Calcarea's innovative technology transforms CO2 into ocean salts, reducing emissions from cargo ships

American company Calcarea is developing an innovative technology aimed at reducing carbon dioxide emissions from cargo ships by transforming CO2 into ocean salts. This process, which mimics a natural reaction that occurs in the ocean, could keep carbon locked up for up to 100,000 years.

International shipping, which accounts for around 3% of the world's carbon emissions, is currently not on track to meet its climate goals. Since low-emission fuels such as methanol, hydrogen and ammonia are not available quickly enough, Calcarea's solution could provide a viable alternative.

The company's technology consists of equipping cargo ships with reactors that convert the CO2 emitted by fuel combustion into ocean salts. This is achieved by directing the ship's exhaust fumes into a reactor in the ship's hull, where they are mixed with seawater and limestone. The CO2 from the exhaust reacts with the mixture, producing salt water that locks the CO2 in the form of bicarbonate salts.

Calcarea founder Jess Adkins, a chemical oceanographer at the California Institute of Technology, believes a large-scale reactor could capture and store about half of a ship's CO2 emissions. The reaction, which naturally takes more than 10,000 years, occurs in the Calcarea reactors in about a minute. The salt water produced is harmless to marine life and does not alter the chemical balance of seawater.

Calcarea, which was spun off from Caltech in 2023, has already built two prototype reactors and recently announced a partnership with the research and development group of international shipping company Lomar. Adkins is confident that this partnership will lead to the installation of the first large-scale prototype of his reactor on a ship.

Despite the promising potential of this technology, there are still some engineering challenges to overcome, such as how to install the reactor on the ship and the logistics of loading the limestone. Adkins also cautions that the cost of the system, estimated at about $100 per ton of CO2 captured in the exhaust, includes revenue lost by the ship making room for the reactor at the expense of commercial payload.

However, if successful, Calcarea's technology could play a crucial role in helping the shipping industry decarbonise and meet its climate goals.