Elon Musk-Backed Carbon Capture Technology Really Could Save The World | by Will Lockett | Predict | May, 2023 | Medium

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Elon Musk-Backed Carbon Capture Technology Really Could Save The World

Captura is utterly revolutionary!

Will Lockett

Published in

Predict

5 min read

May 23

1.2K

Carbon capture is one of the most promising pieces of climate technology out there. If used correctly, it has the potential to not only halt climate change, but turn back time and repair the damage we have done. The only problem is most carbon capture systems are insanely expensive and practically impossible to scale to any useful size. But this is where the Cal-tech spin-off Captura comes in. Their ocean-based carbon capture technology is poised to not only be one of the cheapest on the market, but also has the potential to reach the gigatonne-per-year capacity level. No wonder it has attracted massive investment from the DOE and Elon Musk. But how does this technology work? And can it really stop climate change?

Captura’s technology removes carbon dioxide from the ocean. Which, at first glance, seems a little backward; after all, it is atmospheric carbon dioxide that is driving climate change. However, carbon dioxide is soluble, causing the oceans to absorb vast amounts of it. In fact, about 30% of our emissions are absorbed by the ocean each year. Once absorbed, the carbon dioxide turns into mostly bicarbonate with a little bit of carbonic acid.

So, why is this advantageous? Well, these forms of carbon dioxide are far more reactive than gaseous carbon dioxide, which is practically inert. This opens the door to a plethora of brilliant and unique chemical processes for us to utilise to try and remove it and store it away. But water is also around 800 times more dense than air, so the carbon dioxide concentrations in the ocean are actually 120 times higher than in the atmosphere by volume. This increased density can make any carbon capture technology even more efficient.

So, that’s why Captura turned to the oceans. But how does their technology actually work?

They use a process known as electrochemical pH swing, which is far more straightforward than it sounds. All it does is manipulate the ocean water to become more acidic.

To begin with, Captura pumps water out of the ocean and into their device. Once inside, they pass 1% of the sample through a bipolar membrane. This membrane will effectively split the water molecules into hydroxyls and protons. These protons are then added back into the rest of the water. Now, acidity is just a measurement of how many free protons are in a substance, so this process increases the acidity in the water sample. The Bicarbonate in the water reacts with these protons, effectively splitting it back into water and carbon dioxide, which bubbles up out of the water. The carbon dioxide is then syphoned off, and the hydroxyls are put back into the water, neutralising the acidity, and then the water is returned to the oceans. This process is accelerated using a gas-liquid contactor and vacuum pump, allowing Captura to create a purified stream of carbon dioxide that can either be repurposed or stored away in geological formations, such as depleted oil and gas reservoirs.

Water containing less carbon dioxide can absorb it much quicker than those with higher levels. So even though Captura only takes carbon dioxide out of the ocean, it is, in effect, pulling carbon dioxide out of the atmosphere.

So, why is this method better than current air-based carbon capture systems?

Well, air-based carbon capture systems require complex solvents and filters to absorb carbon dioxide rapidly. These are eye-waveringly expensive, take a lot of time and resources to produce, and degrade over time, meaning they must be replaced regularly. Meanwhile, the bipolar membrane that Captura uses lasts an order of magnitude longer and is relatively easy to produce. This not only reduces the upfront investment needed to build a carbon capture plant, but also makes the operational costs tiny in comparison. But more on that in a minute.

Captura is also far more energy efficient than most air-based carbon capture systems. Air-based systems need powerful fans to blow vast amounts of air over their solvents and filters to capture enough carbon dioxide. They then need to use heat to release this stored carbon, so they can syphon it away. Meanwhile, Captura’s pumps only have to move a comparatively small amount of water through their systems, and the acidification process uses a tiny amount of energy. Overall, this means Captura sips energy in comparison to its rivals.

Finally, Cpatura produces very pure carbon dioxide, which can be easily repurposed or sequestered away. Meanwhile, most direct air capture systems have some contamination in their captured carbon dioxide, either from other gases being absorbed by their solvents and filters or the solvents and filters breaking down during the heat-to-release process.

So, what does this translate to? Well, after field-testing their technology, Captura did a detailed internal analysis and predicted that they could capture and sequester carbon for less than $100 per tonne! That is around three to six times less than any other!

Moreover, because their system uses commonly available materials, it can be scaled up exceptionally rapidly with no real supply chain bottlenecks (which have plagued other carbon capture systems). Captura reckons this will enable them to scale up to the gigatonne (a billion tonnes) capacity!

The Average US citizen has an annual carbon dioxide footprint of 14.24 tonnes, meaning it would only cost $1,424 per year to offset using Captura’s technology! This also means that if they can reach a capacity of a gigatonne per year, they can offset 70,000,000 US citizens’ emissions, equivalent to 21% of the US population.

With stats like this, it’s no wonder the DOE awarded Captura $850,000, and Xprize funded them to the tune of £1 million!

But, that price is too expensive for many people to afford, and in fact, it is still too expensive for many governments to afford, as the point at which carbon capture becomes viable is around $50 per tonne. It is also still limited by its capacity, as it would need to scale to a size of 35 gigatonnes per year to fully offset global emissions, which would simply be impossible (or, at the very least, so complicated it is practically impossible).

But over the coming decades, Captura will likely scale its operations, making it cheaper per tonne, and humanity’s carbon emissions will shrink as climate policies take hold. So, who knows, in the coming years, this brilliant, inexpensive and surprisingly scalable technology might be the difference between us missing our net-zero targets and hitting them.

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