Shale Gas - Energy and Climate Change Committee Contents

6  Carbon Footprint of Shale Gas

149.  During our visit to the US, the Environmental Defense Fund (an NGO) gave us a presentation on greenhouse gas emissions from natural gas. It began by noting that over a 20 year time period, the "global warming potential" (GWP) of methane was 72 times that of carbon dioxide, while over a 100-year timescale it was 21-25 times. This was because methane and carbon dioxide have different lifetimes in the atmosphere. However, the Sierra Club (another NGO) told us that fugitive methane emissions could easily be prevented through regulation and enforcement.

150.  The Environmental Defense Fund also told us that there was uncertainty in the upstream (coal mining, gas production, processing, coal transportation, gas transmission and gas storage) emission estimates that fed into these figures. This was significant, as a larger proportion of gas emissions lie upstream in gas relative to coal. If the upstream emissions (carbon dioxide and methane) were twice as high, draft estimates suggested that gas would be approaching 1134 kg CO2/MWh, with coal at around 1300 kg CO2/MWh. On gas leaks, the break-even gas leak rate (that would make the climate impacts of gas the same as coal over 20 years) could be as low 4-6 %. In addition, methane also acted with aerosol particles (sulphates in the atmosphere) to increase global warming. In the US, 4.2% of gas produced on onshore leases was currently vented to the atmosphere or flared—the US Government Accountability Office estimated 40% of this could be captured economically.

151.  Professor Kevin Anderson, Director of the Tyndall Energy Centre, believed that "if you want to abide by your own commitments under the Low Carbon Transition Plan, the Copenhagen Accord, various EU agreements and so forth […] then there simply is not the emission space available in the timeframe that we have to utilise shale gas".[298]

152.  The British Geological Survey stressed to us that "the overall greenhouse footprint of [...] shale gas, including direct and indirect emissions of both CO2 and methane, is not yet fully understood".[299] According to DECC, the carbon footprint of shale gas "depends on the extraction process and emission management […] [and could] be increased further by fugitive emissions of methane".[300] The Tyndall Centre agreed that "the key difference between the [carbon] footprint for shale gas and conventional gas is the extraction process".[301]

153.  However SSE believed that domestically produced shale gas would have the advantage of not "needing to be processed and transported over vast distances", partially offsetting any carbon emissions from production.[302] Nick Grealy, publisher of the gas-commentary website No Hot Air, added his opinion that it was important to note that natural gas could provide immediate "partial decarbonisation of the electricity sector", while other technologies aim for "full decarbonisation at some point several decades away".[303]

154.  IGas Energy also argued that onshore unconventional gas supplies "offer potential carbon savings relative to gas sourced offshore or from overseas" noting "Russian gas […] has a carbon footprint which is 30% greater than domestically produced gas".[304] The UK currently gets less than 2% of its gas from Russia, and this arrived indirectly.[305] However, about 40% of the EU's total gas imports come from Russia.

155.  WWF believed that "the majority of the world's fossil fuel reserves need to stay in the ground".[306] The Tyndall Centre added that without "a meaningful cap on emissions of global GHGs, the exploitation of shale gas is likely to increase net carbon emissions [...] [however] carbon budgets should ensure that shale gas use in the UK should not add to UK emissions".[307]

156.  The Campaign to Protect Rural England (CPRE) drew attention to evidence from Canada that showed "the majority of existing wells in Quebec leak methane" despite industry claims.[308] According to WWF, a preliminary review of shale gas emissions by Cornell University "suggests that there is approximately a 1.5% methane leakage rate for the oil and gas industry and that therefore emissions from coal may be similar to those from natural gas".[309] The Cornell paper itself stated "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".[310]

157.  Jennifer Banks of the WWF told us: "Shale gas inevitably uses more energy than conventional gas exploration because of the hydraulic fracturing process and the injection of high pressure water into the ground".[311] Professor Kevin Anderson believed "there would be very little difference between [conventional and unconventional gas] when you looked at their overall CO2 emissions once combusted".[312]

158.  Simon Toole of DECC told us that "we have legally binding carbon emission reduction requirements […] [but] under every scenario we have looked at […] oil and gas and hydrocarbons will play a significant role to come for some decades […] That is why we have, for example, said that carbon capture and storage future projects should be looking at gas as well as at coal".[313] He added that "by the 2030s […] we ought to be looking at zero emissions from electricity generation […] but I don't see a way in which we can meet our security of supply obligations and try to keep prices affordable without having hydrocarbons in that mix".[314]

159.  We conclude that in planning to decarbonise the energy sector DECC should generally be cautious in its approach to natural gas (and hence unconventional gases such as shale gas). Although gas emissions are less than coal they are higher than many lower carbon technologies.

