Chains of hydroelectric plants along the Lower Sava

Top knowledge and care for the environment, working hand in hand

The hydro power company Hidroelektrarne na spodnji Savi, d.o.o, (HESS) is a commercial enterprise involved in constructing one of the biggest projects in the field of energy and water infrastructure in Slovenia and the wider region.

The project is multi-purpose, and comprises the construction of five hydroelectric power stations along the Lower Sava River, right up to the border with Croatia, and its extensive infrastructure also extends into the area of flood safety. The constructed power plants have a total capacity of 186 MW.

HESS is one of those rare companies that has both the knowledge and experience needed to carry out this kind of project, and coordinate everything from locating the facility to constructing it, followed by the operation and maintenance of the hydro plant. Another key task of the company in the project is coordinating the energy and infrastructure works, since the activities of both parts are connected, and thus the proper coordination of their implementation is all the more important.

Construction of hydro plants along the Lower Sava

Every 42 months since December 2002, when the project was started, a new hydroelectric plant has been built, and along with all the related infrastructure along the River Sava, thus helping to achieve better living conditions for the local communities.

The project of constructing a chain of five hydro plants along the Lower Sava is economically efficient, and principally the result of Slovenian know-how. This is a greenfield investment, where even before construction can begin there is the highly challenging procedure of locating the proposed facility in the physical environment. Using its knowledge and experience, HESS has been doing this successfully for a number of years. In doing so, of course, it adheres to all the related EU directives and the strict Slovenian legislation in this area.

Over the past 10 years, the construction of hydroelectric plants in Europe has stagnated, since all the economically attractive rivers have already been exploited, and one cost of this has been a significant loss of knowledge about how to build such facilities. In this context, it is especially important that HESS is maintaining this knowledge. The construction of the hydro plants is carried out by the project being split into individual segments, which the company then integrates into a complete entity on site. This serves to enable direct collaboration among the project designers, supervisors, equipment manufacturers, software providers, construction contractors and expert institutions during the actual construction, while the investors maintain direct control over the execution of the work. The result is a competitively priced hydro plant.

This project is having a positive effect on Slovenia’s energy sector, since it is providing the country with a growing proportion of its electricity from renewable sources, in line with Directive 2009/28/EC of the European Parliament and of the Council on the promotion of the use of energy from renewable sources. At the same time, it is serving to provide flood protection and a regular financial contribution to local communities. As such, this hydro plant construction project along the Lower Sava is also a major stimulus for the local economy.                                                                                       
Alongside alternative habitats, adherence to the highest environmental standards has resulted in the construction of transit passages for aquatic organisms next to the barriers which have a nature-friendly appearance, and the results of several years of monitoring show they allow the free movement of migrating species around the barriers. Meanwhile the alternative habitats that were created during construction offer refuge to numerous species, and in this way increase the biodiversity in this area.

Objectives and positive effects of construction

The objectives of the investment that have been tracked were set principally in terms of the construction of new capacities for electricity generation from renewable sources, preventing floods and the arrangement of road and municipal infrastructure. Indirectly, the project is also helping to maintain the competitiveness and ability of the Slovenian economy in the field of constructing major energy and water regulation facilities.
The project has numerous positive effects, which can be seen in higher economic growth, a cleaner river owing to the treatment plants that have been installed, and richer groundwater. The new local provisions also allow the development of recreation and tourism at the lakes, along the lines of the projects seen at numerous other lakes around the world.

Current construction status of the five hydro plants

Construction of the Boštanj, Arto–Blanca and Krško plants is complete. All three power plants are in full operation, while the Brežice plant is in the final construction phase, with technical inspection and then the start of trial operation envisaged for the end of September 2017. The last plant in the chain, at Mokrica, is in the process of obtaining environmental approval, with construction due to start in 2018.

Source: Sinfo magazine 

Author: Andrej Štricelj

Photos: Slovenian hydroelectric power company archives