Aliso Canyon methane leak emissions sky-high, pilot scientist found

January 8, 2016
Aerial image of Aliso Canyon natural gas storage facility shot by UC Davis scientist Stephen Conley from his research airplane, which provided the first and, so far, only estimates of methane emissions from an ongoing leak at the facility in the San Fernando Valley. Credit: Stephen Conley/UC Davis photo

A UC Davis scientist flying in a pollution-detecting airplane provided the first, and so far only, estimates of methane emissions spewing from the Aliso Canyon Natural Gas Storage Facility in Southern California since the leak began on Oct. 23, 2015.

Those estimates were provided to the California Air Resources Board in November. Pilot and UC Davis project scientist Stephen Conley continues to measure emissions from the still uncontrolled leak, which has displaced thousands of residents in the affluent Porter Ranch neighborhood in northern Los Angeles. On Jan. 6, Gov. Jerry Brown declared a state of emergency in the community.

To date, Conley estimates that the leak has emitted nearly 80,000 tons of , or about 1,000 tons per day.

'This is big'

In early November, Conley took his first three flights downwind of the facility in his specialized airplane. He was astounded by the figure he recorded: Roughly 1,200 tons of leaked methane per day, or more than 100,000 pounds an hour.

"To put this into perspective, the leak effectively doubles the emission rate for the entire Los Angeles Basin," Conley said. "On a global scale, this is big."

The California Energy Commission contracted with Conley to do the initial flights under an existing contract with UC Davis. The airplane belongs to Conley through his private business, Scientific Aviation, a research flight company.

Those flights took place Nov. 7 and Nov. 10. Emissions were mapped from as low as 200 feet above the ground to the top of the methane plume.

Not just any airplane

The terrain of the facility is choppy and inaccessible at points for ground vehicles, and even satellites are limited in being able to pinpoint the levels of emissions escaping from the source. Measuring the emissions from the air proved an ideal method to get a reliable estimate.

"We have a fully equipped airplane, and this work is perfectly suited for it," Conley said.

It's not just any airplane. Aboard the aircraft is a greenhouse gas analyzer that measures methane plumes in real time. A differential GPS system provides precise wind readings, which is vital for quantifying sources of greenhouse gases, including methane.

The most recent flight was Dec. 23, when Conley recorded approximately 30 tons, or 60,000 pounds, of methane per hour.


Methane is a powerful greenhouse gas and roughly 25 times more potent than carbon dioxide. Porter Ranch residents downwind from the plume have complained of headaches, nausea, dizziness and nosebleeds.

Southern California Gas Co., which owns the Aliso Canyon storage facility, announced in late December that it does not expect crews to plug the leak until at least late February or March.

The Aliso Canyon facility is the largest underground methane storage facility in the western United States.

Explore further: California gas leak forces relocation of thousands since October

Related Stories

Pollution-detecting aircraft hunts for gas leaks

November 28, 2012

(—University of California, Davis, atmospheric scientist Stephen Conley is flying over the spine of California, tracing 600 miles of Pacific Gas and Electric Co.'s natural gas pipeline for methane leaks. Specialized ...

Advanced new camera can measure greenhouse gases

November 30, 2015

A camera so advanced that it can photograph and film methane in the air around us is now presented by a team of researchers from Linköping and Stockholm Universities. It can be an important part of the efforts to measure ...

Recommended for you

New Amazon threat? Deforestation from mining

October 18, 2017

Sprawling mining operations in Brazil are destroying much more of the iconic Amazon forest than previously thought, says the first comprehensive study of mining deforestation in the world's largest tropical rainforest.

Scientists determine source of world's largest mud eruption

October 17, 2017

On May 29, 2006, mud started erupting from several sites on the Indonesian island of Java. Boiling mud, water, rocks and gas poured from newly-created vents in the ground, burying entire towns and compelling many Indonesians ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.