The Ocean as a Climate Superhero: Scaling Carbon Removal with Alkalinity Enhancement

The ocean, covering 71% of our planet, is Earth’s most powerful ally in the fight against climate change. It already absorbs about a third of global CO2 emissions, buffering us against the worst effects of global warming. But scientists are now exploring how to help the ocean do even more, safely, at scale, and in harmony with marine ecosystems.

In a recent Nature Tech Collective x Nui Ocean Series webinar, Dr. Will Burt, VP of Science and Product at Planetary, was invited to discuss one of the most advanced marine carbon dioxide removal approaches: Ocean Alkalinity Enhancement (OAE). Planetary has become a front-runner in this emerging field, delivering the world’s first verified OAE carbon credits and scaling to the kilotonne level of permanent carbon removal.

This conversation offered rare insight into the science, challenges, and promise of using ocean chemistry to restore balance to the planet’s carbon cycle while keeping communities and ecosystems at the heart of innovation. Watch the full session recording below.

Why Does the Ocean Matter for Carbon Removal?

Climate scientists agree: we won't reach net zero without carbon removal. While emissions reduction remains the primary solution, removing CO2 from the atmosphere will become increasingly critical over time.

Carbon removal discussions are often dominated by terrestrial solutions, but the ocean offers unique advantages. Its surface area is enormous and its volume is so vast that storing all excess CO2 since pre-industrial times would change the total carbon pool by less than 1%.

According to analysis from NOAA, OAE ranks highest among carbon removal methods for both scalability and cost potential, making it a logical choice for climate-relevant action.

Comparison of various attributes of carbon removal methods, including the effectiveness (Gt CO2 removal / year), cost range ($ / tCO2 removal), duration (size of dot), and potential for NOAA to contribute for these methods (dot fill).

Source: NOAA, Strategy for NOAA Carbon Dioxide Removal Research (May 2023)

How Does Ocean Alkalinity Enhancement Work?

OAE works by adding natural alkaline minerals to seawater and giving the ocean an “antacid.” Just as antacids neutralize stomach acid, these minerals neutralize carbonic acid in seawater. This creates what scientists call a concentration gradient, a natural pull that draws CO2 from the air into the ocean. The ocean stores this carbon as bicarbonate ions, a stable form that can remain dissolved for tens of thousands of years. The ocean becomes slightly less acidic while permanently storing carbon.

It is a remarkably simple idea built on basic chemistry, yet potentially one of the most scalable and cost-effective ways to remove CO2 while helping to counter ocean acidification.

What Does This Look Like in Practice?

Planetary's facility in Halifax, Nova Scotia, occupies roughly the space of two shipping containers. Despite its modest footprint, it can remove more than five times the carbon of the world's largest direct air capture plant while using minimal electricity.

The process is compact: alkaline material mixes with seawater in tanks, then flows through a pre-existing outfall pipe into the ocean. This small site, co-located with an established power generating station, can remove about 25,000 tonnes of CO2 annually.

Launched as a field trial in 2023, the Halifax site has started delivering third-party-verified carbon credits through the Isometric Registry. Planetary has recently signed a $31 million offtake agreement with Frontier for future credits. 

Each credit represents not just a tonne of CO2 removed, but also a step toward proving OAE as a viable tool in the climate toolkit.

How Do We Know It Is Safe?

Marine carbon removal encompasses vastly different approaches with different risks, costs, and scalability. Ocean Alkalinity Enhancement focuses solely on ocean chemistry, which poses fewer ecosystem risks compared to methods that directly manipulate marine biology.

Planetary operates under a rigorous Monitoring, Reporting, and Verification (MRV) protocol, with continuous sensors, boat-based sampling, and independent verification by environmental data firms. Measurements show predictable effects with no lasting impact on local ocean chemistry: when dosing is active, pH levels rise by 0.3 units (a sign of reduced acidity); when dosing stops, conditions return to normal within minutes. 

The company also tests feedstock materials extensively before use and regularly collects samples to ensure water and sediment quality standards are maintained.

It constantly reviews published literature (which has doubled annually over the past five years) and collaborates with academic researchers studying impacts on local marine life like mussels and phytoplankton.

Can We Measure Carbon Removal in the Open Ocean?

Measuring carbon removal requires careful methodology. Fortunately, the fundamental chemistry of Ocean Alkalinity Enhancement is well-established: scientists know the removal is happening and that it is permanent. Current efforts focus on reducing uncertainties about exact quantities.

Planetary takes a conservative approach, applying significant "uncertainty discounts" that credit less carbon removal than their measurements suggest. While open systems present monitoring challenges compared to closed containers, this is precisely why they are powerful: they leverage the entire ocean to achieve climate-relevant scale. Additionally, Planetary operates on coastlines, where access to in-situ measurements present less of a logistics challenge than the open ocean.

How Do Communities Fit In?

Community engagement can make or break carbon removal projects. Planetary has iterated upon their community engagement processes, initially splitting leadership attention between science and community relations before hiring dedicated community specialists.

Their approach follows a progression from informing communities to consulting, involving, collaborating, and ultimately empowering the coastal communities they work with. For example, their Nova Scotia project is at the collaboration stage, with diverse local and provincial groups actively engaged. Recent gatherings have revealed impressive breadth and depth of community involvement which is essential for long-term success.

This social dimension also strengthens science. Local stakeholders often help monitor impacts, provide context for environmental change, and keep the work grounded in shared stewardship of marine ecosystems.

Are Regulators Onboard?

Regulatory reception has been quite positive. In Canada, both provincial and federal regulators recognize the benefits of OAE, and carbon removal broadly, beyond climate impact, including economic opportunities. They are actively working with Planetary to establish appropriate pathways.

In the United States, the EPA has created clear pathways for OAE through permanent outfalls. The UK has similarly shown openness. Rather than facing regulatory roadblocks, the field is experiencing constructive collaboration.

Can This Approach Scale Affordably?

Frontier’s recent offtake agreement with Planetary signals buyer demand for OAE credits, as well as an expectation to see costs decline over time. The company has a five-year pathway that would bring costs close to $50 per tonne of CO2.

Cost reductions come from the process's inherent simplicity: leveraging existing infrastructure like wastewater outfalls, co-locating alkalinity sources near dosing sites, and developing low-emission supply chains. In Nova Scotia, regional stakeholders are already collaborating to make the supply chain greener and cheaper, recognizing that Planetary's success benefits the entire region.

What Does the Future Hold?

OAE is built on fundamental chemistry, is highly scalable, and poses minimal risk when done correctly. Planetary’s work shows what’s possible when rigorous science, transparency, and community collaboration come together - and this is the real breakthrough. In less than five years, the company has gone from lab experiments to delivering verified carbon removals at the kilotonne scale, while prioritizing ecological integrity.

Climate change demands urgent action at unprecedented scale. While reducing emissions remains paramount, carbon removal will play an increasingly vital role. The ocean’s power is vast, and harnessing it responsibly could help rewrite the story of climate action, one molecule, one coastal project, and one community at a time.