As this winter's freezing weather puts great pressure on gas supplies, countries are using new technology to exploit existing energy reserves

Over a few years since commercial operations began at scale, shale gas has helped consumer gas prices in the US to fall by about a third; it's offered gas security to the US and Canada for maybe 100 years; and it's presented an opportunity to generate electricity at half the CO2 emissions of coal. This is a wooded state, and timber is a steady earner for people in the countryside. But follow the new roads snaking into the forests and you'll find a new source of wealth - brought up from nearly two and a half miles below ground.