America's Energy Future Technology and Transformation (2009) / Chapter Skim
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5 Alternative Transportation Fuels
5 Alternative Transportation Fuels
Pages 211-270
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From page 211... ...
While coal liquefaction is potentially a major source of alternative liquid transportation fuels, the technology is capital intensive. Moreover, on a life-cycle 211
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From page 212... ...
This chapter assesses the potential for using coal and biomass to produce liq uid fuels in the United States; provides consistent analyses of technologies for the production of alternative liquid transportation fuels; and discusses the potential for use of coal and biomass to substantially reduce U.S. dependence on conven tional crude oil and also reduce greenhouse gas emissions in the transportation sector.
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From page 213... ...
. Assuming that technologies for conversion will be commercially viable, liquid fuels made from lignocellulosic biomass2 can offer major greenhouse gas reductions relative to petroleum-based fuels, as long as the biomass feedstock is a residual product of some forestry and farming operations or is grown on marginal lands that are not used for food and feed crop production.
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From page 214... ...
per year of biomass could potentially be made available for the pro duction of liquid transportation fuels using technologies and management prac tices of 2008 and (2) that the cellulosic biomass supply could increase to about 550 million dry tons (500 million dry tonnes)
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From page 215... ...
all cellulosic biomass estimated to be available for energy production would be used to make liquid fuels. The last assumption allowed the committee to estimate the potential amount of such fuel that could be produced.
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From page 216... ...
, 40–50 miles has historically been the maximum distance con sidered economically feasible for biomass transport. An estimated 290 sites could supply from 1,500 up to 10,000 dry tons per day (from 0.5 million to 3.7 million dry tons per year)
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From page 217... ...
Findings: Biomass Supply and Cost An estimated annual supply of 400 million dry tons of cellulosic biomass could be produced sustainably with technologies and management practices already available in 2008. The amount of biomass deliverable to conversion facilities could probably be increased to about 550 million dry tons by 2020.
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From page 218... ...
of liquid transportation fuels uses approximately 7 million tons of coal per annum, 100 such plants -- producing 5 million bbl/d of liquid transportation fuels -- would require about 700 million tons of coal per year, or a 70 percent increase in the nation's coal consumption. That would require major increases in coal-mining and transportation infrastruc ture, both in bringing coal from the mines to the plants and in bringing fuel from the plants to the market.
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From page 219... ...
The analysis could include several scenarios, one of which would assume that the United States will move rapidly toward increasing use of coal-based liquid fuels for transportation to improve energy security. An improved understanding of the immediate and long-term environmental effects of increased mining, transpor tation, and use of coal would be an important goal of the analysis.
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From page 220... ...
of coal, biomass, or combined coal and bio mass into liquid transportation fuels. Biochemical conversion typically uses enzymes to transform starch (from grains)
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From page 221... ...
Although the committee focused on cellulosic ethanol as the most deployable technology over the next 10 years, it sees a long-term transition to conversion of cellulosic biomass to higher-energy alcohols or hydrocarbons -- so-called advanced biofuels -- as having significant long-term potential. The challenge in biochemical conversion of biomass into fuels is to first break down the resistant structure of a plant's cell wall and then to break down the cellulose into five-carbon and six-carbon sugars fermentable by microorganisms; the effectiveness with which this sugar is generated is critical to economic biofuel production.
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From page 222... ...
, and plants size (40 and 100 million gallons per year, corresponding to daily feed rates of 1400 and 3500 dry tons, respectively)
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From page 223... ...
If ethanol is to replace a substantial volume of transportation gasoline, an expanded infrastructure will be required for its distribution. (The transport and distribution of synthetic diesel and gasoline produced from thermochemical conversion are less challenging because they are compatible with the existing infrastructure for petroleum-based fuels.)
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From page 224... ...
