The maintenance operations planned for some of the hydropower complexes this winter could be postponed in order to ensure that these power plants and the reservoir storage capacities will be available during the cold season. The assets, energy and trading management teams have reviewed the maintenance plans, recalculated the costs and drawn up new production plans to determine where they can gain valuable kWh this winter. For example, at the pumped storage power plant of Forces Motrices Hongrin-Léman (FMHL), the renovation work on the East adduction gallery, which is being carried out over three seasons, was initially planned to take place between July 2022 and March 2023. However, renovation work will now stop in mid-December. This urgent measure will enable us to harness more natural inflows and thus increase by 10 GWh the energy available for this winter.
In Martigny, Forces Motrices de Martigny-Bourg postponed the repair of the penstock’s anti-corrosion protection, the renewal of the coupling station and the installation of a new turbine on the tailrace – works requiring the shutdown of this run-of-river power plant. The energy increase will be 15 GWh this winter.
The most important measure concerns Forces Motrices de la Gougra’s storage power plant in the Val d'Anniviers. All renovation works have been postponed until next year, allowing an additional 150 GWh to be gained for the first quarter of 2023.
Forces Motrices de la Gougra are currently renovating the Mottec and Vissoie power plants. Two of the three units in the Mottec power plant have already been refurbished in the last two years. The postponement therefore concerns the third unit for which we still have to replace the turbine. In Vissoie, we are planning to replace all three units in the power plant over three years. The start of this work has been postponed for one year.
We also have to renew the anti-corrosion protection of the reinforced shaft that connects the Moiry dam to the Mottec power plant, which means taking the entire facility out of service. This work will not start until next year.
Once completed, the renovation work will increase the capacity of the Mottec power plant from 69 to 87 MW, and the Vissoie plant from 46 to 57 MW. This will enable us to produce approximately 8 million additional kWh per year and reach an average annual production of 650 GWh. It will also allow us to increase the water flow and, in turn, the facility’s power by 25%. The facilities will thus benefit from a wider adjustment range for electricity grid services (ancillary services). The postponement of the work means that we will have to wait another year before we can enjoy these benefits.
We are currently in intensive discussions with the suppliers and partners involved, as we all need to review schedules, payment plans, warranty conditions and find solutions for storing parts in production.
These measures certainly come at a cost, but this is more than offset by the additional energy we will be able to make available in the critical late winter months. The Moiry reservoir is currently full and we will therefore be able to operate the facilities at full capacity in the first quarter of 2023. Such measures have allowed Alpiq to participate in the Swiss confederation’s hydropower reserve.