Central heating and heat supply on a scale such as that of the city of Sofia is already being denied as inefficient, and in Europe the development of heat pumps and decentralized heating, where there are much less heat losses, is on the map. Therefore, by the end of the year, a new European strategy for geothermal energy and heat pumps will be published, experts told 3eNews.
It is much more economically expedient to plan heating systems at the level of districts or buildings than one plant of the type of the capital district heating system. The proof of the inefficiency of such energy capacities is also their financial indebtedness, which in the particular case of the city of Sofia works only because, if it stops working, we put the electricity system of southwestern Bulgaria at risk. The topic will most likely become the "hot potato" during the election campaign in the capital, as heating obligations exceed BGN 1.6 billion and continue to grow every day. This was commented by the green policy specialist Georgi Stefanov. He was also a scientific observer of the first geothermal project in Hungary 7 years ago, when they closed their coal-fired thermal power plant in the Budapest area and replaced it with a geothermal plant, and according to him, he is one of the few specialists with practical experience in this field in our country.
Already at the beginning of the year, changes were adopted in the Law on Renewable Energy Sources, where we were the first in Bulgaria to adopt legislation giving a definition for geothermal energy, which was missing until now, he added. Geothermal energy is already by definition divided into three - low-temperature, medium-temperature and high-temperature geothermal energy, which are respectively located in the shallow, medium-depth and deep geological layers.
The geothermal sources, which are at a shallow depth, practically technologically represent the various heat pumps and, to be honest, have nothing to do with the constant use of water. Medium temperatures are most often associated with hot mineral water. Deep geothermal sources also have nothing to do with water, because with them we are most often talking about the heat of the rocks and the earth's bowels, explained Stefanov.
Bulgaria is the last country in the EU to introduce legislation to support the accelerated introduction of heat pumps, and on these indicators, we lag behind all countries in Eastern Europe.
At the moment, for several months, the Bulgarian Association for Geothermal Energy has proposed legislative amendments through the Law on Renewable Energy Sources, which address changes to the Law on Water, the Law on Underground Resources and the Law on Spatial Planning, which are expected to be considered and voted on in The National Assembly after September. These amendments will in practice unlock the potential for the implementation of geothermal projects in Bulgaria and will ensure the goals set in the Recovery Plan in this area. In this regard, Bulgaria is somewhat ahead of a number of other countries that still do not have comprehensive legislation to address geothermal sources and heat pumps, the expert believes. This will allow us to solve our problem and legalize the installation of heat pumps. At the moment, everyone who installs heat pumps puts them on the edge of the law, comments Stefanov, and this problem becomes insurmountable if we talk about installing industrial heating installations and heat pumps, which are practically absent in our country.
It is proper in Bulgaria to divide the utilization of this energy. Everywhere in Europe, shallow geothermal sources, i.e., heat pumps, are without a permit regime and their rapid development is based on the utilization of the constant temperature at a shallow depth, which provides high efficiency for heating in winter and cooling in summer. That is why, for these installations, there should not be heavy requirements and regimes for their installation. These heat pumps are usually installed at a depth of several meters to several tens of meters.
Medium-temperature or medium-depth geothermal sources fall within the boundaries where hot mineral water aquifers mainly fall, which are in the range between 200 and 800 meters. Stefanov commented that this resource and its use will remain under the groundwater use regime, where we have good legislation.
Deep or high-temperature geothermal sources are suitable for the production of electrical energy, since there the goal is to reach geological layers where the temperature of the earth's interior can reach and exceed 120-150 degrees and more. It is at such deposits that the possibility of producing electricity, laid down in the Recovery and Sustainability Plan of Bulgaria. These geological layers are most often found at a great depth between 2800 to 6000-7000 meters, but in these cases, we are talking about heat from the rocks and in no case about mineral waters. Such extraction from a high-temperature source would be possible within the meaning of the Law on Underground Resources in conjunction with the Law on Concessions, which concentrate the extraction of all minerals and there would be a definition of what actually constitutes deep geothermal energy, which is a resource to be explored and mined.
Bulgaria should also think in the direction of developing its geothermal sources. It is important to work in the perspective of medium-depth wells, but also to bear in mind that a large part of the mineral water is rich in sulfur and we often have the smell of rotten eggs known from balneological complexes. Thus, when building a geothermal plant utilizing waters and fluids with a high mineral content, it should be taken into account that there may be such waters with strong unpleasant odors. There are 3000 boreholes with warm mineral water in Bulgaria, of which about 300 are actually used. Many of them have a high mineral content, smell or have harmful chemical ingredients, which means that these 90% of the boreholes are simply not suitable for drinking needs or balneological procedures. This of course does not mean that these resources are not suitable for geothermal energy and heating. The question is how to manage this process sustainably, so for example if a borehole does not have a large enough flow to be utilized. That is why preliminary studies and pilot projects in this direction are of particular importance, so that each installation can work flawlessly and geothermal installations are recognized by society and business as a basic RES power that will lead to the stabilization of the prices of energy resources and will ensure energy security and independence.
The Ministry of Energy also gained practical experience in this direction through the realization of several pilot installations financed under the Norwegian program in Bulgarian municipalities in the last year. In practice, we already have six municipalities that have installed geothermal installations, representing deep heat pumps, in a regime of missing legislation.
Stefanov recalled that last year the development of geothermal energy was included in the territorial plan for a just transition of Kyustendil region with a planned resource of BGN 80 million, and now this source will be able to be distributed in all three territorial plans.
Geothermal energy and heat pumps are an alternative to conventional heating and are the safest option for modernization and decarbonization of gas and coal heating systems, together with the construction of solar heating systems. One thing is certain, it is necessary to renew and modernize the heating networks, which are owned by the heating utilities, because any technology is much more economically advantageous if we reduce losses. In our country, unfortunately, we are failing precisely in this area, and the proof of this is the huge water losses in the water supply network, on which Bulgaria still cannot make significant progress despite the billions of investments in the water supply companies in recent years.