Utilities are facing major challenges in the coming decades. Current policy envisions a transition to a sustainable energy supply, while ensuring security of supply. Therefore, current energy policy is spurring utilities to improve the sustainability of their coal-fired power plants.
Co-firing biomass is one of the major measures widely applied to reduce CO2 emissions. Since the mid-1990s, power plants designed to burn pulverized coal have additionally been firing organic materials, such as wood and agricultural waste. However, coal-fired power plants are not designed to process biomass, which limits the co-firing percentage to some 5%-10%. With investments in dedicated supply chains and biomass pre-treatment equipment co-firing percentages of 25%-50% (thermal) have already been achieved.
From the fuel perspective, the ideal situation is to process the biomass so that its properties resemble those of coal. The main form of processed biomass currently in use is wood pellets – pelletised dry sawdust – because it is a relatively clean fuel that is internationally available, easy to handle (free flowing capabilities, less dust emission) and has relatively low transport cost. Wood pellets work well in coal-fired plants and are now regarded as a well-proven technology.