Author: Dragutin Domitrovic, construction manager of the first Croatian geothermal power plant Velika 1 and a member of OIEH
I am glad to see general support for the green revolution and the new momentum for renewable energy sources in the media today: from European political leaders, our (and the world’s) reputable businessmen and energy professionals to Croatian citizens who sent messages to the evening show “Open” – it seems as there is hardly anyone who would return to the energy of the old and well-beaten practices in which fossil fuels predominate. There is probably a large number of our fellow citizens, both in Croatia and on the entire planet, which may never have seemed so small, who during this terrible and enthusiastic momentum of saving themselves and the world from the virus realized that climate change is a kind of pandemic, only killing much more slowly and much more thoroughly.
My joy from the previous paragraph, however, is slightly diminished by the fact that in all praises for renewable energy sources, geothermal energy is mentioned only sometimes and seemingly shyly, usual topics are solar energy, wind and hydroelectric power plants and biomass. I can somehow understand this restraint towards geothermal energy on an experiential level: we all feel the sun, wind and water on our skin, so they are easy to understand, and each of us has put some logs of biomass once in a lifetime (or at least saw someone lodge it) in a village stove or city tile stove. Geothermal energy is not so intuitive. Hot geothermal water is situated miles deep in pores and crevices of rocks deposited millions of years ago. These rocks need to be drilled with deep and technically demanding wells to bring water to the surface. Then the heat of the water is used to start turbines or heat buildings, dryers and greenhouses, and the cooled water is then, so that no one can see or experience it, returned underground via steel pipes to some other wells that return it to the same rock, on the same depth from which it originally came. When preparatory geological and geophysical works are added to this, which determine from the surface which is the best place to drill production and impression wells, all this must seem very complex and exotic to someone who is not from that profession. So complex, in fact, that to this day I have never seen a symbol that would clearly, unambiguously and recognizably represent geothermal energy: the wind for the symbol has a wind turbine, the sun has solar collectors, biomass usually a leaf, and geothermal is probably too complicated for such a simple representation. (I invite designers to refute me and come up with some ingenious graphic solution! I offer all possible technological explanations for free.)
Exotic or not, geothermal energy is under our feet and cries to be used. In the continental part of Croatia, hot water is at quite accessible depths: the above-average high geothermal gradient of this area means that the temperature of 150 degrees Celsius will be found at a depth of about 3000 meters, and at slightly greater depths temperatures above 200 degrees Celsius are reached. In other parts of Europe, the temperature of 150 ° C can only be found at depths greater than 5000 meters, which makes drilling geothermal wells much more expensive and technically demanding.
The fact that the Pannonian part of Croatia is extensively explored, due to its decades-long history of oil and gas extraction, is also important for the successful exploitation of geothermal resources: in the second half of the 20th century, the former company INA – Naftaplin drilled more than 4,000 exploration and development wells in that area, so the regional knowledge of the underworld is very good. Therefore, the probability of finding favourable geothermal deposits is high or, in the vocabulary of the profession: the geological risk is low.
Just over two months ago, I referred to the information of the Croatian Hydrocarbon Agency and stated that there is a capacity in Croatia to build geothermal power plants with a total capacity of 500 MWe, but the diligent engineering team of the Agency continued to analyze available data from the aforementioned thousands of drilled wells. To date, they have reached an amount of possible total power of geothermal power plants greater than 830 MWe, which is almost two and a half times more than the Croatian share in the Krsko nuclear power plant! I believe that such energy capital simply must not be neglected.
If we take the mentioned 830 MWe as a reference number and compare with it the power of 10 MWe which, according to the agreement, is delivered to the electricity network by the first and only Croatian geothermal power plant, built in Ciglena near Bjelovar, the calculation will show that at this moment a bit more than 1 % of Croatia’s geothermal-electric capacity is exploited, and the remaining 99 percent has yet to be brought into production.
