Biofuels, Solar and Wind as Renewable Energy Systems_Benefits and Risks Episode 2 Part 6 docx

364 D. Pimentel, T.W. Patzek petroleum used in the U.S. was about 1,200 billion liters in 2004–2005 (USCB, 2004– 2005). To produce the 18.9 billion liters of ethanol, about 5.0 million ha or 20% of U.S. corn land is used. Furthermore, the 18.9 billion liters of ethanol (energy equiva- lent to 12.5 billion liters of vehicle liquid fuel) provides only 1% of the petroleum utilized by U.S. each year. If corn-ethanol production were expanded to using 100% of U.S. corn production, this would provide only 7% of the petroleum needs! 14.7 Ethanol Production and Use in Brazil In contrast, Brazil can fuel most of its automobiles and other vehicles with ethanol because Brazilians consume only 9% of the U.S. consumption in petroleum (BP, 2005). Since 1984 the portion of Brazilian sugarcane used for ethanol decreased from a peak of 70% to about 55% in 2000 (Schmitz et al., 2003). During that time the percentage of ethanol cars declined from 94% in 1984 to less than 1% in 1996 (Rosillo-Calle and Cortez, 1998). The difference included gasoline for the cars. Flex cars replaced the ethanol cars and as a result Brazil’s oil consumption has increased 42% during the last decade (BP, 2001, 2005). Proponents of ethanol point to the production of ethanol in Brazil but ignore the fact that the U.S. now produces more ethanol (18.9 billion liters ethanol per year) compared with Brazil that produces about 15.1 billion liters per year (Calibre, 2006). Brazil is fortunate to have the land and climate suitable for sugarcane. Sugarcane is a more efficient feedstock for ethanol production than corn grain (Patzek and Pimentel, 2005). However, because Brazilian energy balance is only slightly posi- tive (1 kcal:2.28 kcal), the Brazilians need to heavily subsidize their ethanol industry as does the U.S In the 1980s and 1990s the Brazilian government sold ethanol to the public for 22c per liter, but it cost the government 33 c per liter to produce (Pimentel, 2003). Because other priorities emerged in Brazil, the government has since abandoned directlysubsidizingethanol(SpiritsLow, 1999; Coelho et al.,2002). Now the consumer is paying the subsidy directly at the pump (Pimentel, 2003). The total Brazilian subsidy is estimated to be about 50% for ethanol production (CIA, 2005). Earlier it was mentioned that it costs 26c to produce a liter of ethanol in Brazil that sells for 86c per liter (Calibre, 2006). Brazilian gasoline sells for nearly $1.23 per liter or about 43% higher than a liter of ethanol (R.M Boddey, Senior Scientist, Empresa Brasileira de Pesquisa Agropecuaria (Embrapa), Brasil, personal communication, 2007). Thus, higher gasoline prices help subsidize the cost of ethanol production in Brazil (CIA, 2005). 14.8 Environmental Impacts Some of the economic and energy contributions of ethanol production both in the U.S. and Brazil are negated by the widespread environmental pollution problems associated with ethanol production using sugarcane. Many of the environmental impacts in Brazil associated with sugarcane production also occur in the U.S. 14 Ethanol Production 365 sugarcane production. Sugarcane production causes more intense soil erosion than any crop produced in Brazil because the total sugarcane biomass is harvested and processed in ethanol production. This removal of most of the biomass leaves the soil unprotected and exposed to erosion from rainfall and wind energy. For example, soil erosion with sugarcane cultivation is reported to have the highest soil erosion rate in all Brazilian agriculture, averaging 31 t/ha/yr (Sparovek and Schung, 2001). The 31 t/ha soil loss is 30–60 times greater than sustainability of the soil in agriculture (Troeh et al., 2004; Pimentel, 2006). In addition, sugarcane production uses larger quantities of herbicides and insec- ticides and nitrogen fertilizer (Tables 14.1 and 14.2) than