Geothermal power: getting into hot water

Switzerland’s geothermal power cure – energy provided from underground sources – is nothing new in Switzerland.

“Taking a cure” at a Swiss mountain thermal spa is a tradition that has been enjoyed by Europe’s elite for centuries. Only since the beginning of this century, however, has geothermal power begun to be taken seriously as a replacement for nuclear energy for heating and electricity generation purposes.

The term “geothermal energy” refers to the energy stored in the form of heat below the earth’s surface, which is produced from the decay of naturally occurring elements. The temperature 15 metres underground is relatively constant throughout the year, around 7°C –13°C, but at greater depths it generally increases by about 25°C for each 1,000 metres. Hot underground water for domestic heating purposes can be tapped by using enhanced technologies, but it is only possible to generate electricity in geothermal power plants when temperatures exceed 100°C.

Switzerland has some 50,000 small geothermal users who harness the technology to heat houses, apartments, offices and hotels – the highest density of such users in the world. The heat is exploited by means of borehole heat exchangers. While individual houses need only one borehole, office blocks and bigger buildings require several. The method is increasingly finding favour with both families and businesses, who can recoup their initial outlay in just a few years.

On an industrial scale, recent years have witnessed a few mishaps caused by geothermal drilling, including minor earthquakes in northern Switzerland. A quake measuring 3.5 on the Richter scale shook Basel in 2006, causing damage to buildings. The project there was aborted and the petro-thermal system in use was discontinued. Last July, engineers unexpectedly encountered gas in St Gallen while drilling for the country’s first geothermal power plant. A 3.6 Richter-scale quake resulted, followed by several minor tremors. Further testing continues using 3-D seismic surveying, and the site should be operational later this year.

Despite such incidents, both citizens and geothermal experts appear confident that the future for geothermal energy in Switzerland is bright. Last year, Switzerland ranked third among countries making advancements in enhanced geothermal systems (EGS), according to a report by the US-based Geothermal Energy Association. And according to the website geothermalgenius.org, more than 75% of new homes constructed in the country have geothermal systems.

No electricity is currently produced in Switzerland from geothermal sources, although projects in Avenches (VD), St Gallen (SG) and Lavey-les-Bains (VD) are in advanced stages. Geo-Energie Suisse has chosen the ancient Roman capital of Avenches to develop its EGS facility to provide both heat and electricity. The project involves drilling 4,000 metres into the earth’s crust without inadvertently triggering tremors or releasing gases. Drilling is not expected to begin before 2016 at the earliest. In Lavey-les-Bains, opposition to the geothermal project proposed by AGEPP (Alpine Geothermal Power Production) has reportedly been assuaged. Drilling for future heating of the spa and the production of energy for over 1,000 homes is expected to begin by 2015.

At present Switzerland has nine facilities using underground water sources for heating purposes. Only the plant in St Gallen may eventually produce electricity along with heat. One of the main obstacles is depth. At the moment, few drilling installations have gone as deep as 3,000 metres. But once the technology is mature and this obstacle is overcome, the SFOE believes that facilities could be built where energy is needed the most – on the Swiss plateau between Geneva and St Gallen.

Alongside the sun and wind, geothermal energy is one of a number of renewable sources that are in the Swiss power mix for the year 2050. SFOE notes that this clean source of energy is CO₂ free and that its plants require very little space. Nevertheless, production costs remain unclear.

Experts predict that by 2030 about a dozen geothermal plants will be operational. And in the longer term, SFOE says on its website, “it is conceivable that a significant proportion of the electricity consumed in Switzerland could be produced at geothermal power plants.”