The global fight against climate change, coupled with the recent energy crisis which followed the Russian invasion of Ukraine, have increased the use of renewable energy sources. In particular, over the past years, geothermal energy has been rediscovered as a clean and reliable source of heat and electricity.
According to the Global geothermal market and technology assessment published by the International Renewable Energy Agency (IRENA), the growth in the use of geothermal energy worldwide has been driven by multiple factors. First, energy demand is increasing as a result of economic growth. At the same time, to counteract climate change and to move towards a green economy, there is a global effort to transition to renewable energy sources. Finally, the demand for sustainable heat is also increasing, leading to a growing trend towards the use of geothermal resources for heating and cooling applications where technically and economically feasible.
So far, geothermal energy in electricity generation has grown at a modest rate of around 3.5 per cent annually, reaching a total installed capacity of approximately 15.96 gigawatts electric (GWe ) in 2021. As a result, geothermal still accounts for a mere 0.5 per cent of renewables-based installed capacity for electricity generation and heating and cooling, globally.
Despite all its advantages (like the fact that it can provide both electricity and heat, as well as value-added mineral extraction; it provides reliable generation with high plant efficiency, low greenhouse gas emissions and a small ecological footprint; and has low operating costs), geothermal energy development faces challenges that have limited its development, even in regions endowed with easily accessible resources. In fact, geothermal projects have longer project development timelines compared to other renewables, require higher upfront capital expenditures and face high risk during the early phases of exploration. Other challenges identified by IRENA are related to financing, policy and regulatory frameworks, institutional and technical expertise and technological advancement.
However, there are also many opportunities to overcome these challenges to market growth. Examples include expanding and interconnecting regional electricity grids to export geothermal electricity from countries with high potential; leveraging oil and gas expertise and technology to scale up geothermal development; recovering minerals from geothermal brines; increasing synergies with green hydrogen production; improving the efficiency of electricity production from medium-temperature geothermal resources and so on.
IRENA is recommending to promote a widespread development and use of all available sources of geothermal energy; positioning geothermal energy as a key contributor to the achievement of sustainable development goals and climate action; improving enabling frameworks to foster investments in geothermal energy; fostering cross-industry synergies and harmonisation between geothermal and other sectors; promoting technological innovation, research and development to scale up geothermal development; and strengthening international, regional and national co-operation among partners.
Turkey, a leader in geothermal energy in CEE
Overall, in Central and Eastern Europe, high-enthalpy geothermal resources are present mainly in volcanic areas in the eastern Mediterranean region (Greece, Turkey) and the northern Caucasus area. Elevated temperatures are also present in sedimentary basins such as the Pannonian Basin (Bosnia and Herzegovina, Croatia, Hungary, Poland, Romania, Serbia, Slovenia, Slovakia and Ukraine) and the Southern Permian Basin (from Poland to the United Kingdom).
The country within CEE, where geothermal has been proliferating the most is Turkey, with 30 MWe installed in 2008, 1,549 MWe in 2019 and 1,676 MWe in 2022. Turkey is also the leader in geothermal heating and cooling, with 3,488 MWth installed mostly used for bathing and swimming, district heating, greenhouse heating and individual space heating.
There are many other countries in Southeast Europe using geothermal heat, for instance, Slovenia, with 31 locations, primarily used for bathing and individual space heating; Greece, with 25 locations, mainly used for greenhouse heating and some individual space heating; and Romania, with 40 locations, mostly used for bathing, individual space heating, greenhouse heating and district heating. Speaking of geothermal greenhouse heating, Hungary ranks among the top five countries worldwide.
Finally, in Croatia, the country’s first geothermal power plant, a 17.5 MWe Velika Ciglena unit, was inaugurated in 2019.
Leveraging the oil and gas industry: the example of Hungary
In particular, countries from Central and Eastern Europe could leverage their oil and gas industries as their experience and technologies could significantly contribute to the development of geothermal resources in deep sedimentary basins.
For example, in 2021, Hungary implemented its first closed-loop geothermal heating system in an abandoned oil well in Kiskunhalas, to generate small-scale thermal power using the Wells for Heat Exchanging Advanced Technology (WeHEAT). A geothermal pilot plant produces around 0.5 MWth of renewable heat for heating and cooling use. The project received support from the National Research, Development and Innovation Fund of Hungary. It is considered a showcase example that could be implemented throughout the country, as Hungary has over 8,000 deep out-of-use oil and gas wells, as well as scaled up globally.
Geothermal energy could also exploit its synergy with green hydrogen. Until now, the renewable energy focus has been on solar, wind and hydropower as the favoured renewable energy sources powering green hydrogen. However, also the use of geothermal energy for green hydrogen production has great potential, as geothermal provides stable electric and thermal power and enhanced efficiency. Green hydrogen production from existing geothermal plants could allow the expansion of resource use by taking advantage of existing field facilities and improving projects’ economies of scale. It could be especially beneficial in markets with limited growth and demand for electricity or market conditions.