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2 Feedstocks and Conversion Technologies “This is a big deal, because we are saying the primary amount of biomass will come from energy crops that have not yet been established, have not yet had enough research and information on optimizing production yield and systems. There is a lot of work to be done to make this come true.” Bryce Stokes “We have the land, the will, and by bringing our sciences together we can provide the way for using biomass for feedstocks and commodities in our biorefineries.” Bryce Stokes “Initially, advanced biofuels will be produced in integrated supply chains; no one will grow new crops without an assured customer, and no one will finance or build new conversion capacity without an assured source of feedstock. Truly fungible products will be traded as commodities, but most products will also form part of an end-to-end supply chain in early applications.” Bryan Duff INTRODUCTION developing a cost-effective system for getting widely dis- tributed, non-uniform biomass to fuel, chemical, and power As participants in the workshop discussed, biomass production sites. In the meantime, research has developed utilization is an important addition to the nation’s energy a variety of biological and thermochemical schemes for economy. Bryce Stokes explained the future potential of turning biomass into fuels, chemicals, and energy. The list biomass production in the United States and noted that the of building blocks, secondary chemicals, intermediates, and billion-ton goal is attainable. Biomass could potentially be end products that can be made from biomass feedstocks is used to displace about 30 percent of the petroleum consump- virtually limitless, just as it is with petroleum. tion or produce 5 percent of the electricity used in America. Brian Duff pointed out that biomass is also very useful for transportation, as it can be processed into high-density fuels FEEDSTOCKS AND RAW MATERIALS for a wide variety of vehicles. The participants in the work- Bryce Stokes noted that the United States has abundant, shop discussed in detail the challenges and opportunities for renewable biomass resources to use for feedstocks, although developing biomass utilization for both electricity generation the supply today and the form in which most of it exists is and production of fuels and chemical feedstocks. not sufficient to meet the 30 percent petroleum displacement The United States has enough land and technological goal that the nation needs for energy, chemicals, and other knowledge to produce over one billion tons of biomass m ­ aterials. However, he said, with the supply of land in the per year at $60 or less per ton for use in making fuels and United States, combined with the nation’s technological chemicals and generating power without impacting current prowess and its people, it should be possible to grow enough uses agricultural and forestry acreage, noted Bryce Stokes, biomass to meet those needs. Moreover, it should be possible senior advisor with CNJV, a contractor to DOE. to do so within a resource management and sustainability A significant amount of that biomass will come from framework that meets other social demands. increased production of energy crops, with increased use of Starting with available land, Stokes explained that there corn stover and straws also making a significant contribution are six major classes of land, drawing mainly from a 2011 to the increase, said Stokes. Brian Duff, chief engineer and report from the U.S. Department of Agriculture:1 acting deployment team leader for the Office of Biomass Program at DOE, said that there is also a real opportunity to make efficient use of the woody component of municipal 1Nickerson, C., R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses solid waste and construction and demolition wood. How- of Land in the United States, 2007. Economic Information Bulletin No. 89. December 2011 [online]. Available: http://www.epure.org/pdf/0w3ea6c089- ever, a major challenge to utilizing these resources will be 8164-d04c.pdf. 5

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6 OPPORTUNITIES AND OBSTACLES IN LARGE-SCALE BIOMASS UTILIZATION • Cropland, which includes all land currently used to Biomass Resources grow crops, idle cropland, and cropland used only Stokes discussed some of the major forest and agri- for pasture. Total cropland in the lower 48 states is cultural biomass resources that could serve as feedstocks. approximately 408 million acres.2 Forest resources include logging residues, which are very • Grassland pasture and range, including permanent inexpensive to buy, but collecting them and converting them grassland and other non-forested range and pasture, into something that can be transported can be expensive. totals about 612 million acres.3 Forest thinnings are trees removed for fire control or health • Forest-use land is total forestland as classified by improvements and the wood is usually not sellable, so it the U.S. Department of Agriculture (USDA) Forest could be used as a feedstock resource. Conventional wood, Service, excluding an estimated 80 million acres used in contrast, is marketable, but Stokes said that some of p ­ rimarily for parks, wildlife areas, and other uses. this wood may be diverted for use as