Cable connection to the main Hydro-Québec grid through Gaspésie

Hydro-Québec plans to install a link consisting of two subsea cables extending approximately 225 km to connect the archipelago to Gaspésie between Cap-aux-Meules substation and Percé substation, in Val-d’Espoir. Commissioning is planned for 2027.

The project also includes the construction of two underground transmission lines between the subsea cables and existing systems:

  • A line extending 8–20 km between the Gaspésie coast and Percé substation
  • A line extending some 8 km between the Gaspésie coast and Cap-aux-Meules substation
  • The cables will have an 80-MW capacity.

Finally the project calls for the addition of two converters:

  • One at Percé substation, to convert the alternating current into direct current, and
  • Another at Cap-aux-Meules, to convert the direct current back into alternating current
Video: Connecting Îles-de-la-Madeleine: Making the islands even greener

Stringent requirements for project execution

In developing each new project, we work to strike a balance between the following four aspects: reliability, community needs, environmental factors and economic considerations.

  • Maintain employment levels and create new opportunities
  • Adapt energy efficiency programs (such as the Efficient Energy Use Program)
  • Hydropower supplied by two strong cables with an 80-MW capacity
  • Durable solution that will meet the needs of island residents for the next 40 years or more
  • Seabed uses and particularities taken into account in designing and installing subsea cables
  • Preservation of the thermal power plant as a microgrid backup facility for greater flexibility (intermittent production, maintenance, to manage peaks in demand, etc.)
  • Respect our employment-related commitments
  • Economic spinoffs during construction and operations
  • Use of green energy as a lever for economic development (capacity exceeds current needs)
  • Lower Hydro-Québec costs – conducive to maintaining affordable rates

  • Reduction in greenhouse gas emissions by 94%
  • Factor conducive to converting all customers to electric heating
  • Limited environmental impact
  • Factor conducive to the electrification of ground and maritime transportation

Marine surveys

An initial series of geophysical surveys was carried out in May and June 2019 and a second series of geophysical and geotechnical surveys took place in spring and summer 2021. The seabed was studied and mapped to determine its bathymetry and surface sediments (in the top five metres) and to image the seabed, in particular to identify obstacles.

The surveys enabled us to identify a route for the cables, determine our installation methods and calculate project costs. We took advantage of the geotechnical surveys to conduct benthic fauna sampling and learn more about the benthic communities found along the subsea cable route.

From 2018 to 2020, oceanographic moorings have been installed at depths of 10 m and 100 m from October to April close to the Gaspésie and Îles-de-la-Madeleine coasts in order to collect data on:

  • Waves (amplitude, direction, statistics)
  • Water conductivity
  • Water temperature
  • Tides
  • Currents (speed and direction) along the entire water column

Technical description of the project

At this stage of the project, it is too early to determine schedules and work methods. However, we will endeavor to tailor them to the concerns of the community and users.

Choice of sites

Hydro‑Québec began by defining a study area in order to develop alternative routes for the underground and underwater line between Percé and Cap-aux-Meules substations. The approximately 10,560 km2 study area covers both marine and terrestrial areas and is large enough to take into account technical constraints and sensitive environmental aspects. It avoids protected marine areas, provincial borders, special purpose sites (e.g., military) and the Irving Whale shipwreck.

Hydro-Québec wishes to design a project that will respect various technical, economic, social and environmental criteria. To do so, the project team will adapt the project and construction methods to minimize impacts. This approach includes close collaboration with land users, and fishers in particular.

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