HYDROGEN PRODUCTION FROM WASTE BIOMASS IN SUPERCRITICAL WATER

摘要

Energy from biomass may contribute in a considerable amount to the growing future energy demand. The use of biomass is considered an attractive alternative to fossil fuels because of the advantage that it dose not contribute to the net generation of carbon dioxide in the earth's atmosphere. Another advantage of biomass is low sulfur content in comparison with most fossil fuels. Hydrogen is an environmentally clean energy source since it generates no pollutants. To convert biomass to hydrogen furthermore electricity via a fuel cell is an ideal environment-benign approach for energy conversion. Thermochemical process, such as steam gasification is currently being investigated to obtain gases from biomass [1]. Since the specific objective is to produce a maximum of hydrogen to be used in a fuel cell, further improvement must be made to convert the biomass feedstock to a gas rich in hydrogen. Biomass without drying can be directly converted to hydrogen, hydrocarbons and fuels in supercritical water. Because of the high water excess, hydrogen and carbon dioxide are generated at temperatures of 873K or higher instead of the synthesis gas produced during classical gasification processes. In this way, one process step of classical hydrogen generation would no longer be required, namely, the conversion of CO with water into H_2 and CO_2.