Techno-economic Analysis of Renewable Hydrogen Production via SCWG of Biomass Using Glucose as a Model Compound

Abstract

The world’s hydrogen production is around 45 million tons (500 million m3) per year, primarily derived from fossil fuels, of which about 50 % is by steam methane reforming at 800–900 ıC in the presence of a catalyst (typically nickel-based). The production of hydrogen from bio-renewable sources and organic wastes is promising with respect to the environmental problems associated with fossil fuel use and reduction of dependence on the declining fossil-fuel reserves. Hydrogen can be produced by air and/or steam gasification of solid biomass or biomass-derived feedstock products or by-products (e.g. glucose, ethanol and glycerol) at temperatures above 700–800 ıC with or without catalysts. Compared to conventional steam gasification or reforming processes, supercritical water gasification (SCWG) can increase the gasification efficiency, improve the hydrogen yield and reduce tar and coke formation. In addition, SCWG can utilize the wet biomass and wastes directly, eliminating the energy and capital-intensive drying process. Besides the technical challenges for SCWG of biomass in a continuous flow reactor system, e.g., the difficulty in feeding the slurry feedstock into a high-pressure system, determining economic profitability for large-scale processes is essentially needed for future commercialization of the process. This chapter presents the resultsof techno-economic analysis for production of hydrogen from glucose (a biomass model compound) and sewage sludge waste materials via SCWG. Detailed process simulation is carried out for the SCWG process evaluationwith two feedstocks. Cost of hydrogen production and the revenue obtained from different feedstock are also evaluated