Could the oceans help us turn the tide on climate change? That’s the question researchers are hoping to answer with a new piece of machinery they’ve installed in Halifax Harbour that could help reverse the acidification of the sea and mitigate greenhouse gas emissions.
It’s the handiwork of Planetary Technologies, a buzzy startup that last year won U.S.$1 million in the carbon removal XPRIZE, a competition funded by Elon Musk’s foundation to encourage ideas for sucking carbon dioxide out of the air.
The company’s technology relies on an underappreciated function of the oceans: They’re the planet’s biggest carbon sink. Because carbon dioxide dissolves in water, oceans naturally remove around a quarter of human-produced carbon emissions each year. But that comes at a cost: More carbon dioxide makes the water more acidic, which bleaches coral reefs and kills shellfish. The upper layers of the oceans are now 30 percent more acidic than they were before the industrial revolution.
Planetary’s device aims to nudge coastal waters onto a healthier trajectory by delivering what the company describes as “an antacid for the oceans.” This mixture contains a diluted form of magnesium hydroxide, an alkaline mineral that helps balance out the acidity. When this substance is added to water, a three-step process occurs. First, the dissolved carbon dioxide is converted into bicarbonate, a stable molecule that can keep the carbon locked up for thousands of years. As this reaction happens, it creates space for the ocean to take up additional carbon dioxide. Then, over time, more carbon dioxide is pulled out of the air and dissolves in the water.
“You get this double win,” explains Will Burt, Planetary’s chief ocean scientist. “You remove acidity from the oceans and you also allow them to take up more carbon dioxide.”
Here, Burt explains how this technology — known as ocean alkalinity enhancement — could one day remove huge quantities of carbon dioxide from the air, and why the pilot project in Halifax is a vital step on the road to enabling the world’s oceans to become even more effective in tackling climate change.
Can you tell us a bit about the Halifax Harbour project?
This project aims to add alkaline material to the water and study its effects. So, we have built a system that has all the different tools we need to create a slurry out of magnesium hydroxide. We just completed a full week where we turned on the dosing pump each day, and the plan is to keep doing that week after week.
We’ve set up sensors just upstream and downstream of where we put the alkaline material in the water. We’re coordinating with an independent research team from Dalhousie who are taking a variety of samples. They’re basically an independent body that is coming in to say whether or not adding alkalinity is verifiably removing carbon from the atmosphere.
How much of this alkali are you adding?
Today, we added something like 2.5 tonnes of material. That feels like a lot, but when you see it heading out into the ocean, it’s actually very small. We’re taking a responsible approach and starting with the lowest amount that will create an effect we can measure. The Planetary and Dalhousie teams will then meet to go through the data and talk about whether the amount should be increased, ensuring that we’re not seeing a biological impact or impact on the seafloor.
What are the Dal researchers exploring?
Firstly, they are testing different tools for measuring and verifying carbon dioxide uptake. They’re taking water samples, but they’re also using novel technologies like autonomous underwater vehicles and profiling instruments. These systems will be invaluable as we move forward with researching this climate solution.
Secondly, they’re looking for biological impacts. They are taking measurements of phytoplankton and bacteria to make sure we’re not having a negative impact on them. Another group is measuring environmental DNA to check there aren’t any changes to the structure of the ecosystem, like some things growing more readily because of the alkalinity addition. We don’t believe we’ll see these things — if we thought there was a threat of them happening we wouldn’t be doing this — but we need to study them vigorously.
How is it going so far?
A lot of quality control and number crunching needs to happen, so we can’t make any grand statements right away. But it looks as if we are generating a measurable change in the water chemistry, which is really exciting. Where the seawater mixed with slurry is coming out, the pH is higher than it was before. That’s exactly what we want — to decrease the acidity of the water ever so slightly. That means that the amount of carbon dioxide in that seawater has gone down enough for CO2 gas in the air to invade and fill that void.
What’s the potential for this technology if everything goes as planned?
Certain areas of the ocean are going to work really well for alkalinity enhancement. Cornwall in the U.K. is one. Vancouver, I think, has similar promise. I envision regional hubs where many different pipes are adding alkalinity at different rates, using a model that is built for that region. Then, you’re really off to the races in removing significant amounts of carbon dioxide from the atmosphere.
What would you say to someone worried about adding chemicals to the sea?
I’ve lived on the coast my whole life. I am very connected to it, and I understand why a person would feel that way. But I urge people to take a closer look. The word “chemical” has this scary connotation, but the compounds we are adding are already in the ocean in massive quantities. Magnesium is the fourth most abundant compound in the ocean, and the bicarbonate that is created — basically baking soda — is the seventh most abundant ion. The critical thing is that we have guardrails in place so that we know what’s in the products we add and that they pose no water quality concern.
We have to work with communities and help people to get used to this idea. But it comes back to the fact that even a single bay of the ocean is a big place and the amount of change that we are trying to induce is very small at these early stages.
How does it feel to go from theory to practice with this technology?
We’re a very small team; the whole company is about 18 people and there’s five of us on the ground here, so the amount of effort we have to put in to do something pretty extraordinary is amazing. And working alongside Dalhousie — I won’t speak for them — but I think we all feel like we’re doing something pretty special.
This interview has been condensed and edited for clarity. Want to learn more about what it will take to build a sustainable and prosperous planet? Read about the Mission from MaRS Carbon Reduction Accelerator.
Photo: Courtesy of Planetary Technologies