A word from our co-founder and CEO Mike Kelland

While my family lives in Canada, we have deep family roots in Cornwall. My parents immigrated to Canada just before I was born and we have close family members who live there. I built sandcastles as a kid at Praa Sands, Perranporth and Gwithian, and my cousin taught me how to surf the waters of those same beaches. I’ve hiked the entirety of the South West Coastal Path around the Cornish coast. Cornwall has always felt like home.

St Ives Bay is a region of natural beauty where the ocean plays a role in everyone’s life – whether it’s fishing, surfing, hiking, tourism or spending time on the beach. It’s no wonder that people are passionate about the environment in Cornwall.

Unfortunately, no matter how much work we may do to protect our coasts, the climate and oceans in Cornwall are in grave danger.

Over the last 200 years, the world has put over a trillion tonnes of extra carbon dioxide (CO2) into the air. And this vast CO2 dumping is polluting our waters. The ocean and the atmosphere are tightly linked systems – about a third of that CO2 dumped into the atmosphere has ended up as carbonic acid in the ocean. The ocean has also absorbed 90% of the heat caused by climate change.  

In Cornwall, climate change is already posing a threat to the community. With sea-levels rising and increasingly intense rains and drought, the local community is calling for action on climate change. But such calls do not yet account for the impact ocean acidification will have in the region.

We know that, on a global level, our waters are getting more acidic. When the CO2 seeps into the water, it turns into carbonic acid. We need to be clear on this point, ocean acidification because of CO2 pollution is already having a deep impact on marine ecosystems both here and around the world. In particular, shellfish and corals are becoming less abundant in many parts of the world and we are losing their biodiversity. 

My personal commitment is to listen carefully to the concerns of residents in Cornwall, approaching this proposal with full transparency and adjusting our approach as needed based on feedback.

We’ve developed this page to provide overview information. Please see our Cornwall FAQs page for answers to questions we received from the Cornwall community.

If there is something not covered that you would like to know, please get in touch at

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Planetary’s Plans in Cornwall

What are we doing?

After decades of research across the globe on the benefits and impacts of alkalinity addition to seawater, and after years of successful lab testing and modelling, as well as ocean-based research, we are now working on small projects to understand how this system works at specific sites around the world including off the coast of Cornwall. Each site has a unique ecosystem, unique ocean chemistry and unique ocean currents. We employ a prudent, small scale and iterative scale up model at each specific site. 

We are proposing a small project in Cornwall to confirm what the baseline science and our recent research tells us – that our approach works, and that it does not harm ocean ecosystems in this specific region. 

Our process is quite simple:

  • Planetary adds a mild, alkaline substance (Magnesium Hydroxide [Mg(OH)2]) – an antacid – to the ocean. This antacid converts the CO2 already present, which has been absorbed from the atmosphere and is dissolved in seawater as carbonic acid, into carbonates and bicarbonates, the third most abundant ion in seawater.
  • This reduces the acidity of the local marine environment while the converted CO2 becomes a salt (carbonates and bicarbonates) which remains dissolved in the ocean for up to 100,000 years. 
  • Because this process reduces CO2 in the ocean, some of the excess atmospheric CO2 migrates into the ocean to bring the ocean and atmosphere back into equilibrium.
Planetary’s Marine Carbon Dioxide Removal process

In late 2022, Planetary received regulatory permission to add a small amount of magnesium hydroxide Mg(OH)2 – found naturally as the mineral brucite – to the existing wastewater flow in Hayle. Water regulators are familiar with magnesium hydroxide because it is used in wastewater treatment processes at many places around the world. 

Along with the wastewater from the Hayle treatment plant, this Mg(OH)2 will be pumped through the discharge main and released into the sea about 1.5 miles off the coast.

The amount we aim to add is so small as to be difficult to detect with even extremely sensitive measuring instruments. The plan is to add 2.5kg of magnesium hydroxide per 18 tonnes of water. This is a dilution of more than 1:5000. Once the added alkalinity reaches the ocean, it will be nearly undetectable. 

