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APPENDIX C Feedstocks for Producing Alternative Jet Fuels The two primary sources of feedstock for alternative fuels are fossil fuels and bio-derived feed- stocks. Fossil fuel feedstocks include coal and natural gas. Bio-derived feedstocks include plant oils, animal fats, crop residues, woody biomass, municipal solid waste, and other organic mate- rial. Each has relative strengths and weaknesses for the production of alternative jet fuel. Biofuels derived from starch, sugar, animal fats or vegetable oils are generally considered first-generation biofuels. Biodiesel, ethanol, and biogas are commonly recognized as first-generation biofuels that use established technologies. Fuels produced from biomass are referred to as second-generation biofuels and are considered to be more sustainable in the long term with a potentially smaller car- bon footprint. Second-generation biofuels are not produced commercially at this time because numerous technical challenges remain (Naik et al. 2010). The following is a discussion of each potential alternative jet fuel feedstock and the most important considerations for each. C.1 Fossil Fuels Coal and natural gas can be used to make alternative jet fuel with the FT process (see Sec- tion D.1) and are ideal feedstock for FT processes for a variety of reasons. Large FT plants are the most economical, and require ample supplies of feedstock to run at optimal capacity. Because of availability, established and cost effective transportation systems, and developed markets, coal and natural gas can support production at commercial scales. C.1.1 Sources and Availability Ample supplies of coal and natural gas at low per-unit costs support large rates of extraction for sustained periods of time. Costs and methods for coal and natural gas exploration and extrac- tion are well known, and large untapped deposits of both coal and natural gas exist in the United States and elsewhere. C.1.2 Economics and Logistics Coal and natural gas have well-developed markets, supply chains, pricing mechanisms, and risk management tools. From a transportation and logistical perspective, the required rail and pipeline infrastructure in the United States is well developed and is more cost effective than truck transportation. Coal is typically transported by rail, and natural gas is normally shipped by pipeline (EIA 2010). To take advantage of these cost-effective transportation modes, however, an alternative fuel processing facility would need to be located in proximity to existing infra- structure. Construction of new rail lines or pipelines is very expensive and time consuming and would likely compromise the viability of any alternative fuel project. For information of where 74
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Feedstocks for Producing Alternative Jet Fuels 75 existing rail and pipeline infrastructure is located, project developers can consult the National Atlas of the United States (http://www.nationalatlas.gov/natlas/Natlasstart.asp) and the U.S. Department of Transportation's National Pipeline Mapping System (http://www.npms.phmsa.dot.gov/), respectively. Transportation costs for coal and natural gas have been decreasing over the last few decades. The average utility contract cost of coal transportation has decreased sharply from $17/ton in 1980 to about $12/ton in 2005, although the share of transportation as a percentage of delivered price has increased from about 22% to 35% in the same period (Bowen and Irwin 2007). In the case of natural gas, transportation and distribution costs constitute about half of the cost of the product for residential consumers, even as the price of the commodity has fluctuated over time (Natural Gas Supply Association 2010). The average duration of utility coal contracts is sig- nificantly longer than for agricultural commodities, although there has been a decrease from 22 years in the late 1970s to about 14 years in the late 1990s (Bowen and Irwin 2007). Similar to coal, the average contract length for natural gas has decreased from 20 to 25 years to about 8 to 15 years (Neumann and von Hirschhausen 2005). Most agricultural commodities are contracted on an annual basis (MacDonald and Korb 2011). The relevance of long contracts for feedstocks is that they give processors a better estimate of future costs, which helps in the financial plan- ning. Year-to-year contracts common in agricultural commodities do not offer this advantage for long-term planning. C.1.3 Environmental Considerations The life-cycle GHG footprint of alternative jet fuels from other fossil fuels can be two to three times that of conventional jet fuel (see Box 2). Alternative jet fuel produced through the FT process from natural gas can have a GHG footprint approximately 116% that of