a feedstock resource. Forest-use land totals 576 million acres in the lower Fuelwood is wood that goes to the pulp and paper industry 48 states.4 for making heat and power for their plants. It also includes • Special-uses land includes areas for rural transporta- a few of the electrical power plants that use wood. Finally, tion, recreation and wildlife, various public instal- there are the mill residues, pulping liquors, and urban wood lations and facilities, farmsteads, and farm roads, resides, such as waste paper and yard trimmings, that could including the 80 million acres of forested land noted serve as energy feedstocks, though collection is the big issue above. There are approximately 169 million acres in because many of these are diffuse resources. this category.5 Agricultural resources include grains that go into bio- • Miscellaneous land includes areas in various uses not fuel production, oil crops, and crop residues. Energy crops inventoried, marshes, open swamps, bare rock areas, include perennial grasses, such as switchgrass, bluestem, desert, tundra, and other land generally of low agricul- Miscanthus, and others, and perennial wood crops, which tural value and total about 68 million acres.6 include poplar, willow, pine, and eucalyptus, among ­ thers.o • The urban land base includes streams and canals less Agriculture also generates animal manures and food and than an eighth of a mile wide, and ponds, lakes, and feed processing residues that could serve as production reservoirs covering less than 40 acres. This category feedstocks, as well as municipal solid waste, landfill gases, total about 60 million acres.7 and annual energy crops such as sorghum. He then reviewed the 2011 update of DOE’s Billion-Ton Land use is not uniform across the United States but varies report, for which he was a co-lead. The Billion-Ton Update according to soil type, climatic conditions, and other facts. examines the nation’s capacity to produce a billion dry tons Figure 2-1 shows the major uses of land in 2007. of biomass resources annually in the 48 coterminous states for energy uses without impacting other vital U.S. farm and forest products, such as food, feed, and fiber crops. The study provides industry, policy makers, and the agricultural com- munity with county-level data and includes analyses of cur- 2Nickerson, C., R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses rent U.S. feedstock capacity and the potential for growth in of Land in the United States, 2007. Economic Information Bulletin No. 89. December 2011 [online]. Available: http://www.epure.org/pdf/0w3ea6c089- crops and agricultural products for clean energy applications. 8164-d04c.pdf. He noted that the 2011 study, unlike the earlier 2005 study, 3Nickerson, C., R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses examined both current use and potential use up to 2030, and of Land in the United States, 2007. Economic Information Bulletin No. 89. it included methodology to examine biomass potential at December 2011 [online]. Available: http://www.epure.org/pdf/0w3ea6c089- the county level. The 2011 study also included the costs for 8164-d04c.pdf. 4Nickerson, C., R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses getting biomass to the roadside for transport and includes of Land in the United States, 2007. Economic Information Bulletin No. 89. scenarios based on crop yields and tillage practices as well December 2011 [online]. Available: http://www.epure.org/pdf/0w3ea6c089- as sustainability criteria. The report, as well as all of the data, 8164-d04c.pdf. are available at www.bioenergykdf.net. 5Nickerson, C., R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses To develop county-level projections, Stokes and his col- of Land in the United States, 2007. Economic Information Bulletin No. 89. December 2011 [online]. Available: http://www.epure.org/pdf/0w3ea6c089- leagues used the POLYSYS economic model developed at 8164-d04c.pdf. the University of Tennessee Agricultural Policy Analysis 6Nickerson, C., R. Ebel, A. Borchers, and F. Carriazo. 2011. Major Uses Center (www.agpolicy.org). This model is anchored to of Land in the United States, 2007. Economic Information Bulletin No. 89. the USDA’s 10-year baseline projections for eight major December 2011 [online]. Available: http://www.epure.org/pdf/0w3ea6c089- crops, and it includes projections for biomass resources that 8164-d04c.pdf. 7Lubowski, R.N., M. Vesterby, S. Bucholtz, A. Baez, and M. Roberts. include corn stover, straws, and energy crops. The model 2006. Major Uses of Land in the United States, 2002. Economic Information also incorporates USDA-projected demands for food, feed, Bulletin No. (EIB-14) May 2006. industry, and export, and works on a land base that includes

