Ocean water and seashells: possible climate change solution?

A recent article showcases an effort by the UCLA Chemical and Biomolecular Engineering department to utilize the ocean’s incredible ability to absorb carbon dioxide and combat climate change, termed "SeaChange". The ocean is already known to absorb carbon dioxide: 30% of CO2 emissions since the industrial revolution have been absorbed by the ocean, and it is 150x more efficient by volume than air in absorbing CO2. Research by their department has showcased a method of removing CO2 from the ocean, therefore allowing the ocean to regain its capacity for more CO2 from the air. If successful, this technology could hold many advantages over other CO2 removal and storage systems because of its efficiency, and utilization of natural resources.

Figure 1: Professor Dante Simonetti of UCLA Samueli Chemical and Biomolecular Engineering Department showcasing SeaChange.

“sCS2” is the name given to the concept in their research: this process uses a single-step carbon sequestration and storage method in order to remove CO2 from ocean water. The process uses “electrolytic carbonate mineral precipitation using renewable energy” in order to dissolve and remove CO2. A potential system would use electrolysis to make the water alkaline, which then allows reactions to occur where calcium and magnesium (already in water) combined with CO2 to precipitate into limestone (calcium carbonate, CaCO3) and magnesite (magnesium carbonate, MgCO3) - this mimics how seashells occur. Since CO2 is sequestered from the water, CO2 can then be absorbed from the air, helping to remove greenhouse gas from the atmosphere. Because this process is relatively simple and produces a durable CO2 storage solution in the form of seashells, sCS2 could be a major step towards utilizing the ocean in removing greenhouse gasses and mitigating climate change.

Figure 2: Depiction of a model system that utilizes sCS2 and shows how CO2 would be sequesterd from seawater and then returned.

A model of a potential sCS2 system is shown above: water flows into the system where an electrical charge is passed through it, precipitate is released into the ocean once CO2 is sequestered from the water, and then the depleted water would then flow out of the system. Practical implementation of a sCS2 system is dependent on a variety of factors, and obviously may not lead to a climate change solution within the near future. For example, this process would have to be scaled up tremendously: the goal is to capture 10 billion metric tons of CO2 per year, which would require 1,800 sCS2 plants. While 1,800 plants may seem feasible, this would yield costs “in the trillions of dollars.” On the other hand, another byproduct of sCS2 is the clean fuel source, hydrogen. This may be a benefit, but it is questionable whether this is significant enough to alleviate the economic problems of the system. Ultimately, removing greenhouse gas is a pressing issue the scientific community will continue to face: one single solution will definitely not solve all of our problems, however this could be a significant step towards new methods of removing CO2 from the atmosphere.

References

1.

California researchers attempt ocean climate solution. NBC News. Published April 21, 2023. Accessed April 30, 2023. https://www.nbcnews.com/science/environment/california-researchers-attempt-ocean-climate-solution-rcna80861

2.

Could the ocean hold the key to reducing carbon dioxide in the atmosphere? | UCLA. Accessed April 30, 2023. https://newsroom.ucla.edu/releases/using-seawater-to-reduce-co2-in-atmosphere