Biochemical conversion processes, as configured in cellulosic-ethanol plants, produce a stream of relatively pure CO2 from the fermenter that can be dried, compressed, and made ready for geologic storage or used in enhanced oil recov ery with little additional cost. Geologic storage of the CO2 from biochemical conversion of plant matter (such as cellulosic biomass)
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From page 225... ...
These challenges will need to be resolved by R&D and demonstration if major advances in the production of alternative liquid fuels from renewable resources are to be realized. Research support from the federal government could help focus advances in bioengineering and the expanding biotechnologies on the development of advanced biofuels.
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From page 226... ...
Sasol now produces more than 165,000 bbl/d of transportation fuels from coal, and it has built large plants based on conversion of natural gas into synthesis gas, which is then converted into diesel and gasoline by FT. As with several other ready-to-deploy technologies, FT will likely undergo significant pro cess improvements by 2020.
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From page 227... ...
Inclusion of biomass in the feedstock with coal decreases the greenhouse gas life-cycle emissions because the biomass takes up atmospheric CO2 during its growth. Thus, it is possible to optimize the biomass-plus-coal indirect liquefaction process to produce liquid fuels that have somewhat lower life-cycle greenhouse gas emissions than does gasoline, and even to make carbon-neutral liquid fuels if geologic storage of CO2 is used.
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From page 228... ...
Some key results of the analysis are given in Table 5.4, and the complete results are contained in the report Liquid Transportation Fuels from Coal and Biomass: Technological Status, Costs, and Environmental Impacts (NAS-NAE NRC, 2009)
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From page 229... ...
Total liquid fuels cost ($/gal 1.50 1.64 1.57 2.52 3.32 of gasoline equivalent) Break-even oil price ($/bbl)
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From page 230... ...
As a first step toward accelerating the commercial demonstration of coal-to liquid and coal-and-biomass-to-liquid fuels technology and addressing the CO2 storage issue, commercial-scale demonstration plants could serve as sources of CO2 for geologic storage demonstration projects. So-called capture-ready plants that vented CO2 would create liquid fuels with higher CO2 emissions per unit of usable energy than petroleum-based fuels produce; commercialization of these plants would not be encouraged unless they were integrated with geologic storage of CO2 at their start-up.
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From page 231... ...
Biomass gasification and combined biomass and coal gasification have potential CO2-reduction benefits, but they can be brought to commercialization only if such practical issues are resolved. Findings: Thermochemical Conversion Technologies for the indirect liquefaction of coal to transportation fuels are commercially deployable today; without geologic storage of the CO2 produced in the conversion, however, greenhouse gas life-cycle emissions will be about twice those of petroleum-based fuels.
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From page 232... ...
If decisions to proceed with com mercial demonstrations are made soon so that the plants could start up in 4–5 years, and if CCS is demonstrated to be safe and viable, those technologies would be commercially deployable by 2020. The technology for producing liquid transportation fuels from biomass or from combined biomass and coal via thermochemical conversion has been demonstrated but requires additional development to be ready for commercial deployment.
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From page 233... ...
The analyses presented in this section use those inputs to derive life-cycle costs and CO2 emissions for the alternative fuels. To examine the potential supply of liquid transportation fuels from non petroleum sources, the committee developed estimates of the unit costs and quan tities of various biomass sources that could be made available.
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From page 234... ...
Various combinations of biomass feedstocks could, in principle, be converted with either thermochemical or biochemical con version processes.6 However, rather than examining all possible combinations, the committee first examined the cost of and CO2 emission associated with each of the various thermochemical and biochemical conversion processes by using a generic biomass feedstock with approximately a median cost and biochemical composi tion (the committee used Miscanthus in the analysis) and then examined the costs, supplies, and CO2 emissions associated with one thermochemical conversion pro cess and one biochemical conversion process that would use each of the different biomass feedstocks.
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From page 235... ...
