IN Brief:
- The Brunsbüttel battery will provide 254MW of power and around 1,000MWh of energy storage.
- A new substation will connect the asset directly to 50Hertz’s 380kV transmission network.
- Vattenfall expects commissioning by the end of 2028 as its owned and optimised storage portfolios expand.
Vattenfall has taken a final investment decision on a 254MW battery energy storage system at Brunsbüttel in northern Germany, advancing what will become the company’s largest battery project to date. The standalone system will provide around 1,000MWh of energy capacity and is expected to enter operation by the end of 2028.
The stated ratings give the project a discharge duration of just under four hours at maximum output, placing Brunsbüttel among the larger utility-scale batteries being developed for multi-market operation rather than short-duration frequency response alone. Vattenfall plans to connect the system to the 50Hertz transmission network at 380kV through a new substation.
The battery will occupy the site of the former Brunsbüttel nuclear power station, which is being decommissioned after decades as part of northern Germany’s power system. The nuclear plant entered service in 1976, generated around 118TWh during its operating life, and has remained permanently shut since 2007.
A battery cannot reproduce the continuous generation characteristics of a nuclear unit, but established power sites can retain considerable infrastructure value after the original plant closes. Land, access, transmission geography, and decades of utility engineering can all support redevelopment, even where new connection equipment remains necessary.
Brunsbüttel will require a new substation rather than simply taking over the former plant’s connection. The 380kV interface will place the battery directly on the extra-high-voltage transmission system, where a 254MW charge or discharge represents a substantial network movement. Protection, power conversion, dispatch control, connection compliance, and coordination with 50Hertz will therefore form major parts of the final engineering and commissioning programme.
Germany’s storage pipeline is expanding quickly enough for network access to become as important as battery procurement. The country’s transmission system operators expect large-scale battery capacity to exceed 80GW by 2040, according to figures cited by Vattenfall. At that level, storage becomes a material part of network operation while simultaneously competing with generation, industrial loads, and other projects for connection capacity.
Regulatory treatment is also affecting delivery schedules. Germany has preserved grid-fee exemptions for qualifying storage projects commissioned by August 2029, giving near-term developments greater certainty over one component of operating cost. Brunsbüttel’s planned end-2028 completion falls inside that window, although its economics will still depend on connection arrangements, capital expenditure, degradation, market revenues, and the final dispatch strategy.
Vattenfall currently has around 150MW of battery capacity in operation and another 120MW under construction, with most existing developments co-located with wind or solar generation. Brunsbüttel would increase the owned portfolio sharply and add a much larger standalone asset directly connected to the transmission system.
The utility is building a parallel storage position through optimisation contracts for third-party batteries, targeting up to 1,500MW under optimisation by 2029. In the Netherlands, Vattenfall has already secured dispatch rights over the 200MW/800MWh Sirius battery through a long-term tolling agreement linked to time-dependent transmission rights.
Ownership and optimisation expose the company to different parts of the storage business. An asset owner carries construction, equipment availability, degradation, financing, and long-term operating risk, while an optimiser concentrates more heavily on dispatch and the value available across wholesale, balancing, and ancillary-service markets. Combining both models allows a utility to build controllable flexibility without having to own every megawatt physically.
The commercial environment will become more competitive as additional European batteries connect. Storage can arbitrage price differences, provide reserve services, support balancing, and respond rapidly to changing system conditions, but revenues from individual markets are unlikely to remain static as participation increases.
Long-duration infrastructure economics therefore depend increasingly on combining several revenue routes rather than assuming that one high-value service will support an asset for its entire life. Connection rights, cycling limits, equipment warranties, availability, and market access become part of the same investment case.
Brunsbüttel reaches FID with several of the harder parameters already fixed: scale, site, transmission voltage, network operator, and commissioning target. Delivery now has to turn those specifications into a 1GWh operating asset before the end of 2028, by which point Germany’s storage market and the competition for grid capacity are both likely to be substantially larger.
