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Methane and the greenhouse-gas footprint of natural gas from shale formations

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In the quest to find solutions to the problem of greenhouse gas (GHG) emissions and climate change, many have pointed to natural gas as a cleaner burning fuel that could displace dirtier fuels such as coal or oil and help the world transition to alternative sources of energy. However, recent research has focused on the more intensive, “unconventional” industrial process that is being used to extract natural gas from shale formations — called hydraulic fracturing, or “hydrofracking” — and the waste gas that seeps out.

A 2011 study by Cornell University published in Climatic Change, “Methane and the Greenhouse-gas Footprint of Natural Gas from Shale Formations,” calculates the climate impact of unconventional natural gas extraction. Though carbon dioxide is the best known of the GHG that trap heat in the Earth’s atmosphere, methane gas can have an even more powerful effect.

The study’s findings include:

  • Between 3.6 and 7.9% of the methane escapes into the atmosphere during shale-gas production due to venting and well leaks; this level is at least 30% higher than that released during conventional natural gas production.
  • On a 20-year time horizon, the GHG footprint for shale gas is up to 43% higher than conventional natural gas, 50% greater than oil and 20% higher than coal for the same amount of energy produced by each of those other sources.

The researchers conclude that 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.” The study’s authors encourage policymakers to account for the full GHG footprint of unconventional gas as they chart the energy future and urge carbon trading markets, which currently have outdated models, to modify their valuations accordingly.

Tags: carbon, coal, fossil fuels, global warming, greenhouse gases, fracking

    Writer: | Last updated: May 5, 2011

    Citation: Howarth, Robert, W.; et al.“Methane and the Greenhouse-gas Footprint of Natural Gas from Shale Formations,” Climatic Change, June 2011, Vol. 106, Issue 4, 679-690.DOI: 10.1007/s10584-011-0061-5

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    Analysis assignments

    Read the issue-related ABC News story "Is Natural Gas a Cleaner Alternative Energy or a Danger to Communities?"

    1. If you were to rewrite the article based on knowledge of the study, what key changes would you make?

    Read the full Climate Change journal study "Methane and the Greenhouse-Gas Footprint of Natural Gas from Shale Formations."

    1. Summarize the study in fewer than 40 words.
    2. Express the study's key term(s) in language a lay audience can understand.
    3. Evaluate the study's limitations. (For example: Do the results conflict with those of other reliable studies? Are there weaknesses in the study's data or research design?)

    Newswriting assignments

    1. Write a lead (or headline or nut graph) based on the study.
    2. Spend 60 minutes exploring the issue by accessing sources of information other than the study. Write a lead (or headline or nut graph) based on the study but informed by the new information. Does the new information significantly change what one would write based on the study alone?
    3. Interview two sources with a stake in or knowledge of the issue. Be prepared to provide them with a short summary of the study in order to get their response to it. Write a 400-word article about the study incorporating material from the interviews.
    4. Spend additional time exploring the issue and then write a 1,200-word background article, focusing on major aspects of the issue.