Bioflex pilot study

Today, there is an increasing demand for robust and flexible energy solutions to meet sustainable development goals. Renewable energy carriers, such as hydrogen and methane can play a key role in the sustainable transition. Although the simultaneous biological production of these components is promising, there is limited work on upscaling development. In the first part of this work, methane and hydrogen were produced from sugar-rich process water, in a two-stage process, by anaerobic microbes. Both pure strains and mixed culture were evaluated for hydrogen production at lab-scale. Mixed anaerobic culture was used after pretreatment for hydrogen production and the effluent was then used as substrate for methane production in pilot reactors of 10 L and 60 L in total volume. The pilot system was operated in continuous and semi-automated mode for 69 days, at 65oC (hydrogen) and 40oC (methane). The highest yields of hydrogen and methane obtained were 1.57 L/Lr/d and 0.91 L/Lr/d, respectively. Out of the 0.91 L/Lr/d production of methane, approximately 0.7 L/Lr/d were produced in the hydrogen reactor and 0.21 L/Lr/d in the methane reactor. anaerobic process. The process led to more efficient methane production and lower biogas emissions from the digestate compared to one-stage biogas production.

The second part of this work is a techno-economic analysis of the integrated two-stage bioprocess and electrolysis. The design of a large-scale integrated process is established, and mass and energy balances are calculated. A study-level cost analysis is performed based on the mass and energy balances. The results indicate that the electrolyser system and the hydrogen compression system are the major cost drivers of the integrated process. Electricity is the major contributor to the operating costs. The calculated pay-back period is highly dependent on the selling price of hydrogen.