Potential capture and conversion of CO2 from oceanwater through mineral carbonation

Carbon dioxide (CO2) emitted by human activities not only brings about a serious greenhouse effect but also accelerates global climate change. This has resulted in extreme climate hazards that can obstruct human development in the near future. Hence, there is an urgent need to achieve carbon neutrality by increasing negative emissions. The ocean plays a vital role in absorbing and sequestering CO2. Current research on marine carbon storage and sink enhancement mainly focuses on biological carbon sequestration using carbon sinks (macroalgae, shellfish, and fisheries). However, seawater inorganic carbon accounts for more than 95 % of the total carbon in marine carbon storage. Increasing total alkalinity at a constant dissolved inorganic carbon shifts the balance of existing seawater carbonate system and prompts a greater absorption of atmospheric CO2, thereby increasing the ocean's carbon sink. This review explores two main mechanisms (i.e., enhanced weathering and ocean alkalinization) and materials (e.g., silicate rocks, metal oxides, and metal hydroxides) that regulate marine chemical carbon sink (MCCS). This work also compares MCCS with other terrestrial and marine carbon sinks and discusses the implementation of MCCS, including the following aspects: chemical reaction rate, cost, and possible ecological and environmental impacts.

Automated summary

Carbon dioxide emitted by human activities has serious impacts on global climate change and extreme climate hazards. Achieving carbon neutrality through increasing negative emissions is urgently needed. The ocean's role in absorbing and sequestering CO2 is crucial, and there is a focus on biological carbon sequestration research. However, inorganic carbon in seawater accounts for over 95% of marine carbon storage, and increasing total alkalinity can enhance the ocean's carbon sink.