As the largest direct air capture plant will suck CO2 from the atmosphere

Inaugurated this Wednesday (8) in Iceland, Orca, the largest industrial plant for direct air capture on the planet, promises to suck tons of carbon dioxide (CO2) from the atmosphere. Plants like this have been promoted by world leaders and giant corporations such as Microsoft in an attempt to erase their legacy of greenhouse gas pollution.

According to The Verge website, the Orca plant is strategically located to test emerging technology. The new plant, built by Swiss company Climeworks, is powered by renewable energy from a nearby geothermal plant.


Fans from the Orca plant suck in the air, which passes through a special solid absorbent filter, and this filter traps carbon dioxide. Image: Climaworks – ORCA

Climeworks also plans to block CO2 captured in basaltic rock formations just three kilometers from the geothermal plant. It’s a storage plan that could sidestep the need for controversial new carbon dioxide pipelines. “It’s going to be, I think, an interesting test case,” says David Morrow, research director at the American University’s Carbon Removal Law and Policy Institute. “But it’s also kind of a baby step in the grand scheme of things.”

According to Climeworks, Orca (Icelandic word for energy) will be able to extract 4,000 tonnes of CO2 annually. That’s roughly how much 790 passenger vehicles can pump in a year – not much, although it’s the largest operation of its kind in the world.

Largest air filtration plant is surprisingly compact

It’s interesting to note that, despite being the world’s largest in the business, Orca is surprisingly compact. Climeworks uses a method called direct solid air capture to absorb CO2.

Basically, it works like this: the fans suck in air, which passes through a special solid absorbent filter, and this filter retains the carbon dioxide.

In an interview with The Verge, Climeworks didn’t go into much detail about how their filters work in an interview, just saying that it will use a base to attract CO2, which is slightly acidic, and when the filter is fully saturated, it is time of the second step of the process. The unit then heats the filter to around 100°C, which releases trapped carbon dioxide.

After the CO2 is separated from the air, it travels through pipes to an adjacent building, where it is mixed with lots of water – about 27 tons of liquid for every ton of carbon dioxide.

This mud then travels only a few hundred meters away, before being injected deep into the ground. Carbonated water reacts with basaltic rock, creating carbonate minerals. After two years, what was once a kind of sparkling water becomes solid rock.

Climeworks is partnering with Carbfix to keep CO2 captured safely in Iceland’s basaltic rock formations. The two companies have already experienced this in a pilot project, but Orca is the duo’s first commercial-scale operation.

Climeworks’ two other commercial-scale direct air capture plants transform carbon dioxide into a product used as a fertilizer or in soft drinks. This CO2 escapes back to the atmosphere relatively quickly. But, stuck in the rock, Carbfix believes that the CO2 captured by Orca can be kept safe for thousands of years.

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Iceland is ideal territory for storing carbon dioxide

Although basalt rock is relatively common around the world, volcanically active Iceland is particularly well suited to storing carbon dioxide because it has a relatively younger basalt.

Fresh basalt is a better home for captured CO2 because it’s more porous – giving carbon more gaps to fill.

By placing Orca in the same remote location where the CO2 will be stored, the operation avoids one of the potential pitfalls with carbon removal: the creation of a new network of pipelines to transport the captured carbon dioxide.

There are already some pipelines that move CO2 so it can be released to the ground and force out of oil reserves, a process called enhanced oil recovery.

One such pipeline was breached in 2020 in Mississippi, hospitalizing residents of a small community.

The other advantage of the plant’s location is the proximity to a geothermal power plant, which provides a constant supply of waste heat and renewable energy.

This, combined with Climeworks’ solid direct air capture process, gives Orca an edge over other competitors.

Even larger direct air capture plants are scheduled to come on stream in Texas and Scotland in the next few years, but these use a different filtration process, which requires much more heat and energy. As a result, they will likely depend on a combination of renewable energy and natural gas.

High cost is an obstacle

Another obstacle that still prevents the direct air capture industry from growing enough, to the point of causing a huge reduction in global greenhouse gas emissions, is the cost.

Microsoft, which last year pledged to capture all of its historic emissions by 2050, is an investor and client of Climeworks. She and other companies can buy Climeworks’ captured CO2 for about $600 a ton, offsetting a ton of their own pollution in the process.

In its fiscal year 2020 alone, Microsoft was responsible for the equivalent of 11,164,000 metric tons of carbon dioxide. By multiplying that by $600, Microsoft will face a bill of nearly $6.7 billion for a year’s worth of pollution.

Unless the price drops significantly, it may not make much financial sense to tackle climate change in this way. And some environmentalists fear that a focus on building this technology could take resources away from other climate solutions, while taking pressure off companies to stop burning fossil fuels.

“One thing people worry about is that all these companies that make net zero promises will just use direct air capture instead of reducing emissions,” says Morrow. “But, it seems to me very unlikely that direct air capture will become cheap enough anytime soon to make sense.”

So while direct air capture may play a small role in helping the world retain some of the planet’s warming emissions, it does not replace the priority of deep cuts in fossil fuel pollution. “It’s at best a supplement that can help us reduce climate change,” says Morrow.

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