This means that you will not be able to see, smell, or taste the alkalinity, even if you are immediately adjacent to the outfall.

The particles of Mg(OH)2 that will be added to the wastewater effluent will be at least five times smaller than the finest particles of beach sand. They will dissolve in a period of days to weeks, delivering what is effectively a slow-release antacid for the ocean.

For research purposes, this tiny amount will be just enough for us to remove atmospheric CO2 and to validate whether our models are correct.

Despite the very small scale of the test, Planetary estimates that the planned alkalinity addition will remove approximately 200 tonnes of net CO2 from the atmosphere (taking into account all emissions associated with the trial activities)  – roughly the equivalent of reversing emissions from a car driving nearly 500,000 miles. All of our carbon accounting from this study will be verified by Isometric, a third-party carbon removal registry and verifier.We will be monitoring all activity and results in collaboration with local stakeholders and experts, including PML Applications and Isometric.

What are we hoping to achieve with this study?

Planetary’s goals for this project are as follows:

Our goal is to validate that adding an antacid to the ocean is a safe and effective way of deacidifying the ocean and capturing atmospheric CO2 at Hayle. Once we have been able to determine that our process demonstrates no local negative effects, we will consider testing at a larger scale. Our conservative approach to incremental testing means that it will take years to reach significant scale in Cornwall. We are eager to engage with community members and leaders to develop a shared vision of long term success.

The research around the world – including our own – has been very promising to date. We have a high degree of confidence that small additions like the ones we have planned are safe.

What brings the team at Planetary to Cornwall?

For Planetary’s process to work, the slightly more alkaline water needs to remain close to the surface – in what’s called the “mixing layer” of the ocean – long enough so that carbon can be absorbed from the atmosphere.

After an extensive review of potential sites, our research proved that the Cornish coast provides the ideal conditions for this kind of study because the water is shallow and turbulent, and the currents keep water near the surface for a long time.

As we continue our work in Cornwall, we are confident that, over time, we will have the opportunity to put Cornwall at the centre of the ocean-based carbon removal industry, serving as a global leader in the fight against climate change and unlocking new jobs in the region.

We believe that our process will not only lead to better local marine environments – lower acidity  improves natural growth in animals like coral and shellfish – but also to a healthier regional economy and a better functioning food chain, benefitting fishing and tourism industries.

Cornwall is not the only location where Planetary is actively seeking to apply and evaluate our process. With presence and team members in Canada, the US, and the UK, Planetary is planning to launch additional trials in Canada in 2023 and a wider set of sites globally in 2024.

Who have we spoken to?

We have been working with environmental charities, regulators, and elected representatives to ensure we are only providing benefit, never harm to Cornwall, its people and the local environment.

We have also engaged and partnered with local universities, scientists and organisations that have been encouraged and motivated by our research, to ensure that this work is conducted with the utmost integrity. Our partners include:

  •  PML Applications, an arm of Plymouth Marine Laboratory (a charity dedicated to developing and applying innovative marine science to improve our oceans), are working with us to validate our science and methodology, including monitoring our test in Cornwall.
  • The National Oceanography Centre (NOC) – one of the world’s top oceanographic institutions providing UK’s National Capability in this area, are collaborating with us to bring additional research funding to the local region.
  • Beyond Cornwall,  we work with Dalhousie University in Canada and Yale, the University of Miami, Aspen Institute and many others in the US and around the world to guide and extend our scientific endeavours.

We have also held two public consultations in the local area to hear first-hand from residents and those working hard to protect Cornwall and its beautiful environment.

Planetary intends to update plans to account for local community feedback. All results from the test will be released publicly, in keeping with our Code of Conduct and integrity to our research and people.

How are we ensuring it is safe?

Safety is a top priority for Planetary – for our local communities, marine life and the planet.

Let’s remember that the biggest harm is already being done by the trillions of tonnes of CO2 we have been pumping out into the air and into the ocean over the last 200 years. That damage will continue to grow, almost imperceptibly but persistently, until we act to stop it. We agree with the call to dramatically reduce CO2 emissions immediately.

