World Environment Day – 5 June

05 Jun, 2019
World Environment Day   –  5 June

On World Environment Day, celebrated on the 5th of June every year, we wish to highlight the importance of having a responsible attitude to the environment, which is also reflected in this year's campaign slogan "Together we can beat air pollution".

Environmental pollution, climate change, and importance of the water's potential

Caused by greenhouse gas emissions, climate change is becoming a major challenge of the 21st century all around the world and as such will require shifts to be made in most of the human activities, including behaviour and lifestyle, as well as in terms of technology, development and innovation. People have already started to grasp the gravity of the situation, namely that climate change is – in part at least – caused by our releasing of large quantities of carbon dioxide into the air. To help preserve our planet, dramatic shifts will need to be made both at the national level and the level of individual businesses, sectors, regions and local environments and, ultimately, by every one of us. Individual governments have already started amending the legislation in order to reduce CO2 emissions, also by promoting and encouraging a more widespread use of renewable energy sources for generating electricity (solar, hydro, wind), which are the right answer to climate change and play a crucial part, in addition to nuclear energy, in reversing the trends of increased generation of carbon dioxide.

At HESS we see renewable energy sources as essential components in the efforts tied to the climate- and energy-related challenges of the future. By tapping water as the cleanest source of energy, we generate electricity and provide Slovenia with a fairly large proportion of electricity from renewable sources.

The chain of hydroelectric power plants on the lower course of the Sava River (HPP Mokrice included) will generate a combined total of 695 GWh of clean electricity, enough to satisfy the annual electricity consumption needs of nearly 200,000 average Slovenian households. If this amount of electricity came from a modern coal-burning thermal power plant (such as TEŠ 6) instead of hydroelectric power plants, this would have generated an additional 605 thousand tonnes of CO2 emissions annually (302 kg CO2 per country resident), which would present a substantial deviation from the commitments under the Kyoto Protocol.

"Climate change is inevitable, and if we don't immediately respond to it by reducing our carbon footprint, the trend of increasing temperatures on the planet will spiral upwards. Water, food and energy are the three components essential for a nation to survive in the long run. If these three components are not secured, no nation can survive. That is why the energy industry's answer to climate change lies first and foremost in hydroelectric power plants, which allow the development of all the three components: they generate electricity, retain huge amounts of surface and underground water to be put to good use, and enable reliable and secure food production unaffected by climate change," highlights Bogdan Barbič, HESS Director.

All the hydroelectric power plants in Slovenia account for around one-third of the country's annual electricity generation output. In terms of harnessing the environmentally acceptable potential of water for generating electricity, there is ample room for further development.

Flood protection, provision of drinking water

The climate change we are experiencing is not only affecting the atmosphere but also the watercourses. As a result, we can expect to see an increasing number of floods and larger variations between minimum and maximum flow rates. The multipurpose project to build a chain of hydroelectric power plants on the lower course of the Sava River successfully addresses this issue as well. Through suitable infrastructural modifications and configurations, we provide the local environment with flood protection, well-maintained watercourses, farmland irrigation, groundwater protection, raised water table and the resulting preservation of drinking water supplies, as well as reliable supply of quality drinking water for the local population.

Responsibility to the natural environment

Recognizing the importance of protecting and preserving the environment, we at HESS work to fulfill our commitments and obligations as required by the applicable environmental legislation, administrative authorizations, design and technical documentation, results of implemented monitoring programs, the Act on the Conditions of the Concession for Harnessing the Energy Potential, and the Concession Agreement for Harnessing the Energy Potential of the Lower Sava River. So in addition to regular maintenance activities in ecological terms, we also carry out monitoring of environmental impacts with the aim of gauging an impact's scope and scale, identifying the corresponding trends and defining potential courses of action in response to the impacts brought about by the construction and operation of the hydroelectric power plants. We conduct technical monitoring of the reservoirs and monitoring of surface water. In addition to the technical monitoring, seismic and land surveying monitoring are also carried out at the dam structures of the individual hydroelectric power plants.

The company HESS performs regular tours of inspection of the reservoirs in order to check up on the growth of the plantings, identify the presence and spreading of non-native invasive plant species, any releases of untreated wastewater from wastewater treatment facilities, the presence of algal overgrowth, etc. We remove non-native invasive plant species during regular maintenance activities on the reservoir banks, carry out maintenance on aquatic organism passage facilities, and properly handle and dispose of all waste (including floating debris) that accumulates at the hydroelectric power plants.

Handling of floating debris

Most of the debris carried by the Sava is of organic origin (driftwood, foliage …) and comes from the entire upstream sections of the rivers Sava (Zasavje region, upper course of the river) and Savinja, floating downriver with the current all the way to the discharge. The waste that the two rivers carry along with the organic debris is unfortunately largely the result of irresponsible human activity along the basins of the rivers.

The floating debris and waste are generally stopped by the power plants' floating barrier curtains, which prevent the intake gratings on turbine penstocks from getting clogged, consequently protecting the turbine equipment against damage. This aspect is absolutely essential for the safe and reliable operation of the hydroelectric power plants. However, mostly during periods of high water levels and high flow rates, fairly large amounts of floating debris gets carried over or under the protective floating barrier curtain. HESS is obligated to remove any such debris, and we do so by using a trash rack cleaning machine. The trash and organic debris that is removed is then deposited in a dedicated disposal site. The removal of floating debris and waste directly from in front of the floating barrier curtain, however, has not been envisaged in the project design and cannot be carried out with the machinery we have at our disposal. So the remaining debris is carried over the sluice gates and downriver during periods of high flow rates. HESS has implemented and runs a floating debris management system in compliance with the Act on the Conditions of the Concession.

The reservoir of HPP Vrhovo, which is managed and maintained by the company SEL, has a barrage (floating barrier) installed for stopping the debris carried from the upper courses of the rivers Sava and Savinja. There, too, floating debris is extracted from the Sava and transported to a disposal site. At high flow rates, the barrage tears open in a controlled manner, establishing the natural flow of the river to avoid any damage to the systems and equipment (particularly hydromechanical equipment) of the hydroelectric power plants downstream, which is essential for ensuring safe and reliable propagation of flood waves along the entire length of the Sava.


As a company specializing in generating electricity from renewable energy sources, we are fully aware of the importance of protecting the environment, but some situations are simply beyond our control and we can only do what's in our power – physically and legally. We all must keep in mind that our future and the future of the generations to come also depends on the way each one of us interacts with the environment, so we should all think about how we handle and dispose of waste, how much food we discard each day, how we get around in our day-to-day activities… And not just on World Environment Day – treating the environment we live in with respect should be a daily concern and responsibility for each one of us.


To learn more about this year's World Environment Day campaign, visit: