Shale Gas - Energy and Climate Change Contents


Memorandum submitted by the World Coal Association

1.  Given the recent increase in shale gas extraction in the United States and the subsequent deliberations on shale gas development in other countries, including the UK, the World Coal Association (WCA) welcomes the call for written evidence for the forthcoming inquiry into shale gas, launched by the Energy and Climate Change Committee.

2.  As a non-profit, non-governmental industry association working internationally on behalf of the world's major coal producers and stakeholders, WCA follows closely the work of energy research institutes and other international organisations. It is as an association analysing and disseminating information on energy-related issues that we would like to contribute to this public inquiry.

3.  In this response, the WCA has sought to address one of the four questions posed in the Energy and Climate Change Committee's call for written evidence:

  • How does the carbon footprint of shale gas compare to other fossil fuels?

Academic studies and other documents referred to in this response are available in the annex to this document.

POSSIBLE GREENHOUSE FOOTPRINT OF NATURAL GAS FROM SHALE GAS FORMATIONS

4.  The carbon footprint of coal extraction and coal combustion is now well documented. However, due to the recent character of large scale shale gas extraction in the USA, the overall greenhouse footprint of the so called shale gas, including direct and indirect emissions of both CO2 and methane, is not yet fully understood.

5.  An assessment of greenhouse footprint of natural gas from shale formations obtained by high-volume, slick-water hydraulic fracturing, undertaken by professor of Ecology & Environmental Biology at Cornell University, Robert W. Howarth, indicates that high volume slick-water hydraulic fracturing, an extraction method which, combined with horizontal drilling techniques, allowed a substantial increase in shale gas extraction productivity in the USA, might substantially increase the overall greenhouse footprint of natural gas extracted from shale formations (Annex I and II) This is mainly due to potential leakages of methane gas which, according to the IPCC, is a greenhouse gas 72 times more powerful than CO2 during the first 20 years after its release (Annex III).

6.  This would make the overall greenhouse footprint of shale gas similar to the one of coal at a low end estimate and substantially greater at a high end estimate. In fact, in the light of this study, it seems important to consider the overall greenhouse gas footprint of shale gas, as opposed to a carbon footprint which takes account exclusively of CO2 emissions.

THE IMPORTANCE OF A FULL GREENHOUSE FOOTPRINT APPROACH IN THE CONTEXT OF THE CURRENT POLICY CONTEXT

7.  We encourage the Energy and Climate Change Committee to investigate the possible greenhouse footprint of shale gas before further encouraging the development of shale gas extraction in the UK and to take account of its findings when considering the introduction of an Emission Performance Standard (EPS).

8.  Given the current increase in natural gas consumption in the UK, as stimulated by the EU Emissions Trading Scheme and by parallel environmental policies and owing to the fact that more investors are now considering shale gas extraction on UK territory, it is important that the greenhouse footprint of natural gas from shale formations is more understood.

9.  This is especially important in the light of a possible introduction of an Emission Performance Standard, considered by the current government. In fact, if introduced, an EPS will likely take account of CO2 emissions associated with the combustion process of natural gas and coal. As a result, there is a potential that other greenhouse gas emissions at the extraction stage could be ignored. This could lead to shifts in the UK's energy mix which might produce unintended and adverse environmental effects to the ones desired.

10.  In fact, in the USA, where shale gas extraction is most developed, National Academy of Sciences and the Council of Scientific Presidents have called for caution before proceeding with further development of the unconventional technology of natural gas extraction.

11.  The WCA hopes that this response to the Energy and Climate Change Committee's call for written evidence will encourage further investigation of the overall greenhouse gas footprint of natural gas obtained from shale formations and will contribute to stimulating an informed debate about the possible environmental impacts of shale gas.