Figure 5.4 shows the estimated gasoline-equivalent7 costs of alternative liquid fuels, without a CO2 price, produced from biomass, coal, or combined coal and biomass. Liquid fuels are produced using biochemical conversion -- to make cellulosic ethanol from Miscanthus -- or using thermochemical conversion via FT or MTG.
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From page 236... ...
In contrast, CO2 emissions of cellulosic ethanol with out CCS are close to zero. Figure 5.4 shows that FT coal-to-liquid fuel products with and without geo logic CO2 storage are cost-competitive at gasoline-equivalent prices below $70/bbl (this represents equivalent crude-oil prices of about $55/bbl)
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From page 237... ...
With CCS, the life-cycle CO2 emissions from FT and MTG are about the same as those from petroleum gasoline. The biochemical conversion of biomass produces fuels that are more expen sive than coal-to-liquid fuels because the conversion plants are small and the feedstock is more expensive -- biomass costs almost four times as much as coal on an energy-equivalent basis.
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From page 238... ...
Gasoline at crude oil price of $60/bbl 075 095 Gasoline at crude oil price of $100/bbl 115 135 Cellulosic ethanol 115 110 Biomass-to-liquid without CCS 140 130 Biomass-to-liquid with CCS 150 115 Coal-to-liquid without CCS 065 120 Coal-to-liquid with CCS 070 090 Coal-and-biomass-to-liquid without CCS 095 120 Coal-and-biomass-to-liquid with CCS 110 100 aNumbers are rounded to nearest $5. Estimated costs of fuel products for coal-to-liquids conversion represent the mean costs of fuels produced via FT and MTG.
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From page 239... ...
For example, thermochemical conversion of biomass costs about $150/bbl of gasoline equivalent with CCS, but with the carbon price and CCS, the produced fuels become competitive with petroleum-based fuels at about $115/bbl of gasoline equivalent ($100/bbl of crude oil equivalent)
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From page 240... ...
240 Additional Transportation Cost Nonfeedstock Operating Cost 220 Capital Cost 200 Feedstock Cost Total Cost (without carbon price) 180 160 $114 $132 $134 140 $126 $121 $121 $111 $105 $116 120 $115 $95 $95 $94 100 $88 80 60 40 20 0 –20 –40 –60 BTL CFT CBFT CFT-CCS CMTG CMTG-CCS Corn Ethanol CBMTG CBMTG-CCS Crude Oil @ $60/bbl Crude Oil @ $100/bbl Cellulosic Ethanol BTL-CCS CBFT-CCS FIGURE 5.6 Cost of alternative liquid fuels produced from coal, biomass, or coal and biomass with a $50/tonne CO2 price.
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From page 241... ...
To provide a more complete picture of alternative liquid fuels, the supply function from Figure 5.3 for all biomass feedstocks has been combined with the conversion-cost estimates. (The potential supply of gasoline and diesel from coal-to-liquids technology is discussed in the section below titled "Deployment of Alternative Transportation Fuels.")
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From page 242... ...
shows potential supply and not the committee's projected penetration of cellulosic ethanol in 2020. This is because it does not incorporate lags in implementation of the technology that will result because of the time required to obtain permits for and build the infrastructure to produce and transport these alternative liquid fuels.
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From page 243... ...
Thus the estimates represent the maximum potential supply.) Findings: Costs and Supply Alternative liquid transportation fuels from coal and biomass have the potential to play an important role in helping the United States to address issues of energy security, supply diversification, and greenhouse gas emissions with technologies that are commercially deployable by 2020.
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From page 244... ...
To illustrate the lag between the time when technology becomes com mercially deployable and the time when significant market penetration of its prod uct occurs, the committee developed a few plausible scenarios. Cellulosic Ethanol Regarding biochemical conversion to cellulosic ethanol, the committee took into account the current activities with demonstration plants, the announced com mercial plants, the DOE road map, and the rate of construction of grain ethanol plants.
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From page 245... ...
