Nathalie Taiana
Geothermal energy – isn’t that the thing about earthquakes? But. Does that still have a future? Yes. And why? Because researchers are in the process of solving the problems.
But let me go back a little: When it comes to our energy supply, everything has its advantages and disadvantages. Oil is cheap, but a climate killer, solar and wind energy are CO2-neutral, but not always available. But there is an energy source that is environmentally friendly and abundant: geothermal energy – or in technical jargon: geothermal energy.
The principle of generating electricity thanks to geothermal energy is relatively simple. First, two boreholes are drilled up to 5000 meters deep, where the temperature is between 100 and 200 degrees. Then water is pumped into the first hole. The water looks for a way through the rock until it reaches the second hole. Because it heats up a lot on the way, it escapes there as steam. This steam rises through the second borehole and drives a turbine that produces electricity.
Difficulties can arise in the construction of such systems. Often the rock is not permeable enough, only little water penetrates spontaneously from the first to the second hole. This can be helped by first pressing cracks into the rock with very high pressure – a bit like the “fracking” process in oil fields. But be careful: if the pressure is too high, you risk triggering an earthquake.
This is exactly what happened in Switzerland’s most famous geothermal project, which took place in Basel in 2006/2007. It had to be canceled because of multiple earthquakes. With a strength of up to 3.4, they were clearly noticeable and left damage to buildings.
Wouldn’t it be possible to produce more gentle cracks and thus eliminate the risk of earthquakes? ETH researchers are currently investigating this question in Val Bedretto. There, in an abandoned side gallery of the Furka Base Tunnel, they have set up a test facility with which they can test new methods – and measure precisely what happens in the process.
For example, the researchers used a type of rubber cork as a seal. This enabled them to press the water into smaller areas of the boreholes in a targeted manner. With success: the tremors were only one hundred thousandths of the strongest earthquake in the Basel project. Another advantage: If you only work on certain areas, you can easily deal with geologically difficult areas.
The results from the Bedretto Valley are very encouraging. And I am convinced that further attempts will soon produce even better results. These advances are important, because in future Switzerland will be CO2– To be able to supply energy neutrally, the Federal Council relies on geothermal energy among other things in the Energy Strategy 2050. The next step is to set up a plant in Haute-Sorne in the canton of Jura. It should provide electricity for around 6,000 households. I am confident that, thanks to further research, geothermal energy can establish itself as an environmentally friendly Swiss energy source.