most other crops produced in Brazil and these chemicals spread to ground and surface water thereby causing significant water pollution (NAS, 2003). Relatively large quantities of water are required to produce sugarcane. Because it takes 12 kg of sugarcane to produce 1 L of ethanol, about 7,000 L of water are needed to produce the required 12 kg of sugarcane per liter of ethanol. Although the Brazilian government has passed legislation to curtail the burning of sugarcane before harvest to reduce air pollution problems, most of the sugarcane in Brazil is still burned and this is resulting in respiratory problems in children and the elderly (Braunbeck et al., 1999; Cancado et al., 2006). The rules need to be enforced to help protect the people from this serious air pollution problem. Addi- tional smoke is released during the removal of forests for sugarcane and other crop production. Between May 2000 and August 2005, Brazil lost more than 132,000 square km of forest, an area larger than Greece (Mongabay, 2006). The harvesting of sugarcane by laborers is hard and dangerous work, cutting the sugarcane with large knives. As Broietti (2003) reported these are dangerous and miserable conditions under which to work. All these factors confirm that the environmental and agricultural system in which Brazilian and U.S. sugarcane is being produced is experiencing major environmental problems. Further, it substantiates the conclusion that the sugarcane production system, and indeed the ethanol production system, are not environmentally sus- tainable now or for the future. Because sugarcane is the raw material for ethanol production in Brazil, it cannot be considered a renewable energy source, considering the production and processing aspects. Another pollution problem concerns the large amounts of waste-water produced by each ethanol plant. As noted, for each liter of ethanol produced using sugarcane, about 10 L of wastewater are produced. This polluting wastewater has a biological oxygen demand (BOD) of 18,000–37,000 mg/liter depending of the type of plant (Kuby et al., 1984). The cost of processing this sewage in terms of energy (4 kWh/kg of BOD) must be included in the cost of producing ethanol (Tables 14.3 and 14.4). 14.9 Air Pollution Reports confirm that ethanol use contributes to air pollution problems when burned in automobiles (Youngquist, 1997; Hodge, 2002, 2003, 2005; Niven, 2005). The use 366 D. Pimentel, T.W. Patzek of fossil fuels, as well as the use of ethanol in cars, releases significant quantities of pollutants to the atmosphere. Furthermore, carbon dioxide emissions released from burning these fossil fuels contribute to global warming and are a serious concern (Schneider et al., 2002). Additional carbon dioxide is released during the fermen- tation process. Also, when the soil is tilled serious soil erosion takes place and soil organic matter is oxidized. When all the air pollutants associated with the entire ethanol production system are considered, the evidence confirms that ethanol pro- duction contributes to the already serious U.S. and Brazilian air pollution problem (Youngquist, 1997; Hodge, 2002, 2003, 2005; Pimentel and Patzek, 2005; Patzek and Pimentel, 2005). 14.10 Food Security At present, world agricultural land supplies more than 99% of all world food (calo- ries), while aquatic ecosystems supply less than 1% (FAO, 2002). Worldwide, dur- ing the last decade, per capita available cropland decreased 20% and irrigation land 12% (Brown, 1997). Furthermore, per capita grain production has been decreas- ing, in part due to increases in the world population (Worldwatch Institute, 2001). Worldwide, diverse cereal grains, including corn, make up 80% of the food of the human food supply (Pimentel and Pimentel, 1996). The current food shortages throughout the world call attention to the impor- tance of continuing U.S. and Brazilian exports of grains and other food crops for human