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FEEDSTOCK AND CONVERSION TECHNOLOGIES 7 FIGURE 2-1  Land use summary. The first diagram shows land use for all states, and the second includes all states except Alaska and ­Hawaii. The land use is significantly affected by Alaska as it has a large forestry-use, special-use and miscellaneous other land areas and small cropland and pasture areas. SOURCE: Cynthia Nickerson, Robert Ebel, Allison Borchers, and Fernando Carriazo. Economic Information Bulletin No. (EIB-89). 67 pp. December 2011. http://www.ers.usda.gov/Publications/EIB89/EIB89.pdf. Figure 2-1 bitmapped uneditable 250 million acres of cropland, 22 million acres of cropland agricultural uses. Land use was assumed to change slowly pasture, 61 million acres for hay production, and 118 mil- between now and 2030, though land use for energy crops lion acres of permanent pasture. The update is based on the will increase from 63 million acres in the baseline scenario USDA baseline scenario extended to 2030 and a high-yield to 79 million acres under the high-yield scenario. Stokes scenario that increases corn yields by 1 percent annually remarked that this is significant because the model predicts over the baseline projections and that energy crop yields that the primary amount of biomass will come from energy increase by 2-4 percent annually as a result of a concerted crops that have not yet been established and for which there research and development effort. The high-yield scenario has not been enough research and information on optimizing also assumes that a larger amount of cropland will move to production yield and systems. no-till practices that allow for greater residue removal for The bottom line, said Stokes, is that current combined feedstock use within sustainability limits that prevent soil resources from forests and agricultural lands total about erosion and retain water and nutrients. Stokes noted that a 473 million dry tons annually at $60 or less per dry ton. significant amount of effort went into modeling crop residue About 45 percent of that is currently produced and the sustainability. remainder is potential additional biomass. Under both The model also assumed that energy crops would only baseline and high yield scenarios, biomass resources are be grown on cropland, cropland pasture, and permanent predicted to total from nearly 1.1 billion dry tons annually pasture without irrigation and using minimum tillage prac- by 2030 under the baseline scenario to as much as 1.6 billion tices. Energy crops also had to pay for themselves; that is, dry tons annually under the high-yield scenario. A significant the economic return had to be greater than that from other amount of that biomass under both scenarios will come from

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8 OPPORTUNITIES AND OBSTACLES IN LARGE-SCALE BIOMASS UTILIZATION increased production of energy crops, with increased use of The Feedstock Delivery System corn stover and straws also making a significant contribution Stokes then turned to the subject of raw material han- to the increase. Very little of the increase comes from forestry dling and supply systems, briefly discussing some of the because current production there is already high. Stokes different systems that are being developed and studied; see made the point that woody mill residues will not contribute Figures 2-3 and 2-4. For example, a system to handle switch- to increased energy production because very little primary grass produces large square bales as the switchgrass is being mill residue goes unused. Waste from pulp and paper mills harvested. The resulting bales require industrial equipment is already being used to make energy, he explained. There to load onto trailers. Another system for switchgrass uses is, however, a real opportunity to make efficient use of the a field chopper and solar energy to dry the harvested grass woody component of municipal solid waste and construction in the field. This type of system eliminates bale handling and demolition wood, with Stokes calling this combined and de-baling and increases the energy density of the final resource a potential gold mine. feedstock, but it does require two passes through the field, Figure 2-2 summarizes all of the data in a county-level one to cut the switchgrass, the second to collect it after dry- map showing that there is the potential to have fairly well ing. He also described a single-pass system (Figure 2-4) for distributed access to many types of feedstocks at the $60 or collecting corn residue that greatly increases the efficiency less per dry ton by 2030. Stokes noted that the Billion-Ton of collection and transport, and systems for harvesting trees study did not include algae as a potential feedstock—algae and short-rotation wood crops such as willow. was the subject of a parallel study—but that it did identify It is important when developing any collection system, 106 million acres of suitable land for algae production with he said, to consider total cost, including the expense of dry- the potential to produce 58 billion gallons of algal oil per ing materials at a refinery and labor costs. He added that a year. Those figures drop to 2.4 million acres of land and 5 bil- possible goal of research and development efforts could be lion gallons of algal oil per year when only considering lands to reduce the variability and uncertainty around feedstock that optimize productivity and minimize water use. These quality specifications in terms of sugar content, moisture, maximally productive sites are clustered in the southwest and ash. A commodity feedstock for energy and chemical and along the Gulf Coast. FIGURE 2-2  Potential county-level resources at $60 per dry ton or less in 2030 under baseline assumptions. SOURCE: 2011 U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry. Figure 2-2

