Biofuels in Perspective

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Biomass Digestion to Methane in Agriculture 193 should have the following characteristics: it should mainly produce rapidly convertible carbohydrates (sugars, starch, cellulose) and contain a minimum of lignin, hemi-cellulose, proteins, minerals, pigments. Equally important is that the mass of produced organic matter per unit are is high, which depends basically on three factors: (1) the climate (2) the land and agricultural techniques applied and (3) the nature of the plant and quality of the seed. In other words, it must maximize the conversion of sunlight to digestible carbohydrate. At present, of the 15,000 kW power of sunlight which one ha of corn receives, hardly 5 is trapped as potential bioethanol power, and a mere 1.5 kW (1 out of 10 000) is recovered as effective bioethanol fuel. To the best of our knowledge, no conventional breeding programme to generate an optimal energy/biogas producing crop has ever been set up. New methods of crop ‘design’ implementing various genetic potentials in a specific plant used for biogas production, should be able to considerably increase the harvesting of the sun energy. At present, considerable effort is underway to design new types of food crops; it stems to reason to expect rapid advances in the design of new biogas-dedicated crops. A second line of progress will be the development of new technologies to produce biogas. Certainly, the current techniques to harvest and preserve the biomass before it is submitted to biogas digestion need to be tuned to the subsequent and overall rate limiting methane production process. With respect to anaerobic digestion itself, two lines of reactor configuration are of value A first line relates to intensive digestion in highly technical hardware, as described above. Plenty of novel concepts will certainly arise and allow to enhance the overall energy recovery. Of special interest is for instance the coupling of anaerobic digestion with subsequent further removal of the residual organics in microbial fuel cells (Rabaey and Verstraete, 2005) Yet, this approach will demand major investments. Although on average a digester constitutes only a relative simple amount of infrastructure representing on average an all-in capex of 1000 Euro per m 3 , its payback at the current energy price of methane (0.2 Euro per m 3 ) and reactor rate of methane production (10 volumes of methane per volume of reactor per day) is still of the order of several years. Hence, it stems to reason to also consider the possibility to harvesting biomass, bringing it together in large scale landfill type reactor system and then utilize this biomass, stored in a less expensive way, over a longer time scale (Verstraete et al., 2005). A third line of improvement must be sought in the better positioning of the biogas produced. At present, the biogas is generally combusted to render electricity. Technology to upgrade it to vehicle fuel is already long time available (Henrich, 1981). Yet, provided it is produced at sufficiently large scale, a thermal conversion to syngas (H2 and CO) is quite possible (Effendi et al., 2005; Wang and Chang, 2005). The advantage of this route is that the conventional petrochemistry can directly tap on this resource and produce from it all possible commodities. Once biogas digestion is linked to conventional petrochemistry, it will have a major inroad to the chemical industry and hence the overall industrial society. 10.6 Conclusions Biogas from agriculture has several strong points. It can deal with a variety of materials and it thus fits perfectly in the various routes of downstream processing of the agro-business. Secondly, it allows recovering energy with a maximum of efficiency because its end product, methane, distils by itself from the mixture which is used to produce the fuel. Third, it can
194 Biofuels be used in a number of ways, going from direct combustion, to conversion to hydrogen and electricity and to cracking and becoming syngas to produce commodity chemicals and materials. Fourth, the technology can be designed at small, medium and even super-large scale in case of landfill storage projects. Finally, and certainly also of critical value, the anaerobic digestion of biomass to biogas allows to recover all plant nutrients and surpasses all other biomass conversion technologies in terms of environmental sustainability, because it can harvest the sun and at the same time return to the soil the undigested plant residues, in the lignin, which will improve the soil organic matter content and the minerals which will allow to grow the next crop without input of major amounts of external fertilizer. References Clausen, E.C., Sitton, O.C. and Gaddy, J.L. 1979. Biological production of methane from energy crops. Biot Bioeng 21: 1209–1219 De Assis, P.E.P. 2006. Integrated production of sugar and alcohol. Int. Workshop on production and use of alcohol. Havana, Cuba. De Baere, L. 2001. Full-scale experience with digestion facilities treating 25.000 and 50.000 ton of biowaste per year. In : Proceedings (Part 2) of 9th World Congress Anaerobic Digestion: ‘Anaerobic Conversion for Sustainability’, Antwerp. EEG, Erneuerbare-Energien-Gesetz. 2004. Bundesgesetzblatt, Teil I, Nr. 40. Bonn. Effendi, A., Hellgardt K., Zhang Z.G. and Yoshida, T. 2005. Optimising H2-production from model biogas to combined steam reforming and CO shift reactions. Fuel 84, 869–874. Hammerschlag, R. 2006. Ethanol’s energy return on investment : A survey of the literature 1990 – present. Environ. Sci; Technol. 1744–1750. Helffrich, D. 2004. Lagerung, Einbringung und Rühren nachwachsender Rohstoffe zur Vergärung in landwirtschaftlichen Biogasanlagen: Biogas – zuverlässige Energie von Wiese und Acker, Fachverband Biogas, Freising, p. 64–67. Henrich, R.A. 1981. Municipal waste to vehicle fuel. Biocycle May-June, 27–29. Hoffmann, M. 2003. Trockenfermentation in der Landwirtschaft: Entwicklung und Stand, in VDI- Berichte 1751, VDI-Verlag, Düsseldorf, p. 193–201. Houghton, J.T. 2001. Climate Change : The Scientific Basis, Cambridge University Press, Cambridge. Kamm, B. and Kamm, M. 2004. Principles of biorefineries. Appl. Microbiol. Biotechnol. 64, 137–145. Karpenstein-Machan, M. 2005. Energiepflanzenbau für Biogasanlagenbetreiber, DLG-Verlag, Frankfurt. Kuratorium für Technik und Bauwesen in der Landwirtschaft (KTBL), Gasausbeute in landwirtschaftlichen Biogasanlagen, Landwirtschaftsverlag. 2005. Münster. Kusch, S. and Oechsner, H. 2005. Biogas production in discontinuously operated solid-phase digestion systems. Proc. of the 7th FAO/SREN-Workshop, Uppsala, Sweden. Lens, P., Westermann, P., Haberbauer, M. and Moreno, A. 2005. Biofuels for Fuel Cells, IWA Publishing, London. Lettinga, G., van Velsen, A.F.M., Hobma, S.W., de Zeeuw, W. and Klapwijk, A. 1980. Use of the upflow sludge blanket (USB) reactor concept for biological wastewater treatment, Especially for anaerobic treatment. Biotechnol. Bioeng. 22, 699–734. Rabaey, K. and Verstraete, W. 2005. Microbial fuel cells: novel biotechnology for energy generation. Trends in biotechnology 23, 291– 298. Schneider, R. 2002. Grundlegende Untersuchungen zur effektiven, kostengünstigen Entfernung von Schwefelwasserstoff aus Biogas – Biogasanlagen: Anforderungen zur Luftreinhaltung, Bayerisches Landesamt für Umweltschutz, Augsburg, p. 25–41.
