Los Angeles Natural Gas Leak Was the Largest Ever in the U.S.

At its peak, the four-month-long rupture emitted enough methane to fill a Rose Bowl-size balloon every day.

Aerial image of the Aliso Canyon natural gas storage facility UC Davis scientist Stephen Conley shot from his airplane, providing the first and so far only estimates of methane emissions from an ongoing leak at the facility in the San Fernando Valley. (Photo: Stephen Conley/UC Davis)

Feb 25, 2016· 3 MIN READ
Taylor Hill is an associate editor at TakePart covering environment and wildlife.

Now that the failed natural gas well in Los Angeles County’s Aliso Canyon has been sealed—112 days after it sprang a leak—the amount of greenhouse gases spewed into the atmosphere can be tallied.

The results are unprecedented.

The blowout was the largest methane leak ever recorded in the United States, according to a study published Thursday in the journal Science.

At its peak, the leak essentially doubled the emissions rate of methane for the entire Los Angeles basin and became the largest known human-caused source of methane in the U.S.—twice as large as the next largest source, an Alabama coal mine.

Immediate impacts from the leak included the evacuation of thousands of residents of the neighboring Porter Ranch community owing to health concerns. The magnitude of the emissions means California could miss hitting its annual greenhouse gas emissions reduction goals.

As a greenhouse gas, methane is a doozy—it’s 80 times more potent than carbon dioxide when it comes to trapping heat in the atmosphere. But in global terms, the Southern California Gas Company leak in Aliso Canyon only represents about .0002 percent of total methane emissions.

“Every molecule of methane in the atmosphere affects climate, but we’re not going to see measurable impacts from this leak,” said Stephen Conley, a University of California, Davis, atmospheric scientist who coauthored the study. “But on a city level, it’s huge. It’s the equivalent of adding the emissions totals of 500,000 to 600,000 cars a year alone.”

The capping of the well doesn’t mean Southern California’s methane problem is solved. Researchers at the University of California, Irvine, found 213 natural gas hot spots in the Los Angeles basin after driving through the region in a van equipped with instruments that measured methane, ethane, carbon monoxide, and carbon dioxide. In a study released this week, the scientists reported that they detected heightened methane emissions at power plants, water treatment facilities, and a truck refueling operation by the Port of Long Beach.

Conley said the Aliso Canyon leak shone a light on the lack of monitoring natural gas operations have.

“It’s important to note that the real-time measurements we got were by accident—there is no program or requirements in place to get these results,” he said.

Conley’s specialty is measuring gas and oil pipeline leaks from the sky. He has a pilot’s license and flies a two-seat airplane, one of only a handful in the nation equipped with sophisticated gear for taking atmospheric measurements.

When the Aliso Canyon leak was detected in October, Conley, 51, was running air patrols over different gas pipelines as part of a trial project for the California Energy Commission.

Commission officials soon asked Conley to start flying over the Aliso Canyon site. His 13 flights over the course of the four-month leak provided data that researchers at the National Oceanic and Atmospheric Administration used to assess the scope of the emissions.

“Our results show how failures of natural gas infrastructure can significantly impact greenhouse gas control efforts,” said NOAA’s Tom Ryerson, a lead author of the study, who pioneered air sampling data collection during the 2010 Deepwater Horizon oil spill.

Conley at Lincoln Regional Airport on Jan. 8. Flying in a pollution-detecting airplane, Conley provided the first estimates of methane emissions spewing from the Southern California leak. (Photo: Joe Proudman/UC Davis)

Data collected from on-the-ground measurements found concentrations of benzene, butanes, pentanes, and other chemicals in the natural gas, which could be responsible for complaints of nausea, dizziness, and headaches from residents.

RELATED: Video Makes Visible California’s Unseen Natural Gas Disaster

Natural gas has long been considered the cleaner fossil fuel. Natural gas power plants emit about half as much greenhouse gas as those that burn coal. But if leaks of natural gas pipelines, storage tanks, and production sites aren’t monitored accurately, it’s hard to determine the true environmental impact of natural gas.

“The gas is considered clean energy, but it really depends on the leak rates,” Conley said.

According to a 2012 study, natural gas power plants are a cleaner alternative for the environment as long as leak rates stay below 3.2 percent. In 2009, the Environmental Protection Agency found a leakage rate of 2.4 percent from natural gas transmission lines.

But with aging infrastructure, pipelines will likely start leaking more, and huge blowouts like Aliso Canyon could happen more frequently. Around 86 percent of natural gas is stockpiled in high-pressure storage tanks just like the Aliso Canyon facility.

Steve Hamburg, chief scientist at the Environmental Defense Fund, said locating and understanding why and how leaks occur is key to limiting those emissions. His team is reviewing 16 peer-reviewed studies on methane emissions to determine where problem areas are—from production to home stoves—and how to fix them.

“If you have a better understanding of when leaks occur, you can start preventative maintenance,” Hamburg said. “You can never eliminate things happening, like when something breaks, but if you have better records and observations, you can better anticipate those issues.”

According to a new draft report by the U.S. Environmental Protection Agency, methane emissions from the oil and gas industry are 27 percent higher than earlier estimates. That will make it more difficult to meet the Obama administration’s goal of reducing methane emissions by 40 to 45 percent by 2025.

A visual of these leaks can be seen in a new map—complete with links to more than 180 infrared camera videos—showing oil and gas pollution. The map, created by environmental groups Earthworks and FracTracker Alliance, includes footage of the Aliso Canyon leak, along with similar methane leaks at a well near Longmont, Colorado, and at a pipeline vent in North Dakota’s Bakken shale region.

Click on the dots to find out information on air pollution events in that region. Click on the arrow in the top left corner for a legend, more details, and video footage. (Map: Earthworks)

EPA Administrator Gina McCarthy has advocated for stepped-up voluntary efforts by companies to control emissions levels. But calling for better monitoring and maintenance of natural gas lines and wells is an issue, Conley said.

“We want to blame the big bad utility companies for not fixing our aging infrastructure, but these groups are often publicly owned, and we don’t want to pay for improvements,” he said. “I hope this study gets people looking for better ways to handle our energy needs.”