition to this overall objective, the program is also charged with considering sustainability and the environmental effects of biofuels on water, soil, atmosphere, and biological diversity. Feedstocks are a major cost of bioethanol production (see Figure 1-1), accounting for approximately 40 percent of total production costs (Wyman, 1999). Studies have shown that improvements in biomass yield are the most effective means of reducing dedicated feedstock costs and have, therefore, attracted major investments in research on breeding and agronomics. Other major opportunities for reducing feedstock costs include improvements in harvesting systems (Tuskan, 1999), derivation of coproducts, and improvements in feedstock quality to reduce processing costs. Initial research was focused on identifying potential species and sites for growing low-cost biomass. More than 100 woody and 35 perennial herbaceous species were screened for their potential biomass yield and their adaptability to various climates (Wright and Tuskan, 1997). Based on this research and industry's interest in using currently available sources of biomass for demonstration projects, the program is now focused on three areas: (1) agricultural and forest residues, (2) woody biomass as a coproduct from short-rotation woody crops grown primarily for other purposes, and (3) perennial herbaceous crops. OFD considers the use of residues, including agricultural, forest, industrial, and municipal wastes, to have high potential as a source of low-cost cellulosic feedstock. Primary agricultural residues include sugarcane bagasse, corn stover, wheat straw, and rice straw. Forest residues include waste from lumber mills, logging, fire control, and thinning operations. OFD estimates that between 100 and 200 million tons of corn stover and wheat straw are potentially available at a cost of less than $45 per ton (OFD, 1998). Studies are under way on the effects of supply, cost, storage, and harvesting corn stover on agronomic systems and soil fertility (Hettenhaus, 1999). Initial research included evaluating the potential of using a number of woody species, including poplar, sweetgum, sycamore, silver maple, black locust, and eucalyptus. However, the program is now focused primarily on poplar because of the broad geographic range over which it can be grown. Rapid acceptance and utilization of hybrid poplars for high-value fiber production by the pulp and paper industry was also a significant factor. OFD has played an important role in the development of poplar hybrids and silvicultural methods now used by forest industries in several parts of the country (Wright and Tuskan, 1997). The high-yield, intensive-culture systems used in the Pacific Northwest are the most dramatic examples. Because of the high value of fiber and wood products compared to bioenergy products, for the near term DOE considers poplars as coproduct systems (i.e., residuals not used for wood or pulp would enter a bioenergy stream). Dedicated energy crops being investigated in the OFD program include switchgrass and willow, both of which are being developed as biomass crops for cellulose-to-ethanol production and as fuel sources for generating electricity. Research on switchgrass has increased in recent years because its economic potential appears to be superior to the potential of woody crops. Switchgrass can be readily grown by farmers using current equipment, and, as a C4 crop (i.e., the initial carbon dioxide fixation products are four-carbon acids), it is suitable for growing in the large areas of warm,
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Review of the Research Strategy for Biomass-Derived Transportation Fuels droughty lands available for bioenergy crops. However, because of the uncertainties in the economic analyses, the suitability of woody crops for integrated, coproduct-oriented systems, and the expectation of greater environmental benefits from tree plantations over herbaceous systems, OFD is also continuing to support research on woody feedstocks. Environmental issues are another important driver of bioenergy crop development. OFD has been working closely with the environmental community and has initiated several in-house studies and studies in partnership with universities to evaluate the environmental aspects of energy crop culture. These studies have focused on the effects on soil fertility, water quality, and wildlife habitats compared to the effects of alternative crops and natural vegetation. OFD has also conducted detailed modeling analyses of life-cycle impacts for carbon management of bioenergy crops compared to fossil-fuel alternatives (Wang, 1997; Wang et al., 1998). Perennial bioenergy cropping systems can provide diverse local environmental benefits (e.g., biofiltration, erosion control, and creation of wildlife habitat), as well as benefits in terms of global carbon management. By evaluating environmental and economic trade-offs at several scales, OFD has provided a foundation for the development of national policies that may help the United States reduce net additions of carbon dioxide to the atmosphere while solving some of the environmental and economic problems of rural communities. ALLOCATION OF FUNDING The feedstock development program involves a wide range of projects both within DOE and in cooperation with universities, industry, and other government agencies (see Table 3-1). Research is divided regionally and nationally. Regional divisions are the Midwest/Plains States (switchgrass and poplar), the Southeast (switchgrass and poplar), the Northeast (willow), the Lake States (poplar), and the Pacific Northwest (poplar). Regional development centers conduct research focused on breeding and agronomics to increase crop yield and on plant physiology and biotechnology. Up to now, Congress has not supported significant increases in funds. In fiscal year 1998, the feedstock development projects accounted for 8.2 percent of the OFD R&D program; in fiscal year 1999, they accounted for 6.7 percent. The request for fiscal year 2000 is 10.3 percent of the OFD budget. OFD's initial