On the role of methane in EPA's draft rule on carbon emissions

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Process of mixing water with fracking fluids to be injected into the ground (Wikimedia Commons)

Process of mixing water with fracking fluids to be injected into the ground (Wikimedia Commons)

The proposed rule on carbon emissions from existing electric power plants released by the Environmental Protection Agency for public comment on June 2 "has a fundamental flaw," according to Prof. Robert Howarth at Cornell University. "It addresses only carbon dioxide emissions, and not emissions of methane, another critically important greenhouse gas." Howarth, who has published research papers raising concerns about methane emissions from natural gas systems, says the EPA plan "should be revised to reflect the importance of methane and the extent of methane emissions from using natural gas."

In our public review comments to the State Department last year on the Sixth U.S. Climate Action Report to the UN Framework Convention on Climate Change, we said CAR-6 lacked a long-term strategy and noted that it did not set post-2020 emissions reductions goals "nor discuss the effects of near-term actions, such as promoting the rapid expansion of natural gas use, that may undermine longer-term efforts to curb emissions and phase out fossil fuels." We said "The administration's promotion of expanded natural gas fracking raises concerns about whether it will carry out an impartial assessment of the implications and risks."

In our comments to the State Department, we noted that the IPCC Fifth Assessment Report (AR5), released in 2013, increased the estimated "Global Warming Potential" of methane in comparison to earlier estimates. The global warming consequences of different gases are based on their concentrations in the atmosphere and the Global Warming Potential (GWP) of each gas relative to CO2. According to AR5, the 100-year GWP for methane without climate-carbon feedbacks is 28 and with those feedbacks it is 34.

In addition, we noted that using a 100-year GWP discounts the near-term impacts of methane. The 20-year GWP for methane with climate-carbon feedbacks is 86, compared to the GWP of 1 for CO2. This adds to concerns about fugitive methane emissions that would erode the advantage of natural gas versus coal.

Now, a Statement on EPA Draft Plan Released June 2, 2014 on “Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units” posted on June 7 by Prof. Robert W. Howarth, The David R. Atkinson Professor of Ecology & Environmental Biology at Cornell University, leads with this:

There is much to commend in the Plan’s goals to reduce carbon dioxide emissions and to promote more production of electricity by renewable sources and more efficient end use of electricity. However, the Plan has a fundamental flaw: it addresses only carbon dioxide emissions, and not emissions of methane, another critically important greenhouse gas. This failure to consider methane causes the Plan to promote a very poor policy – replacing coal-burning power plants with plants run on natural gas (see pages 33-34) – as one of the major four building blocks of the Plan. Recent research indicates that the greenhouse gas footprint of generating electricity from natural gas can exceed that of coal-fired plants (Alvarez et al. 2012; Howarth et al. 2014 and references therein). The Plan should be revised to reflect the importance of methane and the extent of methane emissions from using natural gas.

Howarth discusses the significance of methane's radiative forcing on near-term timescales:

Because the short-term dynamics of the climate system are far more responsive to methane than to carbon dioxide (UNEP/WMO 2011; Shindell et al. 2012), comparing methane and carbon dioxide on shorter time scales is essential if we are to avoid warming the Earth to temperatures that greatly increase the risk of tipping points in the climate over the coming 15 to 35 years (see Howarth et al. 2014 and references therein). At these shorter time scales, the IPCC (2013) states that the global emissions of methane are actually greater than (slightly, for the 10-year time frame) or 80% of (for the 20-year time frame) those of carbon dioxide in terms of their influence on global warming; at both of these shorter time scales, carbon dioxide is responsible for less than half of global GHG emissions, not three-quarters.

Howarth notes that "the Plan seems to limit the focus to emissions at electric-power generating plants rather than include full life-cycle emissions." He notes the current controversy over estimates of methane emissions from the natural gas industry, in which his published research has played a significant role:

Also, the best available evidence indicates that the EPA estimates for methane emissions in the US are much too low (Miller et al. 2013; Brandt et al. 2014; Howarth et al. 2014). EPA aggravated this by reducing their methane emissions for the natural gas industry by a factor of two in 2013, despite increasing evidence that their estimates were already too low (Miller et al. 2013; Brandt et al. 2014; Howarth et al. 2014). The Inspector General for the EPA has called for an improved approach by EPA for estimating methane emissions from the oil and gas industry (U.S. Environmental Protection Agency Office of Inspector General 2013).

There are complex, unresolved scientific and technical questions about the contribution of the natural gas system to global warming. EPA's proposed rule on limiting carbon emissions from power plants, and the Obama Climate Action Plan as a whole, need a serious critical analysis of whether the methane problem is being appropriately dealt with in administration policy -- or whether ExxonMobil, Chesapeake Energy, BP, ConocoPhillips, and other top U.S. natural gas producers need tougher regulation on limiting emissions.

See also:

Joe Romm at Climate Progress: Bridge Or Gangplank? Study Finds Methane Leakage From Gas Fields High Enough To Gut Climate Benefit

Gaius Publius at AmericaBlog: Did the “Clean Natural Gas” (methane) lobby help write EPA “Clean Power Plan”?

Nick Cunningham at Real Clear Energy: Obama's Climate Plan Is Leaking Methane

Earlier posts:

Should EPA’s proposed carbon pollution rule be tougher? (June 4)

Leaked EPA draft fracking guidance raises water contamination concerns

Internal EPA report shows division over fracking contamination study

Fracking Boom Spews Toxic Air Emissions on Texas Residents

Texas Officials Turn Blind Eye to Fracking Industry's Toxic Air Emissions

Review comments on CAR-6: U.S. Climate Action Report draft lacks long-term strategy

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2 Responses to On the role of methane in EPA's draft rule on carbon emissions

  1. alchemist from bristol says:

    "Methane isn't the main culprit behind long-term warming. It stays in the atmosphere for a decade, whereas carbon dioxide can remain for hundreds of years."

    • I don't think we have ten years. Plus, as the earth warms and we switch to natural gas, more methane will be added to the atmosphere from fugitive and area sources, like permafrost melting. With this additional methane, we'll just have continuous ten year cycles.

      In defense of the emissions plan, the issue is combustion and point sources of greenhouse gases. Basically the stack of a power plant. EPA's plan didn't go into life cycle GHG generation. Methane emissions we're adding are mostly fugitive.

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