Why the Czech town Litoměřice now boasts central Europe’s deepest (geothermal) borehole

Photo: Gabriela Hauptvogelová / Czech Radio

Czech geologists and geophysicists have been hard at work drilling the deepest geothermal borehole in all of central Europe. The borehole, on the outskirts of the northern Bohemian town of Litoměřice, is a staggering 1.6 kilometres deep – so far. The ambitious project is part of an ongoing effort to wean the county off of coal, which pollutes the air and accelerates global warming.

Photo: Gabriela Hauptvogelová / Czech Radio
This week, a team of experts led by RINGEN, short for the Research INfrastructure for Geothermal Energy institution, sent a special seismic sensor deep underground. The device is capable of measuring even the slightest vibrations in terra (not-quite-so) firma, explains RINGEN director Tomáš Fischer.

“We have a network of nine stations in total, but those are on the surface and are disturbed by industrial traffic. But if we put the sensor station at that depth, 1.5 kilometres, all this noise is filtered out by rock. And the seismograph detects much more of what’s going on underground.”

That’s important because extracting geothermal energy is a far more exacting science than, say, building a wind or solar plant. And therefore more expensive.

But it’s all part of an overall aim to make practical, and eventually cost-effective use, of the boundless geothermal energy produced by Mother Earth. If all goes well, another borehole in Litoměřice will go even deeper to tap that renewable energy source.

RINGEN, which is the first research institution of its kind in the Czech Republic, was founded and is hosted by the Faculty of Science at Charles University in Prague.

Apart from hoping to harness the power of thermal energy, the RINGEN team is also keen to analyse the properties and behaviour, so to speak, of rocks and fissures found at such depths. The scientists do that in part by using fibre optic cables, says Dr Fischer.

“If we send out a laser pulse, we can determine from its reflection what the temperature is. We have the fibre optic cable now at a depth of 1.6 kilometres – and that allows us to measure the temperature in one-metre intervals along the entire borehole. And in that way, we find where the water flows, because it is actually colder than what surrounds it.”

The whole process of drilling and real-time testing of geothermal boreholes, determining the viability of eventual wells, and building the related infrastructure, can take some 5 to 10 years to realise. The end game is to – by the 2030 target date set by the EU – reduce carbon emissions in the Czech Republic, while increasing efficiency and energy security.

Photo: Gabriela Hauptvogelová / Czech Radio
Currently, the Czech Republic is the fifth-biggest polluter in Europe and the 20th in the world in terms of CO2 emissions, due to coal production, which makes up over a third of the energy mix. But the country is not looking to phase out mining until 2030, at the very earliest, citing the impact on the economy.

Prime Minister Andrej Babiš argues that new nuclear power units must be built – even if in breach of European law – to offset the loss of electricity generated by coal, as renewable energies (solar, biomass, wind and geothermal) are still prohibitively expensive to implement.

More than a dozen centres similar to the RINGEN one in Litoměřice have recently seen government subsidies that they had counted on through 2020, unexpectedly cut.