HyTIME - Combined Biohydrogen and Biogas Production from 2nd Generation Biomass

Abstract

Employment of renewable sources rather than fossil fuels in the production of hydrogen is an important step to achieve a sustainable and environmental friendly hydrogen economy in the future. Besides biomass gasification, production of hydrogen from renewable sources is also possible in a fermentative way through thermophilic (dark) fermentation of biomass. In the European project HyTIME nine partners including universities, knowledge centres and industry work on an integrated, continuous bioprocess for the decentral production of 1-10 kg hydrogen/d. The strategy in HyTIME is to employ thermophilic bacteria, which have shown superior yields in H₂ production from biomass in the previous FP6 IP HYVOLUTION. In this paper, mass and energy balances for process routes based on different feedstock options will be presented and discussed, giving a first glance at feedstock, water, heat and utility demand. Mass and energy balances for the involved process steps and overall process routes are calculated via process simulation tool Aspen Plus (V7.3.2, Aspen Technology Inc., 2012). It is shown that biohydrogen can be successfully produced from verge grass and wheat straw. Based on the experimental results and literature data, process is scaled up to produce 10 kg biohydrogen/d in the raw gas stream. To achieve this, it is necessary to supply 90 kg/h wet verge grass or 46 kg/h wheat straw. Besides biohydrogen, biogas is produced from process residuals and utilized for heat and power generation. According to the calculations, it is possible to produce 48.5 kW and 45.8 kW heat as well as 44.6 kW and 42.2 kW power, from verge grass and wheat straw residuals, respectively. Presented results form the basis for critical evaluation of the proposed process parameters and process routes and give hints for process improvement by applying process integration.