Estimating The Net Energy Balance Of Corn Ethanol

Author : Monia Ben-Khaled
Publisher :
ISBN 13 :
Total Pages : 59 pages
Book Rating : 4.:/5 (663 download)

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Download or read book Comphrensive Resource Balance for Ethanol Produced from Corn and Sugarcane written by Monia Ben-Khaled and published by . This book was released on 2010 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the increase in price of fossil fuels and climate change caused by Greenhouse Gas (GHG) emissions, many countries around the world are trying to produce alternative transportation fuels. Ethanol has emerged as a popular alternative to fossil fuels, especially, in countries such as the U.S. and Brazil. Different feed stocks are being used to produce ethanol, with corn and sugarcane as the major crops currently being converted into ethanol. Ethanol production requires considerable resources. To date energy input has been studied extensively. However, only limited data is available on other resources used, such as water and land, and the environmental degradation due to waste generated and GHG emissions. The primary objective of this study is to estimate the resource balance for ethanol produced from corn and sugarcane in different climatic zones: temperate, dry and tropical for corn, and tropical and dry for sugarcane. The results of the study indicate that ethanol produced from sugarcane uses less or comparable resources compared to ethanol produced from corn. The estimates of Net Energy Value (NEV) for corn ethanol were between -1,656 and 6,305 Btu per gallon, while those of sugarcane ethanol were between 57,606 and 61,319 Btu per gallon for different climatic zones considered in this study. Moreover, the highest estimated water requirements, for dry climate, were 2,650 and 2,050 gallons of water per gallon of ethanol for corn and sugarcane ethanol, respectively. Results for carbon dioxide released to the environment from corn ethanol with respect to fossil fuels show a reduction of 44, 26 and 51 percent for tropical, dry and temperate climate zones, respectively. On the other hand, results show a reduction of 62 and 57 percent for carbon dioxide emissions from ethanol produced from sugarcane in tropical and dry climates, respectively. However, when land use change is accounted for, results indicate a significant increase in carbon dioxide emissions, referred to as carbon debt. Considering the reduction of carbon dioxide emissions resulting from ethanol and the debt amount, the payback time will be very long. Results of this study indicate that if forest is converted into a one cycle cropland, corn ethanol will require a payback period of 300, 672 and 210 years, for tropical, dry and temperate climate zones, respectively. If grassland is converted into cropland, corn ethanol will require a payback period of 112, 242 and 82 years, for tropical, dry and temperate climate zones, respectively. Similarly for sugarcane ethanol, when forests are converted into cropland, the payback period is 102 and 132 years, for tropical and dry climate zones, respectively. If grassland is converted into cropland, the payback period for sugarcane ethanol is 38 and 50 years, for tropical and dry climate zones, respectively. In addition, each gallon of corn ethanol requires about 156, 206 and 135 square feet of land for tropical, dry and temperate climates, respectively. Sugarcane ethanol requires about 75 and 91 square feet for tropical and dry climates, respectively. In addition to carbon dioxide emissions, fertilizers are released to the environment. Results of this study indicate that for corn ethanol, fertilizers released to the environment as surface runoff for nitrogen are estimated as 9,072, 12,247 and 8, 618 milligrams per gallon of ethanol for tropical, dry, and temperate climate zones, respectively. Similarly, for phosphate results were 3,629, 5,897 and 2,268 milligrams per gallon of ethanol for temperate, dry, and tropical climates. As for sugarcane ethanol, results for fertilizers surface runoff are estimated as 908 milligrams per gallon of ethanol for nitrogen, for tropical and dry climate zones, and 4,082 and 4,990 milligrams per gallon of ethanol for phosphate, for tropical and dry climate zones, respectively.