EU CLEAN-COAL TECHNOLOGY - COCOMBUSTION OF COAL AND BIOMASS

Apart from a more economical use of fossil fuels, the application of r egenerative energy sources should be advanced in order to reduce CO2 e missions. One of the alternatives Considered to decrease the net emiss ions of CO2 are the cultivation and combustion of solid biomass, or th e thermal utilization of sewage sludge. There are different types of b iomass which could be used as energy source in power production: (a) s urplus and by-products from agricultural activities within the Europea n Union (EU), e.g., straw, (b) fast growing energy plants from reutili zation of areas which become available by a necessary reduction of agr icultural overproduction within Europe, and (c) wood waste from forest ry or wood processing. In order to achieve a noticeable CO2 reduction, as well as fossil fuel substitution, it is desirable to use fairly la rge quantities of biomass for energy production. However, an exclusive biomass utilization would consequently lead to the construction of ma ny decentralized plants, which is time-consuming and would require hig h financial investments as well as large storage capacities due to the seasonal fuel availability. Go-combustion, in contrast, is considered to be a cheap option for utilizing the existing biomass resources. Fo r these reasons, an EU-project, 'Combined Combustion of Biomass/Sewage Sludge and Coals of High and Low Rank in Different Systems of Semi-in dustrial and Industrial Scale' was launched in 1993. Under the coordin atorship of the Institut fur Verfahrenstechnik und Dampfkesselwesen (I VD), University of Stuttgart, partners from eight European countries i nvestigated the effects of burning sewage sludge, agricultural residua ls, such as straw and manure, as well as especially cultivated energy plants in combination with coals of various ranks and origin. Both the pulverized fuel (PF) and the fluidized bed (FB) mode were tested, ran ging from laboratory rigs to large scale utility boilers. This paper p rovides an overview of the activities of the various partners involved and will, in particular, show the synergetic cooperation towards a co mmon aim. The results of the 2-yr project will be summarized. (C) 1998 Elsevier Science B.V.