focus was on woody crops, for which 37 percent of its research funds were allocated in 1994-1995 (compared to 22 percent for herbaceous crops). However, since 1996, both crop types have received approximately 33 percent of research funds for crop development (see Table 3-2). Allocations for environmental sustainability also increased from 12 percent in 1996 to 20 percent in 1999. The economics of production were a major focus during 1996 and 1997, accounting for 25 percent of funds spent, but received almost no funding in 1999. Research in TABLE 3-1 Participants in the Feedstock Development Program, 1996-1999 Crop Development Woody Crops Iowa State University Mississippi State University Washington State University State University of New York University of Washington Oregon State University U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station Herbaceous Crops Auburn University Oklahoma State University Texas A&M University University of Georgia University of Tennessee Virginia Polytechnic Institute and State University U.S. Department of Agriculture, Natural Resources Conservation Service, Plant Materials Centers U.S. Department of Agriculture, Agricultural Research Service Chariton Valley Resource Conservation and Development District Environmental Sustainability Alabama A&M University Auburn University Clark University Clemson University U.S. Department of Agriculture, Forest Service, Forestry Sciences Laboratory U.S. Department of Agriculture, Center for Forested Wetland Research National Council for Air and Stream Improvement Tennessee Valley Authority Economies Kansas State University University of Tennessee University of Minnesota-Crookston Natural Resources Research Institute U.S. Department of Agriculture, North Central Forest Experiment Station WesMin Resource Conservation and Development Council Source: ORNL, 1999a. biotechnology, which includes tissue culture, genetic mapping, and genetic engineering, has received extremely low funding, ranging from 2 to 4 percent. SHIFT IN STRATEGIC DIRECTION Like other elements of OFD's R&D program, research on feedstocks has been dominated by short-term goals, most of them involving production or commercialization. Investments in new science and technology have been limited in scope and funding. OFD's support for research in biotechnology, molecular genetics, and physiology to provide new options for production systems has been very modest. In general, OFD has focused on the management and
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Review of the Research Strategy for Biomass-Derived Transportation Fuels TABLE 3-2 Allocation of Funds for Feedstock Development Projects Project 1996 1997 1999 Crop developmenta Woody speciesb 28%d 32% 34% Herbaceous speciesc 30% 26% 38% Biotechnology Woody species 4% 3% 2% Herbaceous species 0% 0% 4% Environmental sustainability 12% 13% 20% Economics 26% 26% 2% a Crop development includes management, breeding, and physiology research. b Includes poplar and willow. c Includes switchgrass. d Percentage based on total research funding for all projects. Source: ORNL, 1999b. breeding of biomass feedstocks to provide basic information on the culture of these high-intensity systems and to identify varieties adaptable to the conditions where the feedstocks would be grown. Until these basic parameters were established, it was impossible for OFD to evaluate the economics of the production systems or attract private-sector participants to share the costs of further development. As research in these areas progresses, major improvements are being made in the productivity of both woody and herbaceous crops. Considerable work remains to be done, however, to improve the basic production methods for switchgrass, prompting a recommendation by a panel of reviewers that OFD continue work on production systems and focus work in biotechnology toward defined production targets (OFD, 1998). The feedstock development program is involved in several kinds of partnerships, including interdisciplinary teams of scientists and university-industry-government collaborations in breeding, culture, biotechnology, and analysis of environmental impacts. Through these partnerships, OFD has been able to leverage its investments. Partnerships have been particularly successful with woody crops, where very modest government investments have prompted large contributions of funds or in-kind resources from forest industries, land-grant universities, and the USDA. OFD uses diverse, often informal, methods of project selection and review. Some projects have been selected after a formal call for proposals; some have been arranged by contract with particular institutions; some have been arranged as partnerships with a number of contributors. Formal project reviews have been infrequent and sporadic. Despite this variable structure, the committee believes that OFD's research funds have been allocated effectively. The results of OFD funding have included fundamental advances in breeding, genome analysis, and genetic engineering that have enabled expansions in commercial production and applications of new technologies to crop improvement. Nevertheless, the committee believes that a more formal process for selecting projects and monitoring progress, including regular peer reviews, would ensure quality, especially if the funding base is increased significantly. Although OFD's support for the establishment of basic breeding and production systems for the major bioenergy crops is appropriate, the committee does not believe that OFD should support long-term regional breeding and production programs. Once breeding systems have been established and a number of productive clones or varieties identified for each region, OFD should shift its focus toward research on major technological improvements that would be too costly for regional programs to undertake but could have a national, and even international, impact. This research should include continued studies of the environmental issues raised by newly developed biotechnologies. Responsibility for incremental improvements in breeding and