Although subject to sometimes quite considerable short-term variations, the long term trend for the price of coal, along with other primary energy resources, is upwards. The need to protect the environment has resulted in a reduction in low-cost disposal routes for many waste materials (eg coal processing wastes and sewage sludge) and this has provided a driver to develop alternative ways of dealing with these arisings. Finally, the growth in the use of carbon-neutral renewable technologies has spurred interest in the use of biomass for energy production; on a stand-alone basis and in combination with coal.
These three factors are largely responsible for the use of the so-called ‘low value fuels’ for energy generation. One particular technology stands out as being particularly well suited to utilising low value fuels, circulating fluidised bed combustion (CFBC).
This report sets out examples of the range of low value fuels, their reserves and properties, with particular emphasis on coal-derived materials, the issues for CFB plant in utilising these fuels and selected examples of manufacturer and operator experience with purpose built, or modified CFB plant. Finally an up-do-date global inventory of CFB plants using a range of low value fuels is presented.