Hydroelectric

The Italian expertise

Hydro energy is the first renewable energy source adopted in Italy and Italian companies have been developing, installing and operating hydroelectric power plants for more than one century. Italian companies can provide top technologies and products ranging from tubes, hydro-pumps and turbines, to civil and electro-mechanical planning and construction.

Italian excellences have dealt with design, manufacturing, installation and commissioning of steel penstocks and hydromechanical equipment for hydraulic and hydroelectric projects all over the world.


Hydro power plants

A hydro power plant converts potential energy of water into rotational mechanical energy, which spins a turbine and is directly converted to electricity through a generator
A hydroelectric scheme consists of civil engineering and hydraulic structures and electromechanical equipment. 

A hydroelectric scheme includes:
  • dam or weir across a stream, which may create a reservoir volume, permitting or not permitting the storage of natural flows, with one or multiple intake gates, followed by a stilling basin and silt-trap scour gates;
  • diversion canal and/or diversion tunnel and one forebay, usually provided with outlet works;
  • one or more penstocks conveying water to the hydraulic turbines;
  • powerhouse or power plant, equipped with one or multiple turbine-generator units, which release the turbined water into the streambed downstream of the dam.
Hydro power plants are classified on the basis of the filling period of their reservoir, i.e. the time required to fill the reservoir with a volume of water equal to its active storage capacity, at the yearly mean water inflows.

Accordingly, hydro power plants are categorised as follows:
  • reservoir hydro with a maximum filling period equal to or longer than 400 hours;
  • pondage hydro with a weekly or daily “modulation reservoir” and a filling period shorter than 400 hours and longer than 2 hours;
  • run-of-river hydro without reservoir or with a reservoir having a filling period equal to or shorter than 2 hours. They are generally located along streams or drainage canals; their generation depends on the flow available in the stream or canal. It includes plants in aqueducts where the hydraulic turbine can replace the pressure reducing valve in order to recover the otherwise lost energy.


 Number and capacity of hydro power plants in Italy

2011​ ​ 2012​ ​ 2012/2011 % Change ​
Capacity Class no.​ ​MW no.​ MW​ no.​ MW​
C ≤ 1 MW 1.858​ 567,7​ 1.886​ 590,8​ 1,5​ ​4,1
1 MW < C ≤ 10​ 743​ 2.328,3​ 781​ 2.395,9​ 5,1​ 2,9​
C > 10 MW​ 301​ 15.196,2​ 303​ 15.245,3​ 0,7​

0,3

Total​ 2.902​ 18.092,3​​ 2.970​ 18.232,0 2,3​ 0,8​

 

The table displays the number and gross maximum capacity of renewable hydro power plants, including mixed pumped-storage plants; for the latter, only the generation from natural inflows is taken into account. Pure pumped-storage plants are thus excluded.
The capacity class with the highest number of plants is the one lower than or equal to 1 MW (63%), followed by the one in the range of 1 - 10 MW. The national hydro generating mix mostly consists of few large-sized plants.