Vattenfall greenlights 1 GWh battery at former Brunsbüttel nuclear site

Overview

Updated Sep 11

Vattenfall announced a final investment decision to build a 254-megawatt, 1,000-megawatt-hour battery storage system at the site of its retired Brunsbüttel nuclear power plant in Schleswig-Holstein, Germany. When it comes online by the end of 2028, it will be one of Europe's largest grid-scale batteries, connected to the 380-kilovolt transmission network of operator 50Hertz.

The project turns the plant's land and grid connection into a new role: storing renewable electricity to keep the German grid stable as wind and solar output grows. The 1976-era nuclear plant, shut down permanently since 2007, is being dismantled; the battery is part of a plan to keep the site productive as an energy hub.

Why it matters

If German grid operators are right that battery capacity needs to grow from roughly 11 GW today to over 80 GW by 2040, projects like this show the path from planning approvals to actual construction.

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Key Indicators

254 MW / 1,000 MWh

Power / storage capacity

Installed power output of 254 megawatts with up to 1,000 megawatt-hours of storage.

End of 2028

Target commercial operation

Scheduled connection to the 50Hertz 380 kV grid.

~118 TWh

Electricity produced by old plant

Lifetime output of Brunsbüttel nuclear plant from 1976 to shutdown.

270 MW

Vattenfall's current battery fleet

150 MW in operation plus 120 MW under construction, mostly co-located with renewables.

1,500 MW

Vattenfall optimization target by 2029

Third-party battery capacity the company aims to manage and market.

80 GW by 2040

Projected German battery capacity

Transmission system operators' expectation for large-scale storage by 2040.

Voices

Curated perspectives — historical figures and your fellow readers.

People Involved

Claus Wattendrup

Head of Solar & Batteries at Vattenfall

Leading the Brunsbüttel battery project

Organizations Involved

Vattenfall

State-owned utility

Developer and owner of the Brunsbüttel battery project

Swedish state-owned energy company with 150 MW of batteries in operation and 120 MW under construction.

50Hertz

Transmission system operator

Connecting the battery to Germany's 380 kV grid

German TSO operating the high-voltage grid in eastern Germany, including Schleswig-Holstein, which will host the Brunsbüttel battery connection.

Timeline

February 1976 December 2028

6 events Latest: September 11th, 2026 · 2 months ago

Tap a bar to jump to that date

December 2028
Expected commercial operation
Upcoming Milestone

Battery to be connected to 50Hertz's 380 kV grid, targeted by end of 2028.
December 31st, 2028
September 2026
Story published across energy trade media
Latest Coverage

Energy-Storage.news, Power Technology, and Renewables Now report the decision.
September 11th, 2026
Vattenfall takes final investment decision
Investment Decision

Company commits to 254 MW/1,000 MWh battery at Brunsbüttel, its largest battery project to date.
September 10th, 2026
December 2025
City council approves battery plans
Regulatory

Brunsbüttel municipality grants planning approval for the storage project on the former plant site.
December 2025
June 2007
Plant shut down permanently
Event

Brunsbüttel taken offline; never restarted, even before Germany's post-Fukushima nuclear exit.
June 30th, 2007
February 1976
Brunsbüttel nuclear plant goes online
Milestone

Plant begins operating, eventually producing ~118 TWh over its lifetime.
February 9th, 1976

Scenarios

Brunsbüttel battery operational on schedule by end of 2028

Likely Resolves by End of 2028

Discussed by: Vattenfall management; Energy-Storage.news

With the FID taken and grid connection plans confirmed, the project faces typical construction timelines for large-scale BESS. Vattenfall has executed similar standalone projects in Europe, and land on the decommissioned nuclear site removes the land-acquisition risk that delays many storage projects.

Construction delays push operation into 2029 or later

Possible Resolves by Q2 2029

Discussed by: Energy-Storage.news (transmission interconnection queue challenges)

Germany's grid connection constraints are a known bottleneck for battery projects, with TSO interconnection queues stretching years. Supply chain issues for battery cells or transformer equipment could also delay the project, as seen across the broader European BESS market in 2024-2026.

Scaling: Vattenfall expands third-party optimization business faster than owned assets

Uncertain Resolves by End of 2029

Discussed by: Company's 2029 target of 1,500 MW managed capacity

Vattenfall has stated it aims to optimize 1,500 MW of battery capacity for third-party asset owners by 2029, dwarfing its owned fleet even after Brunsbüttel. If the optimization business grows faster than construction delivers, the company's storage impact could come more from trading services than from its own assets.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

2016-2023

Elverlingsen hybrid battery (Germany, 2016-2023)

German utility RWE operated a large-scale lithium-ion battery at a former coal-fired power plant site in North Rhine-Westphalia, using the existing grid connection to provide frequency regulation.

Then

The facility demonstrated that retired thermal plant sites with strong grid ties could host battery storage.

Now

Paved the way for the current wave of repurposing fossil and nuclear sites across Germany.

Why this matters now

Brunsbüttel follows the same playbook: take a decommissioned thermal asset with proven grid infrastructure and convert it for storage.

2011-2023

German nuclear phase-out completion (2011-2023)

Following the Fukushima disaster, Germany accelerated closure of its nuclear fleet, with the last three plants shutting in April 2023. Brunsbüttel had already been offline since 2007, leaving a decommissioning pipeline stretching decades.

Then

Retired nuclear sites like Brunsbüttel needed new economic purposes as decommissioning proceeded.

Now

Grid connections and cleared land from these plants became prime real estate for renewable and storage infrastructure.

Why this matters now

Brunsbüttel is a concrete example of what nuclear phase-out infrastructure becomes: still energy-producing, just in a different form.