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Construction of HPPs on the lower Sava river

HPPs on lower Sava river

Established in 2008, Hidroelektrarne na Spodnji Savi, d.o.o., (HESS for short) is a Slovenian hydroelectric power company (HSE Group's share: 49 %). Its core mission is to facilitate and promote the construction of new hydroelectric power plants and to engage in electricity generation that is sustainable, reliable, competitive and environmentally friendly.

The company's operations and the construction of hydroelectric power plants are largely regulated by the Concession Agreement for Harnessing the Energy Potential of the Lower Sava River and the Act on the Conditions of the Concession for Harnessing the Energy Potential of the Lower Sava River (ZPKEPS-1). 

Company Hidroelektrarne na spodnji Savi d.o.o. is the protagonist of the largest investment into this country’s power-generation sector – the projected construction of a series of five hydropower plants (HPPs) on the lower reaches of Slovenia’s Sava River; namely: the new run-of -river plants at Boštanj, Blanca, Krško, Brežice and Mokrice. These new facilities, which shall be constructed by 2018, will more than double the power generated on the Sava. Their total output shall account for 21 % of the Slovenian hydropower production, and it is anticipated that they shall meet 6 % of the nation’s energy needs.

More info: http://www.he-ss.si/eng/

Reasons "FOR"

Local and regional development:

  • environmentally friendly structures and their long design life
  • regulation of the Sava watercourse and improved utilisation of this convenient source of power
  • part of the income from the concession levy can be earmarked for the implementation of development programmes
  • creation of new jobs
  • improved protection from flooding

National development:

  • competitiveness of the Slovenian power sector
  • improved situation in relation to the growing consumption of electricity
  • improved stability of power system operation and greater independence
  • appreciation of the national asset base
  • better quality of life


All five hydropower plants are of the flow-of-river-accumulation type featuring two or three bulb turbines or two Kaplan turbines.

Spillage capacity of each hydropower plant: 500 m3/s, five spillage areas with 3,500 m3/s overflow capacity.

Combined total annual production of the hydropower plants: 720 GWh.

Operation: The power plants will operate without crew; they will be managed by the HP chain management centre, and the only people on site will be the regular daily- and annual maintenance staff.

HPP Boštanj

HPP Boštanj

On the Sava river bend at the 46th parallel of latitude.

Special attention is being paid to the protection from flooding.

HPP Boštanj - Basic Details
Rated flow: 500 m3/s (3 x 166,7 m3/s)
Head: 8,20 m
Rated output: 32,5 MW
Average annual production: 115 GWh
Useful volume: 1.000.000 m3
Average annual flow: 235 m3/s

HPP Blanca

HPP Blanca

Near Sevnica.

Minimization of the impact on parts, areas and structures of natural treasures and cultural heritage.

HPP Blanca - Basic Details
Rated flow: 500 m3/s
Head: 10,7 m
Rated output: 42,5 MW
Average annual production: 160 GWh
Useful volume: 1.390.000 m3
Average annual flow: 243 m3/s

HPP Krško

HPP Krško

In the vicinity of the Krško nuclear power plant, where it will be possible to draw on the potential of this longest Slovenian river, whose tributaries gather the waters off more than half of the Slovenian territory.

We designed and provided bays, fish paths, channels and spawning grounds; we provided animal habitats and birds nesting grounds; we also ensured that current farming conditions are 
                                                                maintained and even improved.

HPP Krško - Basic Details:
Rated flow: 500 m3/s
Head: 9,9 m
Rated output: 39,5 MW
Average annual production: 149 GWh
Useful volume: 1.380.000 m3
Average annual flow: 247 m3/s

HPP Brežice

HPP Brežice

Where Sava River achieves an average annual flow of 290 m3 / s.

We are not going to forget the water quality! We will set  oil and grease interceptors to ensure that stormwater from hard surfaces and filtered water from construction buildings will flow  uncontaminated into the Sava River. During the  power plants operations  we will regularly supervise the quantity and ecological and chemical status of water in accordance with the regulations.

HPP Brežice - Basic Details
Rated flow: 500 m3/s
Head: 10,4 m
Rated output: 41,5 MW
Average annual production: 161 GWh
Useful volume: 3.450.000 m3
Average annual flow: 250 m3/s

HPP Mokrice

HPP mokrice

Near the Croatian border, where the Sava River is enriched by the Krka River power, it will have a smoothing reservoir role in the schduled streaming and storage regime on the Sava River.

Here, like in other Lower Sava River plants, we will not ignore the possibility of recreational use of water .

HPP Mokrice - Basic Details
Rated flow: 500 m3/s
Head: 7,58 m
Rated output: 30,5 MW
Average annual production: 135 GWh
Useful volume: 3.750.000 m3
Average annual flow: 305 m3/s