HSE GROUP / Development projects

Hydro power plants on the middle Sava River

HSE is the concessionaire for the energy exploitation of the Sava River in the area between Medvode and Zidani Most. In 2018 talks were relaunched with the authorities to harmonise a concession contract. The construction of all ten planned hydro power plants on the middle Sava River would increase the installed power of hydro power plants on the Sava by 300 MW, and 1 TWh of electricity from renewable sources would be gained, which is currently almost 10% of total electricity produced in Slovenia.

Other renewable energy projects

  • Construction of small hydro power plants in the basins of the Soča and Drava.
  • The Ojstrica wind farm and examining the possibility of building wind farms in Paški Kozjak and Rogatec.

Renovation of sluices

The operational capability of sluice gates is of key importance for the safety of hydro power plants and flood safety, which is why we have been making continuous investments into renovation of sluices and renovation and overhaul of sluice gates and their drives.


OSMOSE is an international research project funded by the European Union as part of the Horizon 2020 programme. The participants in the project are looking for and testing new solutions for a successful transition to a higher share of production of electricity from non-dispatchable renewable energy sources. The four-year project involves 33 partners from nine European countries and various industries (system operator, research institutions and market stakeholders). The project has been estimated at EUR 28.3 million, with the share from the EU amounting to EUR 21.9 million.

The common thread in the search for solutions is recognising and developing opportunities within the existing power system which would enable cost-effective support from conventional power plants and energy storage facilities to non-dispatchable renewable energy sources. This is why the project is called OSMOSE, an acronym for Optimal System-Mix Of flexibility Solutions for European Electricity.

Four demonstrations, supported with prior research and simulations, will be carried out as part of the project. HSE participates in one of the demonstration groups which is looking for flexibility in the form of cooperation between two neighbouring systems and conventional production units. It is about looking for opportunities for trading close to real time by means of so-called FlexEnergy offers, whose implementation would be supervised by system operators.

As an owner and operator of sources of production of electricity, including around half of it from renewable sources, HSE sees in the project a great potential in Slovenia in the sense of, by using innovative approaches, contributing to maintaining the security, stability and reliability of the national system we are used to while including the largest possible share of non-dispatchable renewable energy sources.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement n° 773406.


In the light of the EU commitments taken by the Republic of Slovenia regarding the reduction of greenhouse gas emissions along with the implementation of measures for efficient use of energy and increase of the share of renewable sources, the HSE Group dedicates a lot of attention to the development of environmental projects which we implement in accordance with the existing legislation, and which reduce the environmental impact of the existing energy facilities:

  • Construction of fish ladders and revitalisation of fish population, which we implement on the basis of the Water Directive and the National Water Management Plan (NUV 2);
  • Removing sludge and maintaining energy potential of reservoirs: maintaining the energy potential of reservoirs of the chain of hydro power plants on the rivers Drava and Soča is a continuous process as part of which a useful volume and level of water, and consequently, flood safety, is maintained in the reservoirs of the chain of hydro power plants on the Drava and Soča. As part of these activities, we meet the obligations from the concession contracts for the exploitation of the rivers Drava and Soča for the production of electricity, such as regular removal of deposits, regular maintenance of the riparian area and others.