© NERC All rights reserved Is shale gas a global game- changer? Mike Stephenson
© NERC All rights reserved What’s all the fuss about?
© NERC All rights reserved Source: Nature Sept 2011
© NERC All rights reserved Source: Nature Sept 2011
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Shale basics
© NERC All rights reserved 1 mm
© NERC All rights reserved Where does the organic material come from? Land plant material and seawater algae collect in mud Older, deeper shale layer
© NERC All rights reserved 500 m 0 m Biological decay – biogenic methane Organic matter ‘cooked’ – thermogenic methane Old deep shale layer Burial over millions of years
© NERC All rights reserved Conventional and unconventional
© NERC All rights reserved Conventional and unconventional
© NERC All rights reserved Sand grain gas 0.25mm shale sandstone
© NERC All rights reserved Adsorbed gas and gas in pores
© NERC All rights reserved Shale layer sandstone Cap rock Conventional: Trap Unconventional: Continuous accumulation
© NERC All rights reserved Fracking basics Cracks the shale High pressure water or nitrogen, bar (350 to 700 atmospheres)
© NERC All rights reserved Where is the shale?
© NERC All rights reserved Britain
© NERC All rights reserved Polish shale gas
© NERC All rights reserved Siekierki power station in Warsaw
© NERC All rights reserved Russia and gas
© NERC All rights reserved Poland’s choices? Renewables –little potential? Nuclear, long lead in (10 yrs), expensive Keep burning coal and pay the ?high carbon price Build gas plants (1-2 yrs), pay ETS, rely on imported gas? CCS on coal fired power stations Polish shale gas in gas fired power stations
© NERC All rights reserved If Poland switched from coal fired power stations to gas fired power stations it would cut its CO2 emissions by 41-49%
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Shale gas and the environment
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Clash of cultures
© NERC All rights reserved Groundwater contamination
© NERC All rights reserved Woody material δ 13 C ~ ‰ (Stephenson et al. 2008, 2010) plankton and algae δ 13 C ~ ‰ Basics: Environments, organic matter and δ 13 C Typical lower Carb organic matter δ 13 C ~ ‰
© NERC All rights reserved Basics: Methane – biogenic and thermogenic Biogenic/bacterial (e.g. wetland, landfill) – high C 1 /C 2+ ratio, low δ 13 C values Thermogenic (e.g. natural gas, coalbed methane) – low C 1 /C 2+ ratio, higher (less negative) δ 13 C values
© NERC All rights reserved Contamination from fracking? Osborn et al. 2011, PNAS Studied: Methane in shallow water wells in shale gas areas measured methane content and δ 13 C
© NERC All rights reserved What did they find? Higher methane concentrations in water wells close to shale gas wells δ 13 C suggests thermogenic Authors then say ‘likely to be shale gas from the fracking’ No evidence of contamination with fracking fluids
© NERC All rights reserved Water wells Unlikely to have casing failure on so many new wells Shale well
© NERC All rights reserved Not peer reviewed Dec 2011 Molofsky et al. 2011
© NERC All rights reserved Molofsky et al. 2011
© NERC All rights reserved Molofsky et al. 2011
© NERC All rights reserved Hydraulic connectivity between the shale gas formations and the overlying shallow drinking water aquifers? Hydraulic connectivity? Warner et al. 2012
© NERC All rights reserved Types of groundwater
© NERC All rights reserved Role of science
© NERC All rights reserved Concerns about shale gas Things we don't have to worry about Things we need to regulate carefully for public safety and public opinion Independent science: assess risk Low risk High risk
© NERC All rights reserved Conclusions Shale gas could be a game changer Britain might have substantial potential for shale gas No peer-reviewed evidence of methane contamination from fracking Earthquakes are a natural result of fracking but should be manageable Peer-reviewed independent science has a special role in building regulator, investor and public confidence
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