Ocean carbon dioxide removal (CDR) is one of the climate change solutions gaining popularity lately thanks to its relative simplicity, cost-effectiveness, and large-scale carbon removal potential. Captura is a startup that is accelerating in the carbon removal space, offering a critical tool that removes CO2 from the ocean to stabilize our climate.
It is also a fast-growing new company that has just secured a $12 million Series A funding round from notable investors, on the lookout for the next generation’s best climate-tech solutions. We interviewed Steve Oldham, CEO of Captura and former CEO of direct air capture company Carbon Engineering, who shared with us detailed information about Captura’s technology, future development plans, and scalability potential.
Our first standard question is what is Captura?
Captura is a carbon removal company. We use the ocean as the mechanism to remove CO2 from the atmosphere.
Atmospheric carbon removal is difficult and expensive. It is because taking the CO2 out of the air requires machines that touch the air, chemical absorbents, a lot of energy and land area. The absorbents also have to be regenerated or replaced after that.
Direct air capture is a perfectly good solution, but it’s quite expensive. Meanwhile, the ocean serves as an extremely effective carbon removal device already. It removes about 30% of the CO2 from the atmosphere of the emissions that humans make.
But it does so at the cost of ocean acidification. Fundamentally Captura’s approach is taking CO2 out of the ocean, so that the ocean draws down the same amount of CO2 from the atmosphere. If you can do that in a way that doesn’t harm the ocean, you have a very cost-effective and highly scalable way to take CO2 out of the atmosphere.
The oceans are huge, already there and are completely free to use. So that’s fundamentally the premise of Captura – use the ocean as the mechanism to draw down CO2 from the air without harming the ocean.
Can you tell us a bit more about the history of the company?
Yes, the company is a spin-out of Caltech, the California University in Pasadena. It was founded in late 2021 by two Caltech professors. And essentially, they invented a technology or a new variant of a technology called electrodialysis.
They realized it would be able to remove CO2 from seawater. I joined in April 2022 and as you know, we’ve just completed our first external financing round.
A question for our readers who might not be familiar with how the ocean sequesters carbon. Could you please explain how it stores CO2 naturally?
Fundamentally what happens is Henry’s law, which is a well-established natural law that dictates there is a continuous equilibrium between air and liquid with respect to the percentage of gas.
Basically, as you put more CO2 into the atmosphere through emissions, the liquid which in this case is the ocean, will absorb a commensurate amount of that to stay in equilibrium. And it works the other way too. If you take CO2 out of the atmosphere, then the ocean will release CO2.
So Captura’s approach uses Henry’s law by taking CO2 out of the ocean, which will create an imbalance and the ocean will then, per Henry’s law, draw down CO2 from the atmosphere to make up for the lost amount of carbon dioxide.
The simple evidence of Henry’s law working is a can of coke or soda. If you open a can of coke, the CO2 within the coke will get released back into the atmosphere. Once you open the can, it touches the air, and the air absorbs the CO2 out of the coke.
That’s basically the same phenomenon at work but we do it the other way around. We simply take the CO2 out of the coke, and then the coke draws the CO2 from the air. We do that with ocean water.
So the CO2 has the ability to dissolve in water?
Yes correct. Ocean water is constantly moving between shallow and deep ocean layers. CO2 dissolves in the ocean and when it reaches deep waters, it tends to stay there, sequestered in the ocean.
But the CO2 that’s in the shallow ocean interacts with the atmosphere. So our plants work with the shallow ocean – we take CO2 out of it, put the ocean water back into the shallow ocean so it continues to absorb CO2.
If Captura’s plants didn’t exist, what would happen is the CO2 that’s drawn down from the atmosphere as more emissions are made, would stay in the shallow ocean. That makes the ocean more acidic, and also warms it.
Those two effects – ocean warming and acidification are very bad for marine life and the ocean ecosystem. That’s why the ocean’s role in capturing CO2 is simultaneously good and bad. It’s good in the sense that it reduces the amount of CO2 in the atmosphere, but it’s bad because it leads to negative effects inside the ocean.
How does the carbon removal technology of Captura work? Could you please tell us more about the electrodialysis process you mentioned?
Captura’s plant draws ocean water up, and it flows through the plant. A very small percentage of that ocean water – about half a percent – is taken out and treated through our electrodialysis process.
What electrodialysis does is to dissociate the molecules within saltwater which are sodium chloride, salt, and H2O. The electrodialysis moves those molecules and instead of sodium chloride and water, forms them into an acid and a base of alkali.
