Carbon Capture Is Headed for the High Seas

Unless you live near a port, you probably don’t think much of the tens of thousands of container ships tearing through the seas, hauling some 1.8 billion metric tons of stuff each year. Yet these vessels run on some of the dirtiest fuel there is, spewing more greenhouse gases than airplanes do in the process. The industry is exploring alternative fuels, and electrification, to solve the problem for next-generation ships, but in the meantime a Y Combinator-backed startup is gearing up to (hopefully) help decarbonize the big boats that’re already in the water.

London-based Seabound is currently prototyping carbon capture equipment that connects to ships’ smokestacks, using a “lime-based approach” to cut carbon emissions by as much as 95%, cofounder and CEO Alisha Fredriksson said in a call with TechCrunch. The startup’s tech works by routing the exhaust into a container that’s filled with porous, calcium oxide pebbles, which in turn “bind to carbon dioxide to form calcium carbonate,”—essentially, limestone, per Fredriksson.

Though carbon capture has yet to really catch on for ships, Seabound is just one of the companies out to prove the tech can eventually scale. Others, including Japanese shipping firm K Line and Netherlands-based Value Maritime, are developing their own carbon-capture tech for ships, typically utilizing the better-established, solvent-based approach (which is increasingly used in factories). Yet this comparably tried-and-true method demands more space and energy aboard ships, because the process of isolating the CO2 happens on the vessel, according to Fredriksson.

In contrast, Seabound intends to process the CO2 on land, if at all. When the ships return from their journey, the limestone can be sold as is or separated via heat. In the latter case, the calcium oxide would be reused and the carbon sold for use or sequestration, per Fredriksson, who previously helped build maritime fuel startup Liquid Wind. Her cofounder, CTO Roujia Wen, previously worked on AI products at Amazon.

Seabound says it has signed six letters of intent with “major shipowners,” and it aims to trial the tech aboard ships beginning next year. To get there, the company has secured $4.4 million in a seed round led by Chris Sacca’s Lowercarbon Capital. Several other firms also chipped in on the deal, including Eastern Pacific Shipping, Emles Venture Partners, Hawktail, Rebel Fund and Soma Capital.

Beyond carbon capture, another Y Combinator-backed startup is setting out to decarbonize existing ships via a novel battery-swapping scheme. New Orleans-based Fleetzero aims to power electrified ships using shipping container-sized battery packs, which could be recharged through a network of charging stations at small ports.