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Monday, November 05, 2012
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Shale Gas: A Bridge to Which Climate Future?

By Bruce Ho

If you are familiar with shale gas, you probably have heard the argument that this resource has the potential to be a “bridge” between today’s polluting energy mix and a clean energy future. This argument rests on three basic premises: (1) when burned for energy, shale gas, which is natural gas extracted from shale, emits less carbon dioxide and other air pollutants than either coal or petroleum; (2) there are large, economically-available shale gas resources in the U.S. that could be used to displace a significant portion of the coal used in our power sector and, potentially, the petroleum used for transportation; and (3) for technical, economic, or political reasons, renewable energy and savings from energy efficiency cannot yet provide for all of our energy needs – hence the need for a bridge to get from the coal and petroleum of today to the renewables and energy efficiency of tomorrow.

But while this argument makes at least some sense, significant questions remain. For example, how much cleaner is shale gas than coal and petroleum when you consider the full gas production lifecycle, from hydraulic fracturing (“fracking”) to eventual combustion? Further, even if shale gas is a cleaner fossil fuel, what will be the long-term effect of cheap and abundant gas on the adoption of even cleaner energy efficiency and renewables?

Answering these questions is critical to understanding how shale gas fits into the overall U.S. energy mix. Last month, the Yale Center for Environmental Law and Policy began exploring these issues in the inaugural presentation of the Center’s 2012-2013 Policy Workshop Webinar Series on “Emerging Issues in Shale Gas Development.”

This coming Thursday, November 8 from 12-1pm EST, the Yale Center for Environmental Law and Policy will further explore, through a presentation by Dr. Ramon Alvarez, a senior scientist at the Environmental Defense Fund (EDF), the structural underpinnings of the bridge-to-clean-energy narrative by examining whether shale gas is likely to reduce or only exacerbate climate change. I highly encourage anyone interested in shale gas issues and energy policy more broadly to attend this free online presentation on “What It Takes To Get Sustained Climate Benefits From Natural Gas.” To register for this webinar, click here.

As a preface to Dr. Alvarez’s webinar, I outline below the basic climate case for shale gas as well as two issues that could undermine this case: the possibility that natural gas leakage in the supply chain could, rather than reduce climate change, lead to more global warming; and also the possibility that shale gas might displace cleaner renewable energy and energy efficiency and thus slow the country’s transition away from climate-polluting fossil fuels. Ultimately, understanding these two issues is essential to understanding whether shale gas can be a bridge to a clean energy future or is instead a bridge to nowhere – or worse.

The Basic Climate Case for Shale Gas

Shale gas is not a “clean” fuel. While burning shale gas releases less pollution than coal or petroleum, like any other fossil fuel, burning gas still releases carbon dioxide pollution and contributes to climate change. Moreover, as Yale Professor of Hydrology Jim Saiers discussed in the Center’s first shale gas webinar last month, there are a variety of non-climate related environmental impacts associated with shale gas drilling, including air and water pollution, water usage, and land disturbance. While some of these impacts may be avoidable with proper regulation and industry best practices, some will likely still occur.

Yet the climate case for shale gas does not rely on the total elimination of climate-related impacts. Rather, the climate case is based on the fact that, on a per-unit energy basis, natural gas emits less carbon dioxide than either coal or petroleum (e.g., a kilowatt-hour of electricity generated from natural gas results in less carbon pollution than a kilowatt-hour from coal). Recent data from the U.S. Energy Information Administration (EIA) bear out the potential climate benefits. According to the EIA, natural gas is beginning to displace coal in the power sector, largely as a result of domestic shale gas production. And this shift is at least partly responsible for a decline in carbon pollution from the U.S. energy sector in recent years. (Another significant reason was the recession, which caused total U.S. energy use to fall.) These data support the first two premises of the bridge-to-clean-energy narrative described above. The third premise – that natural gas is needed due to the current limits of renewable energy and energy efficiency – is a matter of debate. But even studies that show that existing clean energy technologies could satisfy U.S. energy needs often acknowledge that this shift is unlikely to occur overnight. Some researchers also argue that fast-starting natural gas power plants can help integrate variable wind and solar energy by helping fill in gaps in renewable generation. If these propositions are true, shale gas could very well help slow the rate of climate change relative to the status quo.

