The Greek grid system is not flexible and stable enough, to accommodate large amount of intermittent RES penetration. The major production share is based on conventional thermal units (lignite and combined cycle) with high technical minima and inability of adaptation to frequent capacity fluctuations. In order to ensure efficient integration of RES and better adjustment of thermal plant operation, pumped storage power plants are crucial for a secure supply of electricity and as a back-up for intermittent renewables, as they can provide large-scale storage capacity and several distinct Ancillary Services to the system. Beyond electricity, the Pumped Storage Complex delivers other services to the system, such as frequency control, voltage control, spinning reserve, standing reserve, black start, remote automatic generation control, grid loss compensation and emergency control action. Pumped storage is the most mature and reliable technology, suitable for large energy storage rates, from both technical and economical points of view.

The project’s impact on the internal energy market and the national economy is particularly positive, due to the reduction of the import deficit(mainly natural gas), and the greenhouse gas emissions (as a result of the lignite combustion). The hydroelectric production in an interconnected transmission grid contributes to the reduction of wind power variability and uncertainty, provides firm capacity and entails significant economic benefits in the electricity market. The above mentioned contributions to the power system are vital for the completion of the Internal Energy Market. The existence of a competitive market is intended to give European consumers a better solution instead of imported fuels and to make the market accessible for all producers, especially those investing in renewable energy.

The project has a significant cross-border impact to the neighbouring countries, due to the energy transfer between Member States. The total interconnection capacity with neighbouring countries is 2000 MW, 1300 MW of which is between Greece and other Member States (Italy and Bulgaria) and 700 MW with third countries (Albania, FYROM and Turkey). The contribution of the project to energy transfer abroad is particularly considerable. According to the “National Renewable Energy Action Plan in the scope of directive 2009/28/EC” of the Greek Ministry of Environment, Energy and Climate Change, the expected transfer of Renewable Energy Sources from Greece to other EU Member States will be equivalent to 856 ktoe in 2015 and 529 ktoe in 2020. PCI 3.24 is expected to produce 816 GWh/ year, approx. 70 ktoe/year, therefore it will assist the energy transfer abroad in a significant way.

As stated, the project’s contribution to sustainability is particularly important, as it assists the EU target of 20% greenhouse gas emissions reduction until 2020. Additionally, the reservoir is estimated to contribute both towards increasing biodiversity, as well as the populations of specific groups or species that benefit from deeper waters with lower flow rate and soft substrate. This is expected to happen due to the increase, over time, of sediment at the bottom of the reservoir. In terms of species or groups with wider living space, such as mammals, reptiles, birds, etc., the reservoir is expected to function in a positive way by increasing the total biomass of the food chain.

The project’s implementation could contribute significantly to social and economic development of the local community. The Project’s Owner will try to develop initiatives modeled on local needs and potential. Furthermore, by choosing, whenever possible, regional and local contractors and suppliers and hiring local personnel, during both the construction and operation phase, the project could benefit directly and indirectly the economy of the areas in which it operates. Finally, the formulation of the lake and the improvement of access roads could create additional leisure facilities in the area and attract visitors and tourists.