December 2010

Annex I

Howart, R W Preliminary assessment of the greenhouse gas emissions from natural gas obtained by hydraulic fracturing, Department of Ecology and Evolutionary Biology, Cornell University, 1 April 2010

CORNELL UNIVERSITY

Department of Ecology and Evolutionary Biology

Preliminary Assessment of the Greenhouse Gas Emissions from Natural Gas obtained by Hydraulic Fracturing

Robert W Howarth

David R Atkinson Professor of Ecology & Environmental Biology, Cornell University (1 April 2010 Draft)

Natural gas is being widely advertised and promoted as a clean burning fuel that produces less greenhouse gas emissions than coal when burned. While it is true that less carbon dioxide is emitted from burning natural gas than from burning coal per unit of energy generated, the combustion emissions are only part of story and the comparison is quite misleading. A complete consideration of all emissions from using natural gas seems likely to make natural gas far less attractive than oil and not significantly better than coal in terms of the consequences for global warming.

There is an urgent need for a comprehensive assessment of the full range of emission of greenhouse gases from using natural gas obtained by high-volume, slick water hydraulic fracturing (HVSWHF, or "hydrofracking"). I am aware of no such analysis that is publicly available. Some information suggests that one or more assessments may have been conducted by industry groups, but if so these are available only to industry on a confidential basis. If such assessments exist, they have not been subjected to external, unbiased scientific review.

A first attempt at comparing the total emissions of greenhouse gas emissions from HVWWHF obtained natural gas suggests that they are 2.4-fold greater than are the emissions just from the combustion of the natural gas. This estimate is highly uncertain, but is likely conservative, with true emissions being even greater. When the total emissions of greenhouse gases are considered, Greenhouse gas emissions from HVSWHF-obtained natural gas are estimated to be 60% more than for diesel fuel and gasoline. HVSWHF-obtained natural gas and coal from mountain-top removal probably have similar releases. These numbers should be treated with caution. Nonetheless, until better estimates are generated and rigorously reviewed, society should be wary of claims that natural gas is a desirable fuel in terms of the consequences on global warming. Far better would be to rapidly move towards an economy based on renewable fuels. Recent studies indicate the U.S. and the world could rely 100% on such green energy sources within 20 years if we dedicate ourselves to that course. See Jacobson & Delucchi (2009) A Path to Sustainable Energy by 2030, Scientific American 301: 58-65.

Presentation of assumptions and uncertainties behind estimates:

Considering the release during combustion alone, greenhouse gas emissions from burning natural gas average 13.7 g C of CO2 per million joules of energy compared to 18.6 for gasoline, 18.9 for diesel fuel, and 24.0 for bituminous coal (U. S. Department of Energy: http://www.eia.doe.gov/oiaf/1605/coefficients.html). Additional emissions of greenhouse gas occur during the development, processing, and transport of natural gas (due to the use of fossil fuels to build pipelines, truck water, drill wells, make the compounds used in drilling and fracturing, and treat wastes, and the loss of carbon-trapping forests). I am aware of no rigorous estimate for these additional greenhouse gas emissions, but they appear likely to equal at least one third of those released during combustion (4.5 g C of CO2 per million joules of energy). For comparison, the greenhouse gas emissions from obtaining, processing, and transporting diesel fuel and gasoline are in the range of 8% (Howarth et al. 2009: http://cip.cornell.edu/biofuels/), or perhaps 1.5 g C of CO2 per million joules of energy. Note that as fossil fuel energy resources become more diffuse and difficult to obtain (as is gas in the Marcellus Shale), the energy needed to extract them and the greenhouse gas emissions associated with this effort go up substantially.

The leakage of methane gas during production, transport, processing, and use of natural gas is probably a far more important consideration. Methane is by the far the major component of natural gas, and it is a powerful greenhouse gas: 72-times more powerful than is CO2 per molecule in the atmosphere (Table 2.14 in the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4), Climate Change 2007: The Physical Science Basis. http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_wg1_report_the_physical_science_basis.htm ). Note that this comparison of the global warming potential of methane with CO2 is based on a 20-year assessment time; the factor decreases to 25-fold for an 100-year assessment time. The shorter time with the higher relative global warming potential is the appropriate one, if one is concerned about the effects of methane during the time a natural gas field is developed, and for the few decades after production in the field ends. Since methane is such a powerful greenhouse gas, even small leakages of natural gas to the atmosphere have very large consequences on global warming.