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FEEDSTOCK AND CONVERSION TECHNOLOGIES 9 FIGURE 2-3  Bulk-format system to harvest, handle, store, and deliver low-moisture switchgrass. SOURCE: Image taken from Stokes presentation. Figure 2-3 4 bitmapped images, combined cropped slightly to make them even sized FIGURE 2-4  Single-pass harvest system for corn and corn stover. SOURCE: AGCO Corporation. production, explained Stokes, needs to be reliably available, DOE program, for example, is focusing on genomics-based have uniform density and stability, and must be readily research that will lead to the improved use of biomass and Figure 2-4 feedstocks for the production of fuels. This five-year, stored. As far as algae is concerned, he explained that the big- plant bitmapped uneditable effort focuses on a range of plants, including gest production barrier today is that the fundamental biology $40.1 million of algae is poorly understood. There is active fundamental rice, switchgrass, sorghum, and poplar, among others. The and applied research ongoing on algae as a potential source private sector is involved, as well, developing high-biomass of biomass, but he noted that translating indoor lab results dedicated energy crops with increased nitrogen use effi- to outdoor production environments is not a trivial matter. ciency. Stokes noted one effort, the Knowledge Discovery A variety of different programs are addressing research Framework supported by DOE, that will serve as a biomass and development needs to address the grand challenges and research and development resource library into which the achieve the vision of producing one billion tons of biomass large network of institutions in the Regional Biomass Feed- annually at a cost of $60 or less per ton. A joint USDA- stock Partnership will deposit data annually.

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10 OPPORTUNITIES AND OBSTACLES IN LARGE-SCALE BIOMASS UTILIZATION The Uniform Commodity Feedstock Vision the Billion-Ton report, but that they do have real potential as energy and chemical feedstocks. He noted that some studies The bottom line, said Stokes, is that there needs to be a are including those sources. In response to a comment from transition from picking up materials with inefficient systems Rich Green, of DOE, about the feasibility of boosting yields and just chopping it up or baling it and hauling it to the of biomass crops, Stokes noted that the Billion-Ton report biorefinery. This approach, he said, is not meeting quality places great faith in research, and particularly genomics, to specs, is not integrating well into biorefineries, and is wast- boost crop yields. ing money. Instead of trying to feed biomass directly to a biorefinery, the desired system should aim to transform raw biomass into high-density, stable, commodity feedstocks CONVERSION TECHNOLOGIES at or close to the site of production. Biomass preprocessing at Brian Duff, from DOE, began his presentation with a local preprocessing depots could become the link between review of why biomass and biofuels are so important. He biomass producers and refiners. Such depots would provide said that while he would focus his remarks on biofuels, he flexibility for local communities to produce feedstocks cus- considers biofuels to be a representative subclass of chemi- tomized for biochemical, thermochemical, and combustion cal products that should be made from biomass. He also conversion facilities. But in addition, he said, preprocess- noted that it is important to consider what he characterized ing depots would also enable the production of renewable as the awe-inspiring scale of today’s global petrochemical products, such as livestock feeds and soil amendments, that industry when thinking about where the biomass conversion would increase the economic return on such facilities. Stokes field is today. He added, though, that today is a very excit- described an ongoing effort at the Idaho National Laboratory ing time for this nascent endeavor given the convergence of to develop a highly instrumented, portable, modular process the chemical sciences, synthetic biology, biotechnology, and demonstration unit designed to represent one replicable environ­mental biotechnology. depot that would address scale-up issues and produce quan- Energy, said Duff, is a global challenge involving issues of tities of densified materials meeting specific formulations. security, the environment, and the economy, and clean energy In a uniform commodity feedstock vision, preprocessing offers potential solutions for each of these. Clean energy can depots would serve biomass production operations within translate into energy self-reliance and developing a stable, a 5- to 20-mile radius. The uniform feedstock would then diverse energy supply that does not depend on importing oil be transported by interstate trucks, short-line railroads, and from countries that can be antagonistic toward the United internal waterways to shipping terminals similar to central- States. Developing locally produced clean, renewable energy ized grain elevators and then on to biorefineries as needed. could also reduce the amount that our military now spends In closing, Stokes said that the physical and composi- to protect our access to imported oil. In terms of the envi- tional