What is fracking and why is it controversial?
Drilling companies suggest trillions of cubic feet of shale gas may be recoverable from underneath parts of the UK through a process known as "fracking". Hydraulic fracturing, or fracking, is a technique designed to recover gas and oil from shale rock. But how does it work and why is it controversial? What is fracking? Fracking is the process of drilling down into the earth before a high-pressure water mixture is directed at the rock to release the gas inside. Water, sand and chemicals are injected into the rock at high pressure which allows the gas to flow out to the head of the well. The process can be carried out vertically or, more commonly, by drilling horizontally to the rock layer and can create new pathways to release gas or can be used to extend existing channels. The term fracking refers to how the rock is fractured apart by the high pressure mixture. Is fracking taking place in the UK? No. Applications have also been submitted in Yorkshire and Nottinghamshire. Image copyright Reuters