Assessing the Production of Sugarcane-Derived Ethanol in Iran as a Transport Fuel from Economical and Environmental Point of View

Transcription

1 Journal of Environmental Science and Engineering, 5 (2011) D DAVID PUBLISHING Assessing the Production of Sugarcane-Derived Ethanol in Iran as a Transport Fuel from Economical and Environmental Point of View Sh. Bahadori Faculty of Economic and Administrative Sciences, Ferdowsi University of Mashhad, Mashhad , Iran Received: May 16, 2011 / Accepted: June 16, 2011 / Published: December 20, Abstract: Bioethanol is an attractive renewable energy resource that can be produced from agricultural feed stocks such as sugarcane, corn, sugar beet, wheat, barley and many types of waste biomass materials. It can be used as a transport fuel, mainly as a biofuel additive for gasoline called gasohol. In this study the possibility of using ethanol as a gasoline additive from economic, environmental and agricultural point of view in Iran is investigated. Daily gasoline consumption of Iran is about 66 million liters and 34% of this amount is imported. We consider the production of sugarcane-derived ethanol to displace 15% of gasoline use in Iran. With existing technology, 450,000 hectares of land, 21 standard distillery and US $3,600 million investment will be required to produce this amount of ethanol. This is just about 60% of the money that currently Iran expends annually for importing about 5.8 million tones of gasoline. Key words: Bioethanol, sugarcane, biofuel, gasoline, gasohol. 1. Introduction World ethanol production for transport fuel tripled between 2000 and 2007 from 17 billion to more than 52 billion liters. From 2007 to 2008, world fuel ethanol production increased 32% and the share of ethanol in global gasoline type fuel use increased from 3.7% to 5.4%. Brazil and the United States were responsible for 89.2% of the world s ethanol fuel production in 2008 [1]. These statistics clearly show the importance and world tendency for using ethanol as a transport fuel. Therefore, it is completely important for Iran that by dependence to imported gasoline, high crude oil prices, non renewability of fossil fuels and global warming something has to be done to reduce dependence and emissions derived from fossil fuel combustion. Ethanol can be produced from sugarcane Corresponding author: Sh. Bahadori, master, main research fields: renewable and non-renewable energy resources and energy economics. sherkobahadori@gmail.com. in Khuzestan province with minimal environmental impact and in sufficient quantities to be part of the solution. Today Khuzestan is responsible for more than 99% of sugarcane produced in Iran [2] and can play an important role in satisfying future ethanol demand. The proper climate, fertile lands and industrial implant allows sugarcane production at high yields even more than global average. The total production of sugarcane has rapidly increased in the previous decade. This increase is attributed to a combination of higher yields and seeded area. The study s objective is to evaluate the Khuzestan s potential for substituting 15% (3600 million liters annually) of the domestic demand of gasoline by sugarcane-derived ethanol. The study covered issues such as resources: land, people, infrastructure, as well as economic, environment and social impacts for the country due to this projection of major increase in ethanol production. We report here on the land and

2 Assessing the Production of Sugarcane-Derived Ethanol in Iran as a Transport Fuel from 1643 infrastructure requirements and potential environmental impacts of the proposed project. 2. Importance of Ethanol Ethanol is an alternative fuel for gasoline that is receiving great attention worldwide because it is a renewable and environmental friendly fuel therefore its rate of consumption is increasing dramatically recently. As you can see in Fig. 1, global fuel ethanol production grew 31% to 35 million tones of oil equivalent (1.2 million barrels per day on volumetric basis) in 2008 [3]. Ethanol can be used either pure or in blends with gasoline but at low concentrations it is not necessary to do any modification in spark-ignition (SI) engines but for using pure ethanol some modifications are necessary [4]. E15 (ethanol 15% and gasoline 85% by volume) is a low concentration blend and the most common combination of ethanol and gasoline that is suited renewable, bio-based and eco-friendly for spark-ignition (SI) engines. Due to mentioned environmental and economic benefits of E15, this ratio has been chosen. 3. A Brief Review of Sugarcane Production in Iran Production of sugar from sugarcane was undertaken in the 1950s along the Caspian Sea and Mazandaran province on a small scale. Food and Agriculture Organization (FAO) invited foreign experts to Khuzestan to conduct feasibility studies on sugarcane cultivation and in June 1957, the study proposed cultivation of sugarcane near Shoush city in an area of 12,000 hectares. Later, Haft-Tappeh Company was established for the purpose [5]. Based on official announcement of Agricultural Jihad Ministry 60,946 hectares with average yield of 87 tonne/ha is dedicated to sugar cane production in The yield reached to 94 tonnes per hectare in 2009 but the land under sugarcane cultivation is not formally announced yet [2]. Fig. 1 World ethanol production. 4. Suggested Project of Ethanol Production in Iran Iran gasoline consumption is about 66 million liters per day, slightly more than 24 billion liters per year. The study assesses to provide 15% of current gasoline consumption by sugarcane derived ethanol as a gasoline additive. To achieve this goal Iran should produce about 3.6 billion liters ethanol annually. About 85 liters of ethanol can be extracted from one tone of sugarcane based on current technology. Therefore 42,350,000 tonnes of sugarcane should be produced. With average yield of 94 tonnes per hectare of sugarcane it would take 450,000 hectares of sugarcane to provide enough feedstock to meet the projected demand of 3.6 billion liters of ethanol. Khuzestan because of its climate conditions, dry growing season and abundant and productive land has a high capability of producing sugarcane. There are a lot of proper sites for cultivating sugarcane in Khuzestan as you can see in Figs. 2 and 3 [6]. For example the irrigable soil in vicinity of Karkheh and Dez dam and the basin of Karun River respectively in north and southwest of Ahwaz and also the alluvial dry soil in south of Ahwaz have high capability for cultivating sugarcane if the water is supplied. Khuzestan currently has 2,488,608 hectares pasture and 1,146,700 hectares cropland. Of the cropland, 973,125 hectares are used for grains, 84,232 hectares are used for industrial products such as sugarcane and sugar beet, 42,092 hectares are used for vegetables, 36,798 hectares are used as melon bed and 10,453 are

