A Glimpse into the Future of Carbon Capture
It could be a scene straight out of a science fiction movie. Towering over the dark, mossy lava fields of Iceland, a sprawling complex of noisy machines, domes, and zig-zagging silver pipes stands tall. This is the world's largest direct air capture (DAC) facility, known as Mammoth, developed by the Swiss firm Climeworks.
Located 30 kilometers (19 miles) southwest of Reykjavik, the capital of Iceland, this facility has been operational for two months, actively sucking global-warming carbon dioxide (CO2) out of the air and then storing it deep underground, where it eventually turns to stone.
Currently, there are 12 collector containers in place, but over the coming months, the plan is to install 72 of these units, circling the large processing hall. "That will enable us to capture 36,000 tons of CO2 every year," explains Douglas Chan, the chief commercial officer of Climeworks.
The premise behind this technology is to directly reverse the emissions that have already been released into the atmosphere. Each collector unit is equipped with a dozen powerful fans that can, every 40 seconds, suck up enough air to fill an Olympic-sized 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," elaborates Mr. Chan.
This large-scale direct air capture facility in Iceland represents a glimpse into the future of carbon capture efforts, as the world grapples with the pressing challenge of mitigating the effects of climate change.
The Challenges of Capturing a Minuscule Fraction of the Atmosphere
While carbon dioxide (CO2) only makes up a tiny proportion of the Earth's atmosphere, just 0.04%, capturing it still requires a significant amount of electricity. This is a key challenge facing the Mammoth direct air capture facility in Iceland.
To address this, the Mammoth plant is situated next to a neighboring geothermal power plant, which provides the necessary electricity to power the operation. This arrangement ensures that the Mammoth facility operates without generating any additional emissions.
Once the collection chambers within the Mammoth facility are full, they are flushed out using hot steam that is piped into the processing hall. Inside the hall, two enormous balloons can be seen overhead, each holding a single tonne of the captured CO2.
This captured CO2 is then mixed with fresh water in an adjacent tower, in a process described by Dr. Martin Voigt from the Icelandic firm Carbfix as "almost like a shower." As the water trickles down from the top, the CO2 is dissolved into the water.
The CO2-laden water is then pumped more than 700 meters underground, through injection wells hidden inside two white, igloo-like domes nearby. This is where the CO2 is permanently stored, ultimately turning into stone through a process developed by Carbfix.
The challenge of capturing a minuscule fraction of the atmosphere, like the 0.04% that CO2 makes up, requires innovative solutions and significant infrastructure, as demonstrated by the Mammoth facility in Iceland.
The Rapid Mineralization of Captured Carbon in Iceland's Volcanic Basalt
As Dr. Martin Voigt, from the Icelandic firm Carbfix, shows me a lump of black, porous basalt rock from a recent volcanic eruption, he explains the important role this volcanic bedrock plays in the carbon capture and storage process.
"This is a fresh basalt here," he says, pointing out the numerous tiny holes and high porosity of the rock. "You can see there's a lot of porosity."
Iceland's abundance of volcanic basalt provides the perfect storage reservoir for the captured carbon dioxide (CO2). When the CO2 interacts with the other elements present in the basalt, a reaction is triggered, and the CO2 quickly solidifies, becoming locked away as carbonate minerals.
Examining a sample of the drilled-out rock, Dr. Voigt points out the "whitish specks" that have now filled many of the pores. "Some of these are carbonate minerals. They contain the mineralized CO2," he explains.
The process is remarkably fast, according to Dr. Voigt. "We're not talking about millions of years," he says enthusiastically. "Around 95% of the CO2 was mineralized within two years in the pilot project. This is incredibly fast. On geological timescales at least."
The ability of Iceland's volcanic basalt to rapidly mineralize captured CO2 is a key advantage of the carbon storage process developed by Carbfix, making it a highly efficient and effective solution for locking away the captured greenhouse gas.
The Scale and Cost Dynamics of Direct Air Capture
The Mammoth direct air capture facility in Iceland has an impressive capacity, capable of removing 36,000 tonnes of carbon dioxide (CO2) per year. This is equivalent to taking 8,000 petrol cars off the road, making Mammoth almost 10 times larger than Climeworks' first commercial plant, Orca.
However, the process of capturing and storing a tonne of CO2 is currently quite costly, with Climeworks estimating it at almost $1,000 (£774) per tonne. To generate revenue, the company sells carbon offsets to a range of clients, including Microsoft, H&M, JP Morgan Chase, Shopify, and Lego, as well as over 20,000 individual subscribers on their website.
Despite the high initial costs, Mr. Chan, a representative of Climeworks, believes that technological improvements and scaling up of operations will drive down future costs significantly. He states that the company's goal is to reach a cost of capture between $300 and $400 per tonne by the end of the decade.
Microsoft's senior director of energy and carbon removal, Brian Marrs, has previously acknowledged the importance of carbon removal, stating, "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."
In the future, the Mammoth facility may be dwarfed by the US-based Project Cypress, which is set to break ground in 2026. Climeworks hopes that Project Cypress will be able to remove up to a million tonnes of CO2 annually, using new technology that they claim will be cheaper and more energy-efficient than their current solutions.
The scaling up of direct air capture projects and the continued drive to reduce costs are crucial for making this technology a viable and accessible solution in the fight against climate change.
Concerns and Criticisms Surrounding Direct Air Capture Technology
While the potential of direct air capture (DAC) technology is widely recognized, it is not without its critics who argue that the technology has been overhyped, pointing to several key issues.
One of the primary criticisms is the high costs associated with DAC. Capturing and storing a single tonne of CO2 can cost almost $1,000, making it a very expensive process. Additionally, critics highlight the high energy consumption required to operate DAC facilities, which can limit their scalability and sustainability.
Another point of contention raised by the critics is the limited scale of current DAC projects. Compared to the vast quantities of emissions that need to be addressed, the removal capacity of even the largest DAC plants, like Mammoth in Iceland, is seen as relatively small.
Dr. Edvard Júlíus Sólnes, a professor at the University of Iceland and former Icelandic Environment Minister, argues that capturing CO2 directly from the source, such as smokestacks, would be a far more efficient approach. He states, "It's much easier to remove the carbon dioxide directly from smokestacks."
These criticisms underscore the need for continued technological advancements, cost reductions, and scaling up of DAC projects to make the technology a viable and impactful solution in the fight against climate change. While the potential of DAC is recognized, addressing the concerns raised by the critics will be crucial for its widespread adoption and effective implementation.
Reference: Adrienne M. (6 Aug, 2024) Carbon Capture: A Promising Approach or an Inefficient Way to Tackle CO2?
Retrieved from https://www.bbc.co.uk/news/articles/clmydee2grno Is carbon capture an efficient way to tackle CO2?
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