characteristics of the feedstock determine conversion ronment, clean energy means clean air, mitigating climate process and process efficiency and costs. One of the goals change, and reducing greenhouse emissions. of research is to increase the value of the biomass feedstock, Clean energy can also translate into jobs, rural economic which would increase costs on the front end, but reduce costs development, and rebuilding a manufacturing base, as further at the conversion end. Another goal going forward well as maintaining our innovation edge and reducing our should be to increase biomass accessibility, he said. The dependence on a resource whose price fluctuations have a nation has sufficient biomass resources, but its distribution significant impact on the economy. DOE estimates that each does not match that of industry today. Finally, conservation biorefinery would produce 50-75 new direct jobs and an addi- and operational practices affect not only costs but intangible tional 3,000 indirect jobs supporting the biorefinery and its benefits for society as a whole. In summary, the United States employees. A local source of clean energy would also have has the land, the will, and by bringing our sciences together, a major impact on the nation’s balance of trade, potentially we can provide the way to use biomass for feedstocks and eliminating the flow of $300 billion a year in economic value commodities in our biorefineries. out of the country that could instead go to biomass producers and processers here in the United States (Figure 2-5). Devel- Discussion oping a sustainable local source of biofuels will contribute greatly to maintaining the nation’s economic prosperity and Paul Bryan asked Stokes to list a few low-hanging fruits quality life, said Duff. in terms of biomass supply. In response, he listed forestry He noted that the Department of Defense and the airline residues and crop residues. Since these are already produced, industry are, at least in part, driving the demand to develop the development of economical collection and preprocessing biofuels. The airline industry, for example, will have to meet systems could produce results in the short term. European sustainability and biofuels requirements. Other Emily Carter, from Princeton University, asked about the considerations, he said, are that liquid fuels are a premium potential importance of algae and oil crops. Stokes replied product application unmatched in terms of energy density that there was not enough information to include those in

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FEEDSTOCK AND CONVERSION TECHNOLOGIES 11 FIGURE 2-5  The value of biofuels. The cost difference between importing crude oil and biomass. SOURCE: EIA Annual Energy Review (Duff presentation). and convenience. In the near term, biofuels are the only of biomass needed to support that infrastructure will not be alternative that fits the U.S. lifestyle. In addition, given that available immediately either. It will be necessary to balance biomass is not unlimited, the “best use” of biomass dictates the pace of the transition with the cost of the resulting disrup- that it be used in the highest value product applications. And tions. Economics, he said, must be the driving force behind Figure 2-5 transition. However, the economics of oil presents a real while converting the nation’s auto and truck fleet to electric- this ity sounds like a laudable goal, Duff added, that does not uneditable bitmapped problem given that there are many non-monetized costs that solve the greenhouse gas emissions as long as powerplants do not appear in the price of oil. Biofuels, for example, have produce electricity using coal and natural gas. Liquid fuels to meet a greenhouse gas emissions reduction requirement from biomass, he stated, are really the only option in the to meet the requirements of the Renewable Fuel Standard near term. (RFS2) that oil does not. As Duff put it, biofuels have to perform all of the miracles of sustainability and still be priced lower than oil. That is a conundrum that challenges The Potential of Biomass for Fuels, Chemicals, and Power the biofuels community. He also noted that even under the Biomass, said Duff, has the potential to dramatically provisions of RFS2, biofuels will only replace less than a reduce dependence on foreign oil for fuels and chemicals. It quarter of the U.S. demand for liquid fuels. can also promote the use of a diverse, domestic and sustain- According to DOE estimates, said Duff, the use of agricul- able energy resource and establish a domestic bioeconomy, tural, forest, and urban waste streams, combined with energy as well as reduce carbon emissions from energy production crops and algae, could replace about 50 percent of imported and consumption. He estimated that a national system of crude oil. What is needed to meet this target, he explained, biorefineries would consist of 300 to 500 plants, creating jobs are flexible platforms that can process current and future in rural economies that cannot be outsourced. Developing a products, and a portfolio approach that can be optimized biomass-based fuel economy would reduce carbon emissions across multiple feedstocks and regions. In thinking about and mitigate the direct and indirect costs of oil imports, with such platforms, Duff’s