3 1644 Assessing the Production of Sugarcane-Derived Ethanol in Iran as a Transport Fuel from Fig. 2 Khuzestan geological map. Fig. 3 Khuzestan farm land map. used for provender and other products. Sugarcane cultivation can be expanded only in 18% current pasture area of Khuzestan. Therefore, there would be no competition between food and fuel. A standard distillery (ethanol mill) is defined as a mill crushing 2 million tonnes of sugarcane per year and producing 1 million liters per day of fuel ethanol during 170 days of operation (totally 170 million liters ethanol per year) based on current technology [7]. Therefore, 21 standard distilleries are necessary for producing 3.6 billion liters of ethanol annually. We can divide these distilleries to some clusters which can be placed in the areas that have agricultural capability to support sugarcane production and logistics for ethanol shipment. These standard distilleries produce only ethanol and bagasse is used for producing electricity to supply energy demand of each facility. Excess electricity can be sold to the grid. The cost of each ethanol mill is estimated at US $100 million for implementing facility and an additional US $40 million agricultural related investment. The total investment would be around US $3 billion plus anther US $600 million for implementation of new sugarcane production. Total cost of project is estimated to be US $3.6 billion. Total cost of the project is just about 60% of the money that currently Iran expends annually for importing 5.8 million tones of gasoline (price of gasoline is US $1,050 per tone) [8]. Each ethanol mill will produce 170 million liters of ethanol and 80 GW h of electric energy per year. Price of electricity is about US $0.08 per kw h [9] and price of gasoline is US $1,050 per tonne. We use ethanol as substitute of gasoline therefore if we consider the same value for produced ethanol the investment will result in total revenue of around US $125 million for each ethanol mill and overall revenue of US $2,625 million for whole 21 ethanol mills annually and we should subtract the cost of production from the overall revenue. Price of raw sugarcane is US $33 per tone and the processing cost of produced ethanol is US $0.20 per liter [10]. Therefore, the production cost of produced ethanol will be US $0.59 per liter. Total cost will be US $2,125 million for producing 3.6 billion liters annually. If we subtract the total revenue from total cost, we will have the net profit that is equal to US $500 million. The implementation of this project will generate about 180,000 direct and indirect jobs [11]. Also by

