COO-Trois-Pont Pumped Storage Upgrade

The Challenge

Increase the storage and power performance of the existing Coo pumped‑storage plant by 7.5% while safeguarding reliable operations for the next 40 years. The upgrade had to be conceived and delivered on a live, grid‑critical asset, balancing stringent technical, scheduling and regulatory requirements.

The Solution

Tractebel delivered end‑to‑end Owner’s Engineering services across all project phases: a feasibility study followed by finite element analysis (FEA) and fatigue calculations for key components; preparation of tender documents for construction and for equipment procurement/erection; evaluation of bids and support to contract negotiations. During execution, our teams provided continuous technical and contractual assistance, detailed design reviews, factory inspections, construction supervision and commissioning support—ensuring that every decision aligned with performance, safety, and lifetime objectives.

The Impact

The project delivers a 7.5% capacity uplift, translating into +450 MWh of additional energy storage (linked to +600,000 m³ of reservoir volume) and +79 MW of power output (3 × 26.5 MW), while setting the plant up for four decades of reliable service. This performance step‑change also enables eligibility for an 80% grid‑cost exemption over five years, strengthening the project’s economics and the plant’s role in Belgium’s flexible, low‑carbon power system.