Substituting Coal for Gas

160.  WWF believed that "while it makes sense to burn lower carbon fuels such as gas […] this argument is only valid where there is evidence that gas is being used as a direct substitution, not in addition, to coal".[315] They added that any "new 'dash for gas' driven by the shale gas boom could seriously undermine the UK's ability to meet […] [emissions reduction] targets".[316] WWF also noted that "the average emissions from a new CCGT [combined cycle gas turbine] power station are around eight times higher than the CCC's recommended target of 50g CO2/kWh by 2030".[317] Jennifer Banks was concerned that "gas may displace renewable energy".[318]

161.  Professor Anderson pointed out that "[Gas] is very cheap to build at about £350 a kilowatt, much cheaper than renewables, much cheaper than coal, much much cheaper than nuclear". However, he added "we need to make that transition to renewables as a matter of some significant urgency […] any mechanism that takes away the incentives to move towards renewables cannot be a good deal […] there simply is not the emissions space available in the timeframe that we have to utilise shale gas".[319] It was the Tyndall Centre's opinion that "shale gas would still only be a low-carbon fuel source if allied with, as yet unproven, carbon capture and storage [CCS] technologies".[320]

162.  The Tyndall Centre, however, found there was "little evidence […] that shale gas is currently or expected to, substitute, at any significant level for coal [in the US]".[321] They pointed out that in the International Energy Agency "Blue Map Scenario"—which leads to a 50% reduction in global emissions by 2050—"power generation and fuel switching [coal to gas, for example] accounts for only 5% of required emission reductions".[322] Professor Selley of Imperial College believed that "shale gas may however be a temporary stop gap […] until replaced by nuclear or renewable energy sources".[323] However, the Geological Society's Jonathan Craig told us that the "US are very much looking at using natural gas […] to reduce their dependence on coal […] in order to cut their carbon emissions […] [gas] need to make a contribution [to emissions] in the UK as well".[324]

163.  The Minister told us that it was not DECC's expectation that "shale gas in the United Kingdom would lead to a greater use of gas, but it would lead to a replacement of import […] we are not expecting to see this lead to a surge of extra gas plants". Q 300

164.  Shale gas could lead to a switch from coal to gas for electricity generation, thereby cutting carbon emissions, particularly projected emissions from developing economies. We conclude that this will help to reduce the impacts of climate change, but will not be sufficient to meet long term emissions reduction targets and avoid the worst effects of global climate disruption.

165.  The emergence of shale gas increases the urgency of making carbon capture and storage (CCS) technology work for gas as well as coal. We recommend that both gas and coal carbon capture technology should be pursued in parallel and with equal urgency.

298   Q 74 Back

299   Ev w1 (WCA) Back

300   Ev 57 (DECC) Back

301   Ev 86 (Tyndall) Back

302   Ev w9 (SSE) Back

303   Ev 96 (Grealy) Back

304   Ev 75 (IGas) Back

305   Jim Watson, "UK Gas Security: Threat and Mitigation Strategies", University of Sussex, January 2010 Back

306   Ev 100 (WWF) Back

307   Ev 86 (Tyndall) Back

308   Ev w8 (CPRE) Back

309   Ev 100 (WWF) Back

310   Robert W. Howarth, "Preliminary Assessment of the Greenhouse Gas Emissions from Natural Gas obtained by Hydraulic Fracturing", Cornell University, 1 April 2010 Back

311   Q 71  Back

312   Q 71 Back

313   Q 304  Back

314   Q 304 Back

315   Ev 100 (WWF) Back

316   Ev 100 (WWF) Back

317   Ev 100 (WWF) Back

318   Q 74 Back

319   Q 74  Back

320   Ev 86 (Tyndall) Back

321   Ev 86 (Tyndall) Back

322   Ev 86 (Tyndall) Back

323   Ev 71 (BGS) Back

324   Q 192 Back

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Prepared 23 May 2011