It should be noted that this does not yet cover the amount of available thermal energy for direct use in heating buildings and in industry and agriculture. For this area of application of geothermal energy, deposits of significantly lower temperatures, which are usually located at shallower depths, are also acceptable. The importance of direct usage of geothermal heat as a substitute for the usage of fossil fuels in heating was recognized by the German Federal Council, the Bundesrat, which considered the draft Coal Leaving Act (Kohleausstiegsgesetz) at its session held this year on 13th March. “With the help of geothermal energy, greenhouse gas emissions from the networked heat supply can be significantly reduced. In addition, there is a possibility of producing basic electricity without emissions.” At the same session, several measures aimed at facilitating the use of geothermal energy were proposed. There are also many interesting locations in Croatia for the development of geothermal heating systems, and one of such examples is Karlovac, which wants to transfer its existing city heating plant from fuel oil to geothermal sources. That is why that city founded the company GeotermiKA Ltd., which in the meantime has won research rights in the geothermal exploration area “Karlovac 1”, and preparations are underway for realisation of this project.
The recent drop in oil prices has been truly dramatic: major benchmarks such as Europe’s Brent and America’s WTI (West Texas Intermediate) have lost two-thirds of their value in a matter of weeks, falling from an average of about $ 60 a barrel to just $ 20 and oil derivatives due to global quarantine and overcrowded American crude oil depots at one point even caused an unprecedented effect of the negative price of futures contracts for WTI oil. This black news for the oil industry hides a positive effect for geothermal power engineers – a significant reduction in the prices of various services (very similar in oil and geothermal projects), including drilling and equipping wells. This will ultimately result in a reduction in initial investment in geothermal projects and their ability to offer electricity at more affordable prices.
Additional benefits for investors in geothermal projects and lowering of final purchase prices of electricity could be achieved by significant investments in the construction of exploration wells by the Ministry of Environmental Protection and Energy or the Croatian Hydrocarbon Agency, and using well-planned European Union funds for these investments. Therewith the European Union’s aspirations for energy sustainability and independence expressed by the European Green Deal will be put into practice in a very concrete way. From the text of the recent proposal for amendments to the Law on Exploration and Exploitation of Hydrocarbons, it can be read that legal preconditions are being created in order to enable the Agency to prepare itself particularly for such a role. In addition, there are mechanisms to attract funds from specialized investment funds for investments in geothermal energy, the sole purpose of which is not only to achieve the highest possible return on investment but also to promote the implementation of renewable sources, especially geothermal energy.
Politics has always (rightly) liked to emphasize the possibility of job creation, and since the consequences of the coronavirus pandemic have affected us economically, we have been talking and working mainly on preserving existing jobs. I would like to point out that geothermal projects can also help with that. Namely, during the construction of the geothermal power plant in Ciglena, almost 70 percent of the total investment was realised by domestic companies, and in a year and a half of the most intensive activities on the construction site, several dozen workers were engaged all the time. With the completion of the power plant and its commissioning, the local community got ten quality jobs. (Those who believe that this is not much have to consider this fact from the perspective of ten local families, who have earned regular incomes and will not consider emigrating from their area.) If we multiply these figures by dozens of possible similar projects, the impact of geothermal investments on the local and regional economy could be significant and it would be a shame to miss the strong investor interest that exists at the moment.
Finally, I sincerely hope that in the near future, the largest energy companies in Croatia – HEP and INA – will reach for hot water from the depths of Croatia as an opportunity for each of them to expand their portfolio in their own way. HEP has already shown its willingness to invest in the world of renewable energy sources by intensive last year’s investments in RES projects, so it will probably be ready to join the initial wave of development of Croatian geothermal energy if there are interesting opportunities. INA, on the other hand, already has significant hot water reserves among its current resources: some still active oil and gas fields have marginal aquifers with temperatures ranging from 120 to 190 degrees Celsius, and a large number of oil and gas wells have been watered over time, and therewith became better candidates for geothermal energy production than for production of fossil hydrocarbons. Given the rich and long-term experience of INA’s oil engineers and geologists and the fundamental similarity in the exploitation of oil and geothermal deposits, their step towards a geothermal transition should not be too dramatic.