production systems should be relegated to private industry, regional USDA programs, or land-grant universities, as appropriate. Biotechnology presents a major opportunity for improving biomass crop yield and product quality in the midterm to long term. However, at OFD's current level of activity, little progress can be expected. In the last few years, ''genomics" has become a major scientific and commercial enterprise worldwide (Box 3-1), and private sector investments now exceed $200 million per year, dwarfing public-sector investments (NRC, 1998a). As a result of research on genomics, the agricultural seed and chemical industries have been radically restructured. Discoveries are being made daily, providing new tools for understanding and solving problems in crop production. These discoveries have no historic parallels in biology and are creating a wealth of new information for researchers. OFD should take advantage of advances in genomics in its attempts to bring down the costs of bioenergy crop production. Leveraging these advances will require significant studies in bioenergy crops. Because of the high functional conservation across species of protein-encoding gene sequences, genes identified in model organisms can be rapidly identified and studied in biomass crops, but only if gene catalogs and genetic engineering methods have been developed. Because genetic mapping, gene function studies in transgenic plants, and field trials of newly created materials will take a long time, OFD should begin work soon so that improved varieties are ready for production systems in the 2010 to 2020 time frame. GENOMICS Major investments will be required to develop the genomics tools and genetic engineering systems to make genomics technology applicable to bioenergy crops.
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Review of the Research Strategy for Biomass-Derived Transportation Fuels BOX 3-1 What Is Genomics? Genomics is the intensive, large-scale study of the structure and function of genes. The initial focus of genomics research is on mapping and sequencing large numbers of genes. A typical plant contains about 20,000 genes. Studies can range from the development of maps of the genome to determining the complete DNA sequence of all chromosomes The next phase of genomics research involves clarifying gene function at the cellular and organismal levels, This includes determining how they are regulated, how they interact, how variations in structure affect function, and how they can be used in genetic engineering. Genomics technology can lead to the development of new, high-yield, pest-resistant varieties of plants and enable major modifications to the production characteristics and feedstock quality that would be very difficult to achieve via traditional breeding. Once the necessary genes are available in the gene pools of bioenergy crops, genomics could also enable the production of novel coproducts. The following key elements of advanced biotechnology will be necessary for bioenergy crops: large sets of gene sequences from bioenergy crops that represent most of the functional genes in their genomes maps of the genetic and physical locations of genes, including their locations with reference to the complete gene sequences of model plant species (e.g., Arabidopsis thaliana) methods for rapid and inexpensive mapping and expression studies of the genes that affect economically important traits efficient means of producing transgenic plants to test the function of isolated and modified genes, including genes from other species OFD should carefully assess its goals for improving feedstock via genomics biotechnology and focus on the areas that are technically feasible and most likely to lead to reductions in cost. A detailed list of the tools and research projects needed to implement genomics in a bioenergy crop, using poplar as an example, is provided in Appendix E. The two model species on which OFD has chosen to focus, poplar and switchgrass, both have major advantages that will facilitate the application of biotechnology. As a member of the monocotyledonous grass family Poaceae, switchgrass is closely related to rice, maize, sorghum, and sugarcane, organisms that are also being intensively studied. More than 76,000 genes (i.e., distinct expressed sequence tags) have already been determined from maize by private industry. The entire rice genome is being sequenced by an international public consortium. The extensive synteny (conservation of gene order) between the switchgrass genome and these well studied genomes should facilitate the rapid gene-level analysis of switchgrass. Some obstacles must first be overcome, however, before biotechnology can be effectively applied to switchgrass. First, substantial progress will have to be made on breeding and production systems. Then, because of its polyploid nature and lack of a gene-transfer system, considerable work will be necessary on basic genetic and tissue culture protocols as a basis for the development of genetic mapping and transformation methods (ORNL, 1998). Poplars and willows, which are members of the dicotyledonous family Salicaceae, have no close relatives under genomic study. However, these species have a number of traits that would facilitate genomic studies. Most of them are diploids and have a small genome, which would simplify gene identification and mapping. Many can be readily crossed, producing hybrids that show heterosis, which would facilitate genetic mapping. Several pedigrees already exist for poplars as a result of breeding programs and ongoing genomic studies. And poplars can be readily transformed via methods of asexual gene transfer; thus they have given rise to many more transgenic plants than any other woody species. OFD funds have contributed to this capability through support of the crop development centers in the Pacific Northwest (PNW, 1999). In addition to their biological tractability, both poplars and willows are of considerable interest to other organizations that might cofund genomic research. The USDA and other multispecies grass genome programs (e.g., International Grass Genome Initiative) are logical partners for research on switchgrass, and the forest industry and the U.S. Forest Service are logical participants in studies of poplar. Although poplars are not a major economic species for the forestry industry, they are widely recognized for their value as a model species for forest biotechnology. Poplars can provide the proof of concept for biotechnology targets much faster and at much lower cost than conifers, the main commercial species for most forest industries. The DOE Agenda 2020 program, which is funded by the DOE Office of Industrial Technologies, is an example of a grant program
