Geothermal energy is based on an alluring idea: that the earth’s crust maintains a constant heat generated by the fiery molten core, 4000 miles below. Three or four miles from the surface, this heat might be a manageable 300 degrees Fahrenheit. It is thus accessible in much the same way that an oil well might be with the added benefits of being a zero carbon alternative that is easily replenished. Water is introduced into pipes and heated to produce steam which is converted to energy by turbine. So far so renewable, but unlike wind and solar that require storage or grid interconnection to overcome problems of intermittent supply, geothermal energy is constant.
So why is this apparently magical formula not in wider use? Objections mirror those that are frequently levelled at fracking, namely fear of earthquakes and release of toxins such as sulphur dioxide and silica. Drilling is complex and expensive and the process uses a vast amount of water. However, in addition to the benefits described above, the process also boasts the smallest of footprints, damaging very little land surface. Indeed, it is even possible to build facilities beneath the ground. Costs are competitive and heading downward.
Global geothermal generation capacity was a mere 12GW in 2014 and, in the UK, the only operational plant produces district heating for the hospital and university in Southampton as well as a local shopping centre.
Iceland is the poster boy of geothermal energy for its relative importance within the national mix: 68% of primary energy, 90% of residential heating and 29% of total electricity are supplied by this subterranean source.
In fact, the USA has five times the installed capacity of Iceland while the Philippines has almost three times and Indonesia twice the amount.
But Iceland is still the trailblazer. A country that was the third poorest in the world, just 70 years ago, Iceland, better than most, has used its natural resources to shape its inward investment strategy, internal economy and exports, successfully positioning itself as an ideal location for the world’s data centres, gaining energy independence through its exploitation of geothermal sources and exporting that same expertise to Africa.
Once again, the country is in the vanguard. Last week, the Iceland Deep Drilling Project (IDDP) confirmed that it had penetrated 4,500m into the heart of a volcano on the Reykjanes Peninsula in the south-west of the country. The company is on track to meet its target depth of 5km within the next fortnight. The deeper you go, the hotter the rock and the more powerful the energy released. Could geothermal come of age in 2017?