Solar-Powered Carbon Fixation for Food and Feed Production Using Microorganisms-A Comparative Techno-Economic Analysis

Abstract

This study evaluates the techno-economic feasibility of five solar-powered concepts for the production of autotrophic microorganisms for food and feed production; the main focus is on three concepts based on hydrogen-oxidizing bacteria (HOB), which are further compared to two microalgae-related concepts. Two locations with markedly different solar conditions are considered (Finland and Morocco), in which Morocco was found to be the most economically competitive for the cultivation of microalgae in open ponds and closed systems (1.4 and 1.9 € kg^-1, respectively). Biomass production by combined water electrolysis and HOB cultivation results in higher costs for all three considered concepts. Among these, the lowest production cost of 5.3 € kg^-1 is associated with grid-assisted electricity use in Finland, while the highest production cost of >9.1 € kg^-1 is determined for concepts using solely photovoltaics and/or photoelectrochemical technology for on-site electricity production and solar-energy conversion to H₂ by water electrolysis. All assessed concepts are capital intensive. Furthermore, a sensitivity analysis suggests that the production costs of HOB biomass can be lowered down to 2.1 € kg^-1 by optimization of the process parameters among which volumetric productivity, electricity strategy, and electricity costs have the highest cost-saving potentials. The study reveals that continuously available electricity and H₂ supply are essential for the development of a viable HOB concept due to the capital intensity of the needed technologies. In addition, volumetric productivity is the key parameter that needs to be optimized to increase the economic competitiveness of HOB production.

Figure 1

Block flow diagrams of concepts. (A) Algae-based biomass production concepts, algae-open and algae-closed; (B) Concepts utilizing PV and electrolysis combined with hydrogenotrophic fermentation, PV-e-HOB (dashed line), and PVGrid-e-HOB (dash dot line); (C) Concepts employing PEC water electrolysis and hydrogenotrophic fermentation, PEC-HOB.

Figure 2

Total production cost of all concepts (“MAR” Morocco scenario, “FIN” Finland scenario) (A) and breakdown of variable production costs (B). The displayed variable cost parameters include CO₂, grid electricity (Grid E), fuel, fresh water, and nutrients ammonia as well as DAP.

Figure 3

Sensitivity of production costs on key parameters in the scenario Morocco. Parameters exceeding 10% change in baseline cost are shown. Blue bars indicate baseline costs for each concept with variability of the costs by different parameters under favorable and less favorable conditions indicated by green and orange bars, respectively.