Potential environmental concern on direct combustion. With support from the European Union and the US Dept of Energy, several power companies have successfully completed tests of direct and indirect cofiring utilizing a range of boiler types and fuels including several types of wood, sewage sludge and straw. Testing was largely successful with no major technical obstacles encountered. However, areas of concern were identified including the potential for ash with high chlorine and alkali content to cause fouling, corrosion and SCR catalyst degradation, difficulties in storing and processing low density fuels, and the limited ability to utilize commingled ash. The economic feasibility of bioelectricity in Europe is improving at a significant rate.
Pyrolysis is the only technology that directly yields a liquid fuel.
Larger scale fast pyrolysis processes are under construction. More attention is being paid to the liquid properties. There is a greater awareness of the potential of liquid bio-fuels. There is an increasing interest in chemical products. We have seen a growth by a factor of 8 in US over 18 years up to 1.4 billion gallons for fuel blending.