Natural gas from shale contributes to global warming


Texas Barnett Shale gas drilling rig near Alvarado, Texas

Texas Barnett Shale gas drilling rig near Alvarado, Texas

New study demonstrates that shale gas is not the planet-friendly gas it is thought to be

Natural gas extracted from shale formations has a greater greenhouse gas footprint – in the form of methane emissions – than conventional gas, oil and coal over a 20 year period. This calls into question the logic of its use as a climate-friendly alternative to fossil fuels, according to Robert Howarth and colleagues, from Cornell University in New York. Their work (1) is published online in Springer’s journal, Climatic Change Letters (2).

Shale gas* has become an increasingly important source of natural gas in the United States over the past decade. Howarth and team evaluated the greenhouse gas footprint of natural gas, obtained by high-volume hydraulic fracturing of shale formations, focusing on methane emissions. They analyzed the most recently published data – in particular, the technical background document on greenhouse gas emissions from the oil and gas industry (EPA 2010), as well as a report on natural gas losses on federal lands from the General Accountability Office (GAO 2010).

They calculated that, overall, during the life cycle of an average shale-gas well, between four to eight percent of the total production of the well is emitted to the atmosphere as methane, via routine venting and equipment leaks, as well as with flow-back return fluids during drill out following the fracturing of the shale formations. Routine production and downstream methane emissions are also large, but comparable to those of conventional gas.

Methane is a far more potent greenhouse gas than carbon dioxide, but methane also has a 10-fold shorter residence time in the atmosphere. As a result, its effect on global warming falls more rapidly. Methane dominates the greenhouse gas footprint for shale gas on a 20 year horizon, contributing up to three times more than does direct carbon dioxide emission. At this time scale, the footprint for shale gas is at least 20 percent greater than that for coal, and perhaps twice as great.

Robert Howarth concludes: “The large greenhouse gas 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. The full footprint should be used in planning for alternative energy futures that adequately consider global climate change.”

*Shale gas is extracted by a high-volume hydraulic fracturing (fracking) process. Large volumes of water are forced under pressure into the shale to fracture and re-fracture the rock to boost gas flow. A significant amount of water returns to the surface as flow-back within the first few days to weeks after injection and is accompanied by large quantities of methane.

Reference

(1) Howarth RW et al (2011). Methane and greenhouse-gas footprint of natural gas from shale formations. Climatic Change Letters. PDF (Click here) DOI 10.1007/s10584-011-0061-5

(2) Climatic Change Letters is an additional section of the journal Climatic Change.

Contact: Hanna Sigmann, hanna.sigmann@springer.com, 49-622-148-78414, Springer

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One Response to Natural gas from shale contributes to global warming

  1. Alan Burke says:

    Date 16 April 2011, the US House of Representatives Committee on Energy & Commerce release a report on “fracking”:

    Committee Democrats Release New Report Detailing Hydraulic Fracturing Products

    Apr 16, 2011

    Today Energy and Commerce Committee Ranking Member Henry A. Waxman, Natural Resources Committee Ranking Member Edward J. Markey, and Oversight and Investigations Subcommittee Ranking Member Diana DeGette released a new report that summarizes the types, volumes, and chemical contents of the hydraulic fracturing products used by the 14 leading oil and gas service companies. The report contains the first comprehensive national inventory of chemicals used by hydraulic fracturing companies during the drilling process.

    “Hydraulic fracturing has helped to expand natural gas production in the United States, but we must ensure that these new resources don’t come at the expense of public health,” said Rep. Waxman. “This report shows that these companies are injecting millions of gallons of products that contain potentially hazardous chemicals, including known carcinogens. I urge EPA and DOE to make certain that we have strong protections in place to prevent these chemicals from entering drinking water supplies.”

    “With our river ways and drinking water at stake, it’s an absolute necessity that the American public knows what is in these fracking chemicals,” said Rep. Markey. “This report is the most comprehensive look yet at the composition of the chemicals used in the fracking process, and should help the industry, the government, and the American public push for a safer way to extract natural gas.”

    “It is deeply disturbing to discover the content and quantity of toxic chemicals, like benzene and lead, being injected into the ground without the knowledge of the communities whose health could be affected,” said Rep. DeGette. “Of particular concern to me is that we learned that over the four-year period studied, over one and a half million gallons of carcinogens were injected into the ground in Colorado. Many companies were also unable to even identify some of the chemicals they were using in their own activities, unfortunately underscoring that voluntary industry disclosure is not enough to ensure the economic benefits of natural gas production do not come at the cost of our families’ health.”

    During the last Congress, the Committee launched an investigation into the practice of hydraulic fracturing in the United States, asking the leading oil and gas service companies to disclose information on the products used in this process between 2005 and 2009.

    The Democratic Committee staff analyzed the data provided by the companies about their practices, finding that:

    The 14 leading oil and gas service companies used more than 780 million gallons of hydraulic fracturing products, not including water added at the well site. Overall, the companies used more than 2,500 hydraulic fracturing products containing 750 different chemicals and other components.

    The components used in the hydraulic fracturing products ranged from generally harmless and common substances, such as salt and citric acid, to extremely toxic substances, such as benzene and lead. Some companies even used instant coffee and walnut hulls in their fracturing fluids.

    Between 2005 and 2009, the oil and gas service companies used hydraulic fracturing products containing 29 chemicals that are known or possible human carcinogens, regulated under the Safe Drinking Water Act (SDWA) for their risks to human health, or listed as hazardous air pollutants under the Clean Air Act.

    The BTEX compounds – benzene, toluene, xylene, and ethylbenzene – are SDWA contaminants and hazardous air pollutants. Benzene also is a known human carcinogen. The hydraulic fracturing companies injected 11.4 million gallons of products containing at least one BTEX chemical over the five-year period.

    Methanol, which was used in 342 hydraulic fracturing products, was the most widely used chemical between 2005 and 2009. The substance is a hazardous air pollutant and is on the candidate list for potential regulation under SDWA. Isopropyl alcohol, 2-butoxyethanol, and ethylene glycol were the other most widely used chemicals.

    Many of the hydraulic fracturing fluids contain chemical components that are listed as “proprietary” or “trade secret.” The companies used 94 million gallons of 279 products that contained at least one chemical or component that the manufacturers deemed proprietary or a trade secret. In many instances, the oil and gas service companies were unable to identify these “proprietary” chemicals, suggesting that the companies are injecting fluids containing chemicals that they themselves cannot identify.

    Due to an embargo break, the committee is releasing the report this evening iead on Monday morning.
    Related Documents:
    Hydraulic Fracturing Report, April 18, 2011. Download

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