USC and Caltech Researchers Develop Innovative Technology to Halve Shipping Industry Carbon Emissions
June 25, 2025 — Scientists at the University of Southern California (USC) and the California Institute of Technology (Caltech), collaborating with startup Calcarea, have unveiled a groundbreaking shipboard carbon capture system that could reduce carbon dioxide (CO2) emissions from maritime shipping by up to 50%. This advancement offers a promising solution to decarbonize an industry responsible for nearly 3% of global greenhouse gas emissions.
A Simple Yet Effective Approach to Combat Shipping Emissions
Maritime shipping is notoriously difficult to decarbonize, with current alternatives such as low-carbon fuels and electrification often proving too costly or impractical for long-distance voyages. The new system, described in the journal Science Advances, leverages a natural oceanic process to buffer CO2 directly onboard ships without extensive retrofitting.
William Berelson, Paxson H. Offield Professor in Coastal and Marine Systems at USC Dornsife and co-corresponding author of the study, explained, “What’s beautiful about this is how simple it is. We’re speeding up a process the ocean already uses to buffer CO2 — but doing it on a ship, and in a way that can meaningfully reduce emissions at scale.”
How the Technology Works
As ships travel through seawater, exhaust CO2 is absorbed into seawater pumped onboard, which becomes slightly acidic. This acidic water is then passed through a bed of limestone, where a chemical reaction converts the CO2 into bicarbonate — a stable, non-toxic compound naturally present in the ocean. The treated water, now stripped of excess CO2, is safely discharged back into the sea.
Berelson highlighted, “This started as a pure science question: How does the ocean buffer CO2? From there, we realized we might have a real-world solution that could help fight climate change.”
From Laboratory to Real-World Application
The research team conducted rigorous laboratory experiments and modeling to validate the system’s efficiency and environmental safety. Their controlled tests with seawater, limestone, and CO2 closely matched theoretical predictions, providing confidence that the process can be scaled for use on actual vessels.
Sophisticated oceanic simulations assessed the impact of releasing treated water into the sea along shipping routes, such as between China and Los Angeles over a decade. Findings confirmed negligible effects on ocean pH and chemistry, reassuring that the process is environmentally sound.
Jess Adkins, co-founder and CEO of Calcarea and Smits Family Professor of Geochemistry and Global Environmental Science at Caltech, emphasized, “We see our approach as a complementary strategy that could help ships reduce their environmental impact without major design overhauls.”
Commercialization and Future Prospects
Working closely with industry partners, Calcarea aims to transition this technology from the lab to operational vessels. The company is actively engaged in discussions with commercial shippers and exploring pilot programs to demonstrate the system’s efficacy in real-world conditions.
Previously, Calcarea announced a collaboration with Lomar Shipping’s corporate venture lab, Lomar Labs, to further develop and deploy the carbon capture technology at scale.
Adkins stated, “Scalability is built into our design. We’re engineering a system that can integrate with existing vessels and be adopted fleetwide. By working directly with industry partners, we’re accelerating the path from lab to ocean.”
Berelson, also a co-founder and scientific advisor for Calcarea, continues to investigate the underlying chemistry and potential long-term impacts on ocean ecosystems.
A Step Toward Sustainable Shipping
With maritime shipping projected to remain a significant contributor to global emissions, this technology offers a viable path to reducing the environmental footprint of the sector substantially. The researchers estimate that widespread adoption could cut shipping-related CO2 emissions by half, a scale of impact essential for addressing climate change.
Berelson concluded, “It’s not going to happen overnight, but it shows what’s possible.”
For more information on USC’s environmental initiatives, visit the Assignment: Earth project page.
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