Enormous Methane Leak From Ohio Gas Well Was One of Worst in American History, Satellites Reveal

In February and March 2018, a gas well blowout in Belmont County, Ohio leaked methane—a potent greenhouse gas—into the atmosphere. Now, analysis of satellite data has revealed that the relatively little-known leak was one of the most significant ever to occur in the country.

In a study published in the Proceedings of the National Academy of Sciences, a team of scientists estimated that the gas well—owned by ExxonMobil—leaked around 120 metric tons of methane per hour over a period of 20 days before the company managed to fix the problem. This amounted to a total of more than 50,000 tons of methane.

The authors—led by Sudhanshu Pandey from SRON Netherlands Institute for Space Research—said that the hourly emission rate from the leak was about twice that of the widely reported event at an oil and gas storage facility in Alison Canyon, California, which took place in 2015—the largest known methane leak in the country.

While the emission rate of the Ohio event was higher, the California event lasted longer and produced more emissions overall, The New York Times reported. Nevertheless, the leak at the Belmont County well still released vast amounts of methane into the atmosphere, according to the researchers. In fact, it emitted more of the gas in 20 days than the oil and gas industries of some European nations do in a year.

"Assuming the detected emission represents the average rate for the 20-day blowout period, we find the total methane emission from the well blowout is comparable to one-quarter of the entire state of Ohio's reported annual oil and natural gas methane emission, or, alternatively, a substantial fraction of the annual anthropogenic methane emissions from several European countries," the authors wrote in the study.

The scientists detected the leak using an instrument known as TROPOMI on the recently launched European Space Agency satellite Copernicus Sentinel-5P, which is designed to continuously monitor methane and other pollutants.

"Methane emissions due to accidents in the oil and natural gas sector are very challenging to monitor, and hence are seldom considered in emission inventories and reporting," the authors wrote in the paper. "One of the main reasons is the lack of measurements during such events. Our work demonstrates the strength and effectiveness of routine satellite measurements in detecting and quantifying greenhouse gas emission from unpredictable events."

These satellite measurements could have significant implications given that emissions from the fossil fuel industry are one of the major sources of atmospheric methane. Gas leakages such as these can release large amounts of the gas in relatively short periods of time.

Although carbon dioxide is much abundant in the atmosphere and thus is more commonly associated with global warming, methane is around 30 times more potent as a greenhouse gas. In addition to the fossil fuel industry, the main sources of methane pollution are landfill sites, livestock farming, rice agriculture and wetlands.

methane leak
Data from the Copernicus Sentinel satellite methane measurements. Copernicus Sentinel data, processed by SRON

"The current warming that we are experiencing, one-quarter of it is caused by anthropogenic methane—the additional methane caused by human activity," Steven Hamburg, chief scientist at the Environmental Defense Fund and a co-author of the study, told CNN.

The Ohio incident did not garner much attention at the time, although 100 residents within a 100-mile radius had to be evacuated from their homes while workers attempted to fix the leak. Some of these residents had complained of health issues such as throat irritation, dizziness and breathing problems, Miranda Leppla, head of energy policy at the Ohio Environmental Council, told the Times.

Exxon spokesman, Casey Norton, told the Times that the company's own scientists had analyzed the emissions from the leak and come to a smaller estimate than the one in the latest paper. He said the company was in contact with the researchers to discuss the "discrepancy and see if there's anything we can learn."

"This was an anomaly," he said. "This is not something that happens on any regular basis. And we do our very best to prevent this from ever happening."

In a statement provided to Newsweek, the company said that it deeply regretted the incident and had "instituted systematic well-design and monitoring procedures to prevent it from recurring."

"ExxonMobil continues to work with government laboratories, universities and others to identify the most cost effective and best performing technology, including satellites, that can be adopted by all producers to detect, repair and accurately measure methane," a spokesperson said.

This article was updated to include a statement from ExxonMobil.