Carbon capture is headed for the high seas –

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

London-based Seabound is currently prototyping carbon capture equipment that will connect to ships’ chimneys, using a “lime-based approach” to reduce carbon emissions by as much as 95%, said co-founder and CEO Alisha Fredriksson in a conversation with The startup’s technology works by channeling the outlet into a container filled with porous, calcium oxide pebbles, which in turn “bind with carbon dioxide to form calcium carbonate,” essentially limestone, according to Fredriksson.

While carbon capture hasn’t caught on for ships yet, Seabound is just one of the companies looking to prove that the technology can eventually scale. Others including Japanese shipping company K-line and located in the Netherlands Value Maritimedevelop their own technology for capturing carbon for ships, usually using the better established, solvent based approach (which is increasingly being used in factories). Still, this similar proven method requires more space and energy on board ships because the process of isolating the CO2 takes place on the ship, Fredriksson said.

Seabound, on the other hand, plans to process the CO2 on land, if at all. When the ships return from their voyage, the limestone can be sold as is or separated via heat. In the latter case, the calcium oxide would be recycled and the carbon sold for use or storage, according to Fredriksson, who previously helped set up the marine fuel startup. liquid wind† Her co-founder, CTO Roujia Wen, previously worked on AI products at Amazon.

Seabound says it has signed six letters of intent with “major shipowners,” and plans to test the technology aboard ships early next year. To get there, the company raised $4.4 million in a seed round led by Chris Sacca’s Lowercarbon Capital. Several other companies have also partnered in the deal, including Eastern Pacific Shipping, Emles Venture Partners, Hawktail, Rebel Fund and Soma Capital.

In addition to carbon capture, another Y Combinator-backed startup plans to decarbonize existing ships through a new battery swap scheme. New Orleans-based Fleetzero aims to power electric ships with sea container-sized battery packs that can be charged via a network of charging stations in small ports.