Fracking aims to extract gas and oil locked in shale rocks by blasting them with a mixture of water, sand and chemicals and fracturing the rocks.
The technique was invented in the 1950s. But its use has been boosted by new technology that allows horizontal drilling.
Fracking can also be used to blast methane gas out of coal seams if they are too deep to mine.
Fracking is dangerous. Cancer?causing chemicals can leak into drinking water. A study of the Tara gas fields in Australia found that 44 percent of the wells leaked methane gas.
Some leaks were at dangerous levels and one was at levels high enough to explode. Yet Dart Energy is now using this technology in Aberdeen.
Fracking by Cuadrilla Resources has caused earthquakes in Blackpool. Cuadrilla’s own report found the quakes were caused when fracking fluid blasted into a previously unknown faultline underground.
Some of Cuadrilla’s fracking plans, such as in Balcombe, Sussex, are within much less than 2,000 feet of groundwater.
Getting water to supply the fracking fluid can cause more disruption. Studies in Australia have found that fracking operations can cause groundwater levels to drop by as much as 15 metres.