Natural gas has been hyped as a cleaner replacement for coal and oil, a "bridge" between these fossil fuels and renewable energy. But a new Cornell University study has found that extracting natural gas from shale is such a large contributor of greenhouse gas emissions that it defeats the purpose—to provide a cleaner alternative—its proponents have claimed for it.
Based on an analysis of the methane that leaks from shale gas wells, the study concludes that using more gas would make climate change worse—not better.
Footprint Exceeds That of Oil or Coal
The authors write in the study, which will be published in Climatic Change: “The large GHG footprint of shale gas undercuts the logic of its use as a bridging fuel over coming decades, if the goal is to reduce global warming.”
They also say: "The GHG footprint of shale gas also exceeds that of oil or coal when considered at decadal time scales, no matter how the gas is used.
A press release for the study explains more:
The natural gas industry already accounts for almost a fifth (17 percent) of the total U.S. greenhouse gas emissions inventory, when analyzed using recently available new evidence. This percentage is predicted to grow to almost one quarter (23 percent) as shale gas continues to replace conventional natural gas.
AP sums up the significance of this study and the ongoing debate around natural gas:
The U.S. Energy Information Administration projects that unconventional gas, mainly from shale, will supply nearly half of U.S. gas production by 2035. One benefit of tapping shale gas reserves like the Marcellus Shale beneath southern New York, Pennsylvania, Ohio and West Virginia, is the belief it produces less greenhouse gas than coal.
Opponents of shale development cite potential damage to health and the environment from hydraulic fracturing, or "fracking," which injects a well with chemically treated water to stimulate production. They also have seized on the greenhouse gas study published by Cornell's Robert Howarth in the journal Climatic Change last spring.
In that study, and in a follow-up released on Thursday, Howarth said methane leakage at the well, along aging pipelines and at other points give shale gas development a worse greenhouse gas footprint than that of coal. He estimated that as much as 8 percent of methane from shale gas production escapes into the atmosphere, where it is a far more potent greenhouse gas than carbon dioxide.