Methane Emissions in Colorado Exceed EPA Estimates; Fracking?

by Emil Morhardt

Colorado’s north Front Range, north of Denver and east of Boulder and Fort Collins has become a frackers’ paradise, with 24,000 active wells in 2012, 10,000 of them drilled since 2005. In the hot muggy summers, volatile organic compounds, including methane, ethane, propane, butane, pentane, and sometimes the carcinogen, benzene (all commonly found in oil and natural gas, O&G) accumulate in the air, leading to elevated ozone levels, and contributing to global warming. Previous estimates of the total amounts released were based on a combination of bottom-up estimates of releases from various sources based on a variety of sampling methods, as well as air samples from tower sampling stations. Extrapolating these to the whole O&G area carries all of the uncertainty associated with each of these estimates. In order to get a top-down, fully integrated estimate, Pétron et al., research scientists at NOAA, sampled the area from an airplane equipped with an instrument that continuously recorded methane, carbon dioxide, and carbon monoxide concentrations, and was also capable of taking discreet air samples for measuring other volatile organic compounds typically released from O&G operations. They found that the concentrations of most volatile organic compounds were twice as high, and that of benzene was seven times as high as previously estimated by the state of Colorado, and the hourly emissions rate was three times as high as estimated by the USEPA. The bottom line is that a lot more methane and other volatile organic carbons being released from the O&G operations than was previously thought.

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Unexpectedly High Methane Concentrations over Shale Gas Fields

by Emil Morhardt

Methane, the main constituent of natural gas (both that from gas wells and from farm operations) is a powerful greenhouse gas, around 30 times more potent than CO2 over the hundred years after it is emitted. It is on the rise, and the culprit might be shale gas development, which utilizes hydraulic fracturing (fracking). Caulton et al. (2014) used an airplane to sample the air above a 2,800-square-kilometer area of the Marcellus shale formation gas fields in Pennsylvania. It was rich in methane, with between 2 and 15 grams heading skyward over each square kilometer every second, the upper limit of which is quite a lot higher than the 5 grams estimated from what was previously known about wellhead methane emissions; the authors suspected that the transient nature of gas leakage might be the reason, making very difficult to come up with an average over time from ground-level measurements. Since they were in an airplane, however, they could circle around areas of high concentrations and pinpoint the source. It turns out that…

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