Continued aggressive capacity build could yield 30 billion gallons of cellulosic ethanol per year by 2030 and up to 40 billion gallons per year of cellulosic ethanol by 2035. The latter would consume about 440 million dry tons of biomass annually and replace 1.7 million barrels per day of petroleum-based fuels.
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From page 246... ...
The analysis shows that capacity growth rates would have to exceed historical rates considerably if 550 million dry tons per year of biomass were to be converted to liquid fuels in 2030. Findings: Coal-and-Biomass-to-Liquid Fuels If commercial demonstration of cellulosic-ethanol plants is successful and com mercial deployment begins in 2015, and if it is assumed that capacity will grow by 50 percent each year, cellulosic ethanol with low CO2 life-cycle emissions can replace up to 0.5 million barrels of gasoline equivalent per day by 2020 and 1.7 million barrels per day by 2035.
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From page 247... ...
and the scale of current petroleum imports (about 56 percent of the petroleum used in the United States is imported) , a business-as-usual approach is insufficient to address the need to find alternative liquid transportation fuels, particularly because development and demonstration of technology, construction of plants, and implementation of infrastructure require 10–20 years per cycle.
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From page 248... ...
ENVIRONMENTAL IMPACTS BEYOND GREENHOUSE GAS EMISSIONS Biomass Supply Although greenhouse gas emissions have been the central environmental focus regarding biomass production for alternative liquid fuels, other key effects must also be considered. On the one hand, lignocellulosic biomass feedstocks offer dis tinct advantages over food crop feedstocks with respect to water-use efficiency, nutrient and sediment loading in waterways, enhancement of soil fertility, emis sions of criteria pollutants, and safeguarding habitat for wildlife and other species, especially those that provide biocontrol services for crop production.
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From page 249... ...
Water usage in thermochemical conversion plants depends primarily on the water-use philosophy implicit in the plant design. For the conversion of coal and combined coal and biomass to transportation fuels with all water streams recycled or reused, the major consumptive use of water would generally be for cooling, hydrogen, and solids handling.
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From page 250... ...
In other words, failure to link the critical environmental, economic, and social needs and address them as an integrated system could reduce the availability of biomass for conversion to levels significantly below the 550 million tons techni cally deployable in 2020. Challenge 2 For the thermochemical conversion of coal, or of combined coal and biomass, to have any significant impact on reducing U.S.
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From page 251... ...
Meanwhile, ultimate requirements for selection, design, monitoring, carbon accounting procedures, liability, and associated regulatory frameworks have yet to be developed, creating the possibility of delay in initiating demonstration projects and, later, in licensing individual commercial projects. Large-scale demonstrations and establishment of procedures for operation and long-term monitoring of CCS have to be actively pursued in the next few years if thermochemical conversion of biomass and coal is to be ready for commercial deployment by 2020.
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From page 252... ...
But the costs of fuels are dynamic, fluctuating as a result of externalities such as the costs of feedstocks, labor, and construction; the economic environment; and government policies. With the wide variation in most commodity prices, especially for oil, investors will need to have confidence that policies -- including carbon caps, carbon price, mandated greenhouse gas reductions, or tariffs on imported oil -- will ensure that alterna tive liquid transportation fuels can compete with fuels refined from crude oil.
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From page 253... ...
As currently envisioned, it involves the biochemical conversion of sugars or starches (from sugar beets, sugar cane, corn, wheat, or cassava) into biobutanol using a genetically engineered microorganism, Clostridium beijernickii BA101.
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From page 254... ...
. Therefore approaches to developing hydrocarbon fuels produced directly from biomass, and that are analogous to fuels produced from petroleum, are being explored (Huber et al., 2006)
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From page 255... ...
