Hydropower in Central Italy: current status and future prospects

The largest source of renewable energy comes from a proven technology, hydropower. Hydropower is renewable because it draws its essential energy from the sun which drives the hydrological cycle which, in turn, provides a continuous renewable supply of water. The main goal of this paper is to optimize the use of hydropower resources in Umbria, a region of Central Italy. To this scope, we initially analyse the currently operating hydroelectric plants, taking into account both those of great size and the very small installations. Successively, we discuss the perspectives of this area in terms of exploitable hydraulic potential. It has been found that in Umbria are currently working 38 hydropower installations: 84% of them are run-of-river power plants, 10% are hydropower stations with a reservoir, while 6% works in both ways. Currently, 70 turbines are working: 41 are Francis, while the remaining, excluding a small Pelton and a Banki-Michell, are characterized by high degrees of reaction (Kaplan or helixes). The total installed hydroelectric capacity is over 650 MW, corresponding to an average annual production of approximately 1415 GWh. Most of these hydropower plants, 35 corresponding to 92% of the total, is privately owned: 13 from a big multinational company, 16 from small and medium size companies, 6 from private people. Only 3 installations are owned by municipalities. The described situation characterizes the Umbria region as a geographic area where the ratio between the exploited potential and the economically feasible potential has already reached a value not far from its physiological limit. In this context it is clear that in Umbria no large installations (> 10 MW) can be planned; instead, considering also the low number of existing hydropower stations with respect to the extension of the area (currently equal to 1 plant for each 222 Km2), a significant potential for the realization of small run-of-river power plants exists. At the moment 5 new hydropower plants are under construction, while about 100 small installations (<2 MW) are waiting to finalize their authorization process, during which the following issues are typically addressed and resolved by the local scientific community: 1) the increase of hydraulic risk produced during extreme precipitation events; 2) the management of hydrometric stations located near the new installations; 3) the environmental impact; 4) the definition of selection criteria when in the same location there are two or more requests of hydropower installations.