HYDROGEN-PRODUCTION FROM WASTES

A process for the conversion of municipal solid waste, automobile shre dder residue and other plastic/rubber wastes to hydrogen is described both from a technical and an economic point of view. Pilot-plant and m odeling results are tools in the analysis. The conversion is carried o ut in two major process steps. The first or pre-treatment step is base d on pyrolysis and results in an intermediate product containing appro ximately 90% of the primary feed in a suitable physical form for the s econd step. This second step is Texaco's high-temperature, high-pressu re gasifier which is based on partial oxidation and converts the organ ic components to synthesis gas (CO and H-2). Total thermal conversion efficiency for waste to hydrogen is found to be a strong function of f eedstock quality. For typical MSW feedstocks, an efficiency of 40-50% is predicted for an integrated process. Fossil-fuel feedstocks such as waste plastics and scrap tires result in efficiencies of the order 60 -70%. The cost of produced hydrogen is approximately $15/GJ for typica l MSW with a tipping fee of $50/ton, but drops to $6/ton for high-plas tics waste that carry a tipping fee of $100/ton. (C) 1998 Elsevier Sci ence Ltd. All rights reserved.