An hydraulic turbine uses the potential energy of a water stream with an height difference between upstream and downstream sections. Turbines transform the potential energy into mechanical energy by the rotation impressed to the turbine axis by the mass of water passing through. The mechanical power obtained can be used directly to perform work (as in our ancestors mills ) or to produce electricity with the connection, trough a suitable gear, of the turbine axis to a generator. Today many opportunities are available for small-scale hydropower plants (2-3kW). In this case the turbine, which is the main component of the plant, can operate directly into the water stream, while larger size plant (> 20 kW), may use special civil works as adduction channels, filling tanks , penstock etc.., conducting water from the upstream section of the water stream and returning it to the river at a downstream point after the passage of water in the turbine. From operational point of view these micro plants are very easy to handle thanks to the remote monitoring and control systems applied and a limited demand of ordinary and extraordinary maintenance.

Restag supplies and installs :

- micro hydraulic systems rated less than 20 kW ( This power rating is the limit for home consumption; these plants are not considered electrical workshops and consequently have no right to sell the energy produced). Accordingly there is no taxation on their electricity production in accordance with Law 133/99, and they don’t have to be registered by UTF (Ufficio Tecnico di Finanza) because are not considered Electrical Workshops) .

- mini hydraulic systems with nominal power from 20 kW to 100 kW (plants capable of self-consuming the energy produced, in whole or in part, but also to sell the surplus). In this case, the installation is considered an Electrical Workshops and then an UTF application is required, with a consequent taxation; for mini hydraulic plants there are incentives related to energy sale price, while subsidies are related to operations, such as green certificates, as indicated by the “Bersani Decree”, and Recs certificates, a voluntary system of European green certification.