The most recent data I could find for the US (from 2006) suggest a leakage rate from the oil and gas industry of an amount of methane equal to 1.5% of the natural gas consumed (based on leakage data reported in EPA (2008) Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990 - 2006 and consumption data from the U.S. Department of Energy: http://www.eia.doe.gov/pub/oil_gas/natural_gas/data_publications/natural_gas_monthly/current/pdf/table_02.pdf). This leakage rate is roughly equal to that estimated by the EPA in 1997 (http://p2pays.net/ref/07/06348.pdf). However, as noted by Andrew Revkin in the New York Times in October 2009, the actual leakage is not well known, as monitoring is quite limited, and "government scientists and some industry officials caution that the real figure is actually higher" (http://www.nytimes.com/2009/10/15/business/energyenvironment/15degrees.html?_r=2&scp=1&sq=natural%20gas%20leaks%20tanks&st=cse).

If we assume a 1.5% leakage rate, this would have a greenhouse gas warming potential equal to 14.8 g C of CO2 per million joules of energy. This would be additive to the emissions during combustion (13.7 g C of CO2 per million joules of energy) and to the emissions associated with obtaining and transporting the natural gas (very roughly estimated above as 4.5 g C of CO2 per million joules of energy). Total greenhouse gas emissions from natural gas from hydraulic fracturing may, therefore, be equivalent to 33 g C of CO2 per million joules of energy. For diesel fuel or gasoline, the total greenhouse gas emissions are equivalent to approximately 20.3 g C of CO2 per million joules of energy.

The comparison with coal is difficult, as the energy needs and greenhouse gas emissions from mining and transporting the coal are not well known. As a first cut, it may make sense to assume that these are roughly equal to those for obtaining shale gas. Some methane leakage also occurs when mining coal, but the amount varies greatly with the type and location of the coal and the mining technology used. A preliminary assessment suggests methane leakage is less than for natural gas. If so, total emissions from coal are probably quite similar to those for natural gas obtained from shale formations such as the Marcellus Shale.

Annex II

Howart, R W Assessment of the greenhouse gas footprint of natural gas from shale formations obtained by high-volume, slick-water hydraulic fracturing, Department of Ecology and Evolutionary Biology, Cornell University, 15 November 2010

CORNELL UNIVERSITY

Department of Ecology and Evolutionary Biology

Assessment of the Greenhouse Gas Footprint of Natural Gas from Shale Formations Obtained by High-Volume, Slick-Water Hydraulic Fracturing Robert W. Howarth

David R Atkinson Professor of Ecology & Environmental Biology, Cornell University (15 November 2010)

Natural gas is widely advertised and promoted as a clean burning fuel that produces less greenhouse gas emissions than coal when burned. While it is true that less carbon dioxide is emitted from burning natural gas than from burning coal per unit of energy generated, the combustion emissions are only part of story and the comparison is quite misleading. With funding from the Park Foundation, my colleagues Renee Santoro, Tony Ingraffea, and I have assessed the likely footprint from natural gas in comparison to coal. We have now submitted a manuscript for publication in a peer-reviewed journal. A summary figure from the submission is shown here. Please note this should be treated tentatively, as changes or refinements in response to reviewer comments are likely. We nonetheless post the update now due to the tremendous interest in the topic, and its importance in deciding the wisdom of viewing natural gas as a transitional fuel over the coming decades, with a lower greenhouse gas footprint than coal. The figure illustrates a comparison using a 20-year horizon for the relative importance of methane and carbon dioxide.

We urge caution in viewing natural gas as good fuel choice for the future. Using the best available science, we conclude that natural gas is no better than coal and may in fact be worse than coal in terms of its greenhouse gas footprint when evaluated over the time course of the next several decades. Note that both the National Academy of Sciences and the Council of Scientific Society Presidents have urged great caution before proceeding with the development of diffuse natural gas from shale formations using unconventional technology. See: National Research Council (2009). Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use. National Academy of Sciences Press; and Letter to President Obama and senior administration officials, 4 May 2009, from the Council of Scientific Society Presidents. http://www.eeb.cornell.edu/howarth/CCSP%20letter%20on%20energy%20&%20environment.pdf

Annex III

Lifetimes, radiative efficiencies and direct global warming potential relative to CO2, source: Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007, page 212.




 
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Prepared 23 May 2011