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Biofuels Biofuels. Edited by Wim So
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Biofuels Edited by WIM SOETAERT Ghe
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Contents Series Preface ix Preface
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Contents vii 6.3 Biomass Gasificati
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Series Preface Renewable resources,
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Preface This volume on Biofuels fit
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Editors List of Contributors Wim So
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1 Biofuels in Perspective W. Soetae
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Table 1.1 Approximate average world
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Table 1.3 Energy yields of bio-ener
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Biofuels in Perspective 7 is burnt
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2 Sustainable Production of Cellulo
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Sustainable Production of Cellulosi
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Figure 2.9 2004 US adoption rates o
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3 Bio-Ethanol Development in the US
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Bio-Ethanol Development in the USA
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Biorefineries in Production (115) B
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Cost of Cellulosic Ethanol, $ per g
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4 Bio-Ethanol Development(s) in Bra
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Bio-Ethanol Development(s) in Brazi
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Share of energy consumption 100% 90
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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
Page 157 and 158: 142 Biofuels (a) 34 kDa 31 kDa 34 k
Page 159 and 160: 144 Biofuels preparation of whole-c
Page 161 and 162: ability to reduce flocculation (% o
Page 163 and 164: 148 Biofuels 5. R. C. Strayer, J. A
Page 165 and 166: 150 Biofuels 46. H. Fukuda, Immobil
Page 168 and 169: 9 Production of Biodiesel from Wast
Page 170 and 171: Production of Biodiesel from Waste
Page 174 and 175: 9.3.2 Processing of Crude and Waste
Page 176 and 177: Heavy layer from alkaline neutralis
Page 182 and 183: CPO I 1 1 Heating 60°C Reaction st
Page 184 and 185: References Production of Biodiesel
Page 186 and 187: 10 Biomass Digestion to Methane in
Page 188 and 189: Cow manure Pig manure Yard manure B
Page 190 and 191: Number of plants 3000 2500 2000 150
Page 192 and 193: Biomass Digestion to Methane in Agr
Page 196 and 197: Table 10.4 Alternative forms of ene
Page 200 and 201: Wet fermentation 3 - 10% TS applica
Page 202 and 203: Rel. Frequency [%] 35 30 25 20 15 1
Page 204 and 205: Steam 2 1 Energy crops (& manure) D
Page 210: Biomass Digestion to Methane in Agr
Page 213 and 214: 198 Biofuels 11.1 Introduction Hydr
Page 215 and 216: 200 Biofuels lactate 6 glucose 1 GA
Page 217 and 218: Table 11.2 Continued Organism Domai
Page 219 and 220: 204 Biofuels NADH is that the react
Page 221 and 222: 206 Biofuels Clostridium thermocell
Page 223 and 224: 208 Biofuels in particular in Cl. p
Page 225 and 226: 210 Biofuels ferredoxin-dependent m
Page 227 and 228: 212 Biofuels Concentration (mM) 45
Page 229 and 230: 214 Biofuels genes of the glycolysi
Page 231 and 232: 216 Biofuels 11. S. Tanisho and Y.
Page 233 and 234: 218 Biofuels 49. M. J. Axley, D. A.
Page 235 and 236: 220 Biofuels 83. P. J. Silva, E. C.
Page 238 and 239: 12 Improving Sustainability of the
Page 240 and 241: Table 12.1 Corn ethanol dry mill: e
Page 242 and 243: Table 12.2 Atmospheric CO2 (equival
Page 244 and 245: Table 12.3 Incremental CO2 equivale
Page 246 and 247: Improving Sustainability of the Cor
Page 248 and 249: Improving Sustainability of the Cor
Page 250 and 251: Index italic entries indicate refer
Page 252 and 253: iorefineries 3, 10, 11, 41 and corn
Page 254 and 255: policy (official) 59-61 production
Page 256 and 257: NADH 200-6, 207, 210 natural gas 1
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