nutrition. The expanding world population that now numbers 6.5 billion, further complicates and stresses the food security problem now and for the future (PRB, 2006). Almost a quarter million people are added each day to the world population, and each of these human beings requires adequate food. Today, the mal- nourished people in the world number more than 3.7 billion (WHO, 2006). This is the largest number of malnourished people and proportion ever reported in history. Malnourished people are highly susceptible to various serious diseases and this is reflected in the rapid rise in the number of seriously infected people in the world, with diseases like tuberculosis, malaria, and AIDS, as reported by the World Health Organization (Kim, 2002; Pimentel et al., 2006). 14.11 Food versus the Fuel Issue Using sugarcane, a human food resource, for ethanol production, raises ethical and moral issues (Wald, 2006). Expanding ethanol production entails diverting valuable cropland from the production of food crops needed to nourish people. The ener- getic and environmental aspects, as well as the moral and ethical issues also deserve serious consideration. In spite of oil and natural gas shortages now facing the U.S., ethanol production is forcing the U.S. to import more oil and natural gas to produce ethanol and other biofuels (Pimentel and Patzek, 2005). 14 Ethanol Production 367 The expansion of ethanol production in the U.S. and Brazil is having negative impacts on food production and food exports (Chang, 2006), and is likely to have further negative impacts on food production and the environment. Furthermore, increasing oil and natural gas imports in the U.S. and other coun- tries drives up the price of oil and gas. This is especially critical for the poor in developing countries of the world. Even now this is documented by the fact that worldwide per capita fertilizer use has been declining for the last decade because of the increased costs for the poor farmers of the world (Worldwatch Institute, 2001). 14.12 Summary For a thorough and up-to-date evaluation of all the fossil energy costs of ethanol production from sugarcane in both the U.S. and Brazil, every energy input in the biomass production and ultimate conversion process must be included. In this study, more than 12 energy inputs in average U.S. and Brazilian sugarcane production are evaluated. Then in the fermentation/distillation operation, 9 more fossil fuel inputs are identified and included. Some energy and economic credits are given for the bagasse to reduce the energy inputs required for steam and electricity. Based on all the fossil energy inputs in U.S. sugarcane conversion process, a total of 1.48 kcal of ethanol is produced per 1 kcal of fossil energy expended. In Brazil, a total of 2.28 kcal of ethanol is produced per 1 kcal of fossil energy expended. Some pro-ethanol investigators have overlooked various energy inputs in U.S. and Brazilian sugarcane production, including farm labor, farm machinery, pro- cessing machinery, and others. In other studies, unrealistic low energy costs were attributed to such energy inputs, as nitrogen fertilizer, insecticides, and herbicides (Corn-Ethanol, 2007). Both the U.S. and Brazil heavily subsidize ethanol production. The data suggest that billions of dollars are invested in subsidies and this significantly increases the costs to the consumers. The environmental costs associated with producing ethanol in the U.S. and Brazil are significant but have been generally overlooked. The negative environmental impacts on the availability of cropland and freshwater, as well as on air pollution and public health, have yet to be carefully assessed. These environmental costs in terms of energy and economics should be calculated and included in future ethanol analyses so that sound assessments can be made. In addition, the production of ethanol in the U.S. and Brazil further confirms that the mission of converting biomass into ethanol will not replace oil. This mission is impossible. General concern has been expressed about taking food crops to produce ethanol for burning in automobiles instead of using these crops as food for the many mal- nourished people in the world. The World Health Organization reports that more than 3.7 billion humans are currently malnourished in the world – the largest number of malnourished ever in history. 