Maggia power plants

Maggia Kraftwerke AG / Officine Idroelettriche della Maggia SA
legal form	Aktiengesellschaft (Switzerland)
founding	December 10, 1949
Seat	Locarno TI Switzerland
management	Hofstetter Marold
Branch	power supply
Website	www.ofima.ch

Maggia power plants
Three of the eight reservoirs of the Maggia power plants near Robièi. From left to right: Lago del Zött , Lago di Robièi and Lago dei Cavagnöö .
location
Canton Ticino , Switzerland
Coordinates	698805  /  109749
country	Switzerland  Ticino
place	Val Bavona , Valle Maggia
Waters	Lago di Robièi , Lago del Narèt , Lago del Sambuco , Lago dei Cavagnöö , Griessee , Lago Sfundau , Lago di Palagnedra , Lago del Zött , Maggia , Bavona , Rovana , Isorno , Melezza
Data
Type	Storage power plant group with two pumped storage power plants
Primary energy	water
power	turbine: 596 MW pump: 162 MW
owner	Maggia Kraftwerke AG owned by: Axpo Holding (30%) Canton of Ticino (20%) Alpiq Holding (12.5%) IWB (12.5%) EWZ (10%) BKW Energie AG (10%) Energie Wasser Bern (5%)
Project start	1949
Start of operations	1955
Energy fed in 2019	1378 GWh
was standing	2020

The Maggia Kraftwerke AG , Italian Officine Idroelettriche della Maggia SA , shortly Ofima , based in Locarno uses the water power in the catchment area of the river Maggia in Canton Ticino for generating electrical energy. It is the most powerful power plant group in Ticino.

history

On March 10, 1949, the Grand Council of the Canton of Ticino granted the concession for the use of the Maggia and its tributaries as far as Lake Maggiore, and Ofima was founded on December 10 of the same year. In the years 1950 to 1955, the first expansion stage with the reservoir Lago del Sambuco and the power plants Peccia, Cavergno and Verbano was created. The concession for this runs until 2035. In the 1960s, the storage basins Lago dei Cavagnöö , Lago del Narèt , Lago di Robièi , Lago del Zött and the Bavona power plant, which are licensed until 2048, followed.

A third stage originally planned was not implemented. For example, thought was given to the Laghi della Crosa at the back of the Val Calnègia at a kote of 2,116  m above sea level. M. damming up and their water with a 7.5 km long tunnel to a center on the Alp Zött, which would have released the water into the Lago del Zött. The damming of Lago Bianco and the construction of run-of-river power stations near Cevio or in the side valleys of Calneggia and Vergeletto were also dispensed with. Other projects in the third stage were included in the second stage, such as B. the construction of the Lago del Zött or the use of the Lago Sfundau.

Robièi tunnel accident

In the second expansion phase, a serious accident at work occurred during the construction of the 13 km long free surface tunnel between the Altstafel machine house and Lago di Robièi. The tunnel was ready broken out, the breakdown between the Bedrettotal and Robièi in mid 1965. To the finishing works on the south end of the tunnel not to hinder, was about 3.2 km from Robièi away a bulkhead ^▼ in the tunnels built to the ground and stopped seeping water from the uphill part of the tunnel. The accumulated water in the upper part of the tunnel had to be drained from time to time through a slide valve with a diameter of approx. 30 cm in the bulkhead into the part of the tunnel down the valley. This work was carried out once in 1965 and was repeated on February 15, 1966, with an estimated 4000 m³ of water to be drained. Because of the stale, oxygen-poor air built up on the bulkhead, two firefighters from Locarno were commissioned with this work , who, equipped with breathing apparatus , climbed to the bulkhead accompanied by the Robièi site manager. They were able to open the slide properly, but the escort team, who had remained at a safe distance, noticed a short time after opening the slide that the light from the lamps of the ascended had disappeared. Later they could only be recovered dead. Two groups of Italian guest workers died on the north side of the bulkhead . In total, the accident claimed 17 lives, who had died from suffocation. It caused international tensions between Switzerland and Italy because Italy questioned the safety of the construction sites in Switzerland. The accident occurred just six months after the accident on the construction site of the Mattmark dam , where the demolition of the Allalin glacier destroyed the barracks on the construction site and 88 construction workers were killed - mostly Italians.

Holdings

The following companies are involved in Maggia Kraftwerke AG:

• Axpo Holding (30%)
• Canton of Ticino (20%)
• Alpiq Holding (12.5%)
• IWB (12.5%)
• Electricity company of the city of Zurich (10%)
• BKW Energie AG (10%)
• Energie Wasser Bern (5%)

Power plants

Maggia Kraftwerke AG Reservoirs and power plants in the Maggia catchment area

Legend Griessee 2386  m Altstafel power plant 1975  m Cantonal border Valais - Ticino Lake Naret 2310  m Setting of 5 streams Lake Cavagnöö 2310  m Version of 6 streams Robiei power station 1878  m Setting of 3 streams Lago di Robiei , Lago del Zött 1940  m Lago del Sambuco 1461  m Setting of 2 streams Bavona power plant 1050  m Peccia power station 1036  m Setting of 2 streams Setting of 3 streams Peccia compensation pool 1032  m Cavergno power station 528  m Version of 8 streams Melezza tributary Lago di Palagnedra reservoir 486  m Overflow into the equalization pool Lago di Palagnedra compensation basin 486  m Bypass tunnel compensation basin Melezza drain Verbano power station 203  m Lake Maggiore near Brissago 193  m

The power plants have a total installed capacity of almost 600 MW ( megawatts ). The storage lakes of the power plant group serve not only to cover the additional energy requirement in winter but also to generate peak energy .

