Biofuels in Perspective

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Sustainable Production of Cellulosic Feedstock 13 In colloquies with farmers, potential processors and other stakeholders conducted by DOE during 2001 and again in 2003, there was general agreement that corn stover and cereal straw are the most likely near-term feedstocks for commercial-scale production of ethanol from cellulosic biomass. 8 However, farmers participating in the six Feedstock Roadmap Colloquies stated that the minimum price farmers would accept to collect biomass would be $50 per dry ton, or a return of at least $20 per acre net margin. 9 At $50 per dry ton, the amount of economically recoverable, sustainably available biomass is more than double the amount estimated in the USDA/DOE report. Over 200 million dry tons of corn stover alone could be collected, enough to triple current ethanol production. Future availability of feedstocks will depend on several variables, including crop acreage planted to meet competing demands; continued improvements derived from agricultural biotechnology; cropping practices and soil-quality maintenance considerations; and state and federal farm and energy policies. Coordination of farm and energy policies at both state and federal levels can serve to incentivize production, harvest and delivery of a variety of feedstocks to biorefineries. As crop markets change – due to changing demand for food, animal feed, exports, and fuel and consumer products – farmers can be expected to adjust crop planting strategies to maximize their returns. As biorefinery construction creates markets for crop residues, farmers will have to adopt practices that lead to economic and sustainable removal. New models for maintaining soil quality also will be needed. Models based on soil organic material are currently in development. 2.3 Feedstock Options Corn stover and cereal straw make up more than 80 % of currently available residues under both the USDA/DOE analysis and the $50 per dry ton scenario. Corn is the largest grain crop in the United States. Currently, 50 % of the corn biomass, about 250 million dry tons, is left in the field after harvest. Most of the available cereal straw biomass is from wheat (see Figure 2.3). Rice is also an important source, particularly in Texas and California. Sorghum, barley and oats have smaller potential. There are significant regional differences in crop characteristics to consider, as well as differences in harvesting mechanics for stover and straw. More corn stover is available than straw, but straw is more readily removed (although in some areas it must be left in the field to retain moisture in the soil). Straw collection infrastructure is generally well developed, while corn stover collection is not. When cereal grain is ready to harvest, straw usually contains 20 % moisture or less, suitable for baling. In contrast, stover contains 50 % moisture and must remain in the field to dry and be collected later, depending on the weather. A wet harvest season can prevent its collection entirely. Corn stover yields are 3–5 times greater – or more – on a per acre basis than straw from cereal crops. Unless cereal crops are irrigated, there is little straw left to collect. For example, the average dry land wheat straw yield is between 40 and 45 bushels per acre compared to 140–200 bushels per acre or more for corn stover. The equivalent of 20 bushels of straw must be left on the surface to comply with erosion guidelines with no-till. The
14 Biofuels Figure 2.3 Baling and collection technology for wheat straw has already been developed for a variety of commercial uses, such as animal bedding, landscape mulch, erosion control, and as a building material. Source: USDA Agricultural Research Service.
Page 2 and 3: Biofuels Biofuels. Edited by Wim So
Page 4 and 5: Biofuels Edited by WIM SOETAERT Ghe
Page 6 and 7: Contents Series Preface ix Preface
Page 8 and 9: Contents vii 6.3 Biomass Gasificati
Page 10 and 11: Series Preface Renewable resources,
Page 12 and 13: Preface This volume on Biofuels fit
Page 14 and 15: Editors List of Contributors Wim So
Page 16 and 17: 1 Biofuels in Perspective W. Soetae
Page 18 and 19: Table 1.1 Approximate average world
Page 20 and 21: Table 1.3 Energy yields of bio-ener
Page 22 and 23: Biofuels in Perspective 7 is burnt
Page 24 and 25: 2 Sustainable Production of Cellulo
Page 26 and 27: Sustainable Production of Cellulosi
Page 38 and 39: Figure 2.9 2004 US adoption rates o
Page 54 and 55: 3 Bio-Ethanol Development in the US
Page 56 and 57: Bio-Ethanol Development in the USA
Page 58 and 59: Biorefineries in Production (115) B
Page 66 and 67: Cost of Cellulosic Ethanol, $ per g
Page 70 and 71: 4 Bio-Ethanol Development(s) in Bra
Page 72 and 73: Bio-Ethanol Development(s) in Brazi
Page 74 and 75: Share of energy consumption 100% 90
Page 76 and 77: Bio-Ethanol Development(s) in Brazi
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Bio-Ethanol Development(s) in Brazi
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Table 4.2 Main technological improv
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4.7.4 Use of Fertilizers and Pestic
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78 Biofuels Table 5.1 Biodiesel pro
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80 Biofuels CH 2 O CH O COR R1 + 3
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82 Biofuels short reaction times. 9
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84 Biofuels Table 5.4 Overview on h
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86 Biofuels Table 5.5 Critical cond
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88 Biofuels methoxide as catalyst u
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90 Biofuels KOH Methano Oil/Fat Aci
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92 Biofuels 16. J. Graille, P. Loza
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6 Bio-based Fischer-Tropsch Diesel
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6.2.1.2 Catalysts Bio-based Fischer
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Bio-based Fischer-Tropsch Diesel Pr
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7 Plant Oil Biofuel: Rationale, Pro
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Table 7.1 Market milestones for pla
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Water CO 2 Figure 7.1 Closed CO 2 l
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Plant Oil Biofuel: Rationale, Produ
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130 Biofuels Among the attractive f
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132 Biofuels Table 8.1 Enzymatic tr
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134 Biofuels conversion was maintai
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136 Biofuels (diglycerides) decreas
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138 Biofuels ME content (wt.%) Reac
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140 Biofuels Ratio of initial react
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142 Biofuels (a) 34 kDa 31 kDa 34 k
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144 Biofuels preparation of whole-c
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ability to reduce flocculation (% o
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148 Biofuels 5. R. C. Strayer, J. A
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150 Biofuels 46. H. Fukuda, Immobil
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9 Production of Biodiesel from Wast
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Production of Biodiesel from Waste
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9.3.2 Processing of Crude and Waste
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Heavy layer from alkaline neutralis
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CPO I 1 1 Heating 60°C Reaction st
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References Production of Biodiesel
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10 Biomass Digestion to Methane in
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Cow manure Pig manure Yard manure B
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Number of plants 3000 2500 2000 150
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Biomass Digestion to Methane in Agr
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Table 10.4 Alternative forms of ene
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Wet fermentation 3 - 10% TS applica
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Rel. Frequency [%] 35 30 25 20 15 1
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Steam 2 1 Energy crops (& manure) D
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198 Biofuels 11.1 Introduction Hydr
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200 Biofuels lactate 6 glucose 1 GA
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Table 11.2 Continued Organism Domai
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204 Biofuels NADH is that the react
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206 Biofuels Clostridium thermocell
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208 Biofuels in particular in Cl. p
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210 Biofuels ferredoxin-dependent m
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212 Biofuels Concentration (mM) 45
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214 Biofuels genes of the glycolysi
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216 Biofuels 11. S. Tanisho and Y.
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218 Biofuels 49. M. J. Axley, D. A.
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220 Biofuels 83. P. J. Silva, E. C.
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12 Improving Sustainability of the
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Table 12.1 Corn ethanol dry mill: e
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Table 12.2 Atmospheric CO2 (equival
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Table 12.3 Incremental CO2 equivale
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Improving Sustainability of the Cor
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Improving Sustainability of the Cor
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Index italic entries indicate refer
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iorefineries 3, 10, 11, 41 and corn
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policy (official) 59-61 production
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NADH 200-6, 207, 210 natural gas 1
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