Independent satellite monitoring has detected massive plumes of methane emerging from one of Australia's largest oil and gas complexes.
The persistent clouds above Chevron's Gorgon liquefied natural gas (LNG) plant on Barrow Island off Western Australia's Pilbara coast were picked up by five consecutive passes of the Tanager-1 satellite since November last year.
The most recent, in late August, recorded an average emission rate of about 7.8 tonnes of methane an hour.
That is the equivalent of almost 51 petrol-powered cars driven for one year or burning more than 110,000 kilograms of coal, calculated using an online tool by the US Environmental Protection Agency (US EPA).
Satellite imagery of the alert triggering methane emissions, captured in August 2026. (Supplied: Carbon Mapper)
The repeated detections, the latest far exceeding a "super emitter" event under US EPA guidelines, prompted a United Nations warning to Chevron.
According to the UN, methane is responsible for roughly 25 per cent of global warming and 80 times more harmful a greenhouse gas than carbon dioxide.
Chevron confirmed it had received the alert and was working with the UN Environmental Programme (UNEP) to address it.
However, a UNEP spokesperson told the ABC it had not received formal feedback from either Chevron or the Australian government, and would update its publicly available data when it had.
Chevron was similarly notified about methane emissions at Gorgon in July 2025.
In a statement, Chevron said satellite monitoring came with "a wide range of uncertainty".
“We are engaging with the UNEP, and we are seeking further clarity on their data," a company spokesperson said.
Non-profit Carbon Mapper operates the satellite as part of UNEP's International Methane Emissions Observatory, of which Australia is listed as a key donor.
The satellites monitor emissions from around the world, with the website showing Chevron's Gorgon project as the highest emitter of methane in WA.
State regulators investigating
Chevron is required to log its emissions through the National Greenhouse and Energy Reporting Scheme, with the numbers published annually.
But ABC enquiries to the National Environmental Protection Agency were referred back to state regulators, because methane falls outside Gorgon's federal approval.
The WA government said it was unclear of its role in managing the potential leak.
"The Department of Water and Environmental Regulation is aware of these reports and is investigating them to understand what compliance or regulatory measures may be required,"
a spokesperson said.
The observations of Chevron's Gorgon project ranged from about one to eight tonnes of methane an hour. (Supplied: Chevron)
Conservation Council WA slammed the lack of action.
"What I would hope is that our levels of government are communicating with each other and checking where the responsibility is," executive director Matthew Roberts said.
"Whatever happens, that is a piece of infrastructure from a private corporation that is profiting off of our resources."
Possible operational issue
The high-volume methane release adds to an already troubled environmental record at Gorgon.
The project's highly-touted carbon capture and storage technology has drastically underperformed since operations began in 2016.
Chevron also reported that an unknown amount of gas had seeped into Barrow Island's surface last year.
Chevron did not confirm the cause of the high-volume emissions or whether it had been stopped. (ABC News: Daniel Mercer)
Louis Goddard, head of research at British climate investigative firm Data Desk, said greenhouse gas levels around the facility were "unusual" and consistent, suggesting an operational issue.
"What we're seeing here is a wasting of gas that they've gone to great lengths to extract in the first place,"
he said.
"[The plumes] are certainly larger than some you'd see from individual oil wells and gas wells for one-off incidents."
Mr Goddard and Data Desk pinpointed the emissions as originating from or near Gorgon’s acid gas removal units, which strip impurities from natural gas.
Chevron did not respond to specific questions about the cause of the plumes or if they had been stopped.
University of Western Australia chemical engineering program chair Bruce Norris said closer measurements were needed.
He estimated, based on the five satellite observations, a few thousand tonnes of methane could have been leaked over the course of a year.
For comparison, an ABC investigation revealed that a Santos LNG tank at its Darwin plant had leaked an average of 832 tonnes every year for more than a decade.
"Any one event is generally not extremely significant, but in aggregate, it's more about how all the different companies and how the government are coming together to try and make these measurements," Dr Norris said.