USC innovation may halve shipping emissions

Researchers at USC and Caltech, alongside the startup Calcarea, have created an innovative shipboard system capable of eliminating up to half of the carbon dioxide produced by ships by converting it into an environmentally safe solution.

The advancement, outlined in Science Advances, details how the system could lessen carbon emissions from the maritime sector — one of the globe’s most challenging sectors to decarbonize.

“What’s remarkable about this is its simplicity,” remarked William Berelson, the Paxson H. Offield Professor in Coastal and Marine Systems at the USC Dornsife College of Letters, Arts and Sciences and co-corresponding author of the research. “We’re accelerating a process the ocean naturally uses to counteract CO2 — but implementing it on a ship, and in a way that can substantially lower emissions on a large scale.”

The method imitates a natural chemical process found in ocean waters. As vessels navigate through seawater, CO2 from their emissions is absorbed into the onboard water, causing a slight increase in acidity. This water is subsequently passed through a collection of limestone, where the acid reacts with the stone to create bicarbonate — a safe, stable compound that naturally occurs in seawater. The treated water, now devoid of CO2, is released back into the ocean.

“What excites me the most is that this originated from a fundamental scientific inquiry: How does the ocean manage CO2?” Berelson emphasized. “From that, we realized we could potentially develop a real-world answer that could assist in combating climate change.”

Transitioning from lab to sea

Maritime transport is responsible for nearly 3% of global greenhouse gas emissions. However, present solutions, such as low-carbon fuels and electrification, remain too costly or not feasible for long-range journeys.

“We view our method as a supplementary approach that can enable vessels to decrease their ecological footprint without significant design changes,” stated Jess Adkins, co-founder and CEO of Calcarea and the Smits Family Professor of Geochemistry and Global Environmental Science at Caltech.

In the laboratory, the scientists evaluated crucial components of the method, utilizing regulated quantities of seawater, limestone, and CO2. Their tests closely matched theoretical projections, instilling confidence to expand their modeling to the scale necessary for application on actual ships.

“We aimed to demonstrate that not only did we comprehend the chemistry — we could also forecast the amount of CO2 that would be neutralized,” remarked Berelson. “That enabled us to model how this could appear on a real vessel.”

The research also incorporated advanced ocean simulations to investigate the effects of reintroducing bicarbonate-rich water back into the ocean. Simulations followed a hypothetical ship making repeated trips between China and Los Angeles over a decade, discharging treated water along the route. The models indicated minimal effects on ocean pH and chemistry — a significant verification for the technology’s ecological safety.

The researchers project that extensive implementation of the technique could diminish shipping-associated CO2 emissions by 50%.

“This is the level of scale we require if we are going to significantly reduce global emissions,” Berelson stated. “It won’t be instantaneous, but it illustrates what is achievable.”

Introducing the technology to the market

The academic research is progressing concurrently with Calcarea, a startup aiming to introduce the technology to the market. The company is engaging in initial discussions with commercial shipping entities and investigating pilot programs that would assess the technology on operational vessels.

Calcarea has previously disclosed a partnership with Lomar Shipping’s corporate venture lab, Lomar Labs, to bring their shipboard carbon capture system to market and implement it.

“Scalability is inherent in our design,” Adkins stated. “We’re developing a system that can be integrated with existing vessels and adopted across fleets. By collaborating directly with industry partners, we’re speeding up the transition from lab to ocean.”

Berelson, a co-founder and scientific consultant for Calcarea, continues to investigate the science underpinning the approach, including reaction dynamics and long-term effects on ocean chemistry.