US firm to trap ship engine CO2 emissions into sea salt for 100,000 years

A California Institute of Technology (Caltech) and University of Southern California (USC) spinoff startup has developed a new reactor to turn carbon dioxide (CO2) into harmless salt.

The reactor is aimed at providing the international shipping industry with a safe, effective, and cheap form of carbon capture mechanism.

According to the developers, the technology turns emissions into salts that can lock up CO2 for up to 100,000 years. If deployed en masse, it will also help the International Maritime Organization (IMO).

It will also help the shipping industry meet its 2050 net-zero emissions target. The best part is that the reaction effectively mimics what the oceans already do but in minutes, not thousands of years.

“This is a reaction that the planet has been running for billions of years,” Jess Adkins, a chemical oceanographer from Caltech, told CNN . Adkins is one of the founders of the spinoff startup Calcarea , which designs and tests the reactors.

“If we can just speed it up, we have a shot at a safe and permanent way of storing CO2,” he added.

CO2 to natural salts

Seawater naturally absorbs approximately one-third of the CO2 emitted into the atmosphere. However, this leads to increased acidity and the dissolution of calcium carbonate, which is plentiful in the ocean.

“Calcium carbonate is what coral skeletons, shells, and all the things that make up most of the sediments at the bottom of the ocean are made of,” said Adkins. The dissolved calcium carbonate then reacts with the CO2 in the water to form bicarbonate salts, which locks the CO2 away.

Adkins added, “There are already 38,000 gigatons (38 trillion tons) of bicarbonate in the ocean right now.” Calcarea aims to replicate this natural process by directing the ship’s exhaust fumes to a reactor located in the ship’s hull.

Inside the reactor, the fumes are mixed with seawater and limestone (a calcium carbonate rock). As a result of this mixture, the CO2 in the exhaust fumes interacts with the combination, producing saline water that traps the CO2 in the form of bicarbonate salts.

Adkins explained that one reactor could be enough to capture and store approximately half of a ship’s CO2 emissions. This reaction takes over 10,000 years in the natural world but takes about a minute in Calcarea’s reactors, as per its claim.

According to Adkins, the salty water produced is released into the ocean without posing any threat to marine life or the chemical balance of the seawater.

Calcarea to decarbonize shipping

He also mentioned that the company is exploring the addition of a pre-filter to the system to remove other pollutants from the exhaust that could mix into the water, such as particulates, unburnt fuel, and other contaminants.

So far, Calcarea has constructed two prototype reactors, one at the USC parking lot and another at the Port of Los Angeles. In late May, the company announced a partnership with the research and development arm of international shipping company Lomar.

Adkins is confident that this collaboration will lead to the first full-scale reactor prototype being installed on a ship.

“We think that ships are going to be able to compete with underground CO2 storage,” he told CNN . “Purpose-built ships that pick up CO2 and limestone at a port, go out to sea and just run our reaction — they will be solely machines to efficiently and safely store carbon in the ocean as bicarbonate,” Adkins explained.