Life Cycle Assessment of Microbial Electrosynthesis for Commercial Product Generation

Abstract

Microbial electrosynthesis (MES) uses microbes and electricity to convert CO2 to high-grade chemicals alleviating greenhouse gas (GHG) emissions. Little is known on the environmental loads associated with the scale-up of the technology. Initially, the MES environmental impacts of synthesizing acetic, formic, or propionic acids, methanol, or ethanol were assessed using GaBi LCA software, and electricity produced 60% from fossil fuels. The results show that formic acid production had the lowest environmental impact in all eco-indicators due to the comparatively low energy requirements of its reactor and rectification unit. Second, three different formic acid production methods were compared with MES. Hydrolysis of methyl formate, the main conventional method was shown to be less environmentally harmful than the other three CO2 utilizing technologies analyzed when the electricity used was generated from fossil fuels except for the impact on climate change. Producing electricity from renewable sources (hydro, biogas, wind, and photovoltaic) made MES able to mitigate climate change with the lowest negative impact on the environment compared with others. Synthesis of products through MES using wind generated electricity could provide considerable benefits and should be considered when MES is industrially applied.