Biomedical Engineering Reference
In-Depth Information
Chapter 10
Biomass Cofiring and
Torrefaction
10.1 INTRODUCTION
Direct combustion is an important option for biomass energy conversion, and
it has been used since the dawn of human civilization when man discovered
fire. Direct combustion of biomass is in use in many parts of the world
including Nepal, where it is still the primary source of energy in rural areas.
Greatest use of biomass is in small-scale applications like a domestic stove,
where biomass is used as firewood. Large-scale commercial use, though
growing especially for heating and for electricity production, is still not the
dominant application of biomass. Of late, the motivation for use of biomass
to replace fossil fuels in steam power plants, cement industries, and iron
making is growing because it could reduce carbon footprint of those indus-
tries. Owing to the large difference in combustion properties of biomass and
fossil fuels, it is difficult to replace a fossil fuel entirely in a fossil fuel fired
system with biomass, without any major performance penalty. An
acceptable practical option is partial replacement by cofiring biomass in an
existing fossil fuel fired combustion plant because it reduces the extent of
incompatibility. This chapter examines cofiring of biomass for partial
replacement of fossil fuels in the above industries.
The interest in biomass cofiring is rising because of the growing need for
immediate reduction in greenhouse gas (GHG) emission from large power
plants. Although extensive research on carbon capture and storage for
sequestration (CCS) is being conducted, and many countries have committed
major funds for demonstration plants, wide-scale commercial use of CCS for
reduction in carbon dioxide is not likely to happen in the short term because
of the large number of technical and scale-up issues this technology faces.
Even if CCS overcomes all these issues, the electricity generation cost would
still be high.
Utility industries and regulators around the world have recognized that
for immediate reduction in GHG emission from fossil fuel fired power
plants, one could take an incremental step by cofiring CO 2 neutral biomass
in an existing fossil fuel fired power plant. This being proven and less expen-
sive could be the best near-term solution for GHG reduction. As the amount
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