no great shakes?
Shale gas is the energy miracle that’ll keep the lights on once the oil runs out. Or is it the looming menace that’s going to trigger deadly earthquakes and set fire to our tapwater? Tom Marshall talks to Mike Stephenson of the British Geological Survey (BGS) to sort truth from fiction.
Tom: What is shale gas and how do we get at it?
Mike: Shale is by far the most common sedimentary rock on Earth; there are many thousands of cubic kilometres of it beneath the surface. Usually a few per cent of its volume is organic matter. Like other fossil fuels, this is formed from the remains of ancient living things. Under huge pressures and temperatures underground, and over huge swathes of geological time, this organic carbon gets cooked up to form methane.
To get at it, we have to drill down to the shale and pump in high- pressure water, breaking the rock up so we can pump out the gas. There’s a fundamental link to the climate here: this ancient carbon cooled the Earth when it was absorbed and sequestered; releasing it back into the atmosphere will cause warming.
Tom: How significant are the UK’s reserves in the context of our energy needs?
Mike: Shale gas isn’t like oil or natural gas; there isn’t a fixed amount of it down there waiting to be extracted. It’s more like we’re producing it – in the US they talk about underground shale as ‘the gas factory’. There’s as much gas down there as we choose to produce by fracking the shale, so it’s really about how much fracking we want to do. World shale gas reserves are estimated at 450,000 billion cubic metres (BCM).
PLANET EARTH Spring 2012