Spring warmth had just begun to stir some activity in the brown, stubbly fields of North Dakota in mid-May of 2014. Farmers working there saw some unusual activity overhead, as well. A stubby, instrument-packed airplane with a pointy nose and twin engines began making slow, regular passes over the land, as if it was searching for something.
Certainly the area, part of a huge oil and gas field called the Bakken formation, contained things that were worth searching for. It had gone from economic oblivion to the production of over 10 percent of the nation’s oil production in little more than a decade, and natural gas production had shot up with it.
Along with that came an international mystery. Methane, a major global warming gas, is often found with oil. It is the main component of natural gas, but by 2014 there were mounting suspicions that a lot of it was leaking or being vented into the air over the production fields, rather than being shipped off to market.
Airborne methane poses one of the toughest problems for chemists who study the atmosphere. It is difficult to track using conventional analysis because it has what some scientists call a “noisy signal” that makes it hard to identify where it came from. Bacteria can produce it in wetlands, and cows, termites and some forms of agriculture, such as rice production, emit it.
The plane seemingly loitering overhead that May was a De Havilland Twin Otter, part of the aerial fleet of the National Oceanic and Atmospheric Administration. And the scientists who had sent it to patrol the Bakken were developing a new approach to tracking methane. Among other gases, the plane was hunting for ethane, a colorless, odorless gas. It dissipates in a few weeks, but it is a compound that responds to analysis with a crisp signal and is always found with methane in natural gas emissions.
What they found in the skies over the Bakken that May was the equivalent of 1 to 3 percent of the world’s estimated emissions of ethane floating over a relatively tiny place. It was evidence that the Bakken was leaking raw natural gas, including huge amounts of methane, which is 86 times more potent as a global warmer than carbon dioxide during the first nine years of its life. Then it decays into carbon dioxide, which can last for centuries.
The study concluded that the Bakken was leaking methane at a rate of 275,000 tons per year. That meant finding and closing the leaks would have about the same impact on climate change as removing 1.45 million cars from the nation’s highways for a year. The ethane leak, of similar size, was so big that it was detected in Europe.
“This study provides a key snapshot of Bakken methane emissions that will help answer the bigger question: How much methane is the U.S. emitting, where it is coming from and how is that changing over time?” explained Jeff Peischl, a study author and a scientist working at the University of Colorado, Boulder.
Another author involved with the project, Eric Kort, who teaches climate and space science at the University of Michigan, regards it as a valuable new measuring tool. “We need new measurements using different types and different scales,” Kort said.
“I hope we can use it in places that are further away and where we have far less on-the-ground access. To some degree, what we’d like to be able to do is to do this everywhere,” he added, noting that some of the world’s methane leaks are not obvious and need more attention.
The reason they need more attention is another, more ominous and less understood atmospheric mystery. Detlev Helmig, an atmospheric chemist and group leader at the Institute of Arctic and Alpine Research laboratory at the University of Colorado, Boulder, has spent 10 years studying the strange ups and downs of gases in the atmosphere. And human activities appear to be one of the largest factors. As he explains it, carbon dioxide has expanded by about 33 percent since the industrial age began, while methane emissions have risen by 150 percent.
Then, sometime around 1980, ethane’s increase in the atmosphere hit a plateau. “We were very excited,” he recalled. “Human beings have succeeded in curbing emissions of a gas that’s really not good to have in the atmosphere. So we thought this was a success story.”
‘The equivalent of money escaping into the air’
A few years later, newer data appeared and ethane had started to rise again. This time, it was moving up much more sharply. “And if you look at the geographical distribution of data, it’s pretty obvious most of this is driven by large increases in North America,” Helmig said. “That ties in pretty nicely into many observations of oil and gas basins that have been made over the last five years that show extremely high levels of these light hydrocarbons like ethane.”
