“Planetary can stick it up their waste pipe,” read one of the many waspish placards at the north Cornwall beach where more than 300 protesters gathered on Sunday.
They came to Gwithian beach to object to a proposed carbon dioxide removal scheme by the Canadian company Planetary Technologies – winner of a $1m XPrize for climate change solutions in 2022 – which wants to add magnesium hydroxide to the wastewater pipe at Hayle that stretches out to sea.
The firm’s scientists say the chemical deployment could reduce the acidity of the ocean and remove CO2 from the water, thereby drawing harmful CO2 out of the atmosphere to replace it.
But protesters fear the chemistry may negatively affect the bay of St Ives’ precious marine ecosystem, which includes a grey seal population, and are demanding greater scientific scrutiny.
Senara Wilson Hodges, the protest organiser and a St Ives town councillor, said: “We are all terrified of the climate crisis but you can’t use that fear to say: ‘You’ve got to go ahead with this project.’ We’re worried about what will happen to the local environment if they scale this up and how it will react with the heavy metals from mining waste that’s in the bay.”
Kath Lawrence attended the rally with her partner and their two children. She said: “We spend every spare moment here and often see the seals and dolphins. We’re here today for our children’s futures. We want them to be able to enjoy the bay for years to come.
“We don’t know what the outcome will be if they dump these chemicals into the sea. I’m sure there are more natural ways of solving the climate crisis.”
Cornwall is one of three sites used by Planetary – the other two are in Canada. The bay of St Ives was selected because the seabed is shallow and the water turbulent, allowing for the chemistry to remain in the upper layer of the ocean for longer.
Planetary’s first small-scale trial in Cornwall was conducted in tandem with South West Water in September 2022, without widespread public knowledge.
Independent analysis released last week by PML Applications concluded the trial had “demonstrated alkalinity enhancement … and reduced CO2 at the wastewater plant” and signalled a subtle change in CO2 within 10 metres of the pipe, but crucially the study did not assess impacts on local biology.
Sue Sayer, founder of the Cornwall Seal Group Research Trust, did not dismiss the scheme entirely but said: “Seals are benthic feeders – they feed off the seabed – so if the outflow is sedimenting on the seabed and if it has any toxins attached to it, the seals are going to be ingesting it. They’ll also eat the fish that have been affected by any toxins.
“In the best-case scenario, there are no impacts on the seals; in the worst-case scenario there’s no fish, no seals, no surfers, no tourism, no economy.”
Another 120-day trial is proposed for this summer, using 2.5kg of magnesium hydroxide for every 18 tonnes of water, with the goal of permanently removing 200 net tonnes of CO2 from the atmosphere – roughly equitable to the CO2 produced by a car driving 500,000 miles.
Eventually, Planetary hopes to sequester 1bn net tonnes of CO2 a year from the atmosphere and will make profits by selling “carbon credits” to organisations seeking to mitigate their carbon footprints.
Wilson Hodges told the crowd of residents, surfers and business owners: “We are a community that is under constant pressure. It feels like a never-ending war of attrition as this place is squeezed for profit in every direction. No wonder we have a healthy scepticism about projects that we are told are good for us.”
She has called for a delay to ocean testing, a public consultation and an environmental impact assessment. The government’s Environment Agency said an EIA has been submitted ahead of the second trial and was currently under review.
Mike Kelland, the chief executive and co-founder of Planetary Technologies, said public concern was understandable but misplaced: “People often say to me: ‘You wouldn’t want to swim in this stuff, would you?’ But the answer is that we already do because it’s already widely used in wastewater management.
“The term ‘dumping’ conjures up scary visions but we’re not dumping anything. Nobody’s taking a ship and pouring buckets of chemicals into the ocean, and we’ve never touched any nuclear waste.
“We plan to add a small and carefully controlled amount of magnesium hydroxide to fresh wastewater. The conditions in the north coast of Cornwall are too perfect for it not to be used for this.”
During a community meeting on Friday night, Kelland said the toxic dose for fish is 1,293mg/L but the amount present in the waste pipe during the proposed second trial would be 139mg/L and this would disperse rapidly in the ocean.
“Our maths says a female adult seal would need to consume 100,000 litres of seawater in one go, right next to the diffuser, to get a laxative effect,” he said.
He assured the public his company would be transparent and diligent: “We’ll do baseline and post-trial evaluations, we’ll have moored sensors at the site of the diffusers, and we’ll do extensive monitoring during the study.”
In addition to the money it won last year from the XPrize, which was funded by Elon Musk and the Musk Foundation, Planetary has also received a £250,000 grant from the UK government’s greenhouse gas removals programme and startup funding from Canadian e-commerce company Shopify. The much-maligned South West Water had agreed to allow its wastewater pipe to be used as part of a “long-term financial relationship”, Kelland said.
Planetary’s own carbon footprint has caused concern because it sources magnesium hydroxide from a mine in China before shipping it to the US for grinding. Kelland insisted the scheme has net gains: for every 1kg of magnesium hydroxide used, he calculated that a net carbon benefit of 451g will be produced.
“Reducing all emissions is job number one and nothing we do will make a difference if we don’t achieve that,” he said. “But we also need to act carefully and incrementally with ocean-based carbon removal. At some point, we are all going to run out of time.”
