Estimated reading time: 8 minutes
For years, climate change was spoken about as a far-off threat – serious, but something we’d have time to tackle before it reached us.
Now, however, we know just how misplaced that optimism was. You only need to glance through the news headlines to see that climate change is already causing disruption across the globe. And last year’s report from The Intergovernmental Panel on Climate Change (IPCC) issued a stark warning that change is happening faster than originally predicted.
The urgency of the crisis has sparked heightened interest in new technologies and innovations to reduce greenhouse gas emissions and stave off the worst effects of the changing climate. One area that is increasingly grabbing the attention of policymakers is carbon capture and storage.
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Essentially, this is a suite of technologies that aim to prevent carbon dioxide from being released into the atmosphere, capturing and storing it instead.
At their most ambitious, these technologies may even be able to remove carbon dioxide that is already present in the atmosphere. If done at sufficient scale, such an approach would not just contribute to preventing further warming but could potentially also help to reverse existing changes.
You can see why politicians and policymakers are so keen to explore these technologies further. Indeed, the UK government has recently announced that carbon capture will form a key part of their new energy policy.
But does carbon capture and storage really stack up as an approach? Or is it an expensive distraction from truly impactful action on climate change?
In this blog post, we’re exploring carbon capture in more detail. We’ll look at some of the innovative projects that are starting to take shape and how they could contribute to the fight against climate change. And we’ll also discuss the limitations of these technologies as they stand right now.
Capturing Carbon Dioxide at Source
Carbon capture technologies have been grabbing headlines in recent years, but the basic idea has been around for much longer.
There are already 35 commercial carbon capture facilities in operation around the world. Together, these facilities capture almost 45 million tonnes (Mt) of carbon dioxide every year. For context, global carbon emissions in 2022 are estimated at 40,500 million tonnes (Mt), according to The Global Carbon Project. Clearly, we have some way to go before carbon capture helps us achieve net zero.
However, increased interest and investment in carbon capture technology since 2018 means that the number of schemes in operation is set to rise massively in the next decade. The International Energy Agency (IEA) reports that another 200 planned capture schemes are due to be in operation by 2030.
The majority of these schemes work by capturing carbon emissions at their source. Industrial plants can be built with the technology in place, or have it added retrospectively.
Currently, carbon capture technologies are capable of capturing 90% of the carbon dioxide emissions from power plants and industrial facilities where they are used.
Once captured, the carbon dioxide is compressed into a liquid state so that it can be transported and stored. Typically, it is then injected into the ground, where it is stored in geological formations.
For example, in Scotland, plans are afoot to introduce the first carbon capture and storage facility in Aberdeenshire. Named the Acorn Project, this scheme would capture emissions from the St Fergus gas terminal and pipe it under the North Sea for storage.
The project has yet to be approved, despite being in development for over a decade now. However, the government’s recent commitment to carbon capture means the company behind it is now optimistic that it will be able to go ahead very soon.
Similar projects are already in operation in various countries around the world. But they haven’t always delivered on their promises.
One of the largest carbon capture and storage facilities currently in operation is the Gorgon carbon dioxide injection project in Australia. Led by Chevron, a gas company, the project aims to capture at least 80% of the carbon dioxide emitted by the Gorgon gas fields and inject them into the Dupuy Formation – a geological feature that lies 2km under Barrow Island.
The facility opened in 2019 but has since made headlines for its ongoing failure to meet its targets.
The Gorgon project isn’t alone in missing its targets either – according to the New Scientist, flagship carbon capture facilities at Shute Creek in Wyoming and Boundary Dam in Saskatchewan, Canada are also significantly underperforming against their original targets.
This isn’t to say that carbon capture doesn’t work at all. But it is a worrying trend if we’re relying on these technologies to help us achieve net zero and control the impact of climate change.
Capturing Carbon from the Air?
Of course, not every industry is suitable for direct capture of carbon dioxide at source. And this approach also does nothing to address carbon dioxide already in the atmosphere. So, technologies that address carbon dioxide emissions on site are only part of the story.
An alternative method of carbon capture is Direct Air Capture (DAC). As the name implies, this aims to capture carbon dioxide already present in the atmosphere, sucking it out of the air itself.
One of the major advantages of DAC is that it can offset carbon emissions from industries like aviation and transport, where it is difficult to capture the carbon dioxide at source.
But it is harder to capture carbon from the atmosphere than it is to recover it from industrial facilities and power plants because it is more dilute. As a result, DAC technology is still relatively new and fewer projects use this approach currently.
The IEA reports 18 DAC plants currently operating worldwide. But many more are planned.
One of the pioneers in this area is the Canadian company, Carbon Engineering. The company’s first pilot plant was built in Squamish, British Columbia in 2015. Although small-scale, this pilot project showed what might be possible.
Last year, Carbon Engineering and its partners, 1PointFive, began construction of a large commercial DAC plant in Texas. Once it is operational, the facility will be the largest in the world and the company hopes that it could eventually draw as much as a million tonnes of carbon dioxide from the atmosphere every year.
Meanwhile, over in Iceland, cleantech company Climeworks have already launched a large-scale DAC facility. Named Orca, the plant opened in 2021 and has eight collector containers. Each of these has an annual capacity of 500 tonnes, giving the facility a total capacity of 4,000 tonnes per year.
