Power to Protein Fundamentals Hydrogen Transfer. Final report

In this study, the aim was to gain fundamental insights into the mass transfer of hydrogen in bioreactors in order to promote the biosynthesis of single-cell protein. This is based on the findings from previous project phases (1 and 2) which involved feasibility and experimental studies conducted to progress the highly promising power to protein concept, as investigated by the companies Avecom (Impetus), KWR and Allied Waters. Specifically, the analysis presented in this study targeted the pilot-scale bubble column reactor operated by Avecom to further understand and test the power to protein concept. The activities conducted in order to achieve the above aim are as follows:
– Literature Review: A literature study was conducted to understand what types of reactors are found in literature related to hydrogen mass transfer coefficient and to assess which reactor configuration offers high mass transfer efficiency. Furthermore, based on the optimal reactor configuration, further information on the key operating parameters that are related to the mass transfer of hydrogen gas were identified. Focus was also given in understanding the effect of pressure, gas hold-up and mass transfer coefficient in bubble column reactors as defined by the partners in the previous phase of the project.
– Knowledge Exchange with Experts: A meeting and knowledge exchange session was organised with key experts in the relevant field in order to present the research activities that were conducted in this study. Recommendations from the expert session were taken into consideration and the key takeaway messages are provided in this report. They confirmed that the bubble column reactor provides the best and right configuration for the power to protein concept and advised to obtain additional monitoring data to optimise the modelling of the reactor performance.
– Modelling Study: In this activity, a CFD model was developed and calibrated using the available data to adequately represent the pilot-scale bubble column reactor that is currently being operated by Avecom to further understand and test the power-to-protein concept. Based on the findings from the literature review, a CFD model was developed incorporating the key design and operating parameters of the power-to-protein bioreactor. Various simulations and sensitivity analyses were conducted in order to determine the effects of these different key operating conditions on the mass transfer of hydrogen and gas hold-up to maximise the yield of bacteria in the bioreactor. Based on the results from the model simulations, recommendations for the optimal design of a scale-up bioreactor have been provided. Additionally, the limitations of the current model due to unavailability of necessary data have also been reported as well as recommendations to obtain the necessary data required to further calibrate the model thereby increase the prediction accuracy.