Carbon emission avoidance and capture by producing in-reactor microbial biomass based food, feed and slow release fertilizer: Potentials and limitations.

To adhere to the Paris Agreement of 2015, we need to store several Gigatonnes (Gt) of carbon annually. In the last years, a variety of technologies for carbon capture and storage (CCS) and carbon capture and usage (CCU) have been demonstrated. While conventional CCS and CCU are techno-economically feasible, their climate change mitigation potentials are limited, due to limited amount of CO that can be captured. Hence, there is an urgent need to explore other CCS and CCU routes. Here we discuss an interesting alternative route for capture of carbon dioxide from industrial point sources, using CO-binding, so-called autotrophic aerobic bacteria to produce microbial biomass as a C-storage product. The produced microbial biomass is often referred to as microbial protein (MP) because it has a crude protein content of ~70-75%. Depending on the industrial production process and final quality of the produced MP, it can be used for human consumption as meat replacement, protein supplement in animal diets, or slow-release organic fertilizer thus providing both organic nitrogen and carbon to agricultural soils. Here, we discuss the potentials and limitations of this so far unexplored CCU approach. A preliminary assessment of the economic feasibility of the different routes for CO carbon avoidance, capture and utilization indicates that the value chain to food is becoming attractive and that the other end-points warrant close monitoring over the coming years.