Fracking for gas is highly controversial in the US and the UK as it has been accused of contaminating water courses and causing earthquakes. Yet it provides a cheap source of energy. Beneath England there are thought to be considerable amounts of shale gas and the UK government is considering whether to allow fracking in these areas. Already there is opposition from residents, concerned about pollution and earth tremors. Gaia Vince talks to scientists to find out what fracking involves and what impact it has on the environment, and she discovers what other countries can learn from the pioneers of the technology, the United States.

(Image: Views of the Cuadrilla Fracking Site at Balcombe. Credit: WPA Pool, Getty)