conventional jet fuel, while alternative jet fuel from coal can have a GHG footprint 230% that of conventional jet fuel (Stratton, Wong, and Hileman 2010). Carbon capture and the use of biomass in the Box 2. Brief introduction to life-cycle greenhouse gas analysis. Life-cycle GHG analysis estimates the amount of greenhouse gases (e.g., CO2) released in the full life cycle of an alternative fuel (see Section 5.1 for a more com- plete discussion). This includes emissions from the production, distribution, and combustion of an alternative fuel including extraction, inputs to production such as tillage, planting and harvesting biomass feedstocks, processing and conversion, transportation, and storage. It is a cradle-to-grave estimate of all GHG emissions from the production of the fuel. A key concept in life-cycle GHG analysis is land-use change. Land-use change can lead to indirect GHG emissions. For example, increased demand for feedstocks that compete for land with the existing food and feed production chain (e.g., corn, soy- beans) may lead to conversion of unused land, such as grassland or forests, to agri- culture production. This can result in an increase in CO2 emissions that would be included in the life-cycle GHG analysis. Thus, LCA results can show a significant increase in GHG emissions for alternative fuels made from renewable feedstocks because of indirect land-use change. Inclusion of indirect land-use changes in life- cycle analysis is currently a controversial and politically charged debate.
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76 Guidelines for Integrating Alternative Jet Fuel into the Airport Setting feedstock stream can reduce the GHG footprint to a fraction of that of conventional jet fuel. For example, the use of CCS can lead to alternative jet fuel from coal having a GHG footprint 111% that of conventional jet fuel. Depending on the assumptions of biomass content and land- use change (see more in Section E.1), alternative jet fuel can have a GHG life-cycle footprint 20% to 60% that of conventional jet fuel (Stratton, Wong, and Hileman 2010). Carbon capture and sequestration technologies are currently under development, and their cost and effective- ness are yet to be determined at a commercial scale. C.1.4 Advantages Fossil fuel feedstocks are abundant and available at low cost. They are complementary to the scale and substantial investment necessary to operate FT plants. Both coal and natural gas have well-developed markets and supply chains. Both have been actively traded for many years, so there is ample price history and sophisticated financial instruments, such as futures and options markets, to understand prices and hedge price volatility. Fossil fuel feedstocks, price, and availability are compatible with the large capital investments required to install and operate FT plants. C.1.5 Disadvantages Fossil fuels feedstocks may have a potentially unacceptable life-cycle GHG footprint--two to three times that of conventional jet fuel. FT plants tend to be very large and capital intensive, which may deter commercialization efforts, especially in today's more conservative investment atmosphere. In addition, since there are not many commercial-scale examples in operation, it is difficult to evaluate their economics of production. C.2 Oils and Fats Plant oils and animal fats can be used as feedstocks for making alternative jet fuels via hydroprocessing (see Section D.2). Biodiesel is the only commercial-scale example of a renew- able fuel produced from vegetable oils and other fats. While HEFA and biodiesel are decidedly different products with different applications, the experience of the biodiesel industry illustrates the potential opportunities and challenges associated with the use of vegetable oils and animal fats as feedstock for alternative aviation fuels. C.2.1 Sources and Availability Many different plant oils can be used to make alternative jet fuel, including food oils such as soybean, canola, palm, sunflower, and coconut oil and nonfood oils such as Camelina, Jatropha, algae, and pennycress (Eidman 2007; Paulson and Ginder 2007; Carriquiry and Babcock 2008; IATA 2009; Moser 2009; USDA 2010i). Each has relative strengths and weaknesses. For exam- ple, mustard can be grown with relatively fewer production inputs, but yields less oil than other feedstocks such as canola (USDA 2010g; USDA 2010l). Some of these oils are currently produced at commercial or semicommercial scales in the United States. Others have not yet reached such large scales. Research is ongoing to improve the oil content (yields) and other characteristics that are advantageous to alternative jet fuel production. Nonfood oils such as those based on algae, Jatropha, pennycress, and Camelina are promising potential feedstocks with attractive charac- teristics (Qiang, Du, and Liu 2008; Moser 2009). They are adaptable, grow very quickly, and have higher oil content than other alternative fuel feedstocks (USDA 2010a). Jatropha, an oilseed plant historically grown in tropical areas, has high concentrations of oil and can be grown in poor-
