Reducing Methane Leaks

Every part of the natural gas industry infrastructure emits air pollution, including methane. Methane leaks are easy to ignore because they aren’t visible to the naked eye. Fortunately, some of the most significant sources of air pollution in natural gas infrastructure can be fixed with currently existing technologies and practices.

One major source of air pollution is pneumatic devices, which are used throughout the natural gas supply chain. Pneumatic devices often use gas pressure to perform mechanical functions. By design, most pneumatic devices “bleed” or leak gas when used, but all can be replaced by no-bleed instrument air or electric devices. The reliability and cost-effectiveness of zero-bleed technologies have been well established. Improvements in battery technology and the drop in prices for solar panels have made it economically feasible to use electric pneumatic controllers at well sites without access to grid power. Even in areas with few hours of sunlight solar systems can be used. Solar powered electric pneumatic devices are even used — without backup generators — in northern Canada, in regions that only get 1 to 2 hours of sunlight per day.   

Another significant source of emissions is liquids unloading. During the lifetime of a well, liquids can accumulate in the well and occasionally must be removed. Often, this unloading is done through a “blowdown”, which means that the well is opened so that the gas will push the liquids out. Unsurprisingly, opening a well releases a lot of methane, and potentially toxic pollutants. There are, however, more efficient technologies that operators should adopt for liquids unloading. One technology is a plunger lift, which inserts a tube into the well and separates the gas from the liquids. When this tube is lifted from the well, it removes the liquids. Another is velocity tubing, whereby a tube is placed in the well to decrease the diameter, which causes the liquids to be pushed from the well without emitting methane.

Mandating improved practices works. For example, in 2012 the U.S. Environmental Protection Agency announced that operators will need to adopt  “green completions” practices to flare or capture gas during the completion phase of well development. The decrease in emissions since has been impressive. Data from the Pennsylvania Department of Environmental Protection’s shows that methane pollution from completions went down by over 94%, from 40,000 tons to just 2,200 tons between 2012 and 2014.

By applying up-to-date technologies and best practices, Pennsylvania can cost-effectively cut methane pollution by 40 percent in a relatively short period of time, while supporting Pennsylvania companies that provide methane mitigation technology and services.

 


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