Several small-scale, fixed-bed, updraft gasifiers are operated commercially in Sweden and Finland for the gasification of a wide range of biomass feedstocks, including wood chips, saw mill residues, straw, and RDF (Patel, 1996). The gasifiers are marketed by Carbona Corporation and are refractory-lined shaft furnaces that are fed from the top by a hydraulically operated feeder. The units are equipped with hydraulically rotated mechanical grates at the bottom. Ash sintering is prevented by water vapor contained in the gasification air, and the ash is removed through an ash discharge system installed at the bottom. The moisture content of the feeds can range from 0 to 45%, and the corresponding heating values of the product gas are about 5.5 to 3.8 MJ/m3 (n). The gasifiers can be connected to a hot water or steam boiler depending on whether heat or electric power is desired, or alternatively, the product gas can be used for hot gas generation for kilns and dryers.