Plans to inject carbon dioxide deep under the seabed off WA’s north-west could set a precedent for future oil and gas projects, critics warn, pointing to the hefty clean-up bill following the collapse of another energy company earlier this month as an example of the technology’s risks.

Woodside has an application before the federal government to develop a carbon capture and storage project, which forms part of plans to extract gas from the Browse basin, about 425 kilometres north of Broome.

Under the proposal, the energy giant would use two floating production vessels to extract gas and pipe it about 900 kilometres to the company’s North West Shelf project on the Burrup Peninsula, near Karratha.

To mitigate emissions from the project, Woodside wants to build a system that would re-inject carbon dioxide back into a Jurassic-era rock formation four kilometres below the seabed, where it would remain trapped.

However, that process has drawn the ire of environment groups, concerned not only about the impact on marine life from construction, but also the regular seismic blasting required to monitor the stored carbon dioxide over the decades the project is operational.

Woodside’s proposal to develop the nation’s biggest untapped gas resource was submitted back in 2018, but its carbon capture plans were introduced in 2023 before being resubmitted last month under updated federal environment legislation. Comment on the carbon capture proposal closes on Friday.

However, Australian Marine Conservation Society fossil fuels campaigner Chelsea Deng said the collapse of Pilot Energy last week and subsequent decommissioning headache at the company’s Cliff Head carbon capture and storage project, further down the WA coast near Dongara, was a red flag for the technology.

Deng said seismic blasting – the firing of “air guns” multiple times underwater and using the resulting sound waves to map deposits beneath the sea floor – would be required to monitor Woodside’s carbon storage reservoir for years after the project’s life had come to an end – which, by that stage, it would be the Commonwealth’s responsibility.

“And that is before we even talk about infrastructure cleanup and decommissioning, which is also something that we’re worried about, as we can see with Pilot Energy and the Cliff Head carbon dumping proposal,” she said.

Labor has put the oil and gas industry on notice that it may be on the hook for a clean-up bill in the $200 million range for the removal of a disused oil platform near Dongara that Pilot was working to turn into a carbon capture and storage project.

Woodside’s proposal is one of the first carbon capture and storage projects planned offshore. There are others around the nation, including Chevron’s efforts at its Gorgon gas project on Barrow Island, but those are all onshore.

But even Chevron’s project has its issues – the company wants to ultimately inject 80 per cent of carbon dioxide removed from its extracted gas every year, but has so far lagged well behind that target.

Deng said carbon capture and storage was an expensive, “faulty technology” that had struggled despite billions of dollars being poured into it globally.

“The complexity and the need for customisation for each project means that there is not a lot of learnings across the industry … widely,” she said.

“It makes it extremely difficult to scale as well.”

Woodside, for its part, is confident in the technology’s ability to operate as planned. A company spokesperson said it had been used successfully for decades to support “enhanced oil recovery”, but was now being used for permanent emissions’ storage.

The spokesperson said the Calliance rock formation the Browse project would pump carbon dioxide into could have the capacity to store up to four million tonnes of the greenhouse gas every year.

“All monitoring undertaken for the Browse CCS Project will be carefully planned and managed in accordance with regulatory requirements, including environmental assessments and operational controls,” they said.

“Where required, monitoring activities would be scheduled to avoid sensitive periods for marine species.”

The company hopes to reduce scope 1 greenhouse gas emissions by 53 million tonnes over the life of the Browse project through carbon capture and storage.

Push for minister to consider broader climate impacts of Browse gas

Woodside’s broader ambitions in the Browse basin are facing further pushback, with a coalition of 14 environment groups backing the Australian Conservation Foundation’s request for Environment Minister Murray Watt to consider the climate impacts of the gas project.

The ACF wrote to Watt’s office in February with a “reconsideration request”, citing new research that predicted widespread climate change-driven damage if gas in the Browse basin was extracted and sold.

The research, from Australian National University Professor Sarah Perkins-Kirkpatrick, found emissions from Browse could result in millions more coral colony deaths in future mass bleachings at the Great Barrier Reef.

If the minister accepted the substance of the request, those impacts could be factored into consideration as the government mulled whether to approve the Browse project.

Australian Conservation Foundation campaigner Piper Rollins said the impacts on the nearby Scott Reef coral atoll, and climate damage more broadly, could be “catastrophic”.

“At one end of the pipeline is the [North West Shelf] and at the other end is the Browse drilling at Scott Reef, an ancient coral atoll that is home to endangered whales and turtles,” she said.

The coalition of climate groups have corralled more than 70,000 submissions regarding the reconsideration request, which Rollins said sent a clear message that the community did not want Australia’s reefs sacrificed for Woodside’s profits.

The Woodside spokesperson said the company planned to provide a response to the reconsideration request.

In a statement released last month, Watt described the reconsideration request as “an administrative decision and not a decision on the substantive reconsideration application”.

“As the reconsideration request is currently active, it would not be appropriate to comment further,” the statement read.