We take that acid and put it into the flow of ocean water – that 99 and a half percent that’s flowing through the plant. When you do that it acidifies that portion of the ocean that flows through the plant and forces the CO2 to bubble out. We then collect the CO2 which can be sequestered or turned into a product like a synthetic fuel.
Meanwhile, the ocean water in our plant is now acidic, and decarbonized. We put the alkali back in and that makes the water that comes out of the plant almost neutral. We’ve measured in our pilot system that about 95% of the CO2 content is removed from the water that flows through the plant.
Would you say that ocean carbon removal is more efficient than other engineered methods of carbon dioxide removal?
I think the advantage of our process is that you don’t have to build machines that touch the air. You don’t have to have chemical absorbents, you have no by-products, and you also use less energy because CO2 in the ocean is about 150 times the level of CO2 in the atmosphere.
So we move 150 times less water than CDR mechanisms have to move air. The costs of absorbents, handling byproducts also disappear from our capital structure. And we use less energy, therefore we think it will be substantially lower than direct air capture.
We’re also very scalable because the ocean is 70% of the world’s surface. Fundamentally, our approach uses the ocean to do an enormous amount of the work that technology-based CDR mechanisms like direct air capture have to do themselves.
Around 30% of the world’s emissions are absorbed by the ocean so it’s doing a good job. If that wasn’t happening we would have already had a really bad climate crisis.
The ocean must be getting really acidic then, right?
That’s right. Since pre-industrial times, the ocean acidity increased from pH 8.4 to 8.1 which is a significant move. And we see the impacts of that – blanching of the coral reefs, the Great Barrier Reef dying off – all of these are impacts of rising ocean acidity.
Now probably one of the most important questions – how we are going to stop that? How do you plan to scale your technology to a gigaton removal capacity? Do you aim for this scale of carbon removal?
Absolutely. The climate crisis is such that we need solutions that are very large scale. I have two things to say on this. First of all, we won’t build all the plants ourselves, we will license our technology to partners around the world, who will use it to build a plant. That way, we hope, many of our plants will be constructed in parallel all around the world.
From the technology perspective, the electrodialysis which is the real key and the heart of the system, is quite cheap, and quite scalable. The rest of the equipment in our system is water movement equipment, filtering, pumps which are readily available.
Therefore, for scaling the equipment there is not that much of a challenge. The disadvantage of our system compared to, for example direct air capture, is that we have to be by or on the ocean, we have to be able to use saltwater.
We plan to use onshore facilities like desalination plants. You can add our process to a desalination plant and decarbonize the outflow of the plant. Another area that’s very attractive is offshore oil and gas platforms.
When those become retired as we go through the energy transition, a single oil and gas platform can accommodate up to about million tons of carbon removal using our technology. There are enough oil and gas platforms around the world today to do well over a gigaton of carbon removal.
And then over time, we envisage dedicated capture platforms like those pictured in our website, which will be a dedicated facility built offshore, just like we build dedicated oil and gas platforms today.
Would you tell us more about the pilot that you launched in 2022?
It’s an end-to-end pilot, it’s fully representative of our end-to-end system is Newport Beach in California. It’s a small pilot with the capacity of removing only one ton of CO2 per year. It’s a technology-proving device, so not a commercial plant.
In our facility in Pasadena, we’re building a 100 times scale-up of that pilot, which will be put into the ocean, probably at the end of Q1 this year. With the funding that we just raised, we plan to go to 1,000 tons per year, which will qualify us for the XPRIZE competition. And that’s really a modular building block for larger plants.
What is the largest plant that you envision and what is its CO2 removal capacity?
There really isn’t a limit. The way we think at the moment is that if we use existing infrastructure, like an oil and gas platform, a million tons is probably the largest size you can go. But if you build a dedicated facility, there’s no reason why it can’t be 5 million tons, 10 million tons per year. There’s nothing inherently that limits the size. And of course, the ocean is enormous so plenty of room.
What is the cost of a ton of CO2 removed with Captura?
The cost today is not really relevant because it’s just a small pilot system. We’ve modeled the cost for a large system which was part of our submissions to XPRIZE. We are very confident that the cost will be much less than $100 a ton – the target that the Department of Energy has set in the US for carbon removal.
All we use is ocean water and electricity so our cost base, energy use, and operational costs are lower. We expect it to be well below $100 a ton when we build our systems.
Are there any risks for the ocean from using your technology?
We don’t change the alkalinity of the ocean. We remove CO2 molecules to make room for more CO2 molecules to be sequestered by the ocean. We’ve been working with Ocean Visions, which is a US-based Oceanographic Institute, who have looked into our methodology.