368 D. Pimentel, T.W. Patzek Acknowledgments We would like to thank the following people for their valuable comments and suggestions on earlier drafts of this manuscript: Andrew B. Ferguson, Optimum Population Trust, Oxon, UK; Mario Giampietro, Istituto Nazionale di Ricerca per gli Alimenti e Nutrizione (INRAN), Rome, IT; Matthew Farwell, Alternative Energy, Energy, Nanotechnology, Palo Alto, CA: Marcelo Dias de Oliveira, University of Florida, Gainesville, FL; Odo Primavesi, Empresa Brasileira de Pesquisa Agropecu ´ aria (Embrapa), Brazil; Thomas Standing, San Francisco Public Utilities Commission, San Francisco, CA; Sergio Ulgiati, Department of Chemistry, University of Siena, Italy; Walter Youngquist, Petroleum Consultant, Eugene, OR. This research was supported in part from a grant from the Podell Emertii award at Cornell University. References Blais, J.F., Mamouny, K., Nlombi, K., Sasseville, J.L., & Letourneau, M. (1995). Les mesures deficacite energetique dans le secteur de leau. (In J.L Sassville & J.F. Balis (Eds.), Les Mesures deficacite Energetique pour Lepuration des eaux Usees Municipales: Scientific Report 405, Vol. 3, INRS-Eau, Quebec.). 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Natural Resources Research, 12(4), 229–240 Chapter 15 Ethanol Production Using Corn, Switchgrass and Wood; Biodiesel Production Using Soybean David Pimentel and Tad Patzek Abstract In this analysis, the most recent scientific data for corn, switchgrass, and wood, for fermentation/distillation were used. All current fossil energy inputs used in corn production and for the fermentation/distillation were included to determine the entire energy cost of ethanol production. Additional costs to consumers in- clude federal and state subsidies, plus costs associated with environmental pollu- tion and/or degradation that occur during the entire production process. In addition, an investigation was made concerning the conversion of soybeans into biodiesel fuel. Keywords Energy ·biomass · fuel ·natural resources ·ethanol · biodiesel 15.1 Introduction Green plants, such as corn, soybeans, switchgrass and trees, and all other kinds of biomass, convert solar energy into plant material but require suitable soil, nutrients, and freshwater. In the conversion of the biomass into liquid fuel, water, microor- ganisms, and more energy are required. Andrew Ferguson (2006, personal commu- nication, Optimum Population Trust, Manchester, UK) makes an astute observation that the proportion of sun’s energy that is converted into useful ethanol, even using very positive energy data, only amounts to 5 parts per 10,000, or 0.05% of the solar energy. Some recent papers are claiming returns on ethanol production from corn of any- where from 1.25 kcal to 1.67 kcal per kcal invested (Shapouri et al., 2004; Farrell D. Pimentel College of Agriculture and Life Sciences, Cornell University, 5126 Comstock Hall, Ithaca, NY 15850, e-mail: Dp18@cornell.edu T. Patzek Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, 425 David Hall, MC1716, e-mail: patzek@patzek.CE.berkeley.edu D. Pimentel (ed.), Biofuels, Solar and Wind as Renewable Energy Systems, C  Springer Science+Business Media B.V. 2008 373 374 D. Pimentel, T. Patzek et al., 2006; Hill et al., 2006). These excessively high returns are achieved by either omitting several energy inputs, reducing other energy inputs, or giving credits that are too optimistic for the by-products. 