RWE takes final investment decision to build 1.1 GWh battery in the Netherlands

German energy major RWE has made its final investment decision to build a 400 MW / 1.1 GWh battery storage system at the Moerdijk power station site in the Netherlands using its existing 150 kV substation at Moerdijk-Noord.

The Moerdijk plant, located south of Rotterdam, was primarily a 426 MW gas-fired combined cycle gas turbine (CCGT) power plant, and the site had a small battery system acting as one of the first synthetic inertia batteries on the European grid, via a 7.5 MW / 11 MWh installation.

In a sign of the times, the new battery, with 208 containers from an unspecified manufacturer, will be exactly 100 times larger. The system size at a 2.75-hour duration suggests a split of around 1.92 MW / 5.29 MWh per container, and it will also provide “advanced grid services,” indicating the use of grid-forming inverters.

Construction is scheduled to “start in due course,” said RWE, and commissioning is planned for the second quarter of 2028.

Connection details

Grid connections for generation or demand in the Netherlands are in tremendously short supply, with Transmission System Operator TenneT unable to process an enormous backlog due to system congestion. New batteries added to the grid can either aid the system or add their own capacity demands on already stretched substations and transmission lines.

The Moerdijk battery, however, will be dispatched to relieve congestion. This also plays into the nearby 795 MW offshore wind project between RWE and TotalEnergies, helping store energy when wind output is high.

In the press release, RWE stated: “Through capacity steering agreements with Transmission System Operator TenneT, the battery will be dispatched to relieve congestion in the Noord-Brabant region. Thanks to this development, space is being created on the grid for parties on the waiting list who wish to purchase electricity. TenneT, together with the regional grid operator Enexis, will be investigating what this means in the coming period. The grid operator will take this development, along with other developments in the region, into account when reviewing the congestion management study in December of 2026. The new battery system will also be equipped to provide advanced grid services such as instantaneous reserve (inertia). The Moerdijk site already hosts the first synthetic inertia battery connected to the continental European grid, with a capacity of 7.5 MW/11 MWh.“

Mark Lentjes, Regional Director of TenneT Southern Netherlands, added: “We are pleased that RWE intends to contribute to a more efficient use of the electricity grid in West Brabant with a large-scale battery that acts as a congestion reliever. RWE’s large-scale battery is located close to the 150,000-volt high-voltage substation at Moerdijk-Noord, where it will help to alleviate the regional bottleneck, which in turn has an impact on congestion across the whole of Noord-Brabant.“