Chevron’s recent announcement has turned the spotlight onto the complex and controversial technique of carbon capture and storage (CCS). What is CCS, and why is it so hotly debated?
On Monday, energy company Chevron announced that its Gorgon Liquefied Natural Gas (LNG) project was about to hit a milestone: over two years of operation, nearly five million tonnes of CO2 had been captured and injected underground at Barrow Island, about 1400 km north of Perth off Western Australia’s Pilbara coast.
Even by the most generous estimates – which Chevron is using – the project is some 4.8 million tonnes short of the amount it was supposed to inject. Its initial EPA approval depended on getting underground 80% of the CO2 it emitted over five years; the real proportion is more like 30%.
For comparison: every year, Australia as a whole is responsible for emitting roughly 500 million tonnes of CO2 into the atmosphere. Gorgon is the largest carbon capture project in the country, and, arguably, the world.
So where do we stand with carbon capture and storage (CCS)?
Carbon capture is old tech
Taking the CO2 generated by a polluting process and sealing it away somehow isn’t a new idea.
Using the Gorgon project as an example: methane gas reservoirs often contain carbon dioxide as well, meaning that mining of liquefied natural gas (LNG, or methane gas) emits carbon dioxide. This makes it an emissions-intensive venture before the methane itself is burnt for energy.
Carbon dioxide is separated from LNG during processing and purification. This CO2 is usually vented into the atmosphere, but as part of the Gorgon project’s environmental approval, Chevron was required to build infrastructure that could remove and store all of the carbon dioxide in the gas-production process.
This is, of course, a lot more complex than a few words in a sentence.
“You get your CO2, you compress it to what’s called supercritical CO2, which means it’s dense, it’s like a fluid,” explains Professor Peter Cook, of the Peter Cook Centre for Carbon Capture and Storage Research at the University of Melbourne.
This dense fluid is then pumped into the earth, aiming for specific rock formations that can hold it. “At about 800 metres deep, the pressure is equivalent to supercritical pressure, so if you inject this liquid-like CO2 in the subsurface, it remains in a liquid-like state,” Cook says.
In Gorgon’s case, the CO2 was headed more than two kilometres beneath Barrow Island.
“People say, ‘well, why doesn’t it escape anyway?’ And the answer is, it doesn’t,” says Cook. “In some cases it will react with the rocks. More commonly, the rocks are fairly quartz-like or quartz-rich. They’re not very reactive, so it fills the pore space.”
Around 20–30% of the rock at this depth is actually space, which the liquid CO2 can fill up.
The Gorgon project mirrors the Sleipner project off the coast of Norway, which has been injecting up to a million tonnes per year of CO2 into the substrate beneath the seabed since 1996.
In Australia, the Otway CCS project in Victoria has been operating since 2008.
“For more than a decade, we’ve been injecting CO2 at what I call a commercially significant scale, but not a totally commercial scale,” says Cook, who helped establish Otway.
“Over that period, we’ve injected getting up to a hundred thousand tonnes of CO2.”
Even by the most generous estimates – which Chevron is using – the project is some 4.8 million tonnes short of the amount it was supposed to inject.
If CCS has been viable for 25 years, why is it still relatively rare?
“It does cost money to do,” says Cook.
“The reason why Sleipner was initiated was because the Norwegian government said: ‘We’re going to charge you for CO2 that you release on oil and gas platforms in the North Sea.’ So the company did the sums and decided it’s a lot cheaper to actually put CO2 in the ground rather than give the money to the government.”
This financial incentive doesn’t exist in most other places. “In many other countries, there’s no drivers that exist. There’s no reason why people would do it, so people don’t do it.”
Things are beginning to change. In the US, the 45Q tax credit enacted in 2018 gives companies tax breaks for the amount of CO2 they can capture and either store permanently, or use. Other countries have adopted Norway’s policy of fines for companies that fail to capture their carbon.
“They can be sticks or they can be carrots – that’s really what it amounts to,” says Cook. “At the moment, we don’t have sticks, and we don’t have carrots in Australia.”
While there are incentives for R&D on CCS at the federal level, there’s no formal mandate across the board – and states operate on a case-by-case basis.
Implications for Gorgon
The Gorgon plant’s incentive was the stick: inject 80% of the CO2 emitted, or face consequences. What are those consequences?
“Technically, they should have their licence suspended, because it’s a breach,” says Samantha Hepburn, a professor of mining, energy and environmental law at Deakin University.
“But what seems to be happening is the regulator is giving a range of different dispensations.”
