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BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

18 2 Biofuels under

18 2 Biofuels under study 2.3.3 Miscanthus Figure 2-4 shows the life cycle of Miscanthus compared to two fossil fuels: light oil and natural gas. The utilisation of the Miscanthus is combustion for district heating. 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 agricultural reference system is shown which is replaced by the Miscanthus production. In this case maintenance of fallow land is no longer necessary, as instead Miscanthus is cultivated. These factors are described in some more detail below. Natural gas production Winning of natural gas Desulphurisation Transport (Pipeline) Combustion Light oil alternatively instead of light oil production production Winning of crude oil Transport (Pipeline, Tanker) Refining Transport to end user Combustion Miscanthus production Machines Fuel Fertiliser Biocides Cuttings Agricultural production Harvest Transport to combustion plant Combustion Credits Fallow maintenance Figure 2-4 Schematic life cycle comparison of Miscanthus versus light oil and natural gas respectively 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 light oil for combustion in heating plants. The alternative fossil fuel chain is that for natural gas. In this case the gas is exploited in Norway and the Confederation of Independent States (in equal shares) transported and compressed, processed and distributed to the end user. 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, planting, harvest etc. is also included, as is the production and transport of the cuttings. The Miscanthus is left to grow for 2 years before the first harvest and is then harvested every year until the field is ploughed again after 16 years. Weed control is only required in the first year and fertilising starts in the second year. The impacts of these processes are averaged over the lifetime of the crop in order to obtain annual values. The crop is chopped and transported to the combustion plant where it is burnt and the ash is disposed of in a landfill. Utilisation: All three fuels are balanced with regard to combustion for district heating on the basis of MJ heat output.

2.4 Life cycles of liquid biofuels 19 2.4 Life cycles of liquid biofuels 2.4.1 Rape seed oil methyl ester (RME) Figure 2-5 shows the life cycle of rape seed oil methyl ester (RME) compared to its corresponding fossil fuel, which is conventional diesel fuel for utilisation in transport vehicles. The raw material for RME is rape seed 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 oil production Winning of crude oil Transport (Pipeline, Tanker) Refining Transport to fuel station Combustion RME production Machines Fuel Fertiliser Seeds Biocides Agricultural production Harvest & transport Storage Transport Oil extraction Transesterification Transport Combustion Credits Fallow maintenance Soy bean meal & oil Glycerine production Figure 2-5 Schematic life cycle comparison of rape seed oil methyl ester (RME) 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 oil is extracted from the harvested seeds, producing rape seed meal as a co-product. Both the oil and the meal substitute soy bean oil and meal from production in Brazil. The oil is refined and undergoes transesterification with the use of potassiumhydroxid, methanol and acid – the production and disposal of which are all taken into account. The transesterification process leads to glycerine as a further co-product, substituting conventional glycerine production. Finally, the crude rape seed oil methyl ester is purified, distributed and combusted. 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.

Bioenergy Update 10-02 - General*Bioenergy