KTU professor Mayur Pal: The future of Lithuania’s energy may lie beneath the ground

Rising energy prices, geopolitical instability, and the challenges of climate change are increasingly prompting the question: Can we supply ourselves with energy that is both sustainable and reliable? In search of an answer, more and more attention is being directed towards the Earth’s deep heat. While geothermal energy is most associated with countries such as Iceland or Italy, few know Lithuania also has this clean, stable, and local energy source. In this respect, Lithuania is unique among the Baltic countries.

Professor Mayur Pal from the Faculty of Mathematics and Natural Sciences at Kaunas University of Technology (KTU) and head of the GeoEnergy Research and Innovation Lab at the interdisciplinary prototyping laboratory centre M-Lab says that although the potential for geothermal energy in Lithuania is already recognised, this sector is still underdeveloped.

The water in the Devonian layers has a high enough temperature to be used for heating, but it is too low for efficient electricity generation. These geothermal sources are classified as low-enthalpy, meaning the heat they store is sufficient for direct use, such as for district heating in cities.

“After the closure of the Klaipėda geothermal power plant due to financial and technical difficulties, research into deep geothermal energy in Lithuania has slowed significantly. Although this type of energy has many advantages – it is local, renewable, and independent of imports – it currently accounts for only a small portion of Lithuania’s energy balance,” says Prof Pal.

Moreover, in the southwest of Lithuania lies a geothermal anomaly – an area where favourable conditions for extracting geothermal energy have formed underground, especially in the Devonian and Cambrian layers. This remains an untapped resource, the potential of which interests scientists, but it has yet to receive sufficient political and business support.

“To strengthen the country’s energy independence, it is important to make broader use of local natural resources that are less dependent on external factors,” emphasises the KTU scientist.

An alternative for city heating

KTU professor Pal notes that in western Lithuania, geothermal resources are found at depths of approximately 1000–1500 metres. Sandstone layers are present here, which are not yet fully compacted but have favourable properties – high porosity (meaning the rocks have many cavities where water can accumulate) and good permeability (water can flow easily through these rocks). The temperature of these layers is about 45–46°C, which is sufficient for district heating but too low for electricity generation.

“Deeper, at about 2–2.5 thousand metres, other sandstone deposits are found, with temperatures reaching around 96°C. These layers are theoretically more suitable for electricity generation, but their quality depends heavily on the location: in central Lithuania, these deposits have better porosity and permeability, while in western Lithuania, these properties are poorer,” he explains.

“Nevertheless, while there are geothermal resources in Lithuania, very little is being utilised. Additionally, the country’s reservoirs are characterised by high water salinity and technical challenges related to reinjecting water into the rocks. This complicates their long-term and efficient use, especially when compared to more developed geothermal projects in other European countries,” observes the KTU scientist.

Could reduce dependence on imported electricity

Prof. Pal highlights that the effective use of geothermal energy could significantly reduce Lithuania’s dependence on imported electricity (currently about 70 per cent) and gas, especially in western Lithuania.

“A few hundred MW from Cambrian geothermal systems could offset electricity imports, and Devonian aquifers could replace the use of biomass or gas in district heating networks. It is important to emphasise that, compared to other sources, geothermal energy emits minimal CO₂, and its supply is available around the clock. In contrast, solar and wind energy generation depends on seasonality,” he notes.

According to the KTU scientist, Cambrian geothermal power plants could complement the base capacity of renewable energy sources and help balance the fluctuating outputs from solar and wind energy. Although their capacity would be modest (tens of MW), compared to the hundreds of MW generated by wind farms, they would still make a significant contribution to the overall energy supply.

“Geothermal energy could make up 5–10 per cent of the 45 per cent share of renewable energy sources, which is about 50–100 MW from Cambrian systems,” he says.

This type of energy stands out not only for its stability but also for its versatility – geothermal power plants can be used for both heat and electricity generation. The dual-purpose capability allows for more efficient use of accumulated energy resources, and continuous operation throughout the day increases the system’s reliability, especially for critical infrastructure needs.

A strategic energy source for defence

However, the development of geothermal projects faces challenges: significant initial investment is required, especially if there are no existing wells in the area, and the process from research to operation takes longer than with other renewable sources. Although these power plants are not as powerful as wind farms, their value lies in their stability and ability to provide an uninterrupted supply.

“These very qualities could make geothermal energy play an important role in areas where energy supply interruptions are unacceptable, such as in the defence industry. Its stability and reliability make it a long-term alternative, complementing variable renewable sources,” notes Prof. Mayur Pal of KTU’s Faculty of Mathematics and Natural Sciences.

The KTU scientist believes that Lithuania has great potential to become a leader in geothermal energy in the Baltic region, as Latvia and Estonia do not have such resources. The temperature of Cambrian systems and the flow properties of Devonian layers are unique to Lithuania’s territory.

“Projects such as reviving the Klaipėda geothermal power plant and integrating this energy into district heating could become a model for other countries. Moreover, Lithuania could collaborate with Nordic countries, such as Denmark, which is developing geothermal projects in the Baltic Sea region. This would allow Lithuania to share experiences and attract European Union funding,” he says.

Prof. Pal emphasises that to tap into this potential, investment and political support are necessary, as currently, priority is given to solar and wind energy. If Lithuania commits to actively developing geothermal energy, by 2030, it could become a leading country in the Baltic region in the use of low-enthalpy geothermal energy.