Salman's Infobahn

A wide range of technologies exists to convert the energy stored in biomass to more useful forms of energy. These technologies can be classified according to the principal energy carrier produced in the conversion process. Carriers are in the form of heat, gas, liquid and/or solid products, depending on the extent to which oxygen is admitted to the conversion process (usually as air). The three principal methods of thermo-chemical conversion corresponding to each of these energy carriers are combustion in excess air, gasification in reduced air, and pyrolysis in the absence of air.   Conventional combustion technologies raise steam through the combustion of biomass. This steam may then be expanded through a conventional turbo-alternator to produce electricity. A number of combustion technology variants have been developed. Underfeed stokers are suitable for small scale boilers up to 6 MW th . Grate type boilers are widely deployed. They have relatively low investment costs, low ope...

Pyrolysis is the thermal decomposition of biomass occurring in the absence of oxygen. It  is the fundamental chemical reaction that is the precursor of both the combustion and gasification processes and  occurs naturally in the first two seconds.  The products of biomass pyrolysis include biochar, bio-oil and gases including methane, hydrogen, carbon monoxide, and carbon dioxide.   Depending on the thermal environment and the final temperature, pyrolysis will yield mainly biochar at low temperatures, less than 450  0 C, when the heating rate is quite slow, and mainly gases at high temperatures, greater than 800   0 C, with rapid heating rates. At an intermediate temperature and under relatively high heating rates, the main product is bio-oil. Pyrolysis can be performed at relatively small scale and at remote locations which enhance energy density of the biomass resource and reduce transport and handling costs.    Heat transfer is a critical area in pyrolysis as the pyrolysis process is...