Recent trends in global production and utilization of bio-ethanol fuel
Introduction
With increasing gap between the energy requirement of the industrialized world and inability to replenish such needs from the limited sources of energy like fossil fuels, an ever increasing levels of greenhouse pollution from the combustion of fossil fuels in turn aggravate the perils of global warming and energy crisis [1]. Motor vehicles account for a significant portion of urban air pollution in much of the developing world. According to Goldemberg [2], motor vehicles account for more than 70% of global carbon monoxide (CO) emissions and 19% of global carbon dioxide (CO2) emissions. CO2 emissions from a gallon of gasoline are about 8 kg. For example:There are 700 million light duty vehicles, automobiles, light trucks, SUVs and minivans, on roadways around the world. These numbers are projected to increase to 1.3 billion by 2030, and to over 2 billion vehicles by 2050, with most of the increase coming in developing countries [3]. This growth will affect the stability of ecosystems and global climate as well as global oil reserves.
The world’s total proven oil, natural gas and coal reserves are respectively, 168.6 billion tons, 177.4 trillion cubic meters, and 847.5 billion tons by the end of 2007, according to the recently released 2008 BP Statistical Review of World Energy [4]. With current consumption trends, the reserves-to-production (R/P) ratio of world proven reserves of oil is lower than that of world proven reserves of natural gas and coal — 41.6 years versus 60.3 and 133 years [4], respectively. In 2007, world oil production was 3.90 billion tons, a decrease of 0.2% from the previous year [4]. According to International Energy Agency statistics [5], the transportation sector accounts for about 60% of the world’s total oil consumption. Interest in the use of bio-fuels worldwide has grown strongly in recent years due to the limited oil reserves, concerns about climate change from greenhouse gas emissions and the desire to promote domestic rural economies.
The term bio-fuels can refer to fuels for direct combustion for electricity production, but is generally used for liquid fuels in transportation sector [6]. The use of bio-fuels can contribute to the mitigation of greenhouse gas emissions, provide a clean and therefore sustainable energy source, and increase the agricultural income for rural poor in developing countries. Today, bio-fuels are predominantly produced from biomass resources. Biomass appears to be an attractive feedstock for three main reasons [7], [8], [9]: (1) it is a renewable resource that could be sustainably developed in the future, (2) it appears to have formidably positive environmental properties resulting in no net releases of carbon dioxide and very low sulfur content, and (3) it appears to have significant economic potential provided that fossil fuel prices increase in the future.
Bio-fuels are liquid or gaseous fuels made from plant matter and residues, such as agricultural crops, municipal wastes and agricultural and forestry by-products. Liquid bio-fuels can be used as an alternative fuel for transport, as can other alternatives such as liquid natural gas (LNG), compressed natural gas (CNG), liquefied petroleum gas (LPG) and hydrogen. Bio-fuels could significantly reduce the emissions from the road-transport sector if they were widely adopted. They have been shown to reduce carbon emissions, and may help to increase energy security. There are many different types of bio-fuels, which are produced from various crops and via different processes. Bio-fuels can be classified broadly as bio-diesel and bio-ethanol, and then subdivided into conventional or advanced fuels [10]. This paper summarizes policy and regulatory drivers for bio-ethanol fuel in the major producing countries, describes usage trends and projections, development of biomass feedstocks, and improved conversion technologies.
Section snippets
Policy drivers for bio-ethanol
Bio-fuels are attracting growing interest around the world, with some governments announcing commitments to bio-fuel programs as a way to both reduce greenhouse gas emissions and dependence on petroleum-based fuels. The United States, Brazil, and several EU member states have the largest programs promoting bio-fuels in the world. The recent commitment by the United States government to increase bio-energy threefold in ten years has added impetus to the search for viable bio-fuels [11], [12],
Bio-ethanol trends and projections
Global production of bio-ethanol increased from 17.25 billion liters in 2000 [16] to over 46 billion liters in 2007 [48]. Fig. 1 shows global bio-ethanol production between 2000 and 2007. Bio-ethanol production in 2007 represented about 4% of the 1300 billion liters of gasoline consumed globally [48]. The United States, Brazil, and several EU member states have the largest programs promoting bio-fuels in the world. National bio-fuel policies tend to vary according to available feedstock for
Bio-ethanol as a transportation fuel
Bio-ethanol is ethyl alcohol, grain alcohol, or chemically C2H5OH or EtOH. Bio-ethanol and bio-ethanol/gasoline blends have a long history as alternative transportation fuels. It has been used in Germany and France as early as 1894 by the then incipient industry of internal combustion (IC) engines [55]. Brazil has utilized bio-ethanol as a transportation fuel since 1925. The use of bio-ethanol for fuel was widespread in Europe and the United States until the early 1900s. Because it became more
Biomass sources for bio-ethanol
There is a growing interest worldwide to find out new and cheap carbohydrate sources for production of bio-ethanol [61]. Currently, a heavy focus is on bio-fuels made from crops, such as corn, sugar cane, and soybeans, for use as renewable energy sources. Though it may seem beneficial to use renewable plant materials for bio-fuel, the use of crop residues and other biomass for bio-fuels raises many concerns about major environmental problems, including food shortages and serious destruction of
Bio-ethanol production routes from biomass
To ensure that “good” ethanol is produced, with reference to greenhouse gas (GHG) benefits, the following demands must be met [83]: (1) ethanol plants should use biomass and not fossil fuels, (2) cultivation of annual feedstock crops should be avoided on land rich in carbon (above and below ground), such as peat soils used as permanent grassland, etc., (3) by-products should be utilized efficiently in order to maximize their energy and GHG benefits, and (4) nitrous oxide emissions should be
Bio-ethanol economy
The cost of bio-fuels is also an important consideration; bio-fuels must be competitive with each other and with mineral fuels such as petrol and diesel. This competitiveness ensures a market for the bio-fuel is available, as people will have an incentive to convert to a renewable source of energy. Thus when analyzing crop rotations cost optimization must also be considered [106].
Considering that up to now the cost of bio-ethanol was considerably higher than the cost of fossil gasoline supply,
Limitations on bio-ethanol production
Bio-ethanol production generally utilizes derivatives from food crops such as corn grain and sugar cane, but the limited supply of these crops can lead to competition between their use in bio-ethanol production and food provision [113]. Corn-based bio-ethanol production in most of the countries assessed is limited, especially compared to the United States. Only Canada reported explicit plans for significant future development of corn-based bio-ethanol, although China has used corn as a
Conclusion
Bio-fuels are being promoted in the transportation sector. Many research programs recently focus on the development of concepts such as renewable resources, sustainable development, green energy, eco-friendly process, etc., in the transportation sector. Increasing the use of bio-fuels for energy generation purposes is of particular interest nowadays because they allow mitigation of greenhouse gases, provide means of energy independence and may even offer new employment possibilities.
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