15.2 Energy Inputs in Corn Production The conversion of corn into ethanol by fermentation in a large plant is about 1 liter of ethanol from 2.69 kg of corn grain (approximately 9.5 liters pure ethanol per bushel of corn; see Footnote (a) in Table 15.2) (Pimentel and Patzek, 2005). The production of corn in the United States requires a significant energy and dollar investment for the 14 inputs, including labor, farm machinery, fertilizers, irrigation, pesticides, and electricity (Table 15.1). To produce an average corn yield of 9,400 kg/ha (149 bu/ac) of corn using up-to-date production technologies requires the expenditure of about 8.2 million kcal of energy inputs (mostly natural gas, coal, and oil) listed in Ta- ble 15.1. This is the equivalent of about ∼930 liters of oil equivalents (∼25% of grain energy) expended per hectare of corn. The production costs total about $927/ha for the 9,400 kg/ha or approximately 10c/kg ($2.54/bushel) of corn produced. Full irrigation (when there is insufficient or no rainfall) requires about 100 cm/ha of water per growing season. Because only about 15% of U.S. corn production cur- rently is irrigated (USDA, 1997a), only 8.1 cm per ha of irrigation was included for the growing season. On average irrigation water is pumped from a depth of 100 m (USDA, 1997a). On this basis, the average energy input associated with irrigation is 320,000 kcal per hectare (Table 15.1). 15.2.1 Energy Inputs in Fermentation/Distillation The average costs in terms of energy and dollars for a large (245 to 285 million liters/year), modern drygrind ethanol plant are listed in Table 15.2. In the fermen- tation/distillation process, the corn is finely ground and approximately 15 liters of water are added per 2.69 kg of ground corn. Some of this water is recycled. After fermentation, to obtain a liter of 95% pure ethanol from the 8–12% ethanol beer and 92–88% water mixture, the 1 liter of ethanol must be extracted from approxi- mately 11 liters of the ethanol/ water mixture. Although ethanol boils at about 78 degrees C, and water boils at 100 degrees C, the ethanol is not extracted from the water in the first distillation, which obtains 95% pure ethanol (Maiorella, 1985; Wereko-Brobby and Hagan, 1996; S. Lamberson, personal communication, Cornell University, 2000). To be mixed with gasoline, the 95% ethanol must be further pro- cessed and more water removed, requiring additional fossil energy inputs to achieve 99.5% pure ethanol (Table 15.2). Thus, a total of about 10 liters of wastewater must be removed per liter of ethanol produced, and this relatively large amount of sewage effluent has to be disposed of at an energy, economic, and environmental cost. To produce a liter of 99.5% ethanol uses 46% more fossil energy than the energy produced as ethanol and costs 45c per liter ($1.71 per gallon) (Table 15.2). The corn feedstock requires about 32% of the total energy input. In this analysis, the total cost, including the energy inputs for the fermentation/distillation process and the [...]... effluent Distribution TOTAL 2, 69 0 kgb 2, 69 0 kgb 15,000 L e 3 kgi 4 kgi 8 kgi 2, 64 6,000 kcalj 3 92 kWhj 9 kcal/Lm 20 kg BODn 331 kcal/Lp 2, 355b 322 c 90f 165 o 92o 384o 2, 64 6j 1,011j 9m 69 h 331 7,474 26 5 .27 21 .40d 21 .16g 10 .60 d 10 .60 d 10 .60 d 21 .16k 27 .44l 40.00 6. 00 20 .00p $454 .23 a Output: 1 liter of ethanol = 5,130 kcal (Low heating value) The mean yield of 2. 5 gal pure EtOH per bushel has been obtained from... 1,003h 405j 2, 480l 328 o 27 4r 315u 520 w 320 z 62 0 ee 28 0ee 34ff 169 hh TOTAL Corn yield 9,400 kg/haii a 8 ,22 8 33,840 Costs $ 148 .20 c 103 .21 f 34. 76 20 .80 85 .25 m 48.98p 26 .04s 19.80 74.81x 123 .00aa 124 .00 56. 00 0. 92 61 .20 $ 9 26 .97 kcal input:output 1:4.11 NASS, 20 03 It is assumed that a person works 2, 000 hrs per year and utilizes an average of 8,000 liters of oil equivalents per year c It is assumed that labor... Potassium Limestone Seeds Herbicides Electricity Transport 7.1 hrsa 20 kgd 38.8 La 35.7 La 3.3 La 3.7 kgj 37.8 kgj 14.8 kgj 20 00 kgv 69 .3 kga 1.3 kgj 10 kWhd 154 kgt 28 4b 360 e 442g 27 0h 25 i 59k 156m 48o 562 d 554q 130e 29 s 40u TOTAL Soybean yield 2, 890 kg/haw 2, 959 10,404 Costs $ 92. 