1.10.1 Biomass

Imitating the coal-based process, biomass conversion has also been tried and looks promising. Main sources of biomass are agricultural, horti­cultural, and forest wastes. Municipal organic solid wastes (which are also plenty) are potential resources as well. Considering biomass as a renewable resource, the bioconversion may be pyrolytic, where biogas and bio-oil are the main products and yet the residue contains some calo­rie value which can be further utilized (as adsorbents, filter beds, chars, etc.). Supercritical conversion and superheated steam reformation of bio­mass are recent techniques. During 1990—1997, quite a few reports appeared in the literature showing success and promise of catalytic or uncatalytic reformation of biomass to hydrogen (almost to 18% v/v) without any char or residues.

Temperature ranges of 340-650oC, with pressures of 22-35 MPa, are cited with as low as 30-s residence time, through supercritical flow reac­tors. The raw materials are widely varying: water hyacinth, algae, bagasse, whole biomass, sewage sludge, sawdust, and other effluents rich in organic matters. In some efficient carbon bed-catalyzed reactors, other products (i. e., carbon mono — and dioxides and methane) were also detected.