The Unknowns That Could Undermine This Climate Case

The problem is that shale gas’ contributions to climate change are not limited to the carbon dioxide it emits during combustion. Rather, natural gas, which consists primarily of methane, also contributes to climate change when it is released directly to the atmosphere – intentionally or accidentally – without being burned. In fact, methane is itself a potent greenhouse gas, which, in the near-term (20-year time horizon) is more destructive on an individual molecular basis than carbon dioxide by a factor of 50 or more. Carbon dioxide is the main driver of climate change because much more of it is released globally, but if large amounts of methane also “leak” from the shale gas supply chain, the climate impacts of this resource could be significantly higher than the bridge-to-clean-energy narrative assumes.

The current rate of methane leakage from shale gas wells is unknown. According to a study co-authored by Dr. Alvarez in the Proceedings of the National Academy of Sciences, methane leakage estimates range from 2% to more than 7% of total natural gas produced from shale gas wells. Any methane leakage reduces the potential climate benefits of shale gas relative to other fossil fuels. But for shale gas to be less damaging to the climate than coal, the total leakage from gas wells (as achieved through voluntary industry practices or regulatory mandates) would need to be less than 3.2% of the total gas produced. Anything higher than 3.2%, and shale gas could actually accelerate and worsen climate change relative to coal. In comparison to petroleum, which emits less carbon dioxide than coal but more than natural gas, methane leakage rates would need to be even lower to break even.

Further, while methane leakage is a critical issue, it is just one potential way in which shale gas could worsen climate change. If, for example, cheap and abundant shale gas delays the U.S. transition to renewable and more efficient uses of energy, then the net effect regardless of gas’ benefits relative to coal and petroleum might still be to cause more global warming. Of course, as noted earlier, fast-starting natural gas power plants might also help support increased utilization of variable wind and solar energy by being available to operate on short notice should wind or solar production unexpectedly decline (e.g., due to a sudden slowdown in wind velocities or unexpectedly high cloud cover). This is in contrast to coal plants, which can sometimes take days to start generating power. The net climate effect here could be complicated, though the net effect is ultimately what’s important.

Getting to the Bottom Line on Climate

Understanding these unknowns and determining answers is essential to understanding how shale gas fits into the current U.S. energy picture; the types of policies and practices that may be needed to minimize or avoid adverse shale gas impacts; and the role that shale gas may or may not be able to play in helping the U.S. transition to a clean energy economy.

In his presentation on Thursday, Dr. Alvarez will shed additional light on these issues and their complexities as he discusses the frameworks and research needed to ensure that shale gas development, which is already proceeding rapidly, contributes to a more positive rather than a more destructive climate future. In addition to registering to attend this free webinar, you can learn more about Dr. Alvarez’s research by reading his paper in the Proceedings of the National Academy of Sciences as well as his blog. You can also visit EDF’s website to learn more about the organization’s current work on natural gas, including an initiative to measure methane leakage rates from shale gas wells.

Coming up Next in Emerging Issues in Shale Gas Development

As the Emerging Issues in Shale Gas Development webinar series begins to look at specific policy responses to the environmental impacts of shale gas development, I am pleased to announce that the third webinar in this series will feature Florida State University Law Professor Hannah Wiseman, who has written several leading works on the state of U.S. shale gas regulations (e.g., Risk and Response in Fracturing Policy, Fracturing Regulation Applied, and Regulation of Shale Gas Development, Including Hydraulic Fracturing). On Wednesday, December 5, from 3-4pm EST, Professor Wiseman will discuss the current state of U.S. shale gas regulations, regulatory gaps, and ways in which federal, state, and local regulations may need to change. You can register for Professor Wiseman’s webinar on “Understanding and Improving Regulation of Shale Gas Development” by clicking here.

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