The timetable coincided with the expanding use of hydraulic fracturing, first used in the United States in 1949. According to the Department of Energy, the practice proliferated in the United States during the last decade, particularly in places like the Bakken, where potential oil and gas deposits were trapped in widespread shale formations, which made conventional drilling techniques unproductive.
But producers found that by injecting water, sand and other chemicals into the formation under hydraulic pressure, they could open thousands of cracks in the shale, releasing the trapped fossil fuels. Horizontal drilling was used to drill down into the field and then turn at a right angle to create what amounts to a sump under the cracked formation where the released oil and gas accumulated and could be collected, then lifted to the surface.
According to the American Petroleum Institute, the size and reach of fracturing can be large. Just one well can extend a mile or more deep to penetrate low-lying shale formations. Then its horizontal portion can extend for more than a mile to collect oil and gas.
DOE estimated that by 2013, at least 2 million oil and gas wells in the United States had been hydraulically fractured. Up to 95 percent of new wells are hydraulically fractured, or fracked, to stimulate more rapid production. The output from these wells makes up 43 percent of the oil production and 67 percent of the natural gas production in the United States, according to the agency.
The resulting boom in American oil and gas production brought the industry around to a staunch defense of the practice. In 2014, the American Petroleum Institute published a pamphlet: “Hydraulic Fracking; Unlocking America’s Natural Gas Resources.” It asserts: “As shown by the research, this well-understood phenomenon represents minimal risk to humans, animals, structures or the environment.”
Helmig, a tall, soft-spoken German whose specialty is studying hydrocarbons, thoroughly disagrees with that. Since 2006, he has worked with NOAA’s air sampling system that uses glass flasks to collect atmospheric samples from 44 different sites around the world to track the annual increase of ethane and other so-called volatile organic compounds in the air.
From his ethane research and other international studies, he learned that there appears to be a much higher ethane source in the earth’s Northern Hemisphere than in the Southern and a higher leak rate in the central United States than in more eastern oil and gas fields, and that some oil and gas fields in the central United States leak at much higher rates than others.
Using ethane as a tracer for fugitive methane emissions, his team found two high-emitting sites in the central United States. One was in the Denver-Julesburg Basin, a large oil and gas production area just east of Boulder, Colo., and the other was in the Uinta Basin in eastern Utah, a rural, semiarid production area.
Uinta had 4,300 oil and 6,900 gas wells in operation, and Helmig used a 20-foot-diameter balloon to hoist his measurement apparatus to 200 yards over the fields. It included three tubes that took air samples at each third of the way up and an automated pump that regularly filled glass flasks with air samples. The data he obtained, he explains, were “beautiful.”
“When the ethane goes up, the methane goes up in the Uinta Basin, which means they’re coming from the same source. You can see the ratios; for this amount of ethane, you get so much methane.”
Other scientists remain unconvinced that the behavior of methane, measured on a global scale, is being primarily influenced by oil and gas production. They use another way of tracking methane samples that involves identifying carbon isotopes associated with its sources.
John Miller, a scientist from NASA’s global monitoring division, says the isotopes found in atmospheric samples point to microbes that create methane in wetlands tropical forests and certain forms of agriculture, such as rice growing. Using this method, global maps tracking spikes of emissions don’t point to oil and gas production in the temperate zones of the Northern Hemisphere. “They suggest a tropical source,” according to Miller.
Some scientists involved in this complex dispute still remain intrigued by the natural gas leak rates found in some U.S. oil and gas fields. A more recent study by NOAA in the Uinta Basin found a leak rate that varied between 8.4 and 15.9 percent.
This raises an economic question. “Natural gas is valuable. It is the equivalent of money escaping into the air. If you are a rancher and you raise cows, you want to keep your cattle. If a fence goes down, you want to fix it. Why doesn’t the oil and gas industry want to fix their fences?” mused one scientist, who asked not to be quoted because the matter was outside his area of expertise.
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. E&E provides daily coverage of essential energy and environmental news at www.eenews.net. Click here for the original story.