According to Chevron, they’re planning to make the shortfall up, and are in talks with the Western Australia government to do this. The 18 July deadline had already come from successful negotiations on behalf of Chevron to move their target to a more favourable date. It’s possible the government will grant them yet another end date and longer timeframe to make up the shortfall.
“I don’t think that can continue to happen,” says Hepburn. “At some point, [the government is] going to have to settle on ‘sorry, you haven’t met your obligations, and it’s not possible for you to meet those obligations’.
“The big picture is, what’s the point of keeping this going it it’s not working, and we’re going to continually have shortfalls? Ultimately, what needs to happen is a directive from the EPA to work out just exactly what the design and integrity issues are and whether they’re likely to have success in the near future. And it doesn’t look like that they are.”
“Realistically what that should mean is that the licence should be suspended – but … it won’t be.”
Instead, according to Hepburn, Chevron may buy carbon credits to account for the loss. In his analysis, independent energy journalist Peter Milne estimates this could be on the order of $100 million: a significant amount of money, but small change compared to the $3–4 billion required in the first place to build the CCS infrastructure alone.
What actually went wrong?
If researchers at Otway can run a successful CCS project, why can’t Gorgon?
The precise details of their engineering problems aren’t publicly available. “It’s unfortunate they can’t tell us more about it,” says Cook, who has had no involvement with the Gorgon project. But he believes the deep earth wasn’t the thing that slowed them down.
“It’s actually really on the surface,” he says. “They had problems with corrosion, they had metallurgical problems, they had problems with setting up a second train at the site, which again delayed things.”
“We shouldn’t lay it all at the feet of carbon capture and storage.”
These are all surmountable, provided you have enough engineers. Another issue was water injection: in order to make space for the liquid CO2, groundwater had to be removed. “You’ve then got to reinject it into a different geological horizon, and that was where they had some difficulties,” says Cook.
“So it wasn’t a matter of CO2 that caused that problem. It was this water injectivity issue.”
In short: there were many technical difficulties, but none of them are essentially carbon injection difficulties. “It’s a combination of these things and we shouldn’t lay it all at the feet of CCS,” says Cook.
“It’s part of this general issue of getting a very large, very complex project done.”
Implications for carbon capture
The technology for CCS exists already; while researchers are continually finding ways to improve it, it only requires money and will to work. But – given that money and will hasn’t materialised at a large scale any time in the past decade, and we now have much cheaper energy available in the form of renewables – is it still worth pursuing?
Hepburn is of the opinion that, while “it’s consistent with a transition framework, whereby you gradually phase out fossil fuels,” large-scale gas projects like Gorgon still shouldn’t be getting the green light. “I don’t think it should be approved going forward if the technology’s not there, and I don’t think we should simply be using dispensations because we can’t afford to do that.”
“Carbon capture is consistent with a transition framework, whereby you gradually phase out fossil fuels.”
If there’s no evidence Chevron – or its competitors – can learn from the mistakes of Gorgon, she argues, then other companies shouldn’t be given the opportunities to make those mistakes – and nor should regulators be cutting them any breaks if the projects are approved.
“If Chevron can’t get it right with Shell and Exxon [who are major partners in the Gorgon project], then who’s going to get it right?” she asks. “Is it possible to get it right? I’m sure that it is, but it does take time, and the question is, do we have that time?”
While Cook believes a low-emissions world, with CCS, is the most feasible future option, even a world that ran on 100% renewable energy would require carbon storage for some industrial operations, and negative emissions endeavours.
“[The idea of CCS] started out as a single monolithic power station: you capture the CO2, you put it in the ground. But now we’re talking about a much more diverse range of CO2 sources,” he says.
Cement- and steel-making are two obvious candidates for CCS: they use industrial processes that can’t immediately be done without emitting CO2 (although green steel, using hydrogen, is on the horizon).
The other avenue is in negative emissions technology. The IPCC asserts that large-scale negative emissions technology is likely to be needed to meet the Paris Agreement targets. While there are a range of biological and geological ways to do this, direct-air carbon capture and storage is also an avenue worth pursuing. Research is being done on removing CO2 directly from the atmosphere, and – once it’s removed – it will need somewhere to go. It can be made into other products to recoup some losses, but injection is still one of the most viable storage methods.
“I think it’s unfortunate that in some people’s minds, CCS is somehow the spawn of the devil,” says Cook. “People [have] this vision that it’s all about coal. It’s not. It’s about carbon, in its various forms.”
Ellen Phiddian is a science journalist at Cosmos. She has a BSc (Honours) in chemistry and science communication, and an MSc in science communication, both from the Australian National University.