Based on work thus far, the keys to success in these processes appear to be the achievement of sufficient yield of the hydrocarbon product, development of highactivity catalysts with long-term stability, and minimization of coking reactions. Bacteria- and Yeast-Based Direct Routes to Biofuels With the rapid growth of synthetic biology and the enhanced ability to engineer organisms' metabolic pathways so as to produce specific chemical products, new approaches to renewable fuel production are emerging (Savage, 2007)
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From page 256... ...
Technologies to Improve Biochemical Conversion Significant advances are being made in the areas of genomics, molecular breeding, synthetic biology, and metabolic and bioprocess engineering that will likely enable innovation and advancement in the development of alternative transportation fuels. These and related technologies have the potential to greatly accelerate the creation of dedicated or dual-purpose energy crops as well as of microorganisms useful both for feedstock-conversion processes and biofuel production.
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From page 257... ...
And the rapid and inexpensive sequencing of fermentative and photosynthetic microorganisms in particular is redefining and shortening the timelines associated with straindevelopment programs for converting sugars, lignocellulosic materials, and CO2 into alternative liquid fuels. Strains generated through classical mutagenesis that have improved biocatalytic properties can now be analyzed at the molecular level to determine the specific genetic changes that result in the improved phenotype, allowing those changes to be implemented in other strains.
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From page 258... ...
OTHER TRANSPORTATION-FUEL OPTIONS READY FOR DEPLOYMENT BY 2020 AND 2035 So far in this chapter, the committe has focused strictly on certain liquid fuels and considered only biomass and coal as feedstocks, but in this section it explores the advantages and disadvantages of other known transportation-fuel options. The first to be considered is compressed natural gas (CNG)
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From page 259... ...
. But natural gas is the cleanest and most efficient hydrocarbon fuel -- it is environmentally superior to coal for electric power generation -- and for similar reasons it could be a sound choice for transportation fuels.
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From page 260... ...
to the number of natural gas refueling stations. According to Yeh (2007)
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From page 261... ...
Sasol in Nigeria and Qatar, as well as Shell in Malaysia and Qatar, produce GTL diesel fuel; a number of companies, including World GTL and Conoco Phillips, have plans to build GTL plants in the next several years. Because the economics of GTL plants are very closely tied to the natural gas price, viability depends in large part on inexpensive stranded gas.
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From page 262... ...
into a marketable product. Currently, however, while methanol is pro duced primarily from natural gas, it is used principally as a commodity chemical.
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From page 263... ...
Hydrogen Hydrogen, like electricity, is an energy carrier that can be generated from a wide variety of sources, including nuclear energy, renewable energy, and fossil fuels. Hydrogen also can be made from water via the process of electrolysis, although this appears to be more expensive than reforming natural gas.
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From page 264... ...
This section provides a synopsis of the National Research Council report Transitions to Alternative Transportation Technologies -- A Focus on Hydrogen (NRC, 2008) , which concluded that the maximum practical number of HFCVs that could be operating in 2020 would be about 2 million, among 280 million LDVs in the United States.
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From page 265... ...
After that, there would be a net payoff to the country, which cumulatively would balance the prior subsidies by about 2028. Substantial and sustained R&D programs will be required to reduce the costs and improve the durability of fuel cells, develop new onboard hydrogen-storage technologies, and reduce hydrogen production costs.
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From page 266... ...
20,000 0 2000 2010 2020 2030 2040 2050 Year FIGURE 5.10 Oil consumption for combined HFCVs, high-efficiency conventional vehi cles, and biofuels compared with reference case. Source: NRC, 2008.
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From page 267... ...
HFCVs can yield large and sustained reductions in U.S. oil consumption and greenhouse gas emissions, but several decades will be needed to realize those potential long-term benefits.
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From page 268... ...
2008a. Natural gas consumption by end use.
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From page 269... ...
2009. Liquid Transportation Fuels from Coal and Biomass: Technological Status, Costs, and Environmental Impacts.
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From page 270... ...
2007. An empirical analysis on the adoption of alternative fuel vehicles: The case of natural gas vehicles.
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