Conceptual Design of a Hydroelectric Power Plant on the Mura River – Hrastje Mota

Electricity production using hydroelectric power plants today represents one of the most environmentally acceptable and '** green' methods of generating electrical energy. This method of electricity production represents the only alternative to nuclear and thermal energy, which is why it is crucial to exploit the still ** untapped water potential in the territory of the Republic of Slovenia by constructing new power plants or by renovating and increasing the capacity of existing hydroelectric power plants. Planning such a large project as a hydroelectric power plant is a very demanding activity that must be studied in detail beforehand, and many different aspects must be taken into account, as the Mura River and the surrounding area are protected by ** Natura 2000**. Analysis of both variants showed that construction of the first variant of the hydroelectric power plant is more sensible – that is, construction of one power plant.

Problem

Electricity production using hydroelectric power plants today represents one of the most environmentally acceptable and '** green' methods of generating electrical energy. This method of electricity production represents the only alternative to nuclear and thermal energy, which is why it is crucial to exploit the still ** untapped water potential in the territory of the Republic of Slovenia by constructing new power plants or by renovating and increasing the capacity of existing hydroelectric power plants. The author described Slovenia's energy balance in the diploma thesis.

He established that their daily electricity needs are greater than their production capacities, which is why approximately half of the energy must be obtained through imports every year. Although Slovenia's import energy dependence decreases every year, it nevertheless amounted to 45.1% in 2014. The reasons for Slovenia's ever-decreasing import energy dependence can be attributed to the ** growing environmental awareness** of people, who are increasingly aware of the harmful climate impacts caused by fossil fuels.

Therefore, Slovenia is increasingly turning to exploiting the water potential of their rivers. Construction of hydroelectric power plants on the Mura River and exploitation of its good hydrological conditions only became topical when the Drava River had already been more or less completely exploited for energy. Below, he briefly described the Mura River and presented the power plants currently operating on it.

The Mura River is already exploited for energy by a whole series of power plants operating in the territory of the Republic of Austria. The last hydroelectric power plant, Spielfeld, is built just before the section of the river where the Mura riverbed becomes the state border between the Republic of Austria and the Republic of Slovenia. The only power plant operating on the Mura River in Slovenia is the small hydroelectric power plant Ceršak, which has an installed flow of 27.3 m³/s and a power output of 0.662 MW.

On the Austrian side of the Mura, 32 hydroelectric power plants are in operation. The first three are storage plants, whilst the remaining 29 are run-of-river type. Given the flow or quantity of water flowing through the Mura riverbed, only construction of a run-of-river hydroelectric power plant is feasible in Slovenia.

These are built on watercourses that have large flows with relatively small drops. These two data points (flow and drop) are the key factors that tell us what power the power plant will have or how much electrical energy can be produced in a given time period. Electrical energy is obtained by using the kinetic energy that water acquires from the drop to drive or rotate a turbine – this produces electrical energy, which is then carried via power lines into the electricity grid.

The project to construct a hydroelectric power plant on the Mura has a multidisciplinary character. Construction of the energy facility would thus have a positive impact on agriculture, forestry, the environment (water quality, groundwater), social aspects and the economy.

Solution and Method

Planning such a large project as a hydroelectric power plant is a very demanding activity that must be studied in detail beforehand, and many different aspects must be taken into account, as the Mura River and the surrounding area are protected by Natura 2000. Natura 2000 represents a European ecological network of important nature areas, formed on the basis of the Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora and the Directive on the Conservation of Wild Birds. The objectives of Natura 2000 are to ** preserve natural habitats and thereby animal and plant diversity in the European Union.** The main objective of the diploma thesis was to present possible conceptual solutions and the temporal and financial frameworks for constructing the facility, which he did.

Two variants for constructing the Hrastje Mota hydroelectric power plant are addressed in the conceptual solutions. The first variant involves construction of one hydroelectric power plant (2 possible locations), whilst the second variant envisages construction of two hydroelectric power plants with lower weir structure stages.

Results

Analysis of both variants showed that construction of the first variant of the hydroelectric power plant is more sensible – that is, construction of one power plant. The only advantage that appears with construction of two power plants is in the height of the embankments, as with variant 1 the embankment height would amount to approximately 10 m, whilst with variant 2 this height would be reduced to 5.5–6 m. Lower embankments automatically also mean lower implementation costs, but we must not forget that in this case we need 2 such facilities.

This means that costs are automatically doubled and that the total price is therefore higher than with variant 1. We must also not forget that with construction of two power plants, the costs of other elements are also doubled: construction pit, access road, connection power line, overflow fields, number of gates, larger/more expensive units, all other equipment (cranes, transformers, switchgear, auxiliary systems). Dravske elektrarne Maribor are in the phase of obtaining the necessary documents for preparation of an environmental report.

Preparation of the environmental report and environmental impact assessment represent the basis for placing the facility in a protected area and obtaining environmental consent, which is why special attention must be devoted to the preparation of these documents.