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Feedstocks for Producing Alternative Jet Fuels 77 quality soils not suitable for traditional agricultural crops. It may be adaptable in southern regions of the United States (FAO 2009; USDA 2010l). Pennycress, Camelina, and other tree oils also are promising potential feedstocks with high oil content that have the potential to be grown without competing for land availability with traditional crops. Microalgae have been shown to have particularly attractive characteristics. Alga is plant that grows in water and has a remarkable capability of producing large amounts of oil. Of the several types of algae, two of them--cyanobacteria and microalgae--grow in diverse environments, including wastewater and salt water. Microalgae and cyanobacteria produce oil via photosynthe- sis, in open or closed ponds, or in the dark using nutrients supplied by the growers (DOE 2010). Another remarkable property of algae is that, unlike other plants used for biofuels, they do not compete with food stocks for land and do not consume water. Some strains of algae have the potential to produce more than 30 times the amount of oil per acre per year than any other plant currently used to produce alternative fuels (Verrengia 2009); see Table 16. However, current production yields are not commercially viable. Jet fuel derived from algae holds great promise as a second-generation biofuel to satisfy the needs of the aviation industry. However, the technical promise is tempered by concerns about the financial and environmental viability of turning algae into fuel. The primary concern and unresolved issue with algae from open-pond and closed-pond systems is the energy cost and life- cycle carbon impacts of maintaining temperature and extracting water. These leave algae-based fuels as having potentially uncompetitive cost and unacceptable carbon life-cycle footprint out- comes based on currently reported research (Stratton, Wong, and Hileman 2010). The process of creating jet fuel from algae is still very much in the research stage. As a result, it is difficult to discuss economic and production issues in detail. Animal fats (tallow), frying oils, and greases may also be used to produce alternative jet fuel. Expanding the use of frying oils and greases may represent a potential alternative fuel feedstock. Generally considered waste products, these materials are more economically attractive than refined vegetable oils. However, quality control problems with this feedstock may produce unacceptable fuels and require additional processing (Eidman 2007; Canakci and Sanli 2008; USDA 2010q). These materials are also in limited supply, thereby constraining their use as a fuel on a commercial scale (Knothe 2010). Tallow, a rendered form of animal fat that is high in triglycerides, can also be used in the HJR processes to make alternative jet fuel (Bauen et al. 2009). Tallow is used in a wide variety of products, including margarine, cooking oil, soap, can- dles, and lubricants (CRB 2008). Availability of tallow is most likely to remain steady as it is a by-product of the meat processing industry. Table 16. Estimates of oil yield potential for different feedstocks (DOE 2010). Feedstock Oil Yield (gallons/acre/year) Soybean 48 Camelina 62 Sunflower 102 Jatropha 202 Oil palm 635 Algae 1,0006,500
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78 Guidelines for Integrating Alternative Jet Fuel into the Airport Setting C.2.2 Economics and Logistics As is the case with the production of biodiesel made from oils and fats, feedstock cost is expected to be the largest cost component in the production of alternative jet fuel from plant oils. Some plant oils that could potentially support commercial-scale production of alternative jet fuel, such as soybean oil, are already expensive to produce. In addition, because soybean and other plant oils are also used for human and animal consumption and in the production of biodiesel, competition for this feedstock is likely to keep prices high. Currently, the high cost of feedstock is limiting the further development and commercialization of the biodiesel industry (Al-Zuhair 2007; Ng, Ng, and Gan 2009). Currently, biodiesel cannot compete with conven- tional diesel and likely will not in the foreseeable future without some form of public policy incentive (Al-Zuhair 2007; Carriquiry and Babcock 2008; Ng, Ng, and Gan 2009). Aviation alter- native fuels such as HEFA production would likely face similar challenges. Therefore, there is great