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BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

20 2 Biofuels under

20 2 Biofuels under study 2.4.2 Sunflower oil methyl ester (SME) Figure 2-6 shows the life cycle of sunflower oil methyl ester (SME) compared to its corresponding fossil fuel, which is conventional diesel oil for utilisation in transport vehicles. The raw material for SME is sunflower oil. The left hand side of the diagram shows the various steps of conventional fuel production, whereas the middle column represents the biofuel chain. On the right hand side the equivalent conventional processes are shown which are being replaced as a consequence of the biodiesel production – i. e. these can be regarded as “credits” because the environmental effects arising through them can be “saved”. For example maintenance of fallow land is no longer necessary, as instead rape seed is cultivated. Diesel fuel production Winning of crude oil Transport (Pipeline, Tanker) Refining Transport to fuel station Combustion Sunflower methyl ester production Machines Fuel Fertiliser Seeds Biocides Agricultural pro- duction (seeds) Harvest & transport Storage Transport Oil extraction Transesterification Transport Combustion Credits Fallow maintenance Soy bean meal & oil Glycerine production Figure 2-6 Schematic life cycle comparison of sunflower oil methyl ester (SME) versus diesel oil Details of the life cycle steps Fossil fuel chain: The crude oil is extracted in OPEC-countries and transported to Europe using average distances. In Europe the oil is refined in order to produce standard diesel fuel for combustion in transport vehicles. Then again the fuel undergoes transport until it has reached the filling station. These assumptions are based on expert judgements and are considered to represent the marginal technology. Biofuel chain: The production, application and partial leaching of agrochemicals such as chemical fertiliser and herbicides are taken into account, assuming good agricultural practice. The use of tractors for field preparation, sowing, harvest etc. is also included, as is the production and transport of the seeds. The harvested seeds are transported and stored. Then they are transported to the oil mill where the hulls are removed and used for electricity generation. The oil is extracted from the seeds and the meal which is obtained as a co-product is used for animal feed, substituting soy bean meal. The oil is refined and undergoes transesterification. The transesterification process leads to glycerine as a further co-product, substituting conventional glycerine production. Finally, the crude sunflower oil methyl ester is purified, distributed and used for combustion in diesel engines. Utilisation: The comparison is based on the utilisation of both types of fuel in a passenger car according to the EURO-4 emission standard obligatory up from 2005. The reference unit is one kilometre of distance driven.

2.4 Life cycles of liquid biofuels 21 2.4.3 ETBE from sugar beet Figure 2-7 shows the life cycle of ETBE (ethyl-tertiary-butyl-ether). The corresponding fossil fuel is MTBE for utilisation in transport vehicles. ETBE is produced from sugar beets. The left hand side of the diagram shows the various steps of conventional fuel production, whereas the middle column represents the biofuel chain. On the right hand side processes are shown which are counted as “credits” for the biofuel system. Thus for example the maintenance of fallow land is no longer necessary, as instead sugar beet is cultivated. These factors are described in some more detail below. MTBE production Winning of natural gas Transport (Pipeline) MeOH production MTBE production (using iso-butene) and blending with gasoline Transport to end user Combustion ETBE production ( sugar beet) Machines Fuel Fertiliser Biocides Cuttings Agricultural production Harvest & transport Sugar extraction, fermentation, dehydration Transport ETBE production (using iso-butene) and blending with gasoline Transport Combustion Figure 2-7 Schematic life cycle comparison of ETBE versus MTBE Details of the life cycle steps Credits Fallow maintenance Heat production Heat & pow er production Fossil fuel chain: MTBE is produced from oil and natural gas. The crude oil and natural gas are exploited and transported to Europe, where the oil is refined to produce iso-butene (besides other fuels) and the gas is used to produce methanol. These two are processed to obtain MTBE, which is blended with gasoline for combustion in car engines. These assumptions are based on expert judgements and are considered to represent the marginal technology. Biofuel chain: The production, application and partial leaching of agrochemicals such as chemical fertiliser and herbicides are taken into account, assuming good agricultural practice. The use of tractors for field preparation, sowing, harvest etc. is also included, as is the production and transport of the seeds. The beets are harvested and transported, while the leaves are left in the field. The sugar is extracted from the beets and fermented to produce ethanol, which is distilled and dehydrated. The remaining slop is fermented to give biogas for heat production and the chips are used for heat and power production, substituting conventional heat and power production. The ethanol is transported to the refinery and ETBE is produced from this and iso-butene. Finally it is blended with gasoline for combustion in car engines. Utilisation: The comparison is based on the utilisation of both types of fuel in a passenger car according to the EURO-4 emission standard obligatory up from 2005. The reference unit is one kilometre of distance driven.

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