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Gasification of biomass is usually understood to mean pyrolysis of dry material, usually wood. This process has been known and used for many years, but does not produce natural gas. Its product is called syngas, which is a mixture of carbon monoxide and hydrogen, and cannot be used with the same infrastructure as natural gas. The Genifuel gasifier (licensed from Battelle using patents developed at the Pacific Northwest National Laboratory by research scientist Doug Elliott and colleagues in the Chemical and Biological Process Group), uses instead a wet process catalyzed to yield rapid and almost complete conversion of the biomass, producing clean renewable natural gas as the product. This process operates at much lower temperatures than other gasification methods, approximately 350oC and 21 MPa (662oF and 3000 psi), making the construction and operation of the equipment easier. The gasifier yields both a product gas and steam, which contains the carbon dioxide produced during gasification. After condensation, the water enriched with dissolved carbon dioxide is recycled to the growth ponds to accelerate growth of the next generation of biomass while reducing emissions to nearly zero. For a more detailed description of the gasification process, see Elliott's original paper on catalytic gasification of wet biomass. (Paper made available by permission of The Institution of Chemical Engineers.) |
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