interest in alternative oilseed feedstocks such as Jatropha, pennycress, and Camelina that can be produced at a lower cost. Soybean oil and other oilseed feedstocks have well-developed markets, available risk manage- ment tools, and well-developed supply chains. Markets, pricing mechanisms, risk management tools, and contract and supply chain considerations would all have to be developed for algae, Jat- ropha, and other feedstocks not currently produced at a commercial scale. Markets, transporta- tion, and infrastructure considerations for oilseeds not currently produced at a commercial scale, such as mustard or Camelina (both of which have characteristics similar to traditional oilseeds), would be expected to develop and function similarly to existing commodity markets and sys- tems (Olson, pers. comm.). Transportation and logistical considerations for bio-based feedstocks depend greatly on the type of feedstock. For traditional oilseeds such as soybean and canola, project developers can take advantage of existing transportation and logistics infrastructure. Currently, agriculture com- modities are largely transported by rail and truck. For new types of oilseeds, such as Camelina, it is likely that the existing truck and rail transportation and logistics systems will be sufficient. Like coal and natural gas feedstocks, the production facility would have to be located within reach of the existing infrastructure to enjoy the full benefits. If production of oilseeds for bio- fuels were to increase substantially, additional crushing and refining capacity would need to be developed. As is the case with current crushing and refining facilities, additional capacity for new oilseeds would need to be located in proximity to the commodity production area and existing transportation infrastructure to minimize capital costs. Supplies of tallow and municipal solid waste are likely to be constrained by the cost of trans- portation and other logistics. Tallow is typically stored in heated tanks and must be kept at a min- imum of 65°C to thwart the growth of bacteria and enzymatic activity (Food Science Australia 1997). Transportation costs can be expensive due to the need to maintain these specific ambient conditions. These materials are also in limited supply, thereby constraining their use as a fuel on a commercial scale (Knothe 2010). C.2.3 Environmental Considerations Alternative jet fuels from plant oils and fats may have a lower life-cycle GHG footprint compared to conventional jet fuel; however, the life-cycle GHG footprint of alternative jet fuels from plant oils is very dependent on land use. If the plant oil is grown on existing crop- land, the land-use change impact may be limited; however, if forest or grassland needs to be cleared to meet the demand for plant oil, the land-use impact would be significant. Plant oils that can grow in fallow or on marginal lands, such as Jatropha and Camelina, can mitigate some of these concerns.
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Feedstocks for Producing Alternative Jet Fuels 79 C.2.4 Advantages Some plant oils are available in commercial quantities and have developed markets, supply chains, and transportation systems. Some alternative feedstocks have great potential. Some strains of algae have the potential to produce more than 30 times the amount of oil per acre per year than any other plant currently used to produce alternative fuels. C.2.5 Disadvantages Oil-based alternative jet fuel feedstocks will likely have high costs, similar to biodiesel. Cur- rently, feedstock costs make up 80% or more of the cost of HEFA. Improving the productivity of oil plants is critical to achieving competitive costs for alternative jet fuel. USDA has programs in place to improve yields over time, much like the manner in which food crop yields have improved over time. Current production yields for algae are not commercially viable and are still in the research stage. Algae-based fuels may not be cost competitive with conventional fuels and may have an unacceptable carbon life-cycle footprint. Tallow-based oils enjoy a steady supply, but storage and transportation issues may constrain their use as a feedstock. Furthermore, their limited supply may constrain their use on a large- scale commercial basis. C.3 Biomass Feedstocks Biomass feedstocks can consist of any biomass source but are generally divided into three cat- egories: energy crops, agricultural residues, and woody biomass. The potential supply of biomass is substantial, although there are considerable constraints related to its bulk. Biomass can be used with the FT process to produce alternative jet fuel. C.3.1 Sources and Availability Energy crops are grown specifically for biofuels production, including alternative jet fuel. In order to prevent competition with current