Our Cornwall methods test was based in St. Ives Bay near the town of Hayle. We worked with local utility South West Water and proposed the addition of a diluted form of the mineral magnesium hydroxide to the existing water flow at the water treatment plant in Hayle. The treated water was released into the ocean, just outside St Ives Bay, through the existing diffuser. The goal of this project was to investigate whether adding an antacid to the ocean is a safe and effective way of deacidifying seawater and capturing atmospheric carbon dioxide (CO2), and to determine whether the Cornish coast may be an appropriate site for future OAE deployment.
Planetary has successfully completed its trial operations in Cornwall, UK, gathering valuable scientific data and insights. Although the trial demonstrated great potential, we have decided not to pursue a full programme in Cornwall due to commercial infeasibility.
We are not currently conducting any other trials in the UK, but our vision remains unchanged. We are committed to advancing science-led carbon removal in suitable locations worldwide.
We look forward to future opportunities in the UK, working together to achieve our shared climate goals.
For more information on how this process worked, please see our science pages, and for information on how we maintain safety, see our safety pages. To see information on the project’s current status, recent updates, or available data, see our project update page
What Did the Project in Cornwall Involve?
Planetary worked with South West Water to conduct a study on ocean alkalinity enhancement as a climate change solution.
We proposed adding a diluted form of the mineral magnesium hydroxide to the existing water flow at the South West Water treatment plant in Hayle.
The treated water was released into the ocean through the existing water diffuser located about 2.4 kilometres off the coast.
Specifically, the Hayle study added magnesium at a ratio of about 2.5kg of magnesium hydroxide per 10 tonnes of water. This is a dilution of more than 1:5000. In this amount, once the alkalinity reached the ocean, it is almost undetectable, even with extremely sensitive instruments for measurement. This meant that you were not able to see, smell, or taste the alkalinity – even if you were immediately adjacent to the outfall.
The particles of magnesium hydroxide that were added to the wastewater effluent are at least five times smaller than the finest particles of beach sand.
They dissolved in a period of days to weeks and delivered what is effectively a slow-release antacid to the ocean. For research purposes, this tiny amount was just enough for us to see some CO2 removal and to validate the accuracy of our models.
The Cornish coast was chosen as a project site both because Planetary’s founders have personal connections to the area and because Cornwall provides ideal conditions for OAE.
Cornwall’s shallow and turbulent waters and strong currents ensure water stays in an upper “mixing layer.” Treated water released in Cornwall will stay close to the ocean surface, absorbing CO2 from the atmosphere over a period of months. This means that an OAE project in Cornwall has the potential to be very effective.
For frequently asked questions specific to this project, please visit our Cornwall FAQs.
What Was The Aim of the Study in Cornwall?
Despite the very small scale of the test, Planetary estimated that the proposed alkalinity addition would remove approximately 100 net tonnes of CO2 from the atmosphere (accounting for all emissions associated with the trial activities themselves). This is roughly the equivalent of reversing emissions from a car driving 400,000 km.
This estimate was verified by Isometric, a third-party carbon removal registry and trusted verifier. All activities and results were monitored closely and in collaboration with experts, including the Environment Agency (EA), PML Applications, and Isometric.
Our firm commitment to cautious and responsible testing included comprehensive monitoring techniques, described in this blog post.
This test informed and supported future projects that will work to alleviate local ocean acidification. De-acidification work will help support local fishing and shellfish industries.
With all our sites, we are confident that, over time, we will have the opportunity to put these locations at the forefront of ocean-based carbon removal, helping lead the globe in the fight against climate change, and creating new jobs in the region.
Our work is helping lead global OAE research and study. The United Kingdom can be at the forefront of this research, bringing educational opportunities and funding to the area.
Local Oversight and Community Engagement
Planetary is committed to ensuring that the project in Cornwall abides by the rules and regulations set up by regulatory authorities to protect local marine environments. We have followed the guidance and requirements of the local Environment Agency at every stage of our project.
We have also worked closely with environmental non-profits and elected representatives to ensure that the project is well positioned to create positive environmental impact for both residents and the marine environment.
To date, we have hosted three public consultations in the area to hear first-hand from local communities and those working hard to protect Cornwall and its beautiful environment. We have also met with hundreds of people in private settings in individual and small groups.
We are dedicated to incorporating all feedback towards our goal of co-creating climate solutions that empower local voices.
We have also engaged and collaborated with local academic institutions, scientists, and research organisations to ensure that our work is conducted with the utmost integrity. Our collaborators in the UK include:
- PML Applications, a charitable arm of the Plymouth Marine Laboratory (PML) dedicated to developing and applying innovative marine science to improve our oceans.
- The National Oceanography Centre (NOC), which conducts world leading marine scientific research and ocean measurement technology innovation and operates Europe’s largest fleet of autonomous and robotic vehicles.
Additionally, we are continuing to work extensively with Dalhousie University in Nova Scotia, Yale University and the University of Miami in the United States, and many other groups in Canada, the US and around the globe to guide and extend our scientific endeavours.