A report confirming that shale gas drilling caused two earthquakes off the Lancashire coast in May and June could be expected to cast serious doubt over its future, but many experts appear committed to supporting its contribution to the energy mix.
Developer Cuadrilla commissioned the report into the two earthquakes measuring magnitude 2.5 and 1.3 and last month it concluded it was “highly probable” that they were caused by the controversial process of hydraulic fracturing - known as fracking - at its sites in Lancashire.
In addition to concerns over its safety - problems have occurred in the US with regard to gas infiltrating water supplies - it is a fossil fuel, and current sustainability arguments suggest attention should instead focus on renewables.
It seemed like the death knell had been sounded.
However, experts have suggested that minor seismic events caused by sub-surface drilling are a necessary and acceptable bi-product of exploiting the UK’s shale gas supplies.
Looking at the report, experts told NCE that drilling underground often caused seismic activity and should not necessarily be a cause for alarm.
“A quake of this size [magnitude 2 to 3] is to be expected,” says University of Edinburgh professor Stuart Hazeldine, adding that the findings showed there was no damage to infrastructure, and most people close to the epicentre would not have felt the tremor.
However, Hazeldine says Cuadrilla should have communicated more effectively with the local population about the threat of earthquakes.
“They would have known [there could be tremors caused by drilling] and should have communicated it,” he says.
The report recommends installing an early detection system to mitigate the escalation of seismic events. It also said that there was “an unusual combination of factors” contributing to the two earthquakes.
These include that drilling was taking place near a pre-existing critically stressed fault, and that this fault failed seismically.
The report also says that the chance of a similar magnitude seismic event occurring in the same place is very low.
Hazeldine adds that Cuadrilla may need to use 3D modelling to better map out proposed drilling locations, but even then it is difficult to gain certainty about ground conditions.
“You can’t visualise faults that easily,” he says.
University of Manchester professor of structural geology Ernie Rutter says although fracking can trigger quakes, they occur where there is already a risk and won’t increase their severity.
“We’ve known about drilling causing earthquakes for 60 years,” says Rutter, adding that there was much evidence of such circumstances in the mining industry previously.
But he argues there is even less risk of disruption above ground than there is from mining.
“There’s a much smaller chance of subsidence from fracking because there’s much less material being extracted from the ground,” he says.
Rutter adds that the Cuadrilla drilling was being done in one of the most seismically active areas of the UK, and according to the British Geological Survey earthquakes of up to magnitude of 2 occur on average about 25 times
each year around the country.
Opponents of shale gas drilling believe the seismic events are another reason to abandon exploration.
Friends of the Earth senior climate campaigner Tony Bosworth is calling for a moratorium on fracking following the report, because of the quakes risk and the US problems.
Bosworth is also concerned that any development in shale gas will divert efforts from building new renewable energy projects.
“We are concerned already about a second dash for gas [this decade],” says Bosworth, adding that regardless of whether the gas supplies are boosted by importing it or shale drilling, gas alone will not enable the UK to meet its carbon requirements.
Bosworth is also sceptical about hopes that shale gas would result in lower fuel bills.
“The steep rise in energy prices over the past decade has been due to increases in fossil fuel prices,” he says. “We need get off the fossil fuel hook and deploy renewable energy projects.”
This is easier said than done. Almost all experts are predicting a rise in gas-fired power stations over the next decade as many existing nuclear and coal-fired power stations are decommissioned.
This means more gas will be used in the UK, at least in the shortterm, and any decision to abandon shale gas development will be a diffi cult one for any government.
It’s unclear whether shale gas will have the same impact here as in the US energy market. There both gas prices and reliance on imported supplies have fallen.
By choosing to support shale gas the Department for Energy and Climate Change has to perform a delicate balancing act between ensuring the UK meets its carbon reduction targets, and reducing its reliance on imported gas.