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

Tham khảo tài liệu 'biofuels, solar and wind as renewable energy systems_benefits and risks episode 2 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 364 D. Pimentel T.W. Patzek petroleum used in the U.S. was about 1 200 billion liters in 2004-2005 USCB 20042005 . 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 equivalent 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 positive 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 .