Supporting ENGIE in building a new large-scale battery park in Belgium

ENGIE has begun construction of a new Battery Energy Storage System (BESS) with a capacity of 74 MW/296 MWh at its Coo site in the province of Liège, Belgium. Tractebel is acting as Owner’s Engineer for the project.

Image: 3D modelling of the future BESS in Coo (© ENGIE)

The project will further strengthen Coo’s role as a major energy hub in Belgium, alongside the pumped-storage power plant, solar installations and electric vehicle charging infrastructure. Commissioning is scheduled for early 2028.

As Owner’s Engineer, Tractebel has supported ENGIE since the early development phase of the Coo BESS project. After contributing to the basic design and procurement, Tractebel is now working with ENGIE within an integrated team during project execution, following the same collaborative approach successfully applied for the BESS Drogenbos project. Tractebel is leading the technical oversight of the BESS, electrical, civil and fire safety works, as well as the design coordination and 3D modelling.

Following Vilvoorde, Kallo and Drogenbos, ENGIE is continuing the rollout of its large-scale BESS projects in Belgium. The future battery park at Coo will have an output of 74 MW and a storage capacity of 296 MWh. This will make it possible to store electricity when renewable generation is abundant and feed it back into the grid when demand is higher, delivering power at full capacity for up to four hours.

The project is fully aligned with ENGIE’s ENERGIZE 2030 strategy in Belgium, which focuses, among other priorities, on developing flexible assets capable of supporting the increasing integration of renewable energy into the electricity system. With the BESS projects already in operation or under construction in Vilvoorde (200 MW/800 MWh), Kallo (100 MW/400 MWh), Drogenbos (80 MW/320 MWh) and now Coo (74 MW/296 MWh)—representing a combined capacity of 454 MW and 1,816 MWh—ENGIE further confirms its position as a leading player in battery energy storage in Belgium.

At the Coo site, the new battery park will complement an already highly diversified portfolio of energy assets, including the Coo pumped-storage power plant (1,080 MW), whose capacity will soon be increased by 7.5% and which has been a cornerstone of the flexibility of Belgium’s electricity system for decades. The site also includes solar installations (715 kW, 2,640 photovoltaic panels) and electric vehicle charging infrastructure. The addition of a large-scale BESS will further reinforce Coo’s position as a future-oriented energy hub. The wind farm currently under development along Via Nova could strengthen this role even further.

Preparatory works on the site began in March 2026. Construction of the main project began on 3 August 2026, with commissioning planned for early 2028.