Located 30km (19 miles) southwest of Iceland’s capital Reykjavik, Mammoth is the world’s largest direct air capture (DAC) facility.
Developed by the Swiss company Climeworks, this cutting-edge installation is designed to capture carbon dioxide (CO2) from the atmosphere and store it deep underground, where it solidifies into stone.
Mammoth’s imposing structure stands amidst dark, moss-covered lava fields, comprising stacks of machinery the size of shipping containers, along with domes and intricate networks of silver pipes.
Currently operational for two months, the facility has begun its mission to mitigate global warming by extracting CO2 from the air. This CO2 is then sequestered underground, where it undergoes a process that turns it into solid carbonate minerals, permanently removing it from the atmosphere.
So far, twelve collector units have been installed at Mammoth, with plans to increase this number to 72 in the coming months.
“That will enable us to capture 36,000 tons of CO2 every year,” Climeworks’ chief commercial officer, Douglas Chan, said.
Each unit contains a dozen powerful fans that can suck up enough air every 40 seconds to fill an Olympic swimming pool.
“The technology relies on sucking in lots and lots of air, slowing it down so that the filter can capture it, and then venting the air back out the end,” says Mr Chan.
Given that CO2 constitutes only 0.04% of the atmosphere, capturing it efficiently requires significant energy input. Fortunately, Mammoth is powered by a neighbouring geothermal plant, ensuring that the entire operation is emissions-free.
Once the collection chambers are filled with CO2, they are purged with hot steam, which then carries the gas into a processing hall. Inside, two large balloons can be seen overhead, each holding a tonne of captured CO2. This gas is then mixed with water in an adjacent tower before being pumped into the ground through injection wells housed in white, igloo-like domes.
“It’s almost like a shower,” explains Dr Martin Voigt, from Icelandic firm Carbfix, which has developed a process to turn CO2 into stone.
“From the top, water trickles down. The CO2 is coming up, and we dissolve the CO2.”
The CO2-laden water is injected more than 700 meters deep into Iceland’s volcanic basalt bedrock.
“This is a fresh basalt here,” says Dr Voight, showing me a lump of black rock taken from a recent volcanic eruption, and riddled with tiny holes. “You can see there’s a lot of porosity.”
When the CO2 reacts with minerals in the basalt, it solidifies, locking it away as carbonate rock.
“Here you can see a lot of these pores are now filled with whitish specks,” says Dr Voight, handling a sample of drilled out rock.
“Some of these are carbonate minerals. They contain the mineralised CO2.”
The process is quick, claims Dr Voight enthusiastically. “We’re not talking about millions of years.”
“Around 95% of the CO2 was mineralised within two years in the pilot project. This is incredibly fast. On geological timescales at least.”
Mammoth is capable of removing 36,000 tonnes of CO2 from the atmosphere annually—equivalent to taking 8,000 petrol cars off the road. This makes it almost 10 times larger than Climeworks’ previous facility, Orca.
However, the process is expensive, costing Climeworks nearly $1,000 (£774) per tonne of CO2 removed.
“Mammoth has already sold close to a third of its lifetime capacity,” states Mr Chan, who believes technological improvements and scaling up, will drive down future costs.
“By the end of the decade, we want to be at a cost of capture of between $300 and $400.”
To sustain the operation, Climeworks sells carbon offsets to companies like Microsoft, H&M, JP Morgan Chase, Shopify, and Lego, along with over 20,000 individual subscribers.
“We’re following the science,” Microsoft’s senior director of energy and carbon removal, Brian Marrs, previously told the BBC.
“Carbon removal has to be part of the equation. You can’t reduce emissions that are already in the atmosphere, you have to remove them.”
While Mammoth is currently the largest DAC facility, it will eventually be overshadowed by Project Cypress in the US, which is slated to begin operations in 2026. Climeworks aims for this new facility to capture up to a million tonnes of CO2 annually, using more advanced and cost-effective technology.
Despite the promise of DAC technology, it faces criticism for its high costs, energy demands, and limited scale.
Critics argue that capturing CO2 at the point of emission would be more efficient.
“It’s much easier to remove the carbon dioxide directly from smokestacks,” says Dr Edvard Júlíus Sólnes, a professor at the University of Iceland and former Icelandic Environment Minister.
However, with global CO2 emissions hitting a record high last year, and the UN’s Intergovernmental Panel on Climate Change warning of the urgent need to reduce emissions, many experts believe carbon removal will be essential to combat climate change.
Nevertheless, the reliance on such technologies is controversial, with some warning that it could discourage efforts to reduce emissions at the source.
“We release about 40 billion tonnes of carbon dioxide into the atmosphere every year, so this [DAC] won’t make a dent in the big problem,” says Dr Sólnes.
“We need to divest from fossil fuels and find other sources of energy,” he asserts. “But I think we should use all methods to fight this problem.”
As of now, DAC technology is still in its early stages, with only 27 plants operational worldwide, four of which capture more than 1,000 tonnes of CO2 annually.
Despite these challenges, Climeworks and other companies are pushing forward, with the US government investing $3.5 billion to develop large-scale DAC hubs.
For advocates like Doug Chan, DAC represents a vital tool in the fight against global warming.
“I really do believe direct air capture and other engineered solutions are going to get us to the point that we need to help fight climate change.”
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