I’ve written about natural gas flaring before – the spectacular case of Turkmenistan’s Door to Hell. Flaring is the process through which natural gas that cannot be captured is burned, converting it into carbon dioxide. On a practical level, the practice seems completely counterintuitive. Why would we burn 140 to 150 billion cubic meters of natural gas per year globally when demand clearly exists? Flaring worldwide emits 270 to 290 million tons of carbon dioxide per year – substantially more than just a drop in the bucket.
A satellite image of Texas at night. The large lights represent cities, with San Antonio at the top and Houston at the top right. The band of lights across the middle is all flaring from the Eagle Ford shale (image courtesy Dr. Michael Webber, University of Texas).
The underlying driver of flaring is economics. Natural gas is a cheap commodity with high up-front infrastructure costs. Over time, a large enough gas field will pay for the initial investment required to construct wells, pipelines, and turbines. Where smaller sources are concerned, the resource simply isn’t economically feasible to capture and transport. Sometimes, gas is produced in conjunction with oil; other times, exploration wells might form an outlet for a gas pocket. Unavoidably, gas will find its way from underground formations to the atmosphere.
There are two reasons why natural gas is burned rather than released as is. The first is human safety. While methane itself does not directly pose a health risk, it is both flammable and, in large enough quantities, an asphyxiant (the latter refers to the fact that methane displaces oxygen and thus can lead to suffocation). The second factor is its global warming potential. Methane is more than 20 times more effective than carbon dioxide as a greenhouse gas. The reason CO2 is so often cited as the ‘climate change culprit’ is because much more of it in the atmosphere; however, methane’s high warming potential means that emissions need to be managed effectively.
At the AAAS Science Conference in Chicago, I had a chance to talk to Dr. Michael Webber – an engineering professor at the University of Texas who studies the interactions between water resources and the energy sector. In particular, he has looked at ways to minimize both flaring and water quantity required for shale gas operations. As opposed to conventional gas, which can be easily produced just by drilling a well, shale gas is trapped in small pores that must be hydraulically fractured – cracked using explosive charges and water under high pressure. Hydraulic fracturing uses large volumes of water and produces large quantities of wastewater which must be treated. Dr. Webber suggests that uncaptured gas, which is highest in the initial stages of shale gas operations, can be adapted to produce energy for water treatment onsite. In this win-win scenario, CO2 emissions are minimized and otherwise wasted energy is used to increase water use efficiency. Particularly in states such as Texas, where shale gas is a rapidly growing industry and water resources are scarce, Dr. Webber’s research may play an important role in minimizing the environmental impacts of shale gas production.
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Images from Wikimedia Commons