The thermal power plant of Vouvry, also known as the Chavalon Plant, is a former power station located in the municipality of Vouvry, in the canton of Valais, Switzerland. Until its closure in 1999, the plant utilized heavy fuel oil, combusted to heat a steam generator. The vaporized water then drove a turbine, which powered an alternator.
As Switzerland's sole oil-fired power plant, it was constructed in 1965 by a consortium led by the company (EOS) to address the wintertime electricity production deficits of Swiss hydropower. Initially planned on the territory of the commune of Aigle in the canton of Vaud, it benefited from its proximity to the Collombey refinery, enabling it to produce electricity at preferential rates. However, by the late 1990s, the plant operation had generated significant financial losses, leading the operators to decommission the site. Since then, several rehabilitation projects have been proposed, but the plant remains abandoned.
The plant site, situated approximately 450 meters above the plain, was constructed to limit pollution. It consists of two plateaus and a slope and includes a main building housing the machine room, a 120-meter exhaust chimney, four cooling towers, a cable car station, and 17 villas, which Chavalon employees previously inhabited. The plant is connected to the Collombey refinery by a pipeline that primarily traverses the , which was utilized to provide makeup water. The generated electricity was fed into the Swiss power grid via a 220 kV high-voltage line.
Geography
The Chavalon thermal power plant is situated in Switzerland, in the canton of Valais, on the territory of the municipality of Vouvry. It is located on the natural balcony of Chavalon, at an altitude of 825 meters, with a view of the from an altitude of 450 meters. The plant site is accessible from Vouvry by a cable car which operated between 1965 and 2005. Additionally, a road leads to the plant, diverging from the route to the village of Miex.
The plant buildings are distributed on a slope and two platforms are constructed from biogenic sedimentary rocks and evaporites based on limestone and, on occasion, marl. The platform for the plant building measures 27,000 m², while the one for the cooling towers is 10,000 m², for a total site area of 75,000 m².
History Genesis
In the 1950s, the Raffineries du Rhône company initiated a refinery project in the Swiss Chablais region. The Rhône pipeline was to transport oil from Genoa, Italy, to a refinery originally planned near Aigle in the canton of Vaud. However, since the pipeline passed through Valais, the canton requested that the refinery be located on its soil, and it was ultimately built in Collombey.
In 1959, the company (EOS) sought a solution to enhance its electricity production during winter months. To this end, it prepared a report recommending the expansion of hydroelectric plants and the construction of thermal power plants to address potential production shortages. Additionally, the report considered the feasibility of a nuclear power plant, although this technology was still in its developmental phase at the time. The presence of the Collombey refinery also facilitated the supply of a potential plant at favorable prices, thereby further motivating its construction.
To compensate for the change of canton of the refinery, the new plant was planned on the territory of the commune of Aigle. The project was led by a consortium between EOS and the "Raffineries du Rhône" company. In February 1961, a construction permit application was filed for a 150 MW plant with a 120-meter chimney at the site called "Les Îles." However, the project received 39 objections during the public inquiry, with the majority of concerns about sulfur dioxide (SO2) pollution and its potential impact on the local environment and public health. Following several appeals from the population and the commune of Ollon, the Council of State of Vaud imposed a minimum chimney height of 300 meters. This prompted a reaction from the Federal Office of Aviation, which declared in January 1962 that such a tall chimney would be "extraordinarily dangerous" for air navigation and decided to limit its height to 180 meters. As a result, the consortium was forced to seek a new location.
Subsequently, the project was evaluated at four potential locations, three within the canton of Vaud and one within Valais, at the site. The latter was selected as the most cost-effective option, estimated to be 25% cheaper than the others. To address the chimney issue, a "fumoduc" was proposed, which would vent the smoke to the Pro de Taila at an altitude of 1,270 meters. In 1962, the "Porte-du-Scex thermal power plant" company was established, with shareholders including EOS (40%), CFF (15%), Aluminium Suisse (10%), Lonza (10%), Raffineries du Rhône (5%), and Romande Énergie (5%). However, the soil quality at Porte-du-Scex proved to be inadequate, and ensuring the safety of a "fumoduc" system was challenging. The project was thus relocated once more, this time to the Pro de Taila site, which, however, proved to be excessively isolated. Ultimately, the Chavalon site was selected as a satisfactory compromise. The final construction site was confirmed in May 1963. The ventilation conditions at Chavalon were found to be optimal, and thus the chimney height was set at 120 meters. This height allowed the chimney to vent the plant's smoke at a height of nearly 950 meters above sea level, above the inversion layer (900 meters). Jean Lugeon, director of the Swiss Meteorological Institute, conducted environmental measurements and concluded that the risk of pollution should not exceed the tolerated time limit. The final project was approved on July 10, 1963, and the plant management company changed its name on January 21, 1964, to become "Vouvry SA thermal power plant." Facing financial difficulties, the "Raffineries du Rhône" sold its financial participation to the other shareholders in 1965.
