BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

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.