Bay d’Espoir Hydro Electric Facility Upgrades

One plan for increasing energy capacity while safeguarding the reliability of service to customers is an expansion to add an eighth generating unit, which has long been determined as a viable and preferable resource to develop for additional firm capacity supply for the island.

The Bay d’Espoir Unit 8 Project will supplement the existing Bay d’Espoir development by expanding the existing Powerhouse No. 2 for the addition of a new hydroelectric generating unit.

The Project will include the engineering, procurement, construction, installation, commissioning, and testing of all works associated, including:

• Headrace channel enhancements.
• New intake, intake building, penstock and ancillary services.
• Expansion of existing Powerhouse No. 2.
• New turbine – generator (nominal capacity of 150 MW) to be installed in the Powerhouse No. 2 expansion.
• New transformer and isolated phase bus.
• New auxiliary mechanical, electrical, protection and control, telecontrol and telecommunications and communications equipment.
• Tailrace channel enhancements.
• New 230 kV transmission line from new Unit 8 step-up transformer to the existing Terminal Station No. 2.
• Expansion and modifications to Terminal Station No. 2 to accept transmission line interconnection.

The Bay d’Espoir facility consists of seven hydro units capable of producing a total of over 600MW. These units are fed by three penstocks.

Construction began on Penstock 1 in 1965 and was commissioned along with Units 1 and 2 in 1967. Penstock 1 now requires partial replacement and refurbishment due to recurring weld seam failures and Hydro is undertaking a project to extend the life of the asset and return it to reliable operation.

Work will include (1) excavation, demolition, disposal and replacement of the approximately 1,100 foot long existing steel section including exterior protective coating and associated backfill, (2) detailed inspection of approximately 2,600 foot long existing penstock, including full remediation of any deteriorated welds and/or steel, and application of a protective coating on the interior, and (3) provision of supporting activities, such as excavation and backfilling tasks, drainage system upgrades and installation of pressure monitoring systems.

Penstocks 2 and 3 are expected to require partial replacement and refurbishment due to recurring weld seam failures. This project will extend the life of these assets, returning them to reliable operation.

The penstocks are each approximately 1,200 meters in length and constructed from a series of steel cans that vary in length and plate thickness. The penstocks range in diameter from 5.2 meters at the intake to 4.1 meters at the powerhouse bifurcation and are buried along their entire length.

Work will include (1) excavation, demolition, disposal and replacement of the approximately 335 meter long existing steel section including exterior protective coating and associated backfill; (2) detailed inspection of approximately 792 meter long existing penstock, including full remediation of any deteriorated welds and/or steel, and application of a protective coating on the interior; and (3) provision of supporting activities, such as excavation and backfilling tasks, drainage system upgrades and installation of pressure monitoring systems.

Our assets require proactive monitoring and maintenance to ensure that they are capable of efficient and effective operations. Unit 7 is an existing 154 MW hydroelectric generating unit (the largest unit at our Bay d’Espoir facility), which has been in operation since 1977. A condition assessment completed in 2023 recommended that the unit undergo a major refurbishment in order to extend its operating life, ensure continued reliable operation, and potentially increase energy production. The work being planned will involve the complete dismantling of the unit to allow for replacement of the turbine runner, rewinding the stator, reinsulating the rotor field windings along with inspection, and repair or replacement of numerous components such as the wicket gates, head cover, bottom ring and operating mechanism.