Carbon capture and storage: does it work, and does it mean we can keep burning fossil fuels?

2021-11-09

Does Australia have a bad reputation on climate change?

Among the worst in the world, according to at least one survey of international media and social media content by intelligence and social analytics company Meltwater Australia.

But heading into Glasgow, the federal government did commit Australia to a net zero target by 2050.

Though light on detail, the government’s net zero plan predicts that investing in “priority low emissions technologies” will achieve 40 per cent of our emissions reduction needed to get us there.

One of those “priority” technologies singled out for focus by the government is carbon capture and storage, or CCS.

Proponents of CCS, including Minister for Energy and Emissions Reduction Angus Taylor, argue the technology allows us to continue profiting from fossil fuels while also getting our emissions down.

But critics say CCS is a failed technology that the government is using to delay the inevitable shutdown of our fossil fuel industries.

What is carbon capture and storage?

As the name implies, CCS involves capturing carbon dioxide at the site of production, such as a gas liquefaction plant or coal-fired power station.

The gas is then pumped deep underground where it can migrate into porous substrate, such as sandstone, and be trapped.

There is also carbon capture use/utilisation and storage (CCUS), which usually involves a process known as enhanced oil/gas recovery, where captured carbon dioxide is pumped into depleted oil or gas reservoirs in order to force out any remaining fuel from the reservoir.

Once the hard-to-recover fossil fuel is removed, the captured carbon dioxide then remains trapped inside the underground reservoir.

Does carbon capture and storage work?

Yes, to an extent, but it’s complicated.

CCUS has been in use since the 1970s, when it was known as enhanced oil recovery and its purpose was to increase oil yield rather than sequester emissions.

But fossil fuel industries claim it has also proven effective since then in reducing a proportion of the emissions from some polluting industries.

The first CCS/CCUS projects started out small but have become much more ambitious in recent years, according to Kathryn Amos, head of the University of Adelaide’s Australian School of Petroleum and Energy Resources (ASPER).

Chevron has provided funding for ASPER’s carbon capture and storage research.

“There are a number of CCS projects that work really well around the world,” Dr Amos said.

According to the US Department of Energy’s Carbon Capture and Storage Database, there are 43 active sites where carbon capture and storage is taking place worldwide, including enhanced oil recovery projects.

That includes 10 in the US, five in China and four in Australia.

However, only one of those Australian projects (Gorgon) is on a commercial scale. The other three are small-scale research studies not intended to make an impact on emissions reduction.

Gas giant Santos has a $220 million CCS project in development at Moomba in South Australia, where it plans to store more than 1 million tonnes of CO2 each year, starting in 2024.

That project has been made eligible for receiving carbon credits.

Santos chief executive officer Kevin Gallagher says the project is a “critical step in decarbonising natural gas”.

Matthias Raab, executive director of CO2CRC, an Australian carbon capture utilisation and storage research company, says CCS can help make quick gains in getting our emissions down.

“We need to be genuinely open to what we can do to have the big wins as quickly as we can,” Dr Raab told the ABC’s Science Friction.

“In my eyes, carbon sequestration is a big, big winner.”

But critics, including Mark Ogge from the Australia Institute, say carbon capture and storage is a government fossil fuel handout, which is putting our transition to proven clean technology in peril.

“[Carbon capture and storage in Australia has] been around for about 20 years and it’s led to a huge delay in us doing anything serious about winding back fossil fuel emissions,” Mr Ogge says.

“The amount of CO2 that’s actually captured and put underground is minuscule.

“For every billion dollars of taxpayers’ money that goes into this … every one of those dollars is a dollar not spent on things that are proven to reliably work and can be rolled out now and have huge abatement potential.”

The Gorgon gas facility in Western Australia is the world’s largest “dedicated” CCS project, meaning the captured CO2 isn’t used to extract more fossil fuels.

Despite having the financial backing of Chevron, Exxon Mobil and Shell, and $60 million from the WA government, the project has been racked by technical issues.

Originally supposed to capture 80 per cent of its emissions over a five-year period, it’s never reached full capacity and has only achieved storage of about 30 per cent of emissions with the remaining emissions — estimated to be in the vicinity of 10 million tonnes of CO2 — being released to the atmosphere.

For scale, it was estimated at one point by Climate Analytics that the Gorgon plant was releasing roughly the same amount of CO2 into the atmosphere each year as was being collectively saved by every rooftop solar panel in Australia.

The company had talks in July with the WA government, which could result in Chevron needing to purchase around $100 million in carbon credits.

Majority of CCS projects fail

Encountering problems is far from rare for carbon capture and storage projects.

