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1,000 trillion cubic feet of offshore shale gas? “Don’t believe the figures,” says geologist

  • 19 Apr 2012, 17:00
  • Ros Donald

Reports emerged yesterday that the UK might have around 1,000 trillion cubic feet of offshore shale gas, a figure  the Times and Wall Street Journal are attributing to the British Geological Survey (BGS). But when we asked BGS, it told us it doesn't recognise the estimate, or think that much gas will be recoverable. So what's going on? 

The Times wrote: 

"Yesterday, the British Geological Survey released estimates of Britain's offshore shale gas reserves, which could exceed one trillion cubic feet, more than five times the estimated onshore deposits, it said. This would catapult the UK into the top ranks of worldwide producers of shale gas."

In 2011, BGS estimated the total onshore shale gas resource in the UK at 144 billion cubic metres. It is currently in the process of coming up with a new estimation for onshore resource, but we didn't know anything about a new offshore estimate. So it seemed a bit out of character for BGS to start announcing offshore reserves of 1,000 trillion cubic feet off UK shores.

On investigation, it appears this figure stems from a Reuters report on Tuesday: Exclusive: UK has vast shale gas reserves, geologists say. Reuters quotes a BGS geologist, Nigel Smith, saying: 

"'There will be a lot more offshore shale gas and oil resources than onshore,' [...] UK offshore reserves could be five to 10 times as high as onshore[...]."

Smith made this statement to the UK's energy and climate change committee in February 2011 during an investigation into shale gas.

 But when we asked him whether he'd ever said the UK's offshore reserves equalled 1,000 trillion cubic feet, Smith told us: 

"Don't believe the figures!"

 Shale gas company Cuadrilla last year estimated the UK's onshore reserves at 200 trillion cubic feet. Says Smith: 

"What [the reporter] has done, I think, is take Cuadrilla's 200 [trillion cubic feet] resource and multiplied by five." 

The Cuadrilla figure is not uncontroversial either - an earlier article describes BGS as "sceptical" about it. Reuters seemed to realise this a bit late in the day, as a later version of their report adds the caveat:

"[S]ome experts doubt preliminary onshore reserve figures by private companies." 

Smith advises further caution, saying there's big difference between theoretical reserves and the amount of shale gas ultimately recoverable: 

"We would need to work out the areas of different aged source rocks offshore and plug in some gas contents and thicknesses to come up with a ball-park figure of this theoretical resource. At current technology onshore US only 10% of the resource is actually produced." 

Reuters did mention this, but the Times and WSJ miss that bit out. 

He added that although there are arguments in favour of UK concentrating on offshore reserves - including energy security and minimising potential harm to the public - the day when they are exploitable is still far off. The UK will have to pioneer offshore shale gas drilling because the US, the trailblazer in unconventional gas, has not needed to look further than its onshore reserves. 

It is possible, of course, that there is a significant amount of shale gas offshore. A column in the Economist suggests the UK government has pulled together its own data that also suggests reserves could be significant. And Reuters also claims that energy companies are getting excited about larger than imagined shale gas reserves: 

"Geologists at [...] leading energy companies spoke on condition of anonymity due to the sensitive nature of the dramatically higher estimates, but a consensus of optimism about potential European reserves has grown in the hard-headed commercial sector."

But these estimates don't come from the BGS.

There's another point that the UK will have to take into account if it wants to meet its emissions targets. A column by pro-shale gas pundit Matt Ridley in the Times illustrates the difficulty the UK faces in further cutting emissions if it goes for unconventional gas wholesale. Ridley says:

"[S]hale gas has already cut carbon emissions in a way that wind, biomass and solar power have failed to do". 

He cites a 7 per cent drop in US emissions in 2009 as "caused largely by a switch to shale gas".  There's an obvious problems with his argument: the UK already derives the majority of its electricity from gas, while shale gas in the US has displaced coal-fired plants - as we explain here. If, indeed, shale gas were to displace UK renewables, that won't help us meet our emissions targets

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