By partnering up with respected regional academic institutions – like PML Applications, local universities, and various other accredited laboratories in the South West – Planetary has added another layer of cautiousness and responsible testing. The additional monitoring and biological surveys planned will use multiple sampling approaches as well as  and continuously monitoring sensors key chemical parameters near the outfall. 

At Planetary, we are committed to bringing a high standard of care to our work.      

Our Code of Conduct is our North Star, guiding how we operate in all areas. The first commitment within this is that the environmental impact of our work is our primary measure of success, and we prioritise it ahead of profitability.

How do we know this won’t harm the Cornish marine ecosystem?

What we are doing has been studied by many geologists, scientists and environmentalists around the world over the past three decades. There has been a range of positive evidence that increasing ocean alkalinity can be helpful in and restoring fish and other marine life. For example:

  • In shellfish hatcheries, alkaline materials are frequently used to increase the pH of the seawater to ensure that the juveniles are healthy. See one case study here.
  • Research has shown that marine calcification was enhanced by alkalinity addition, helping to counter the negative effects of ocean acidification on Great Barrier Reef corals and shellfish caused by excess atmospheric CO2  (Albright et al. 2016).
  •  The same study also showed that in Gran Canaria, Spain, alkalinity was added at very high levels and showed no long-term effects on zooplankton. 

At the end of 2022, after successful completion of research on the safety and efficacy of the process, we were granted conditional permission by the Environment Agency to carry out the next stage of testing using the existing wastewater flow at Hayle.

Magnesium Hydroxide Mg(OH)2 is commonly used in wastewater treatment and has been studied for years:

  • Mg(OH)2 is safe to handle and consume when used properly. It is already used to clean up acidic wastewater in treatment plants all over the world, so it is very well studied and well regulated under existing permits.  It is of low toxicity to aquatic organisms and humans. 
  • A critical characteristic of Mg(OH)2 is that it dissolves slowly, limiting its environmental impact. This prevents rapid pH rises at the addition location, after which rapid dilution in the seawater will keep pH well within safe limits.
  • The amount of Mg(OH)2 we are adding to the wastewater is very small. It’s equivalent to less than half a teaspoon into a 15 litre bucket of water, and this will disperse by a factor of 1000 times within about 100 metres of the outfall (a total of 700,000 times more dilute than retail magnesium hydroxide). 

What we’re forming in the ocean when we add Mg(OH)2 are alkaline bicarbonates, which are already among the most abundant ions in seawater. Marine ecosystems are well adapted to this alkalinity; bicarbonates are essential as a substrate for shell formation and for maintaining seawater pH and pH buffering capacity.


The project plan for the study in St Ives is below. This should be considered an outline as there are a number of things that could adjust this plan, including what we hear from the local community.

June 2022 Completion of in-lab and large scale “swimming pool” experimental program
September 2022 Initial systems and methods test in St Ives
October 2022 Begin outreach to governmental and environmental groups in Cornwall
December 2022 Provisional approval of this study from the local regulator was granted with a recommendation to supply more information on 
– Environmental impact 
– Detailed project lifecycle analysis (carbon footprint)
– Risk assessment related to material handling
– Community engagement
February 2023 Release of the Monitoring, Reporting and Verification Framework
February/ March 2023Public information sessions and dialogue with the community at Hayle and in Truro. Engagement with community and conservation groups.
March/ April 2023Complete pre-study biological surveys
Complete planning and submit full plan for permit approval for small scale initial study
Ongoing community engagement. We plan to continue this engagement indefinitely.

Once biological surveys are complete, we have received final approval, and we’ve addressed key concerns from the community, we aim to begin the study. At the moment, this is tentatively scheduled for late spring or early summer of 2023. Once the trial completes, we commit to sharing the results of the science here on this page. 

We have also developed a more detailed FAQ page which is now online.

How to Stay Involved and In Touch

If you are interested in staying involved or hearing more, please contact us at or sign up for the dedicated Cornwall newsletter below.  We’ll continue to update this page as well.

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