Construction has officially started on Green Turtle, Belgium’s largest energy storage facility, a 700 MW/2.8 GWh battery energy storage system (BESS) being developed by GIGA Storage in Dilsen-Stokkem, in the Belgian province of Limburg.

The facility will comprise 640 Tesla Megapack 3 batteries, alongside 188 medium-voltage transformers and four high-voltage transformers. According to the current schedule, Green Turtle is expected to enter operation at the end of March 2028.

Preparatory earthworks and roadworks began in mid-August. Battery installation, cabling and high-voltage infrastructure will follow during the construction phase.

Tesla to supply 640 Megapack 3 units

Tesla has been selected as the engineering, procurement and construction (EPC) partner and will be responsible for engineering and construction, supplying the Megapack 3 batteries and providing long-term maintenance. Stadsbader Contractors will carry out the civil works on Tesla’s behalf.

Green Turtle will use cobalt-free lithium iron phosphate (LFP) batteries, which says combine safety and long service life with reduced dependence on critical raw materials.

The project represents a total investment of approximately €700 million. Its financing reached financial close on 9 July, with a consortium of ten international banks providing €450 million in debt financing and the remainder supplied as equity by InfraVia Capital Partners.

Direct connection to Belgium’s 380 kV grid

The project is being developed on approximately 12 hectares next to Elia’s future high-voltage substation and the 380 kV Van Eyck-Gramme transmission line, allowing the battery system to connect directly to Belgium’s high-voltage grid.

Once operational, Green Turtle will store surplus electricity, including production from solar and wind generation, and return it to the grid when electricity demand exceeds supply. Its capacity will also be available to Belgian transmission system operator Elia and market participants providing grid-balancing and congestion-management services.

At peak periods, estimates the facility will be capable of supplying electricity equivalent to the daily consumption of approximately 385,000 households.

The company describes the 2.8 GWh development as one of Europe’s largest battery storage projects. Green Turtle is also included in the TYNDP 2026 system study and has received the European Commission’s STEP label.