4 Assessing the Production of Sugarcane-Derived Ethanol in Iran as a Transport Fuel from 1645 implementation of this macro project locals will benefit from social development as construction of homes, hospitals, public services, communication and transportation. 5. Environmental Impacts of the Project Replacing fossil fuels such as gasoline and diesel fuel by biofuels is a very controversial topic among researchers. In this section the environmental impacts of using ethanol are discussed and the other impacts are discussed in the next section. If we consider ethanol use in environmental point of view, Net Energy Ratio should be discussed (NER is the output of renewable energy per input of fossil energy). Fossil energy for agricultural-based production includes fossil fuels to drive tractors, produce fertilizer and other chemicals, as well as providing process heat for biofuel production, etc.. If this indicator is zero, it means that the fuel is not renewable at all and it also does not produce useful energy. If the indicator is 1, the fuel is still considered as non-renewable. An infinite indicator shows that the fuel is absolutely renewable and any value higher than 1 shows that the fuel is renewable up to a certain point. Brazilian sugarcane-derived ethanol has a net energy ratio of about 8.0 [12] meaning that there is 8 times more energy in produced ethanol than fossil energy used for its production. This is because of the biomass use (bagasse) in the production process of ethanol. Therefore, one can conclude that sugarcane-derived ethanol to some good point is renewable and eco-friend. NER can be improved by increasing the sugarcane yields and new technology therefore Iranian sugarcane-derived ethanol will have a greater NER than Brazilian due to higher yields (currently sugarcane yield in Iran is 32% greater than brazil). Therefore, the derived ethanol from this projection in Khuzestan province will have a NER of about 10 based on current yields and this ratio can be increased by improved farming techniques, more efficient use of fertilizers and pesticides, higher-yielding crops, and more energy efficient conversion technology. According to US Department of Energy (DOE) cellulosic ethanol reduces greenhouse gas emissions (GHG) by 86% over reformulated gasoline and sugarcane-derived ethanol reduces GHG emissions by 78% while corn-derived ethanol based on the kind of energy used for the process (e.g. petroleum, natural gas or biomass) reduces greenhouse gas emissions from 19% to 52% over gasoline [13]. With abundant gas reservoirs in the Khuzestan province of Iran, natural gas as a clean and cheap source of energy can be used in ethanol mills instead of bagasse that is currently burned as fuel in sugarcane mills. Therefore, the rate of GHG emissions will be reduced too much over gasoline and also the remained bagasse can be used as a source for producing cellulosic ethanol. Puppan [14] shows that biofuels have a close carbon cycle and during the combustion of biofuels in the engines, emissions of CO 2 correspond to the amount that was absorbed from the atmosphere during the growth of these plants. Therefore, the total CO 2 emission due to the ethanol fuel in the exhaust of engines is absorbed by the plant from the atmosphere. According to this point the biofuels can be a solution for global warming and they will play a significant role to mitigate global warming rate. Also a survey which has been done by Najafi et al. [15] indicates that by using ethanol-gasoline blends the concentration of CO and HC emissions in the exhaust of SI engines and also brake specific fuel consumption (bsfc) will decrease. In addition ethanol readily biodegrades without harm to the environment, and is a cheap and eco-friendly source of increasing gasoline octane number as substitute of lead or MTBE additives. Octane number of regular unleaded gasoline is 87 while the octane number of E85 is 105, therefore, ethanol enhances engine performance [16]. Despite of the above environmental advantages of using bioethanol there are some disadvantages such as

5 1646 Assessing the Production of Sugarcane-Derived Ethanol in Iran as a Transport Fuel from the use of large amounts of water, the destruction of forests, the reduction in food production and the increase in soil erosion. With increasing ethanol production, water availability has recently become an issue of concern. For instance, in the US Midwest the Ogallala aquifer, which underlies most of the US corn belt, has decreased over 100 ft since the 1940s [17]. This shows that human water use is exceeding the ability of aquifer recharge. Corn ethanol production with existing technology requires 3-4 L of water per liter of ethanol in the processing phase, while water use for Brazilian ethanol due to sugarcane washing is 50 L water per liter of ethanol [18]. Therefore, efforts are necessary to mitigate any adverse effects and improve water efficiency in aforementioned projection in Khuzestan. Food vs. fuel and forest destruction are the risks of diverting crops for ethanol production. The debate is internationally controversial, with good-and-valid arguments on all sides of this ongoing debate. But in this project sugarcane cultivation is expanded only in 18% current pasture area of Khuzestan that is not used as a farmland. Therefore, the competition between food and fuel and forest destruction will not be happened in this project. Ethanol-enriched gasoline conducts electricity in contrast to gasoline, which is electrical insulator. Therefore, the rate of corrosion of underground storage tanks increases and the risk of leakage to surrounding soil will increase. Also the presence of ethanol in gasoline increases the solubility of petroleum constituents such as benzene, toluene, xylenes and ethylbenzene in water and so there is great concern over groundwater protection [19]. 6. Other Impacts of the Project It is observed that the production of ethanol and other biofuels is mainly based on agriculture raw materials and, therefore, many countries can easily produce it attaining several benefits such as a greater energy security, diversification of energy sources and agriculture, accelerated development of rural areas with the consequent increase in job opportunities in these areas. But instead of these advantages there are some concern such as diverting agricultural resources to fuel instead of food production, use of large amounts of water, the possibility of destruction of forests and pasture and increase in soil degradation [20]. 7. Conclusion Energy security, need to mitigate the greenhouse effect and high crude oil prices are the great incentives for the world over ally and Iran especially, for using ethanol as new source of energy. The discussion here illustrates that large amounts of sugarcane-derived ethanol can be produced in Khuzestan province and can be used as gasoline additive in an environmentally responsible way. But the biofuel production projects should be carried out with full cautiousness. Choosing the proper region respect to weather, fertile lands and other criteria for cultivating agricultural products, having the minimum environmental effects and implementing the project in non cropland farms are some points that should be considered. Also it is important to realize that no single fuel or technology such as sugarcane-derived ethanol can replace fossil fuel alone. Meeting future demands will require new technologies such as improve and lowering the fuel consumption of engines and development of multiple fuels. No technology currently has a zero environmental and social impact but we should develop the best ways that have the least impact. Acknowledgments The author would like to acknowledge the support of my family, and also Saeid Javedan Nejad and Abbas Hosseini, chief engineers of Aghagajari Oil and Gas Producing Company. They provided valuable comments.

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