Chemical synthesis of food from CO₂ for space missions and food resilience

Recyclable food technologies are essential for long-term manned space missions. This research compares customary and alternative space foods to non-biological synthesis (NBS) systems using recycled CO2 . Using electrochemical conversion of CO2 as a starting point, different carbohydrate synthesis routes are reviewed. Sugars and glycerol are considered as final products. Three roundtrip missions with 5 crew members and 3-year duration were analyzed: International Space Station, the Moon, and Mars. The equivalent system mass (ESM) technique was used to compare NBS systems to customarily storing prepackaged food, artificial-light grown Spirulina platensis, hydrogen-oxidizing bacteria (HOB), and microbial electrosynthesis (MES). This allows for a launch cost comparison of systems with different characteristics, including equipment mass, onboard volume, and power and heat rejection requirements. Power consumption was estimated via mass and energy balances using literature values. The Mars mission ESM of the NBS system is estimated within 10-30 tonnes. This was compared to an average of 65 t for Spirulina, 35 t for prepackaged food, 25 t for MES, and 11 t for HOB. NBS is estimated to be among the most energy efficient options, together with HOB and MES. Electricity-to-food conversion efficiencies of 10-21% and single-pass carbon yields up to ~70% are expected for an NBS system. Although NBS is not recommended over all alternatives (i.e., HOB), it is recommended over the prepackaged food and Spirulina benchmarks. These food production technologies could also help humanity survive extreme catastrophes.