Entracque Power Plant
{{Infobox dam
| name = Entracque Power Plant
| name_official = Centrale Idroelettrica Entracque
| image = Entracque diga Chiotas1.jpg
| image_caption = The Chiotas Dam
| image_alt =
| coordinates = {{coord|44|13|29|N|07|23|10|E|type:landmark|display=inline,title}}
| country = Italy
| location = Entracque
| status = O
| construction_began = 1969
| opening = 1982
| demolished =
| cost =
| owner = Enel
| operator =
| res_name = Chiotas Plant: Lago del Chiotas
Rovina Plant: Lago della Rovina
| res_capacity_total = Chiotas Plant total:{{Convert|30200000|m3|acre.ft|0|abbr=on}} Chiotas active: {{Convert|27300000|m3|acre.ft|0|abbr=on}} (active (usable))
Rovina: {{Convert|1200000|m3|acre.ft|0|abbr=on}} (active (usable))
| lower_res_name =Lago della Piastra
| lower_res_capacity_total = Total: {{Convert|12000000|m3|acre.ft|abbr=on}}
Active: {{Convert|9000000|m3|acre.ft|abbr=on}}
| plant_pumpgenerators =Chiotas: 8 x {{convert|148|MW|abbr=on}} Francis-pump turbine
Rovina: 1 x {{convert|133.67|MW|abbr=on}} Francis-pump turbine
| plant_turbines =
| plant_pumps =
| plant_hydraulic_head = Chiotas: {{Convert|1048|m|abbr=on}}
Rovina: {{Convert|598|m|ft|0|abbr=on}}
| plant_capacity = Chiotas: {{convert|1184|MW|abbr=on}} MW
Rovina Plant: 133.67 MW
Total: {{convert|1317.67|MW|abbr=on}}
| plant_capacity_factor =
| plant_annual_gen = Chiotas: {{convert|1040|GWh|abbr=on}}
| website =
| extra =
}}
The Entracque Power Plant, also known as The Upper Gesso Plant, is a pumped-storage hydroelectric power station located in Valle Gesso just south of Entracque, Italy. The power station contains pump-generators for two co-located but hydraulically separated power schemes; the Chiotas-Piastra Plant and Rovina-Piastra Plant. Both plants use separate upper reservoirs but use Lago della Piastra as their common lower reservoir. To produce power, water is released from the upper reservoirs to the power station located at the lower reservoir. The pump-generators re-fill the reservoirs and the process repeats as needed. The Chiotas' upper reservoir, Lago del Chiotas, is located much higher in the valley and larger than Rovina's Lago della Rovina which affords it the ability to produce more electricity. The installed capacity of Chiotas is {{convert|1184|MW}} with a hydraulic head (water drop in elevation) of {{Convert|1048|m|ft|0|abbr=on}} while Rovina has an installed capacity of {{convert|133.67|MW}} and a head of {{Convert|598|m}}. Construction on the plant began in 1962 and operations started in 1982. It is owned and operated by Enel.{{cite web |title=Entracque Power Plant - Enel |url=http://www.entracque.org/divertimenti/energia.aspx |publisher=City of Entracque |accessdate=13 January 2012 |language=Italian |url-status=dead |archiveurl=https://web.archive.org/web/20150629022447/http://www.entracque.org/divertimenti/energia.aspx |archivedate=29 June 2015 }}
Design and operation
File:Entracque Diga piastra.jpg
The Entracque Power Plant is supported by a scheme that also primarily consists of three reservoirs. The lower reservoir used by both the Chiotas and Rovina is Lago della Piastra. The reservoir is located at the base of the valley and was formed by the construction of an {{Convert|88|m|ft|adj=on}} tall gravity dam. Its water level has a normal operating elevation of {{Convert|956|m}} and {{Convert|9000000|m3|acre.ft}} of its total {{Convert|12000000|m3|acre.ft}} storage capacity can be pumped up to the upper reservoirs. The pumping is carried out by the power station's nine Francis pump turbine-generators, eight belong to Chiotas and one to Rovina. When either of the upper reservoirs needs to be filled, water is pumped from Piastra to the Chiotas or Rovina upper reservoirs through a series of penstocks and tunnels. This usually occurs during periods of low energy demand, such as at night, when electricity is cheap.{{cite web |title=The Upper Gesso Plant |url=http://www.wplgroup.com/aci/eu-partners/ees1-site-visit.asp |publisher=Active Communications International |accessdate=13 January 2012 |url-status=dead |archiveurl=https://web.archive.org/web/20120804041717/http://www.wplgroup.com/aci/eu-partners/ees1-site-visit.asp |archivedate=4 August 2012 }}{{cite book|last=Engineers|first=prepared by Task Committee on Pumped Storage of the Committee on Hydropower of the Energy Division of the American Society of Civil|title=Hydroelectric pumped storage technology : international experience|year=1996|publisher=American Soc. of Civil Engineers|location=New York, NY|isbn=0-7844-0144-6|pages=3.7 1–5|url=https://books.google.com/books?id=iCSl-pxL7IwC&q=Chiotas-Piastra+Pumped+Storage+Scheme&pg=PA48-IA151}}
The Rovina's upper reservoir is at an elevation of {{Convert|1535|m}} and is formed by an embankment dam. It has an active capacity of {{Convert|1200000|m3|acre.ft}} and depth of {{Convert|10|m}}. Its catchment area is {{Convert|77.2|km2|mi2}}. The upper Chiotas reservoir was formed with the construction of a {{Convert|130|m|adj=on}} tall arch-gravity dam which lies at an elevation of {{Convert|1978|m}}. The dam's thickness ranges from {{Convert|37.5|m}} at the base to {{Convert|5|m}} at its crest. Its crest is {{Convert|230|m}} long and the dam has a structural volume of {{Convert|360000|m3|cuyd}}. The Chiotas reservoir is also supported by a {{Convert|30|m|adj=on}} tall and {{Convert|70|m|adj=on}} long saddle dam, called Colle Laura, directly to its east. The saddle dam is also equipped with a spillway that has a discharge capacity of {{Convert|240|m3/s|ft3/s}}. The storage capacity of the reservoir is {{Convert|30200000|m3|acre.ft}} while {{Convert|27300000|m3|acre.ft}} can be used for power generation. The catchment area for Chiotas is {{Convert|11.6|km2|mi2}} and the reservoir reaches a maximum depth of {{Convert|118|m}}.
When power generation is required, water is released from either upper reservoir back down to the power station and its generators. The power station is located underground and consists of transformer, valve gallery and generator hall caverns. From the Chiotas reservoir, water is sent back through a {{Convert|7.4|km|adj=on}} long tunnel and when near the power plant, it splits into a {{Convert|1.7|km}} system of penstocks which feed each of its eight {{convert|148|MW}} pump-generators. Water from the Rovina is processed by a single {{convert|133.67|MW}} generator. After the water is used for power generation, it is discharged into a {{Convert|500|m|adj=on}} long tail-race tunnel and into Lago Della Piastra. Both the tail-race and power plant intake are protected from water hammer by surge tanks. The drop in elevation between the upper reservoirs and the power plant afford the Chiotas a maximum hydraulic head of {{Convert|1048|m}} and the Rovina {{Convert|598|m}}.
See also
{{stack|{{Portal|Italy|Water|Renewable energy}}}}
References
{{Reflist}}
External links
- {{Commons category-inline|Chiotas dam}}
{{Piedmont|state=collapsed}}
Category:Pumped-storage hydroelectric power stations in Italy
Category:Underground power stations
Category:Buildings and structures in Piedmont
Category:Buildings and structures in the Province of Cuneo
Category:Dams completed in 1982