A controversial ocean carbon capture experiment in St Ives Bay, Cornwall, in the UK has been cancelled by the company involved as commercially unviable.
Planetary Technologies, a Canadian firm, had aimed to add diluted magnesium hydroxide (an antacid compound) into the bay via a wastewater outfall to neutralise ocean acidity and enhance carbon dioxide absorption from the atmosphere.
The approach, known as ocean alkalinity enhancement, was tested in a 2022 trial, showing potential to safely reduce CO2 levels in seawater.
An independent audit by the UK’s Environment Agency later found the method posed a very low risk to marine life at the trial scale.
Locals and environmental groups opposed scaling up the experiment. Hundreds of protesters rallied at Gwithian Beach, which overlooks the bay, in 2023 and 2024, voicing fears that “dumping” chemicals could harm the bay’s marine ecosystem, including its grey seal population.
Campaigners argued that more evidence was needed to confirm the process was safe for marine wildlife.
Regulators delayed approval for a larger pilot in response to concerns. They also recommended sourcing magnesium hydroxide locally to minimise transport-related impacts.
Planetary Technologies said in a statement that while its Cornwall trial “demonstrated great potential” a full-scale programme was not viable.
The company cited supply chain and cost challenges in sourcing the mineral additive at scale as key factors, alongside the regulatory process and public pushback.
The firm said it had gathered valuable scientific data from the Cornwall tests and no further UK trials were planned.
“Our vision remains unchanged – we are committed to advancing science-led carbon removal in suitable locations worldwide,” the firm stated, indicating it will focus on other locations.
The outcome in Cornwall highlights the barriers experimental carbon capture projects can face, despite UK government backing. While ministers have pledged up to £22bn ($29bn) to support carbon reduction and green technology initiatives, local opposition and regulatory delays continue to slow the progress of projects.