program at DOE considers ferment- positive impacts on the balance of trade and demands on able sugars, syngas, and biological oils from pyrolysis, oil our military. It would also support and potentially expand seeds, and algae. These would be used to produce ethanol, U.S. leadership and innovation in chemical engineering and renewable hydrocarbon fuels that match our current infra- chemistry. structure’s needs, and home heating oil. In creating a biorefinery infrastructure, pace will be as As far as greenhouse gas emissions are concerned, the important as direction, Duff explained. It is not possible to transportation sector’s contribution is dwarfed by the power replace a multi-trillion-dollar petroleum-based infrastructure sector. Of the 985 gigawatts (GW) of electrical power gen- with a biomass-based infrastructure overnight. The supply erated in the United States, biomass—primarily waste and

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12 OPPORTUNITIES AND OBSTACLES IN LARGE-SCALE BIOMASS UTILIZATION wood—accounts for about 13 GW, or 1.3 percent of the total. Biomass Supply and Value Chain Even if all of the 1 billion tons of biomass were diverted At DOE, the biomass program’s strategic focus is on to energy production, it would account for only 47 GW, or achieving sustainability across the supply chain. This 4.7 percent of demand. However, that same 1 billion tons of includes producing feedstocks in a way that preserves nutri- biomass would generate about 65 billion gallons of gasoline, ents and maximizes carbon cycling, as well as minimizing which would meet about 30 percent of U.S. demand. The best the impact on land and resource use. In the conversion phase, use of biomass, said Duff, is for fuels and chemicals, and that the emphasis is on minimizing water consumption and air includes diesel and jet fuel and a variety of specialty chemi- pollution while maximizing efficiency by integrating tech- cals that also come out of every barrel of oil. Duff pointed nology from feedstock to product. In the distribution step, out that although 70.6 percent of a barrel of oil is converted the goal is to reduce the carbon footprint of new facilities into fuels worth $385 billion annually, the 3.4 percent that and to use the co-products in order to maximize return and is converted into petrochemicals is worth some $375 billion minimize risk associated with relying on a single product, annually (Figure 2-6). Tapping into the enormous value of such as ethanol. And finally, there has to be a product that is petrochemicals and specialty chemicals is a place where in demand. Each of these components will need to be inte- chemistry can play a huge role in realizing value from bio- grated, for as Duff said, no one is going to grow a crop if there mass conversion, particularly since these are high value added is no plant to take it to, and no one is going to finance a new products that would use very little of the available biomass. plant if there is no crop or market for its product. FIGURE 2-6  Value in a barrel of crude oil. SOURCE: DOE (Image taken from Duff presentation). Figure 2-6 bitmapped uneditable

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FEEDSTOCK AND CONVERSION TECHNOLOGIES 13 From a value perspective, existing waste streams, both oxide and hydrogen (see Figure 2-7). This process operates agricultural and municipal, have potential because they avoid at very high temperature and also produces unconverted impacts on food, feed, and land, nutrient, and water use. Duff tars that must undergo reforming. Contaminants in syngas said that new oilseed crops, algae, and fast-growing grasses output must be removed to avoid deactivating or destroying and trees are also likely to fit into the value chain needed to the efficiency of downstream catalytic process operations. make competitively priced biofuels. The challenge, as Stokes While gasification works well with petroleum and natural noted earlier, is in integrating all of these different sources of gas, the sulfur, nitrogen, phosphorous, potassium, and min- biomass into a consistent feedstock. He noted that research eral content of biomass complicates matters. Also, the high is under way on a real-time near-infrared monitoring system oxygen content of biomass results in the production of sig- that would provide a compositional analysis of each truck- nificant quantities of carbon dioxide, which reduces carbon load of biomass coming into a preprocessing depot. He also efficiency. Research by chemists and chemical engineers is commented that biomass resources have low energy density, needed to develop new catalysts that resist contamination high water content, are perishable, and above all, have a high and have improved selectivity. The advantage of syngas is oxygen content compared to petroleum. that it creates a blank slate of single carbon atoms that can be Before leaving this subject, Duff commented on the used to build many possible molecules, including gasoline, goal of $60 per dry ton of biomass. Today, companies in diesel, and jet fuel, and a variety of value-added building the United States are building pellet mills to ship biomass blocks such as methanol, ethylene, and naphtha. Syngas, pellets to Europe that sell at a price of $120 per ton. In this said Duff, has the potential to replace