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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.

Tuesday, July 17, 2012

Forbes comes to the fugitive methane party

With the worst U.S. drought in over half a century fueling long-overdue public concern about climate disruption, an article in Forbes has again raised the persistent question about the impact of shale gas on our rapidly warming climate.  The question was first raised by a study from a Cornell University team; it has since been fairly well debunked at least 8 times, most recently by a colleague at Cornell. However, the original study should be credited with raising an essential question about the impact of fugitive emissions from unconventional gas development.

Industry leaders and the investment community alike say that methane emissions from shale gas development must – and can - be addressed. In April of this year, the U.S. EPA issued new rules requiring capture of methane emissions from gas well completions by 2015 and flaring of methane from new gas wells in the interim. But even with new rules in place, the question is not going away. A recent industry survey claims that the estimate for methane emissions from shale gas that informed EPA’s new rule is too high; that was met with sharp criticism by adherents to and authors of the original Cornell study.  

The fact is, methane leakage from shale gas development is a continuing problem. In addition to capturing methane from well completions and minimizing leaks from equipment and distribution systems, the industry must drive well construction mistakes that result in methane leakage to the absolute minimum. That means performing to the highest engineering and construction standards – every well, every time.