The standalone grid-connected project on the former Brunsbüttel nuclear site will be Vattenfall’s largest battery and almost double its current battery capacity.
The project is sited at the decommissioning Brunsbüttel nuclear plant and will connect to the 50Hertz 380 kV transmission system.
Once operational, the battery will nearly double Vattenfall’s standalone battery capacity (company currently has 150 MW in operation and 120 MW under construction).
# Project overview Vattenfall has taken a final investment decision to build a 254 MW battery storage project with about 1,000 MWh of capacity at Brunsbüttel in northern Germany. The system will be a standalone facility built on the site of the former Brunsbüttel nuclear power plant, which is currently being decommissioned. The battery and its grid connection to the 50Hertz 380 kV transmission system are expected to be operational by the end of 2028.
# Why this matters The Brunsbüttel project will be Vattenfall's largest battery to date and will almost double the company's battery capacity. Vattenfall's existing portfolio comprises 150 MW already in operation and 120 MW currently under construction, most of which are co-located with wind and solar assets. The size and standalone nature of Brunsbüttel position it as a utility-scale flexibility asset intended for the transmission network.
# Technical and grid context
# Company strategy and portfolio targets Vattenfall is expanding its flexibility optimisation business. The company says it aims to optimise a battery portfolio of up to 1,500 MW by 2029. Brunsbüttel will be a major asset toward that target, increasing the company's physical battery holdings and its operational scope within electricity markets and grid services.
# Site choice and reuse Placing the battery at the former Brunsbüttel nuclear plant uses an industrial site already connected to high-voltage infrastructure. That reduces the need for greenfield grid reinforcements and keeps the asset close to existing transmission capacity, a practical advantage for a large, grid-facing storage project.
Claus Wattendrup, Vattenfall head of solar & batteries, said the project is "excellent news for Brunsbüttel as an energy hub" and described batteries as playing "a key role in the future energy system, balancing electricity demand and supply."
# Timeline and next steps
# Implications for the German market A project of this scale adds a substantial block of duration-capable storage to Germany's grid. It aligns with broader forecasts for rapid expansion of large-scale batteries and signals that major utilities are investing in standalone, transmission-connected storage as a core part of power system flexibility.
# What to watch next Watch for procurement and construction contracts, permitting milestones tied to the decommissioning site, details on vendor and battery chemistry choices, and how Vattenfall plans to dispatch the asset within its growing optimisation portfolio up to 1,500 MW by 2029.
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