This is a drop in the ocean compared with the current level of carbon dioxide emissions but is a step in the right direction for a technology that is still in its infancy.
However, there are issues with DAC as it currently stands. Removing carbon dioxide directly from the atmosphere is energy-intensive, which brings two huge limitations to the use of this technology.
First is the issue of how to power the facilities. It takes a lot of energy to pull carbon dioxide directly out of the air – one study estimated that powering enough DAC facilities to offset the expected rise in greenhouse gas emissions would take a quarter of the world’s energy by 2100.
That energy has to come from somewhere. And if DAC technology is to assist in the fight against climate change instead of adding to it, it needs to be powered by renewable sources.
Second, DAC is an expensive technology. Current estimates put the costs at between $250 and $600 per tonne of carbon removed. This is a particular barrier because there is currently little commercial drive to tempt companies to overlook the high costs of this technology – it will likely take government incentives to drive investment in DAC facilities.
Still, many of the DAC facilities currently in operation are small-scale pilots, so it is likely that costs would reduce as the technology develops and larger sites come into operation.
Most DAC facilities rely on fans to drive air over the collection substrate so that carbon dioxide can be absorbed. Driving those fans adds to the energy needs of the facility. But the design of the MechanicalTreeTM means that it can use ambient wind power instead, cutting down on both costs and energy requirements.
While you may well be thinking that we already have access to cost-effective, carbon-absorbing forests made from actual, real-life trees, Carbon Collect also points out that the MechanicalTreeTM is a thousand times more efficient than natural trees at removing carbon dioxide from the atmosphere.
So, perhaps the mechanical forests of the future aren’t as bizarre a proposal as they initially sound.
CarbFix, which dissolves captured carbon dioxide in water and then stores it in reactive rocks like basalt.
Photo: Sigurður Ólafur Sigurðsson
What About Storage?
Of course, being able to extract carbon dioxide from the air (or from emissions by industrial plants) is only part of the story. Once removed, all that carbon dioxide needs to go somewhere.
As we’ve already seen, the most common solution is to compress the gas into a liquid form and then store it underground in geological formations.
On the plus side, it seems that we’re unlikely to run out of places to put the extracted carbon dioxide any time soon. Research indicates that there is more than enough storage space available to hold all the carbon dioxide that would need to be captured to meet the IPCC’s global warming targets.
However, the impact of that stored carbon is more of an open question. There’s a risk that stored carbon dioxide could leak out and escape back into the atmosphere or contaminate water supplies. Another potential risk is an increase in seismic activity due to the rise in pressure underground – similar to the effects of fracking.
Fortunately, there may be solutions that reduce these risks. One is the approach pioneered by Icelandic company CarbFix, which dissolves captured carbon dioxide in water and then stores it in reactive rocks like basalt. Within two years, the carbon dioxide reacts with the basalt to form solid carbonates, removing the risk of leakage.
Another option that has recently attracted interest is the suggestion that extracted carbon dioxide could be transformed into baking soda (sodium bicarbonate) and stored in the world’s oceans.
Or why not go further and make use of the byproducts of carbon capture? That’s the approach taken at Tata Chemicals Europe’s Northwich plant.
The facility, which opened in 2022, captures carbon dioxide from the company’s combined heat and power plant, then recycles and purifies it. Finally, the carbon dioxide is used to make high-grade sodium bicarbonate, which is then sold for use in food and medicines.
While this solution feels pleasingly circular, the use of captured carbon dioxide in commercial products should perhaps be considered with some caution. After all, the carbon dioxide in this scenario is simply being reused, not removed altogether.
Is Carbon Capture a Distraction?
Many experts expect carbon capture technologies to play a major part in controlling global warming and meeting net-zero targets. But not everyone sees this new technology as the way forward for the battle against climate change.
Some well-known environmental campaigning groups, including Friends of the Earth and Greenpeace, say that carbon capture is a dangerous distraction that is prolonging the use of fossil fuels. They argue that the investment into carbon capture technologies could be better spent on cutting emissions and properly funding the transition to clean energy.
Tata Chemicals Europe’s Northwich plant captures carbon dioxide to make high-grade sodium bicarbonate, which is then sold for use in food and medicines.
Credit: Tata Group
It is certainly true that carbon capture facilities currently only remove a tiny fraction of the carbon dioxide emitted annually. Many are funded by companies that continue to profit from fossil fuels. And these technologies have yet to prove themselves at any meaningful scale.
Whether you see carbon capture as the path to a brighter future or not, what is clear is that we cannot rely on this technology alone to meet our climate change targets.
At best, carbon capture should be seen as just one in a range of options to tackle global warming, not a silver bullet that will solve all our problems. And it shouldn’t be used as a substitute for divesting from fossil fuels, investing in clean energy, and reducing global emissions.
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Sources and further reading:
Realmonte, G., Drouet, L., Gambhir, A., Glynn, J., Hawkes, A., Köberle, A. C., & Tavoni, M. (2019). An inter-model assessment of the role of direct air capture in deep mitigation pathways. Nature communications, 10(1), 1-12. https://doi.org/10.1038/s41467-019-10842-5