The selection and design of any biomass combustion system are
determined mainly by the characteristics of the fuel to be used, existing
environmental legislation, the costs and performance of the equipment
available, as well as the energy and capacity needed (heat, electricity).
Due to economy of scale effects concerning the fuel feeding system, the
combustion technology, and the flue gas cleaning system, usually
large-scale systems use low-quality fuels, while high-quality fuels are
typically used for small-scale systems. Therefore, large-scale biomass
combustion technologies are often similar to waste combustion systems, but
when clean biomass fuels are utilised, the flue gas cleaning technologies
are less complex and therefore cheaper. Improvements are continuously
being made in fuel preparation, combustion and flue gas cleaning
technologies. This leads to significant improvements in efficiencies, and
reductions in emissions and costs, as well as improved fuel flexibility
and plant availability, and opens new opportunities for biomass combustion
applications under conditions that were too expensive or inadequate before.
For any biomass combustion application, emission reduction and
efficiency improvement are major goals. The results of research projects
and experiences of demonstration plants in one country can have a strong
impact on other countries as well, and here the IEA collaboration plays an
important role in information exchange.
|Lay-out of the Wilderswil heating
plant (6,4 MWth on wood chips + 3 MWth backup on fuel
oil). Courtesy of Schmid AG, Switzerland.