The Bioflex project investigate the compatibility of operation between a two-stage bioprocess and an electrolyser to produce Hydrogen and Methane. Process water from Nordic Sugar in Örtofta, a sugar industry is utilized in the bioreactors. AP2 investigates energy balances and upscaling of the bioprocess, technical compatibility and synergistic effects between electrolysis and the two-step bioprocess. This assignment examines how waste heat from electrolysis can be used to pre-heat process water before entering the bioprocess reactors.

This study analyses three possible configurations of scaled up installation, with a 5MW Alkaline electrolyser and 20m3 bio-Hydrogen reactor and 100m3 bio-Methane reactor. The overall efficiency in combined operation mode and stand-alone operation of electrolyser when connection with a high temperature District Heating Network (DHN) are comparable 86-88%. However, under both these cases come with an installation of heat pump which is cost intensive. For electrolyser sizes less than 5MW, water treatment of the seasonal effluent from bioreactors is less energy efficient. Based on pilot study in AP1, the 20m3 bio-Hydrogen reactor can produce similar amount of Hydrogen as the 5MW electrolyser. The purities of these two methods are different, hence the overall dimensioning of the system would depend on demand and end user for these products.

In the present scenario, with seasonal availability of process water for the bioprocess, the percentage of overlapping working hours of electrolyser and bioreactors varies between 25% to a maximum of 40%. Higher operating hours for bioreactor is recommended to achieve maximum efficiency and consistency of supply.