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BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

16 2 Biofuels under

16 2 Biofuels under study 2.3 Life cycles of solid biofuels 2.3.1 Triticale (whole crops) Figure 2-2 shows the life cycle of triticale compared to its corresponding fossil fuel, which is hard coal. The utilisation of the triticale is co-firing of the grain with hard coal for electricity production. 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 triticale production. The maintenance of fallow land is no longer necessary, as instead triticale is cultivated. These factors are described in some more detail below. Hard coal production Winning of hard coal Transport Combustion for electricity generation Triticale production Machines Fuel Fertiliser Seeds Biocides Agricultural Production Harvest & transport to farm Storage Transport to power plant Co- firing with hard coal for electricity generation Credits Fallow maintenance Figure 2-2 Schematic life cycle comparison of whole crops (triticale) versus hard coal Details of the life cycle steps Fossil fuel chain: The coal is exploited in USA, Canada, Australia and S. Africa (in equal shares) and transported to Europe using average distances. In Europe the coal is combusted for electricity generation. 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. No pest management is carried out. The use of tractors for field preparation, planting, harvest etc. is also included. The biomass is baled and transported to the farm for storage. From there it is transported to the combustion plant where it is co-fired with hard coal for electricity generation. The effects of the disposal of ash in a landfill site are also taken into account. Utilisation: Both fuels are balanced with regard to combustion for electricity production on the basis of kWh electricity output.

2.3 Life cycles of solid biofuels 17 2.3.2 Short rotation willow coppice Figure 2-3 shows the life cycle of short rotation willow coppice (SRC) compared to two fossil fuels: light oil and natural gas. The utilisation of the willow is combustion of the chipped wood 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 willow production. In this case maintenance of fallow land is no longer necessary, as instead willow 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 Short rotation coppice production Machines Fuel Fertiliser Biocides Cuttings Agricultural Production Harvest Transport to combustion plant Combustion Credits Fallow maintenance Figure 2-3 Schematic life cycle comparison of short rotation willow coppice (SRC) 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. Combustion takes place in small-scale residential heating systems. 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 willow is left to grow for 4 years before the first harvest and is then harvested every 3 years until the field is ploughed again after 20 years. The impacts of harvest etc. are averaged over the lifetime of the crop in order to obtain annual values. The wood is chipped and the chips are finally stored and transported before combustion. The effects of the disposal of ash are also taken into account. Utilisation: All three fuels are balanced with regard to combustion for district heating on the basis of MJ heat output.

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