Power-to-Vitamins or Power-to-Protein: An evaluation of the integrated system at an industrial scale from techno-economic perspectives.

We assessed the economic viability of a two-stage system for producing folate- and protein-enriched yeast biomass using acetate derived from CO2 and renewable electric power at a 1,750 m3 scale. In a Power-to-vitamin system producing a biomass product for partial daily protein intakes, heating for nucleic acids removal is unnecessary. Under these conditions, a CO2 input of 31.3 ktCO2 y-1 yields 12.9 ktproduct y-1 containing 813 kgfolate y-1 and 5.6 ktprotein y-1 (43% of yeast biomass). This production volume meets the full recommended daily allowance (RDA) for folate and 5% of RDA for protein of 5.6 million people when each person consumes 6 g of dried yeast product daily. At a selling price of $20 kgproduct-1, the system's payback period is 5 y. In a baseline scenario, the minimum selling price (MSP) is $8.41 kgproduct-1, largely driven by electric-power pricing and energy demand of water electrolysis. An ideal scenario simulation reduced the MSP to $4.53 kgproduct-1, combining: 1) lower water purity requirements for electrolysis; 2) higher yeast production rate; 3) lower electric-power pricing; and 4) no CO2 procurement costs and lower ammonium costs. In a Power-to-protein system with a biomass product designed to meet full daily protein needs, heat treatment is necessary, which increases the MSP to $14.24 kgproduct-1. At a selling price of $20 kgproduct-1, the payback period is 7 y, exhibiting lower overall profitability than the Power-to-vitamin system. Both modeled systems are economically viable at selling prices competitive with plant-, whey-, algae-, and yeast-derived protein products.