Geologists in Iceland are drilling directly into the heart of a hot volcano. Their $20m project will lead to boreholes that could ultimately yield 10 times as much geothermal power as any previous project. It is hoped the endeavour will also reveal more about the nature of mid-ocean ridges where new ocean floor is created. Twenty years ago, geologist Gudmundur Omar Friedleifsson had a surprise when he lowered a thermometer down a borehole. ‘We melted the thermometer,’ he recalls. ‘It was set for 380C; but it just melted. The temperature could have been 400 or even 500.’ Speaking in the first of a new series on BBC Radio 4, called Five Holes in the Ground, he describes how this set him thinking about how much energy it might be possible to extract from Iceland’s volcanic rocks. At depth, the groundwater is way over 100C, but the pressure keeps it liquid. As Dr Friedleifsson puts it: ‘On the surface, you boil your egg at 100 degrees; but if you wanted to boil your egg at a depth of 2,500m, it would take 350.’ Splitting floor The landscape on the Reykjanes Ridge in southwest […]