agricultural production activities and in an attempt to reduce their production costs, energy crops will likely be grown on land that is currently seen as marginal for traditional crop production. In 1984, the U.S. DOE funded the Herbaceous Energy Crops Program (HECP). After evaluation of 35 energy crops of which 18 were perennial grasses, the DOE selected switchgrass as the native grass with the greatest potential as an energy crop. In 1991, the DOE's Bioenergy Feedstock Development Program (BFDP), which evolved from the HECP, continued research on switchgrass and identified the following advantages as an energy crop: (1) capacity for high yields on poor-quality sites not suitable for conventional crops, (2) adaptability to a variety of soils and climatic conditions with relatively low input requirements, (3) easily integrated into conventional farming operations, (4) adaptable to once-per-year har- vesting, and (5) suitable for harvest with conventional hay equipment (Lewandowski et al. 2003; USDA 2010o). In recent years, researchers have focused attention on several other potential energy crops, includ- ing Miscanthus (Lewandowski et al. 2003; Busby et al. 2007; Khanna, Dhungana, and Clifford- Brown 2008; USDA 2010j), energy cane (Mark, Darby, and Salassi 2010), wheatgrass, and bluestem (Nyren et al. 2007). Results to date indicate that some alternative crops may outperform switchgrass in some locations. Energy crop production will likely vary regionally. Agricultural residues such as corn stover and wheat straw are other promising sources of bio- mass feedstock for alternative jet fuel production. Corn stover includes the leaves and stalks of
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80 Guidelines for Integrating Alternative Jet Fuel into the Airport Setting the corn plant; wheat straw is the unharvested wheat stalk. These products account for most of the agricultural residues with feedstock potential (Maung and McCarl 2008). Agricultural residues have an advantage over energy crops because they are not dedicated to energy produc- tion. Corn and wheat are already under production for the grain produced by the plants, and therefore the production cost of the stover and straw is already covered (Gallagher 2006). How- ever, a farmer will likely require payment. It is important to keep in mind that not all of a field's crop residues can be collected. Crop residues have important soil quality benefits, namely nutri- ent cycling and moisture retention. While potential supplies are substantial, research is ongoing to understand how much crop residue biomass can be removed without detrimental impacts. Woody biomass and by-products are also potential feedstocks. The lumber, mill, pulp, and paper industries have long used by-products of mill activities as a source of energy. Most avail- able supplies are currently consumed by the industry (Rousseau 2010). More recently, pyrolysis technology has been developed that uses woody biomass as a feedstock for liquid fuels; however, the conversion process is not yet competitive with petroleum fuels (Rousseau 2010). Milbrandt (2005) estimates the quantities of woody biomass potentially available for biofuels production. Recent declines in these industries, however, are driving down the costs of woody biomass and spurring interest in its use for producing alternative jet fuel (Lane 2010). The type and availability of biomass varies considerably based on geographic region. A list of some existing and potential feedstocks by region across the United States can be found at the USDA National Renewable Energy Lab's interactive Biofuels Atlas (http://maps.nrel.gov/ biomass and http://www.nrel.gov/gis/mapsearch/index.html). The "Billion-ton Report" also details potential biomass resources (Perlack et al. 2005). C.3.2 Economics and Logistics Energy crops would need to be grown on marginal lands not appropriate for traditional agri- culture production in order to keep feedstock cost low. Absent production on marginal lands, energy crops will have to compete for land use with current agriculture production activities and provide a return to producers at least equal to current production. Agriculture residues such as corn stover and wheat straw have an economic advantage over dedicated energy crops because they are by-products of corn and wheat production. Even though the production costs of agri- cultural residues are already covered by existing revenues, producers will likely require additional incentives as compensation for harvest, collection, and transportation costs. Furthermore, agri- cultural residues have soil quality benefits such as nutrient cycling and moisture retention; there- fore, not all agriculture residues could be collected. There are numerous challenges associated with the use of dedicated energy crops and