Food production in space from CO2 using microbial electrosynthesis.

The current food method in space is launching prepackaged food which is costly and unsustainable. Alternatives include growing crops and microalgae single cell protein (SCP) using artificial light photosynthesis, which are energy inefficient. Prepackaged food and microalgae food were compared to microbial electrosynthesis of acetic acid (MES-AA). Since the dominant cost of a space mission is the cost of launching mass, components of a system were converted to an equivalent mass, including power, heat rejection, and volume. Three-year roundtrip crewed missions were evaluated for the International Space Station, the Moon, and Mars. The average Equivalent System Mass (ESM) of MES-AA is 1.38x and 2.84x lower than prepackaged food and microalgae SCP, respectively. The expected electricity-to-calorie conversion efficiency of MES-AA is 19.8 %, consuming 3.45 kW to fully feed five astronauts; diets would realistically include multiple foods. MES-AA has a higher energy efficiency than any currently investigated resilient food in space. MES-AA can provide diet diversity at a lower cost than customarily storing prepackaged food or growing crops in space. Producing food while contributing to closed loop life support in space can contribute to reducing global catastrophic risk and is relevant in off-grid communities, like in rural Alaska.

Microbial Electrosynthesis and Anaerobic Fermentation: An Economic Evaluation for Acetic Acid Production from CO2 and CO.

Microbial electrosynthesis (MES) and anaerobic fermentation (AF) are two biological processes capable of reducing CO2, CO, and water into acetic acid, an essential industrial reagent. In this study, we evaluated investment and production costs of acetic acid via MES and AF, and compared them to industrial chemical processes: methanol carbonylation and ethane direct oxidation. Production and investment costs were found high-priced for MES (1.44 £/kg, 1770 £/t) and AF (4.14 £/kg, 1598 £/t) because of variable and fixed costs and low production yields (100 t/y) compared to methanol carbonylation (0.26 £/kg, 261 £/t) and ethane direct oxidation (0.11 £/kg, 258 £/t). However, integrating AF with MES would reduce the release of CO2, double production rates (200 t/y), and decrease investment costs by 9% (1366 £/t). This resulted into setting the production costs at 0.24 £/kg which is currently market competitive (0.48 £/kg). This economically feasible bioprocess produced molar flow rates of 4550 mol per day from MES and AF independently. Our findings offer a bright opportunity toward the use and scale-up of MES and AF for an economically viable acetic acid production process.