We’ve also just hired an oceanographer and we’ll be working with other ocean-based entities during our Series A to confirm that there is no impact on the ocean water. We also measure the outflow of water from our plants and assess it. So we are very committed to making sure that we engage the ocean community to see that our mechanism is entirely beneficial and not threatening.
What do you plan to do with the CO2 you collect?
We see ourselves as a carbon removal company. And the output of our product is a stream of CO2. How they use it is up to our plant development partners. We expect some of them to sequester it to produce carbon credits. We won’t be sequestering the CO2 ourselves or making fuel.
Do you have any direct competitors?
Ocean-based carbon removal is an early-stage business sector. There are I think three other companies that got an XPRIZE milestone award in the ocean-based arena. But ocean-based solutions differ a lot. For example, there are companies that add limestone to the ocean, to make it more alkaline, which helps with drawdown.
There are companies that grow more kelp in the ocean so that kelp can absorb CO2. We believe that we’re unique in terms of taking CO2 out of the ocean as a product and without affecting the ocean itself. It’s a very early-stage sector. I think we’re one of the first companies to move into Series A in that space.
We also don’t see other companies like Carbon Engineering or Climeworks as competitors because we need all the solutions that we can have to address climate change.
You also recently announced a $12 million funding round, how do you plan to allocate that money?
Broadly speaking, in three areas. The first is ongoing research and development – optimizing and improving the technology. If we want to increase efficiency, reduce energy use – category number one stays research and development in the lab.
Category number two is the piloting programs that I mentioned. We have that 100 ton scale up and then going into 1,000 tons. We’ll be building those systems and fielding them with this funding.
The third area is designing our first large-scale system. Whether that’s a large-scale system that goes to a desalination plant, or to an offshore platform, we want to have a full design for it, and a more detailed cost model work to figure out how we’re going to move this amount of water, what pumps we are going to use, what filters.
We need to come up with a detailed cost of design for a larger plant. And then hopefully in our next funding round, whenever that may be, we’ll be ready to start building the first commercial plant.
When do you expect that could happen?
I’d like to think that within two years, we’ll have started to build our first commercial plant. That’s always difficult to predict as it depends on how the market develops, policy going forward, technology developments.
What would be the size of your large-scale facility?
Often, your first commercial pilot may be smaller. The investors that finance plants like this, normally want to see more of an incremental setup. So our first commercial plant may be smaller, but we’ll see.
Are you in a process of working with other partners? You also announced you are testing the pilot plant with Southern California Gas.
The 100-ton pilot system that we are finishing the construction of right now in our facility was actually funded in partnership with Southern California Gas. They liked the technology and were excited by its potential. They were a really good early supporter.
We expect to work next with all the companies that invested in us – Equinor, Hitachi, Aramco, and we’d like to continue the relationship with SoCal Gas. We also have funding from the Department of Energy, so we do have a widening set of partnerships.
I believe the climate problem is really big and you need the help of everybody who’s willing to help to bring solutions to the table. We’re quite happy to get engineering assistance, advice and deployment sites – we’re happy to get help on all of those things.
And what is next for Captura? What is the next milestone we should look out for?
I think the next milestone would be when we fill the 100-ton system, which will be probably within Q2 of this year. We are also actively considering bringing a couple more investors into this round. We had a lot of interest and a lot of positive reaction to the announcement.
So we may actually expand the funding of this round and raise more money. Those are probably the two things for people to watch out for. Like I said, we have a piloting program to move up to 1,000 tons of carbon removal capacity per year and that system will probably deploy in 2024. Next year or the year after comes the commercial systems.
Are you also planning to grow your team?
I think the company had about eight people when I joined in April and we are twice that size now. We expect to go to about 30 people in this Series A. Yes, we are actively recruiting people right now – chemists, oceanographers, engineers, etc.
As a former CEO of Carbon Engineering, why did you decide to get involved with Captura and ocean carbon removal?
When I joined Carbon Engineering, it was a similar size to what Captura is today. I was the CEO of Carbon Engineering for four years, and during that time the company expanded a lot and so did the market which is all great, I really enjoyed that.
The opportunity to bring another solution to the climate toolbox was very interesting. For me, I enjoy bringing technologies to reality. The opportunity to join Captura to bring an ocean-based solution has great potential.
As I mentioned earlier, I think it’s going to be a really important carbon removal method. So it just fits my interest to bring a technology to market. If I can bring two carbon removal solutions to reality – Carbon Engineering and Captura, I hope my kids will be proud of me.