Biofuels are energy sources derived from biological materials or biomass, and the combustion of these types of fuels is regarded as carbon neutral. Creating the raw material absorbs carbon dioxide, and using those releases an equivalent amount. The emissions from these energy sources belong in the natural circulation, because the carbon dioxide stored in biological material would eventually have been released anyhow, if not through human energy exploitation then through decomposition in nature (Scragg 2009: 167).
Biomass has always been exploited as an energy source by human beings, and can be exploited through different processes for energy generation. First, and most widespread, the biomass can be used for the heating of buildings and to generate electricity. This can be done through the direct combustion in fires and stoves in private homes for heating purposes, through more advanced pellets burning systems in the heating of larger buildings, or as the energy source in an electricity production plant. A second area of use for the biofuels is through co-firing, where the biomass is burned together with coal in power stations, and in
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this way reducing the overall green-house gas emissions from the power station. Thirdly, the biomass can be exploited as a transport fuel. Through different chemical processes, the biomass can be converted into biofuels in gaseous or liquid states that can be used as transport fuels (Scragg 2009: 74-6).
1.4.1 Historical Account
The idea of using biologically based fuels for transport is as old as the motor vehicle industry itself. The early engines where originally designed to be driven by a great variety of fuels, among them alcohol and plant oil based fuels (Olah, Goeppert and Prakash 2006: 177). Henry Ford, the motor vehicle pioneer, called biologically based fuels for transport “the fuels for the future” (Scragg 2009: 107). During the first half of the 20th century, there was a great interest in the development of biologically based fuels. This was especially true in European countries, as this part of the world lacked their own petroleum reserves. Therefore these countries had a greater incentive for the development of other sources of energy in order to reduce their energy dependence. Furthermore, as many European countries had colonies in tropical areas, they had access to natural resources and land areas with low cost production potential (Pahl 2005): 26-7).
Nevertheless fossil fuels soon gained dominance as the energy source of motor vehicles. This was due to the fact that by the beginning of the 20th century these fuel sources had become considerably cheaper to access, produce and supply to the public compared to biologically based fuels (Olah et.al 2006: 177). During the World Wars, the normal supplies of fossil fuels were disrupted by the actions of war, and biologically based fuels were used as emergency substitutes. However, after the Second World War, the world society was flooded with cheap petrol, and the biological fuels industry was to a large extent forgotten. The hegemony of the fossil fuels continued without question until the 1970s and the turbulences in the oil supply of this decade (Pahl 2005: 26-7).
The 1970s oil crises was a consequence of the Yom Kippur War of 1973 and the Iranian revolution in 1979. The Organization for the Oil Exporting Countries (OPEC) organized an oil embargo against the West and the USA for choosing sides in these conflicts. As a result of the embargo energy prices inflated enormously and lead an economic recession (Pahl 2005:
27). These two experiences had showed beyond doubt how dependent the Western countries had made themselves on import of oil. The way of life one knew in these nations at the time
5 was in fact threatened by the insecurity in the oil market. This lead to a revival of the interest in biologically based fuels in the West (Pahl 2005: 28).
1.4.2 Current Biofuels Production and Use
Today’s liquid biofuels can without problems be used in small proponents with conventional fuels in normal vehicles. This is related to the belief in biologically based fuels from the pioneers in the automobile industry, and to the continuous interest in these fuels through history (Scragg 2009: 136). The most common biofuels today are ethanol and biodiesel.
Ethanol accounts for more than three quarters of the current biofuel use. The majority of it is produced in the USA and Brazil, while the European countries are the leading biodiesel producers in the world (World Watch Institute 2007: 3-7).
Ethanol
Ethanol is derived from sugar crops such as sugar cane and sugar beet, or starch crops such as maize or wheat. Through different processes these crops are transformed into ethanol, which can be used as a fuel in a petrol engine (Scragg 2009: 109). Sugar cane is the most significant biofuels crop. The plant is currently the lowest cost crop available for biofuel production, as it contains a large amount of easily accessible sugar. Brazil accounts for the majority of the ethanol produced from sugar cane. Ethanol from sugar beet is mainly produced in Europe.
This plant gives generally good yields of energy in temperate areas, but the total energy yield is low compared to sugar cane production in tropical areas. The crop is more energy and chemical intensive, as the beet must be processed in order to access the sugar. Maize is the most important biofuels source among the starch crops. This is mainly due to the plant’s dominance in the USA. Maize is a land intensive crop, and although the USA and Brazil produce comparable amounts of ethanol, the maize based American ethanol needs almost twice as large a land area as the Brazilian ethanol. In addition the starch also requires a more complicated process before it can be converted into liquid fuels. It must first be converted into sugar and then in a second process to alcohol (World Watch Institute 2007: 25-8). The Brazilian ethanol is the cheapest product among the different types of ethanol that is available on the world market. This is related to the production process, and the growth conditions (The Economist 2005).
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Biodiesel
Biodiesel is derived from plants that store their energy in oil-seeds, e.g. rape seed, soy bean and palm oil (Scragg 2009: 137). The energy yield per hectare in temperate regions is generally lower for oil seeds compared to starch and sugar crops, but these products normally require less processing, and their overall energy balance is more favourable in the long run than for ethanol products. Rapeseed is the most important feedstock for biodiesel in Europe. It gives the highest net energy yield per hectare of the oil-seed crops, when grown in the temperate parts of the world. Soybean is the dominant oil-seed plant on a world basis, but only a very small portion is used as biofuels for transport. Soybeans generate a relatively low energy yield per hectare compared to other oilseed crops. Still the plant is increasingly being used as a feedstock for biofuels. This is related to the crops occurrence and availability, and not to its suitability as a crop for transport fuels. Palm oil is an attractive source of biofuels production, because the net energy yield per hectare is very high. The majority of the palm oil is produced for food consumption, but an increase in the demand for palm oil for the production of biodiesel is expected, especially due to forecasted increase in the import of palm oil to Europe (World Watch Institute 2007: 30-33).