14 April 2011 12:25 [Source: ICIS news]
By Joe Kamalick
WASHINGTON (ICIS)--Academic authors behind a new critique which states shale gas production has a greenhouse gas (GHG) footprint up to 200% greater than coal are full of hot air, ?xml:namespace>
In a paper published this week,
The paper, entitled Methane and the Greenhouse-Gas Footprint of Natural Gas from Shale Formations, says methane is a powerful GHG, thought to have 100 times more warming impact, pound for pound, than carbon dioxide (CO2).
Consequently, the authors argue that even a modest venting of methane from the fracking process could have a far greater impact on global warming than the much higher volumes of CO2 produced by mining and burning coal.
Fracking involves the high-pressure injection of large volumes of water into shale formations to fracture rock, freeing trapped natural gas. Citing a 2010 study by the US Environmental Protection Agency (EPA), Howarth noted a significant amount of water flowed back to the surface days or weeks after injection, accompanied by “large quantities” of methane.
“The amount of methane is far more than could be dissolved in the flow-back fluids, reflecting a mixture of fracture-return fluids and methane gas,” Howarth said.
Drawing on data published by the EPA, The US Department of Energy (DOE) and industry sources, Howarth contended that between 0.6% and 3.2% of the lifetime production of gas from unconventional gas wells, such as those in shale, was emitted as methane during the flow-back period.
Howarth said this, combined with methane venting from wells and during transit of shale gas, meant 3.6% to 7.9% of methane from shale gas production escaped into the atmosphere in venting and leaks during the lifetime of a well.
Using a global warming potential formula, he concluded: “The GHG footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon, but particularly so over 20 years.”
However, Energy in Depth, an industry-supported think tank and advocacy group, challenged Howarth’s assumptions and findings about the amount of lost and unaccounted (LUG) gas in processing and pipeline transmission.
In the report, Howarth said LUG was the difference between measured volume of gas at the wellhead and that purchased and used by consumers, meaning the variance represented leaked gas.
Energy in Depth disputed that conclusion, noting that LUG was an accounting measure that showed how much piped gas was used to power the gathering, processing and compression of the gas in transit, along with removal of inert gases and extraction of liquids.
“LUG gas is not necessarily leaked gas. Howarth bases this entire section of the paper on the notion that natural gas that is considered ‘lost and unaccounted for’ in a pipeline accounting context is natural gas that is simply leaked into the atmosphere, which is an error,” the Energy in Depth analysis said.In the report, Howarth said that compared with coal, the shale gas footprint was at least 20% greater and perhaps more than twice as great on the 20-year horizon. He said the impact of methane was more pronounced than CO2 in the near-term 20-year profile because methane dissipated within 10 to 15 years, while the effect of CO2 was said to last for a century.
“Natural gas is promoted as a bridge fuel over the coming few decades, in part because of its presumed benefit for global warming compared to other fossil fuels,” Howarth noted, adding that the large GHG footprint of shale gas undercut the logic of its use as a bridging fuel over coming decades, if the goal was to reduce global warming.
“The take-home message of our study is that if you do an integration of 20 years following the development of the gas, shale gas is worse than conventional gas and is, in fact, worse than coal and worse than oil,” Howarth said in a Cornell University announcement of the study.
“We are not advocating for more coal or oil, but rather to move to a truly green, renewable future as quickly as possible,” Howarth said, adding that the true environmental consequences of shale gas needed to be looked at.
However, Russell Jones, senior economic advisor at the American Petroleum Institute (API), said that Howarth had admitted that supporting data were faulty and unreliable, while timeframes and formulas were badly distorted and the volume of leaked gas overstated.
“In supporting documents, the authors admit that the data used was of very low quality. This study is really an exercise in selective data and manipulated methodologies used to reach conclusions that deliberately contradict mainstream science,” Jones said.He also questioned the timing of the study’s publication – during congressional hearings that are reviewing fracking and its environmental impact and which could shape
“The timing is suspicious. This study adds confusion that will take a while to sort out and it is harmful to the development of this shale gas resource, which is a major part of
Shale gas resources are estimated to be enough to meet current
As Howarth points out,
The Energy Department, Howarth notes, expects shale gas output to account for 75% of natural gas production growth to 2035, when shale gas will cover 45% of all US domestic gas production.
If fracking were banned, or severely restricted, the impact on
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