Pyrolysis has a requirement for initial energy, in the same way as in straight combustion
some heat in the flame is used to initiate combustion of new feedstock. But the relative
requirements must be carefully compared, together with any difference between pyrolysis
and alternative bioenergy technologies in the energy requirement of feedstock transportation
and drying.
The potential advantage of pyrolysis-derived bioenergy over other bioenergy strategies in
terms of greenhouse gas emissions results not only solely from the retention of up to 50% of
the feedstock carbon in stable biochar, but from indirect savings that may result from the use
of biochar in agriculture, specifically the soil (Gaunt et al., 2008).
Biomass pyrolysis and gasification are well established technologies for the production of
biofuels and syngas. However, commercial exploitation of biochar by-products as a soil
amendments is still in its infancy. In Japan, which has the largest market for such products,
approximately 15 000 t yr-1 is traded annually for soil use (Okimori et al., 2003). More usually
biochar products are gasified for extraction of residual energy, or used in production of high
value products such as activated carbon (Demirbas et al., 2006b).
The pyrolysis process greatly affects the qualities of biochar and its potential value to
agriculture in terms of agronomic performance or in carbon sequestration. The process and
process parameters, principally temperature and furnace residence time, are particularly
important; however, the process and process conditions also interact with feedstock type in
determining the nature of the product.
Pyrolysis has a requirement for initial energy, in the same way as in straight combustion
some heat in the flame is used to initiate combustion of new feedstock. But the relative
requirements must be carefully compared, together with any difference between pyrolysis
and alternative bioenergy technologies in the energy requirement of feedstock transportation
and drying.
The potential advantage of pyrolysis-derived bioenergy over other bioenergy strategies in
terms of greenhouse gas emissions results not only solely from the retention of up to 50% of
the feedstock carbon in stable biochar, but from indirect savings that may result from the use
of biochar in agriculture, specifically the soil (Gaunt et al., 2008).
Biomass pyrolysis and gasification are well established technologies for the production of
biofuels and syngas. However, commercial exploitation of biochar by-products as a soil
amendments is still in its infancy. In Japan, which has the largest market for such products,
approximately 15 000 t yr-1 is traded annually for soil use (Okimori et al., 2003). More usually
biochar products are gasified for extraction of residual energy, or used in production of high
value products such as activated carbon (Demirbas et al., 2006b).
The pyrolysis process greatly affects the qualities of biochar and its potential value to
agriculture in terms of agronomic performance or in carbon sequestration. The process and
process parameters, principally temperature and furnace residence time, are particularly
important; however, the process and process conditions also interact with feedstock type in
determining the nature of the product.
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