The project of the Kozjak na Dravi pumped-storage hydro plant and the 400 kV overhead power line connection to the Maribor electrical substation has been sited with the relevant national spatial plan. The project is included in the “Development plan for the transmission system of the Republic of Slovenia from 2017 to 2026” and is also included, with its 400 MW, as a support point of the electricity network of Slovenia and wider, and reported as a Project of Common Interest (PCI) in the European Union.
Another nine potential locations have been identified by analyses in the “Study of possible locations for a pumped-storage hydro plant on the Drava River". The installed power of an individual pumped-storage hydro plant is between 45 and 300 MW. The existing overhead power lines represent a great advantage for the siting. The hydrological and energy conditions are also favourable – the existing hydro power plants represent the downstream reservoirs.
The purpose and objectives of the introduction of electricity storage facilities are to increase flexible production due to the markedly dynamic operation of the existing units (consumption). As part of the increase of the volume of systemic services, envisaged in the first phase is the installation of an energy storage facility of the size class of 6 to 10 MW. The installation is envisaged within the land plots of the existing hydro power plants. As part of the installation of the storage facilities, a connection is planned to the new field of photovoltaic panels that will be installed on the sunny slope of the supply channel of the Zlatoličje and Formin hydro power plants. The envisaged activation of discharge and accumulation is implemented with regard to the market conditions and the state of regulatory activities, and is managed from the management centre of Dravske elektrarne Maribor (implementation of a virtual power plant). The purpose of the introduction of the storage facilities is also to relieve a part of the burden of the provision of systemic services from the existing production units of the company, as this negatively affects the energy exploitation of the water power and the lifespan of the equipment.
