A new study, jointly carried out by Purdue and Cornell universities, shows shale gas wells to emit high levels of the greenhouse gas methane at a stage previously not associated with greenhouse gas emissions.
The new study was one of the few to use a so-called “top down” approach that measures methane gas levels in the air above wells. It identified seven individual well pads with high emission levels during the drilling process; a stage not previously associated with high levels of emissions.
“These findings present a possible weakness in the current methods to inventory methane emissions and the top-down approach clearly represents an important complementary method that could be added to better define the impacts of shale gas development,” said Paul Shepson, a professor of chemistry and earth atmospheric and planetary sciences at Purdue who co-led the study with Jed Sparks, a professor of ecology and evolutionary biology at Cornell. “This small fraction of the total number of wells was contributing a much larger portion of the total emissions in the area, and the emissions for this stage were not represented in the current inventories.”
Methane – the main component of natural gas – is considered to be less harmful than other fossil fuels because when combusted, it produces about 45% less carbon dioxide than coal while producing the same amount of electricity.
However, when released into the atmosphere in it’s free state, over the period of 25 years, the global warming potential of methane is 72 times that of carbon dioxide.
It is widely known that during shale gas exploration, some amount of methane does get released into the atmosphere. This gas is usually flared to turn it into carbon dioxide, which is less harmful to the environment in its free state than methane.
The discovery that methane is released in the initial, as well as the later stages of well completion, further undermines natural gas’ potential as the ‘environmentally friendlier’ fossil fuel.
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