the entire barrel of oil case, European countries have decided to reduce dependency except perhaps for asphalt. on Russia and Ukraine for natural gas and power and they In pyrolysis, lower temperatures are used to break down are willing to pay a premium price to achieve that goal. He biomass into smaller molecules such as oxygenated aromat- said the only way to get to $60 or lower per dry ton is by ics, ketones, organic acids, and other oxygenates, as well developing processing technologies that increase bulk den- as light hydrocarbon gases (see Figure 2-8). In addition to sity and improve harvesting efficiency. Another possibility the lower energy input to achieve biomass deconstruction, is to realize the potential of algal production of biomass and pyrolysis has a high theoretical yield for liquid products. feedstocks as part of an integrated biorefinery. With upgrading, the pyrolysis products can be fed directly into existing petrochemical refineries. The classic biochemical conversion route involves pre- Conversion Technologies treating biomass with either enzymes or acid to release sug- There are two basic options for converting biomass to ars that are then fermented. Another biochemical route uses product—biochemical and thermochemical. Duff explained anaerobic digestion to produce methane, though several new that there are two classic thermochemical options, gasifica- technologies short-circuit this process prior to full degrada- tion and pyrolysis, each of which produces different inter- tion to methane in order to produce carboxylic acids that mediates. Gasification involves rapid heating and partial can then be converted into diesel and jet fuel. Duff believes oxidation to produce syngas, which is largely carbon mon- there is a great deal of potential for other products to come FIGURE 2-7  Thermochemical conversion of biomass via gasification. SOURCE: DOE (Image taken from Duff presentation).

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14 OPPORTUNITIES AND OBSTACLES IN LARGE-SCALE BIOMASS UTILIZATION Terminal Tank Farm FIGURE 2-8  Thermochemical conversion of biomass via pyrolysis and drop-in points that could use today’s petrochemical infrastructure. SOURCE: Image taken from Duff presentation. out of this type of process development. In addition, there is 2-8Discussion Figure a new process called electrofuels that is attempting to capi- bitmapped uneditable Richard, of Pennsylvania State University, asked talize on geoautotrophs and other bacteria that create energy Tom why so much effort is being put into the production of ­sugars by metabolizing minerals or even electricity and use that from biomass when organic acids may have more uses as energy to produce fuel molecules. DOE is investing heavily chemical feedstocks. Duff agreed with that assessment and in research aimed at developing the electrofuels process to noted that work on oilseeds and algae are more heavily synthesize fuel. There are also hybrid systems under develop- focused on organic acid production. He added that it would ment, such as one that merges syngas production via gasifica- be a good idea to look at the conversion of lignocellulose tion with bacterial fermentation to produce fuel and another into organic acids rather than sugars. that takes the sugars produced from biomass degradation and From the perspective of greenhouse gas mitigation, uses chemical catalysts to convert them into fuel. ­commented David Stern of ExxonMobil, the best use of The last pathway that DOE is investigating uses algal oil biomass would be to burn it and make electricity and he as an intermediate that is then upgraded to make fuel (see wondered why DOE was not looking at the power option Figure 2-9). Again, substantial research and development is for biomass. Duff agreed with that assessment but noted needed for the use of algal oil at a commercial scale. One that converting a billion pounds of biomass into electricity of the most significant challenges algal oil faces is its heavy would be miniscule compared to reducing greenhouse gas use of water. output by the power generating industry. He added that sus- Duff concluded his talk by noting that the list of building tainability is about more than greenhouse gas emissions; in blocks, secondary chemicals, intermediates, and end prod- his mind, quality of life is an important consideration. Stern ucts that can be made from biomass feedstocks is virtually agreed with that remark and added that he felt that the real limitless, just as it is with petroleum. One issue that needs value of biomass conversion lies in rural development and to be solved is the high oxygen content of biomass; aviation job creation as part of the bigger picture of sustainability. fuels, diesel, and gasoline all have low oxygen requirements. Paul Bryan also voiced support for looking at sustainabil- Again, this a place where chemists can contribute greatly by ity through this larger lens. developing catalysts to deoxygenate biomass intermediates.

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FEEDSTOCK AND CONVERSION TECHNOLOGIES 15 Green = algae cell density FIGURE 2-9  The intermediate produced by the algal pathway is algal oil. SOURCE: Image taken from Duff presentation. Figure 2-9 bitmapped uneditable

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