30c 148.00f 20 .18 13. 36 1 .20 2. 29l 23 .44n 4.59p 46. 00v 48.58r 26 .00 0.70 46 .20 $4 72. 84 kcal input:output 1:3. 52 a Ali and. .. Steel Cement 5,5 56 kga 27 0 kWhb 120 Li 1,350,000 kcalb 160 ,000 kcalb 1 52, 000 kcalb 440,000 kcalb 300,000 kcalb 11 kgf 21 kgf 56 kgf TOTAL kcal × 1000 5 ,68 9a 69 7c 1 ,24 8i 1,350b 160 b 152b 440b 300b 60 5g 483g 2, 68 8g 13,8 12 Costs $ $909.03a 18.90d 111 .60 11.06e 1.31e 1 .24 e 3 .61 e 2. 46e 18.72h 18.72h 18.72h $1,115.37 The 1,000 kg of soy oil plus 125 kg of methanol to produce biodiesel has an energy value of... 25 0,000 Le 3 kgg 4 kgg 8 kgg 5,000 kg 24 0 kgi 8.1 tonsi 1 ,25 0 kgj 66 6 kWhi 9 kcal/Lk 40 kg BODl 331 kcal/Lp 1, 968 c 60 0c 140f 165 g 92g 384g 20 0h 0 4,404 minus 1,500 1,703 9 138o 331 500 30d 40m 11g 11g 11g 16h 168 n 36 minus 12 46 40 12 20 8 ,63 4 $ 929 TOTAL a Output: 1 liter of ethanol = 5,130 kcal The ethanol yield here is 20 0 L/t dry biomass (dbm) Iogen suggests 320 L/t dbm of straw that contains 25 %... ethanol to 99.5% Sewage effluent Distribution 5,000 kgb 10 kgm 100 kgc 5,000 kgd 25 0,000 Le 3 kg 4 kg 8 kg 5,000 kg 24 0 kgi 8.1 tonsi 1 ,25 0 kgj 66 6 kWhi 9 kcal/Lk 40 kg BODl 331 kcal/Lq 800 20 0m 1 ,60 0 60 0 140f 165 g 92g 384g 20 0h 0 4,404 minus 1,500 1,703 9 138o 331 500p 20 56 30 40f 11g 11g 11g 16h 168 n 36 minus 12 46 40 12 20 9 , 26 6 $1,005 TOTAL a Output: 1 liter of ethanol = 5,130 kcal 5,000 kg of wood input... Potassium Sulfur Limestone Seeds Herbicides Insecticides Electricity Transport 7 hrsa 20 kgd 65 La 120 kga 101 kga 14.8 kgl 22 kga 1000 kga 5 kgo 1.5 kgq 1 kgq 10 kWha 100 kgs 28 0b 360 e 740g 1, 920 h 417j 48m 10l 28 1d 40p 150p 100 29 r 26 t TOTAL Canola yield 1, 568 kg/ha Costs $ 91.00c 148.00f 35.00 75.00i 71.00k 4.59n 10.00 23 .00 35.00 30.00 20 .00 0.70 30.00 4,401 u $573 .29 5 ,64 5 kcal input:output 1:1. 06. .. per kg q NASS, 20 03 r Input 3 , 26 0 kcal per kg s Cost $.31 per kg t Brees, 20 04 u Input 28 1 kcal per kg v Pimentel and Pimentel, 19 96 w Pimentel and Pimentel, 19 96 x USDA, 1997b y USDA, 1997a z Batty and Keller, 1980 aa Irrigation for 100 cm of water per hectare costs $1,000 (Larsen et al., 20 02) bb Larson and Cardwell, 1999 cc USDA, 20 02 dd USDA, 1991 ee Input 100,000 kcal per kg of herbicide and insecticide... Pimentel and Pimentel, 19 96 e Prorated per hectare and 10 year life of the machinery Tractors weigh from 6 to 7 tons and harvesters 8–10 tons, plus plows, sprayers, and other equipment f Hoffman et al., 1994 g Wilcke and Chaplin, 20 00 h Input 11, 400 kcal per liter i Estimated j Input 10, 125 kcal per liter k NASS, 20 03 l Patzek, 20 04 m Cost $.55 per kg n NASS, 20 03 o Input 4,154 kcal per kg p Cost $. 62 per... present, world agricultural land supplies more than 99% of all world food (calories), while aquatic ecosystems supply less than 1% (FAO, 20 06) Worldwide, during the last decade, per capita available cropland decreased 20 % and irrigation land 12% (Brown, 1997) Furthermore, per capita grain production has been decreasing, in part due to increases in the world population (FAO, 20 06) Worldwide diverse cereal . grain 2, 69 0 kg b 2, 355 b 26 5 .27 Corn transport 2, 69 0 kg b 322 c 21 .40 d Water 15,000 L e 90 f 21 . 16 g Stainless steel 3 kg i 165 o 10 .60 d Steel 4 kg i 92 o 10 .60 d Cement 8 kg i 384 o 10 .60 d Steam. kg p 27 4 r 26 .04 s Lime 1, 120 kg t 315 u 19.80 Seeds 21 kg v 520 w 74.81 x Irrigation 8.1 cm y 320 z 123 .00 aa Herbicides 6 .2 kg bb 62 0 ee 124 .00 Insecticides 2. 8kg cc 28 0 ee 56. 00 Electricity 13.2kWh dd 34 ff 0. 92 Transport. Production 369 DOE. (20 05). Energy efficiency and renewable energy: U.S. Department of Energy. Washington DC. Retrieved January 6, 20 06 from http://www1.eere .energy. gov/biomass/ethanol.html FAO. (20 02) .