A study published in Environmental Research Letters last year found more than 80 per cent had either failed to launch, or failed after launch.

The majority of carbon capture storage projects have failed.(ABC News: William Rollo)

Lead author of that study, Ahmed Abdullah from Carleton University in Canada, says there are some key reasons why they fail.

“The global record of deploying carbon capture is overwhelmingly one of failure when you consider the huge number of projects that have been proposed over the previous two decades,” Assistant Professor Abdullah said.

“The question was, as engineers, can we learn from that failure?”

Paradoxically, they found that it was usually the smaller, less ambitious projects that succeeded.

Of the 14 most expensive US-based projects they looked at, 13 were abandoned.

“It turns out that when government endeavours to fund these projects that are large, shiny and therefore cost a lot of money, but also employ the next generation of advanced technologies, well-advanced technologies often fail,” Dr Abdullah said.

But when they work, what percentage of emissions are captured?

Exact figures are difficult to come by, but Dr Raab estimates it’s in the vicinity of 90 per cent for coal and higher for gas.

“Let’s say 95 per cent plus is being captured and is then being stored geologically,” he said.

But senior scientist with Climate Analytics and lead author of the Intergovernmental Panel on Climate Change’s 4th Assessment Report Bill Hare, says it’s lower than that.

“For projects in Canada, it’s about 60 to 70 per cent,” Dr Hare says.

“The capture [rate in] CO2 reservoirs also turns out to be not complete either. It’s optimistically claimed to be 80 to 90 per cent, but I don’t think there are any examples.

“For enhanced oil recovery, a significant portion of the CO2 comes back to the atmosphere, but it turns out there haven’t been many studies published.”

Where it was once thought that carbon capture and storage would play an important role in getting global emissions down, Dr Hare says green technologies have advanced to the point where that’s no longer the case.

“There are a few sectors where if you’d asked me five or so years ago, I’d have said I can’t see many options [other than CCS], like in cement, steel, fertilisers … but right now in 2021, that looks quite unfeasible,” he said.

“Green steel is now quite famous [using hydrogen], fertiliser is also quite carbon intensive, but it’s looking like you can make fertiliser with green hydrogen, you can make a green ammonia, and away you go.”

Once the CO2 is stored, can it leak?

The possibility of a leakage, and who is responsible for those emissions. is a major problem for carbon capture and storage, according to Dr Hare.

A 3-kilometre-long crack was found near Statoil’s Sleipner carbon capture and storage site in the North Sea in 2011, and the fracture was found to be leaking gases.

While none of the sequestered CO2 was determined to be leaking, the discovery was a wake-up call that more rigorous screening of storage sites was needed.

“The storage of carbon underground is not as straightforward as it sounds,” Dr Hare says.

“One of the most famous ones is the Sleipner field in the North Sea; that’s been well studied and it turns out to have a lot of cracks in it — that’s been a shock and a surprise.

“If anyone says it’s easy and safe and the CO2 will stay underground for a long time, that needs to be treated very sceptically.”

But Dr Amos says the technology is safe, and CO2 can be stored in the same wells where gas has been held for millions of years.

“Some of the targets of CO2 storage are depleted oil and gas reservoirs. We know they’re pretty safe options for storage because those are the locations that were naturally storing gas.”

Dr Raab agrees.

“We’re looking at existing oil and gas reservoirs and the knowledge that we have about how they originated, how they were holding oil and gas and liquids for millions of years,” he says.

He says it’s “no secret” there have been problems in the past, but that the industry has improved its practices.

“I think we need to make an assumption really here that the industry [has come] a long way,” he says.

“There are certain measures that need to be in place to simply ensure the best practices.”

Dr Hare says if there’s a leak down the track, it’s taxpayers that will foot the bill.

“If you look at the new, much-touted methodology for CCS, it’s very weak for monitoring of storage and long-term security, and these issues are essentially put back onto the government,” he says.

“The major proponents of CCS in Australia don’t want that liability. It tells you they’re not stupid, and it makes you wonder about the wisdom of the government accepting liability.”

Dr Raab says liability won’t be an issue.

“This is an extremely well-understood undertaking.”

But Mr Ogge says focusing on the technology is a distraction from the bigger picture.

“It’s a 50-year-old oil and gas industry practice of pumping CO2 into the ground to force out more oil from depleted fields, which increases emissions,” he said.

“It’s been re-branded as carbon capture and storage to basically greenwash it and allow the oil and gas industry to get taxpayer subsidies by presenting it as a climate abatement measure.

“It really is just a complete scam.”

abc.net.au, 9 November 2021
; https://www.abc.net.au