Ultra-Efficient Electrolytic Ocean Carbon Removal Through Capacitive Decarbon Reactors

Direct ocean capture (DOC) is a promising technique for mitigating residual anthropogenic CO2 levels. However, the existing DOC methods are energy-intensive and may have unforeseen effects on marine ecosystems due to the chemical processes involved. We introduce a capacitive decarbon (CDC) reactor that converts carbonate ions into CaCO3, a construction material, using only calcium ions (Ca2+) from seawater and renewable electricity. After optimizations of the electrode and electrolytic reactor, the CDC reactor achieves ocean carbon removal with an exceptionally low energy consumption of 16 kJ mol−1 CO2, which is one order of magnitude lower than previously reported values. This energy requirement increases to 107 kJ mol−1 CO2 when factoring in the seawater intake and pre-treatment. We then used a global integrated analysis model to evaluate the carbon mitigation potential of this approach and found that it can remove about 360 to 1,670 million tonnes of CO2 in 2050 and 2100, respectively, which corresponds to 4.55% and 14.82% of the global carbon sequestration capacity for those years. Given the high efficiency of the CDC reactor, we anticipate it may become a viable solution for sequestering oceanic carbon.