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Review of the Research Strategy for Biomass-Derived Transportation Fuels cofunded by industry and DOE that includes research in biotechnology (AFPA, 1994). Through genetic engineering, new genes, and thus new biochemical pathways, can be transferred into plants enabling the creation of novel coproducts in bioenergy crops. The bioenergy crops of the future may be the feedstock for biorefineries for which energy is only one, perhaps the least valuable, of several products. Coproducts under commercial development via the genetic engineering of plants include vaccines and other high-value pharmaceuticals, industrial and specialty enzymes, and novel fragrances, oils, and plastics. Bioenergy crops might logically be engineered to produce high quantities of cellulytic enzymes, such as cellulase or xylanase, which could be used directly for feedstock processing and thus reduce the cost of cellulase required for production. For other feedstocks, such as corn stover and switchgrass, genes and genetic engineering methods will be available from major biotechnology companies as a result of their work on maize and rice. For poplars, the genes developed for dicot crops can often be directly tested or adapted. Modifications of feedstock biomass are a highly desirable way to facilitate processing; however, the necessary modifications will vary with the energy product and processes. For example, higher lignin quantity is likely to be desirable for combustion to produce electricity because of its high energy density compared to polymerized sugars. For fermentation to ethanol, however, lignin could be reduced or modified so that it can be removed at less expense and with less interference for processing enzymes and microorganisms. Hemicellulose structure also appears to be important for processes that use enzymatic digestion. Feedstock, therefore, will have to be engineered differently for different products, pretreatments, and processing methods. A number of genes are already known that could be tested in transgenic plants for their effects on feedstock processing into ethanol. Many more possibilities for quality engineering will become available as catalogs of genes expressed in lignocellulosic tissues are uncovered by genomics studies (Sterky et al., 1998). To understand how feedstock should be engineered for different products, pretreatments, and processing methods, the research programs of OFD's processing and feedstock development groups should be integrated. Investigations in genetic engineering and genomics of biomass feedstocks could be integrated to avoid duplication of effort via the establishment of virtual centers that would include DOE and other government laboratories, universities, the private sector, and international partners. These virtual centers would be designed to share complementary tasks across several facilities that have the technologies in hand. Some functions that are national in scope may be more effective if they are centralized, but others will be more effective if they are regionalized to take into account study materials created by local breeding programs and genetic traits expressed in specific environments. Studies should be carefully prioritized and monitored by DOE with the aid of a national review panel to ensure that project proposals do not overlap but contribute to the goals of the investigations of the virtual center. Apart from tool development, these investigations should be directed toward target traits that have been selected for their scientific, technological, and economic values, and consider environmental acceptability as well as production goals. CONCLUSIONS Conclusion. Given the resources available to the Office of Fuels Development, the feedstock program funds have been well allocated, and research programs have clarified production and environmental issues. Conclusion. The feedstock program is appropriately involved in extramural projects with investigators from universities, industry, and other government agencies. Conclusion. Given the importance of the cost of dedicated feedstock to the economics of bioenergy production and the potential for technological advances via breeding and biotechnology, research on feedstock development may be inadequately funded to achieve substantial reductions in the cost of feedstock even in the long run. RECOMMENDATIONS Recommendation. A more formal process for the selection and review of feedstock projects and outside participants should be established and the use of peer reviews expanded, especially if there are significant increases in program funding. Recommendation. Because of the many opportunities for genetic improvements in the midterm, the Office of Fuels Development should seriously consider expanding its applied biotechnology and genomics programs to improve feedstock yields, pest resistance, quality, and cropping systems. Although the Office of Fuels Development is well suited to take the lead in these programs, the agency should work in coordination with other government agencies (e.g., U.S. Department of Agriculture and the National Science Foundation) and grant programs, international partners, and the forest, agricultural, and biotechnology industries. Recommendation. Investigations in genetic engineering and the genomics of biomass feedstocks should be integrated to avoid duplication of effort.
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