International shipping, responsible for moving 80% of global trade, significantly contributes to carbon emissions, accounting for approximately 3% worldwide. To address this, the International Maritime Organization has tightened emission targets, aiming for net zero emissions by 2050. Despite this, the availability of low-emission fuels like methanol, hydrogen, and ammonia remains insufficient. Enter Calcarea, a US startup spearheaded by Jess Adkins, a chemical oceanographer from the California Institute of Technology.
Calcarea's innovative solution involves equipping cargo ships with reactors designed to convert CO₂ emissions from fuel combustion into ocean salts. This process, an accelerated version of natural oceanic reactions, offers a promising method for sequestering CO₂ for up to 100,000 years. Adkins explains that the planet has been running a similar reaction for billions of years, and by speeding it up, there is potential for a safe and permanent solution to CO₂ storage.
The natural process involves seawater absorbing CO₂, which makes the water more acidic and dissolves calcium carbonate, abundant in the ocean. This dissolved calcium carbonate then reacts with CO₂ to form bicarbonate salts, effectively locking the CO₂ away. Calcarea's reactors replicate this by funneling ship exhaust fumes into a reactor where they mix with seawater and limestone, creating salty water that locks CO₂ as bicarbonate salts. The resulting water is released back into the ocean, posing no threat to marine life.
Adkins founded Calcarea after two years of development at Caltech. The startup, which has raised $3.5 million, includes co-founders Melissa Gutierrez, Pierre Forin, and USC professor Will Berelson. They have built two prototype reactors, one at USC and another at the Port of Los Angeles. Recently, Calcarea partnered with Lomar's research and development arm to build the first full-scale prototype for installation on a ship.
Calcarea's technology can be adapted to various ship sizes, including the largest Newcastlemax class, capable of carrying 180,000 metric tons of cargo. On such a ship, the reactor would occupy about 4-5% of the deadweight tonnage and use up to 4,000 metric tons of limestone, although not all would be consumed.
Several engineering challenges remain before Calcarea can install its first reactor, including fitting the reactor on ships and establishing a limestone supply chain. The system's estimated cost is about $100 per metric ton of CO₂ captured, accounting for lost revenue due to space occupied by the reactor.
Calcarea’s reactors capture sulfur emissions, harmful to health and the environment, as part of the CO₂ removal process. Other companies, like British Seabound, also work on carbon capture, but produce solid carbonate pebbles that require offloading at ports. Calcarea’s approach, which involves accelerating a natural process, offers a more seamless integration with maritime operations.
Daniel Sigman, a Princeton professor not involved with Calcarea, highlights the advantages of this method: it accelerates a natural process and avoids raising ocean acidity levels, a major concern for marine ecosystems. Calcarea’s founders’ expertise in the ocean’s carbon cycle positions them well to avoid pitfalls that other companies might face.
Adkins envisions Calcarea helping the industry transition to greener fuels. In the future, specialized vessels might be dedicated to capturing and storing CO₂ from the atmosphere in the ocean, potentially competing with underground CO₂ storage. This innovation marks a significant step towards decarbonizing maritime transport and mitigating climate change.
