New ocean carbon removal technique proves successful

The new technique is designed to remove carbon dioxide from the atmosphere by enhancing the alkalinity of treated wastewater before it is discharged out at sea.

In a first-of-its-kind study, PML was commissioned to provide independent and impartial monitoring and analysis of a trial carried out off St Ives Bay (Cornwall, UK) in September 2022 by Canada-based carbon removal company Planetary Technologies.

The trial, which followed a series of lab-based tests and modelling, involved adding a diluted form of the alkaline mineral magnesium hydroxide to wastewater flow at a nearby wastewater treatment plant in St Erth. The treated water was then released four miles offshore through the existing outflow.

Planetary Technologies investigated whether this form of ocean alkalinity enhancement (OAE) is a safe and effective way of deacidifying seawater, which could then draw down atmospheric carbon dioxide (CO2). The company said that seawater naturally absorbs CO2, so the process - which changes the pH of the water - is designed to enhance its carbon removal capacity.