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Friday, July 20, 2012

New Cornell natgas study: substituting gas for coal, oil is biggest available climate stabilization tool

In my previous post, I mentioned a new Cornell University study on the impact of natural gas use on climate change.  Here is some additional information.

Assessing the Greenhouse Impact of Natural Gas (math warning) by Cornell Professor Lawrence M. Cathles was published in the most recent edition of the peer-reviewed journal Geochemistry, Geophysics and Geosystems.  The study compares the climate benefits of substituting natural gas energy for all coal and new oil consumption to replacing all coal and new oil with low‐carbon energy sources such as wind, solar, and nuclear.                        

According to a university press release, Cathles’ research received no outside funding. 

Cathles concludes that no matter the timeframe considered, substituting natural gas energy for all coal and new oil consumption provides about 40 percent of the global warming benefit that a complete switch to low-carbon sources would deliver.

Cathles’ study assesses the climate impact of “unconventional” gas drilling methods, including hydraulic fracturing, considering methane leakage and its climate impact compared to that of CO2.  Methane is 25 times more potent as a greenhouse gas than CO2, but falls out of the atmosphere much more quickly than long-lived (100+ years) CO2.  Cathles comes down on the side of leakage rates closer to 1.5 percent for both conventional and hydrofractured wells, and says that:

“even at higher leakage rates, using natural gas as a transition to low-carbon energy sources is still a better policy than “business as usual” with coal and oil, due to the different rates of decay (and hence long-term global warming effect) of CO2 released in greater amounts by burning coal and oil and any methane released during natural gas extraction.”

Cathles also endorses the use of natural gas as a transition fuel to low-carbon sources, and states the obvious:

“From a greenhouse point of view, it would be better to replace coal electrical facilities with nuclear plants, wind farms and solar panels, but replacing them with natural gas stations will be faster, cheaper and achieve 40 percent of the (low-carbon) benefit. Gas is a natural transition fuel that could represent the biggest stabilization wedge available to us….A faster transition to low-carbon energy sources would decrease greenhouse warming further, but the substitution of natural gas for other fossil fuels is equally beneficial in percentage terms no matter how fast the transition.”

Cathles’ study should not be read as an excuse to downplay methane emissions from the production and use of natural gas.  Those emissions must be minimized as quickly as possible. Nor can we lose sight of the rest of the complicated equation of natural gas – the need to ensure responsible production, something that is both possible and profitable.

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