Return signs 200MW Dutch energy storage long-term agreement with Vattenfall

en.Wedoany.com Reported - On August 31, Return and Vattenfall signed a long-term fixed-price capacity usage agreement for the Sirius battery energy storage project, which also completed its financing arrangements. Located in Winschoten, Groningen province, the Netherlands, Sirius has a capacity of 200MW/800MWh with a four-hour storage duration and a total investment of approximately €180 million, with commercial operation scheduled for the fourth quarter of 2027.

Under the agreement, Vattenfall will acquire the right to use the charging, storage, and power delivery capacity of the Sirius project at a fixed fee and will be responsible for determining the battery's charging and discharging periods. The project will connect to TenneT's Meeden substation and will adopt a Time-Dependent Transmission Rights (TDTR) arrangement, adjusting charging and discharging operations based on available grid capacity.

The financing for the Sirius project has been incorporated into Return's broader battery energy storage project portfolio financing framework, which has secured up to €400 million in financing commitments from lenders including ING, NatWest, Deutsche Bank, ABN AMRO, and Rabobank. The Sirius project itself involves an investment of approximately €180 million, with ING Corporate Finance serving as transaction advisor and ING also participating as a lender in the financing.

Project construction and equipment supply involve Huawei, Hanab, and Omexom, covering battery technology, construction, and installation respectively. According to Return's project documentation, Sirius has a capacity of 200MW/800MWh and is planned to connect to the 220kV grid in the Meeden area.

This collaboration builds on the two companies' previous energy storage capacity cooperation. In 2025, Return and Vattenfall signed a long-term agreement covering 50MW of capacity from Return's Antares energy storage project in Waddinxveen. The Antares project has a total capacity of 100MW/200MWh, and the contract previously signed by the two parties has a term of 8 years.