agricul- ture crop residues as alternative fuel feedstock. Because there are no widely established markets or infrastructure for these types of feedstocks, contracting and supply-chain considerations need to be resolved before producers would be willing to supply a dedicated energy crop or agricul- ture residue. Most energy crops take more than one year to establish, and it is likely there would not be an alternate market for energy crops during that time. Therefore, a producer may require an upfront payment and/or a multiyear contract before producing an energy crop (Leistritz et al. 2009). Furthermore, producers would need to receive a rate of return on energy crops at least equal to what they could expect to receive from current production activities. The Biomass Crop Assistance program created in the 2008 Farm Bill attempts to address these issues by providing payment to farmers for establishing energy crops (USDA 2010b). Harvest of energy crops and agricultural residues adds another dimension of complexity to the logistics of these feedstocks. On the one hand, biomass harvest is seasonal and the timing of the harvest may vary depending on crop and region of the county. On the other hand, alterna-
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Feedstocks for Producing Alternative Jet Fuels 81 tive fuel processing facilities need feedstock year round in order to maximize utilization of cap- ital assets. Therefore, processing facilities will require storage of large quantities of feedstock (DOE 2003; Leistritz et al. 2009; Rentizelas, Tolis, and Tatsiopoulos 2009; Inman et al. 2010). Furthermore, the economics of transporting these bulky and not very dense materials limits their collection to a maximum distance of about 50 miles from the processing facilities (Aden et al. 2002; Hess, Wright, and Kenney 2007; Mapemba et al. 2007; Lazarus 2008; Leistritz et al. 2009). Densification techniques such as grinding, pelleting, and cubing have been examined as ways to improve the bulk density of biomass to improve storage and transportation logistics; however, densification adds to the cost of biomass (DOE 2003; Sokhansanj and Turhollow 2004; Carolan, Joshi, and Dale 2007; Kumar and Sokhansanj 2007; Brechbill and Tyner 2008; Petrolia 2008). The huge quantities of biomass required to support commercial-scale operations make trans- portation and logistical issues very challenging. Densification and pretreatment techniques to address these issues are being studied. Woody biomass not currently utilized for other products and processes, such as harvest residues, faces logistical challenges similar to crop residues and energy crops due to low bulk density. C.3.3 Environmental Considerations Assumptions about life-cycle analysis and land use can have a bearing on the life-cycle GHG footprint of alternative jet fuels made from biomass feedstocks. In order to prevent competing uses for land, dedicated energy crops will need to be grown on land that is marginal for tradi- tional agriculture. Assuming no changes in land use, the life-cycle GHG footprint of alternative jet fuels from biomass can be less than that of conventional jet fuels (see Section E.1). C.3.4 Advantages Energy crops may be able to grow on land not suitable for traditional agriculture, are adapt- able to various soils and climates, and integrate well with conventional agriculture. The use of marginal land for energy crops eliminates the competition for land with traditional agriculture commodity production, reduces production costs, and avoids food-versus-fuel concerns (see Box 3 for more information). Agriculture residues may be available in sufficient quantities to potentially support a commercial conversion facility. Corn stover and wheat straw have the greatest potential as low-cost, first-generation biomass feedstocks. C.3.5 Disadvantages Harvest, storage, transportation, and logistical challenges are major impediments. The low bulk density and the sheer volume of biomass needed to support a commercial conversion facil- ity represent significant hurdles to commercialization. In addition market, supply chain, con- tracting, and other producer issues would also need to be resolved before commercialization efforts would be feasible. C.4 Municipal Solid Waste C.4.1 Sources and Availability MSW includes a wide array of discarded materials such as residential and commercial garbage, plastics, textiles, wood, yard trimmings, and food scraps. In some areas, MSW can also include non- solid materials such as sludge from wastewater treatment plants. Given the diversity of materials involved with MSW, different technologies can be used to produce alternative fuels (Williams
