Microbial Reverse-Electrodialysis Electrolysis and Chemical-Production Cell for H₂ Production and CO₂ Sequestration

Natural mineral carbonation can be accelerated using acid and alkali solutions to enhance atmospheric CO₂ sequestration, but the production of these solutions needs to be carbon-neutral. A microbial reverse-electrodialysis electrolysis and chemical-production cell (MRECC) was developed to produce these solutions and H₂ gas using only renewable energy sources (organic matter and salinity gradient). Using acetate (0.82 g/L) as a fuel for microorganisms to generate electricity in the anode chamber (liquid volume of 28 mL), 0.45 mmol of acid and 1.09 mmol of alkali were produced at production efficiencies of 35% and 86%, respectively, along with 10 mL of H₂ gas. Serpentine dissolution was enhanced 17-87-fold using the acid solution, with approximately 9 mL of CO₂ absorbed and 4 mg of CO₂ fixed as magnesium or calcium carbonates. The operational costs, based on mineral digging and grinding, and water pumping, were estimated to be only $25/metric ton of CO₂ fixed as insoluble carbonates. Considering the additional economic benefits of H₂ generation and possible wastewater treatment, this method may be a cost-effective and environmentally friendly method for CO₂ sequestration.