The roasting must be even, and the grinding process must be finely calibrated so that the resulting coffee allows smooth passage of the hot water that extracts the flavour.

ECONOMIST: Espresso coffee

Chartres said that 70% to 80% of fresh water the world extracts every year is used for growing food.

CNN: The driest season: Global drought causes major worries

It extracts oil from the ground using a method called fracking - pumping down a mixture of sand, water and chemicals at high pressure.

BBC: US to become 'world's biggest oil producer'