Biomass fuel flexibility in future conventional power generation

Power generation from the combustion of solid fuels has been a conventional technology for electricity production in the UK and most of the world for many decades. While the phasing out of coal as a fuel is an important aspect of the ‘decarbonising’ the electricity sector, the respective power plant technology could still play an important role into the future by use of abundant sources of solid biomass fuels. If such resources are to be effectively utilised, it is then necessary to accommodate the wide variation in the characteristics and behaviour of biomass fuels. Some of the key challenges in this context include: control of burn-out efficiency for different fuels; predictability of ash behaviour including operational problems and emissions arising from high ash and high potassium content fuels; the fate of fuel nitrogen content and the consequent effects on NOx emissions. This article presents an overview of these issues, their significance in the context of power plant design and operation and details of some recent research seeking to address them. Results of laboratory scale experiments showing the variation in properties and behaviour of different types of biomass fuel are also presented. These include studies on the relationship between fuel particle size and burn-out duration, gas-phase potassium release from biomass materials during combustion, variability in biomass ash composition and nitrogen release patterns from fuels in high temperature combustion.