Biomass fuel includes wood, and agricultural and food processing wastes, as well as sewage sludge and animal manure. Biomass fuel includes wood, and agricultural and food processing wastes, as well as sewage sludge and animal manure.
Using crop residues, sewage or manure — wastes that are continually generated by society — to generate electricity offers environmental benefits in the form of preserving precious landfill space and reducing overall anthropogenic emissions.
If wood is the primary fuel, there is very little sulphur dioxide (SO2) in waste gases, when compared with say a coal plant.
However some biomass power plants show relatively high NOx (nitrogen oxide gases)emissions when compared to other combustion technologies. Both SO2 and NOx have serious effects on both the environment and human health.
Biomass can be directly burnt or converted to gas before burning. Direct Combustion power plants burn the biomass fuel directly in boilers that supply steam for the same kind of steam-electric generators used to burn fossil fuels. In biomass gasification, biomass is converted into a gas — methane — that can then fuel steam generators, combustion turbines, combined cycle technologies or fuel cells.
The main benefit of biomass gasification, compared to direct combustion, is that extracted gases can be used in a variety of power plant forms.
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Burning biomass in a boiler coupled with CCS allows a power station to have negative emissions overall. (Photo: Ingram) Burning biomass in a boiler coupled with CCS allows a power station to have negative emissions overall.
Conventional CCS on a fossil fuel power station can reduce CO2 emission by 80-90%. However, burning biomass in a boiler coupled with CCS allows a power station to have negative emissions overall. This is because the vegetation will have absorbed CO2 through its lifetime and the CO2 liberated from its burning will be isolated from the atmosphere in storage. Thus even though CCS...