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82 Guidelines for Integrating Alternative Jet Fuel into the Airport Setting Box 3. Questions regarding food versus fuel. The "food-versus-fuel" debate arises from questions related to the use of agricul- tural food commodities for the production of alternative fuels. The debate stems from a spike in animal feed costs and food prices in 2008 and the rapid develop- ment and expansion of the corn ethanol industry. Currently, nearly 35% of the domestic corn crop is used for ethanol production (USDA 2011). Some people fear that the use of corn as a feedstock for alternative fuel production will lead to higher food prices and perhaps even compromise food supplies (Brown 2007; Sagar and Kartha 2007; Vidal 2010). Others argue that the rapid increase in food prices in 2008 was the result of high energy costs, not corn ethanol production (Baffes and Haniotis 2010). Others contend that biofuels can be produced without affecting food production (Dale et al. 2010). The issue has become politically charged, and there is little consensus of the role of alternative fuel production on food produc- tion and prices. Second-generation feedstocks that are not used for food or animal feed and that do not have any indirect land-use effects (see Box 1) would in theory eliminate any potential food-versus-fuel debate. Examples of potential second- generation feedstocks are agricultural residues such as wheat straw and corn stover, dedicated energy crops such as switchgrass, woody biomass, municipal solid waste, alternative oilseed feedstocks such algae and Jatropha, and nonfood oilseeds such as mustard seed and Camelina. However, in order for second-generation feedstocks, with the exception of agricultural crop residues, to have no impact on food or feed production, they would have to be cultivated on land not currently used or suitable for traditional agriculture production. 2007). For example, organic material such as food residues and yard clippings can be combined with FT processes to produce liquid fuels. Vegetable oils and other greases can be used with trans- esterification or hydrogenation processes to produce biodiesel or alternative jet fuel (Wiltsee 1998; IATA 2009). C.4.2 Economics and Logistics Once recyclables are removed, waste-to-energy providers and landfills compete for the remaining MSW. Depending on the locality, MSW generators may pay for its disposal. In some instances, however, depending on the market structure and scarcity value of the waste, MSW generators may receive payment for access to their waste. Because of MSW's bulk, an alternative jet fuel processing plant would need to be sited close to existing waste flows. MSW may need to be preprocessed prior to conversion into feedstock. While the preprocessing technology exists, it can add cost to the entire process. Use of municipal waste as a feedstock provides waste producers with economic benefits that could include reduction of tipping and transportation costs, especially in locations where land- fills are fully depleted and where significant cost and energy resources are used to transport waste to remote locations. Broader community benefits could include reduction of landfills and the methane they produce (Brandes 2007) and potential reduction of greenhouse gases (Shi, Koh, and Tan 2009). The diverse nature of municipal waste necessarily involves diverse supply chains for different types of waste. In general, however, it is expected that project developers interested in using
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Feedstocks for Producing Alternative Jet Fuels 83 municipal waste as feedstock will have to work within the established transportation and logis- tics infrastructure to minimize cost. C.4.3 Environmental Considerations Environmental benefits can be tailored to some extent. If an objective is to maximize life-cycle GHG footprint reduction, then plastics and tires can be left out of the feedstock. If an objective is to eliminate the use of landfills, plastics and tires can be included in the feedstock, although this would suboptimize the potential life-cycle GHG reduction. C.4.4 Advantages Municipalities may recapture some of their waste-collection costs by selling MSW to refiners. In addition, using MSW can reduce the need for landfills and decrease the associated methane and other greenhouse gasses. C.4.5 Disadvantages There are several challenges to using MSW as a feedstock, including consistency and reliability of supply, proximity of waste to the conversion facility, sorting, and preprocessing. The potential perception that an MSW-based alternative jet fuel plant and the accompanying transportation infrastructure degrade the local municipal environment must also be addressed. Furthermore, it needs to be noted that some may perceive use of MSW for fuel as competing with existing recycling programs by diverting waste that would otherwise be recycled to fuel production.