SHALE GAS - A controversial fuel

Shale is a sedimentary rock, derived from clay, the most common on Earth, some forms of which contain methane gas.Huge shale deposits can be found across the world, and reserves are estimated at 448,000 billion cubic metres, the equivalent of 140 years of gas consumption at current levels. Half of the deposits are to be found in Asia and North America. But harnessing the gas is technically complex because unlike pockets of natural gas, it is impossible to pump directly as it is embedded in the rock.But it can be extracted using a process known as hydrofracturing or “hydrofracking”. VIDEOGRAPHIC