In addition to the two double Pelton turbines, two horizontal two-stage radial pumps are installed in the Peccia headquarters, which pump water back from the equalization basin into the Lago del Sambuco during off-peak periods. Since 1991, a small vertical Kaplan turbine has been using the gradient between the Corgello water intake, where water from the Maggia is diverted, and the Peccia compensation basin.

The Robièi water center uses excess energy in the network to pump water from the Lago di Robièi into the Lago dei Cavagnöö. It is equipped with four pump turbines and one Isogyre pump turbine for this purpose . At the time of commissioning, the headquarters was the first machine house in Switzerland to be equipped with reversible pump turbines, which would later become the standard, and at the same time an Isogyre pump turbine was used for the first time in a power plant. The type of pump turbine developed by Ateliers des Charmilles SA in Geneva did not require a change of direction of rotation between pump and turbine operation, which meant that it was possible to switch between the operating modes very quickly.

A special feature is the Altstafel headquarters, the top headquarters of the power plant group, on Valais soil. It is operated by Kraftwerk Aegina AG , in which the Rhonewerke has a 50% stake.

In October 2018, the was small hydropower plant Borgnone put into operation, the turbines the water from the tunnels Cavergno-Palagnedra while the gap between the water intake of Isorno exploits and Lago di Palagnedra. The usable gradient is between 6 and 16 m depending on the water level of the lake.

Headquarters	turbine	mean usable gradient (m)	Revolutions per minute	function	commissioning acceptance	Energy in GWh (per year)	Bottleneck capacity (MW)
Altstafel ▼	1 × Francis	384	1500	turbine	1967	21.6	9.2
Robièi ▼	4 × pump turbo. 1 × Isogyre	338	Francis: 1000 Isogyre: 1500	turbine	1968	30.4	165
				pump		24.9	140
Bavona ▼	2 × Pelton	887	428	turbine	1966	324	124
Peccia ▼ (Sambuco)	2 × double pelton	381	300	turbine	1955	85.4	44
	2 × two-stage radial pumps	374	1000	pump		12	22nd
Peccia ▼ (Corgello)	1 × chaplain			turbine	1991	2	1
Cavergno ▼	4 × Pelton	489	375	turbine	1955	398	104
Borgnone	1 × chaplain	11		turbine	2018	11	2.8
Verbano 1 ▼	4 × Francis	255	600	turbine	1953	346	96
Verbano 2 ▼	1 × Francis	255	500		1973	160	50
Total					Turbine	1378	596
					pump	36.9	162

Reservoirs

Location map of the power plants

The Maggia power plants draw their water from five larger reservoirs and three smaller reservoirs. The Lago del Narèt is a natural lake, the underground drainage of which has been sealed.

Lakes	Dam wall	First Damming	Usable content (Million m³)	Energy content (Million kWh)	Altitude (m above sea level)
Griessee ▼	Weight wall	1965	18th	63	2386
Lago dei Cavagnöö ▼	Arched wall	1968	28	104	2310
Lago Sfundau ▼	sealed Natural lake	1968	4.1	15th	2351
Lake Narèt ▼	Arched wall Weight wall	1969	31.1	115	2310
Lake Robièi ▼	Weight wall	1967	6.5	157	1940
Lago del Zött ▼	Arched wall	1967	1.2	2.4	1940
Lago del Sambuco ▼	Arched wall	1956	63	109	1461
Lake Palagnedra ▼	Arch weight wall	1952	4.8	3	487
Total			157	568

literature

• Ofima (Ed.): Ofima, an exciting challenge . Operator's brochure. ( ofima.ch [PDF]).
• A. Kaech: The hydropower of the Maggia Valley: Description of the concession project from January 1949 . In: Schweizerische Bauzeitung . 1949, doi : 10.5169 / SEALS-84018 .
• Jean-Emile Graeser: The electromechanical equipment of the Robiei cavern center . In: Schweizerische Bauzeitung . 1970, doi : 10.5169 / SEALS-84449 .

Web links

Commons : Maggia Kraftwerke  - Collection of images, videos and audio files

• Officine Idroelettriche della Maggia SA. Retrieved June 6, 2020 (Official Website). 
• Maggia. Images and texts from the 50th anniversary volume of Ofima 1949-1999 . Retrieved June 6, 2020 . 

Individual evidence

1. ^ Officine Idroelettriche della Maggia SA. Commercial register of the canton of Ticino, accessed on June 6, 2020 . 
2. ↑ About OFIMA. OFIMA, accessed June 13, 2020 . 
3. ↑ A. Kaech: The water forces of the Maggia valley
4. ^ Radiotelevisione svizzera: Robiei, 50 anni dalla tragedia. News report on the 50th anniversary of the accident. In: RSINews. Radiotelevisione svizzera, accessed on June 11, 2020 (Italian, at 06:46 the bulkhead with the slide is visible). 
5. ↑ Major risks - if the catastrophe suddenly occurs. SUVA, accessed on June 11, 2020 (section disasters with aftermath ). 
6. ^ Mattmark - the disaster in the Alps. SUVA, accessed on June 11, 2020 . 
7. ^ Officine Idroelettriche della Maggia SA. Retrieved on June 6, 2020 (section Participation ratios in share capital ). 
8. ↑ System scheme. Ofima, accessed June 6, 2020 . 
9. ^ Jean-Emile Graeser: The electromechanical equipment of the Robiei cavern center . 1970, p. 219 , doi : 10.5169 / SEALS-84449 .
10. ↑ EnAlpin AG - Kraftwerk Aegina AG. Retrieved June 8, 2020 . 
11. ↑ Ofima (ed.): Inaugurazione della nuova centrale di Borgnone . October 12, 2018 ( ofima.ch [PDF]).

 Map with all coordinates: OSM | WikiMap