First you leave the autobahn, drive a few kilometres down a country road and turn sharp right at the small sign with the blue GFZ logo. The journey then continues down a bumpy dirt track for almost 400 metres, past the trucks at the gravel pit, and finally the white top of the drilling derrick becomes visible over the tops of the trees. On 19 February, more than 100 geologists, engineers and energy experts from all over Europe took this route from Munich to the tiny village of Dürrnhaar in order to gain nothing less than an exclusive insight into the future of geothermal energy. It bears the somewhat unwieldy name of InnovaRig, is nearly 52 metres tall and, with a 2,700-horsepower drive unit, is powerful enough to drill up to 5,000 metres into the ground. The operators do not aim to extract oil or gas, but are instead raising a very special treasure: hot water. From the end of 2008 this natural resource should be driving a five megawatt power plant that will simultaneously generate both electricity and heat – around the clock and independently of the wind and the sun. The drilling installation in Dürrnhaar is unique. In collaboration with the Herrenknecht tunnel-drilling specialists, the German Research Centre for Geosciences (GFZ) in Potsdam has developed a deep drilling system packed full of innovations. On this sunny February day the guests stand crowded together in the Bavarian countryside stretching their heads in the direction of the derrick. Yet there is no sound and no smell. That is precisely what makes InnovaRig so unique, says Martin Herrenknecht, CEO of the business of the same name: “The installation operates waste-free and so silently that it can even be used in populated areas.” That is an important advantage for geothermal energy, because its use is only economically viable where there is sufficient demand in the immediate vicinity. The assembly of the drills is carried out fully automatically, various drilling techniques can be used – as required – and this “technological masterpiece”, as Herrenknecht puts it, can drill up to 100 metres a day. The expert onlookers nod appreciatively and busily take notes. By the summer, 150 litres of water per second will be flowing to the surface at a temperature of 140 degrees Celsius.
The CEO saves the best until last: “When we reach the water, we will realign the system six metres to drill a second hole.” Enthusiastic applause. After all, that’s never been done before either. Extracting geothermal energy always requires the drilling of two holes: the hot water is pumped out of one hole, the heat is used to produce energy and the cooled water is pumped back into the hot rock formation through a second hole. This used to be an expensive business because the drill had to be dismantled and reassembled at another position – not any more. Using the mobile InnovaRig drill will be significantly cheaper and increase the potential for geothermal energy. The total amount of electricity now generated by the world’s geothermal plants corresponds to the output of seven nuclear power stations. That puts geothermal power far behind other renewables. Its share of environmentally friendly energy in Germany is only 1% (2006). However, new drilling technologies, like in Dürrnhaar, mean the experts are now forecasting strong growth – also in Germany. The first geothermal power plant generating both heat and electricity is already operating in Landau, 360 kilometres from Dürrnhaar. Since late 2007 it has been supplying 6,000 households with electricity and 300 households with heat – emission-free. According to the Federal Environment Ministry, 150 further geothermal plants are being planned. “We want to promote geothermal energy in Germany,” says InnovaRig developer Herrenknecht. The project is likely to be a big success.