Construction and commissioning
Construction commenced in September 1963 with the construction of a 1.2-kilometer access road. The road was designed to accommodate heavy transport vehicles and could support a maximum weight of 130 tonnes. The terrain where the road was constructed presented significant challenges, with retaining walls reaching up to 20 meters. Transporting construction materials was a significant undertaking, with long pieces transported on the road throughout the project. The longest piece transported was a 35-meter crane bridge. The two alternators for the plant were transported from Vouvry in 5 and 3 days, respectively.
Nearly 500 individuals were employed on the construction site, including 220 engaged in civil engineering work. René Vittone, the project's architect, indicated that the workers represented 22 different nationalities. All were supervised by a single site manager who resided on-site, with the construction barracks being repurposed from the Grande-Dixence dam construction. Excavation of the site commenced during the winter of 1963-1964, with a total of 120,000 cubic meters of terrain excavated, including 65,000 cubic meters of rock. In April, the first foundations were poured. The 120-meter-high chimney stack was constructed using a slip form—a mold that is slid along the wall as it is constructed—from July 17 to August 26, at a rate of 3 meters per day. The intensive use of metal frames and prefabricated parts allowed for the rapid construction of the main building, which was completed in November.
The technical equipment for the boilers, the machine room, and the control building was assembled in a workshop between February 1964 and May 1965. Assembly work commenced a month later, with the completion and commissioning of the plant's first production unit in September. The second unit became operational in November 1967. The total cost of the plant's construction was 215 million francs (equivalent to 757 million in 2024).
Operations (1965-1999)
Production
Although the plant was designed to meet winter consumption needs, in the early 1970s, it operated from September to May — or even June — to meet increased electricity demand. During this period, the production units were rarely shut down, with maintenance performed during the year-end holidays, Easter, and the three to four summer months when they were not in operation. The units could operate for up to 6,000 hours per year, consuming nearly 400,000 tonnes of heavy fuel oil to generate 1.8 terawatt-hours (TWh) of electricity.
The first oil crisis of 1973 resulted in a surge in fuel prices, with the price per barrel rising from $3 to $15. This led to a reduction in Chavalon's production, with the operational capacity of the production units limited to 4,000 to 5,000 hours per year, generating 1.35 TWh annually and supplying approximately 300,000 tonnes of fuel.
Following the second oil crisis in 1979, the plant's operating costs increased significantly, resulting in 14 million Swiss francs annual losses. The price of a barrel was $35. Production was slowed and only used to cover winter consumption peaks. Consequently, the plant's shareholders accelerated the depreciation of the installations and limited maintenance and revisions. On July 2, 1999, EOS announced that the plant would be decommissioned once the fuel reserves were depleted. At that time, the site employed 72 people, and it was estimated that production would cease between December 1999 and spring 2000. With the staff already laid off, the stock was quickly burned in September 1999 as a precautionary measure, and the plant was officially closed that same month. During its operational lifetime, the plant produced approximately 21.5 terawatt-hours (TWh) of electricity.
Working conditions
Chavalon, the sole oil-fired thermal power plant in Switzerland, employed a workforce that had undergone training provided by Électricité de France (EDF). This training is conducted at a French thermal power plant for one year, during which time the employees attend courses at EDF's training center. As a result, the plant's staff were qualified in electricity, chemistry, and mechanics, and employees rotated constantly to monitor the plant, which generally operated for 24 hours a day.
During the entire operational period of the plant, employees were permitted to reside with their families at Chavalon. As the villas were allocated to different occupational groups, an employee who changed positions was also required to relocate. Managers were obliged to reside on-site. Some workers, however, resided in Vouvry, and a bus served as a shuttle for them in the morning and evening. Families had access to the cable car at all times, which operated like an elevator. To attend school, a driver collected the children each morning before transporting them by cable car to their educational institution. Roland Fontana, a Chavalon operations agent between 1967 and 1999, noted that "living on-site gave the impression of never leaving work", yet the living environment was "pleasant".
Reassignment projects Following the plant closure, several proposals for its reuse were put forth. The municipality of Vouvry proposed the creation of an energy museum, while EOS initially considered selling portions of the plant to Turkey. In 2001, the cantonal police stored 35 million Swiss francs worth of seized hemp from Bernard Rappaz in the plant's buildings. When Sion was proposed as the host city for the 2026 Winter Olympics, a proposal later rejected by the Valaisan people, the Collombey refinery site was initially proposed for an Olympic village. Chavalon could have complemented this project. Finally, Chavalon was used as a set for television shows or photo shoots, and its chimney also served as a launch pad for base jumpers.