Using sunlight to capture carbon at scale

This new and affordable chemical process captures CO2 that's been absorbed by the ocean

Spotted: Temperatures around the world are on the rise, with the last decade (2011-2020) being the warmest on record. Carbon removal technologies could help us to remove greenhouse gases from the atmosphere and get global warming under control, but many proposed systems have been dismissed as unfeasible. Banyu Carbon hopes to tell a different story.

Previous systems have typically faced challenges because they are expensive and cannot be deployed at the necessary scale. Banyu Carbon, however, has developed a novel photochemical process that relies on sunlight and seawater to remove carbon absorbed by the ocean.

Seawater is pumped into the system and gets temporarily acidified using protons from a photoacid. This makes it easier to extract carbon from the water in the form of CO2 and this removed carbon can either be sequestered or reused. Protons are returned to the photoacid for reuse, and the seawater is pumped back into the ocean – now with a higher pH and lower concentration of CO2. A process of equilibration takes place when carbon is removed from seawater, and, for most of the ocean surface, this results in a commensurate amount of CO2 being removed from the atmosphere. Because this is a quick process (taking a matter of months), Banyu’s technology has the effect of drawing down carbon from the atmosphere.

Banyu Carbon’s new method uses organic compounds that are easy to synthesise and require no rare elements – unlike many other carbon capture technologies. It also requires only a small amount of harvested sunlight, with the excess used to generate solar electricity. Most importantly, the technology can be deployed on a large scale.

The company has completed its seed funding round, raising $6.5 million from investors like United Airline Ventures, Propeller, and the Grantham Foundation. It’s on track to scale up its technology for pilot testing this year and has acquired its first customer in Frontier. Some Frontier member companies – Stripe, Shopify, and H&M – have since made carbon removal purchases from Banyu Carbon.

Written By: Joshua Solomon