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Vattenfall has made the final investment decision to construct its largest battery system in Germany. The project will occupy the site of the former Brunsbüttel nuclear power plant, will have a capacity of 254 MW and up to 1,000 MWh of storage. Additionally, the company aims to commence operations by the end of 2028, increasing its capacity to store power and return it to the grid when necessary.
An area that hosted a nuclear power plant in Germany for decades is set to take on a new role in the electric sector. The Swedish company Vattenfall announced on September 10, 2026, its final investment decision to build a large-scale battery in Brunsbüttel, in the northern part of the country.
According to Vattenfall’s official statement, the venture will have 254 megawatts (MW) of capacity and a storage capability of up to 1,000 megawatt-hours (MWh). Thus, the project will represent the company’s largest battery undertaking.
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However, the installation is not yet operational. The company has approved the investment and aims to complete the battery and its connection to the electrical grid by the end of 2028. This announcement marks a new phase in transforming an old nuclear complex into electricity storage infrastructure.
Vattenfall to Utilize Former Nuclear Plant Site for 254 MW Battery Installation
Vattenfall has chosen the site of the former Brunsbüttel nuclear power plant to establish its new project. For decades, the plant played a significant role in providing electricity to northern Germany.
The plant began operations in 1976 and produced approximately 118 terawatt-hours (TWh) of electricity over its lifetime, according to company information.
However, the facility permanently ceased operations in 2007. Subsequently, following Germany’s decision to abandon nuclear energy in 2011, the company moved forward with preparations for the definitive closure and dismantling of the unit.
Now, Vattenfall intends to leverage the location and characteristics of the land to implement a new energy system. The future battery will have 254 MW of rated capacity and the ability to store up to 1,000 MWh.
Additionally, the company considers the location advantageous for integrating the equipment into the transmission system. Thus, the project demonstrates how companies in the electric sector can give new roles to old plant sites without necessarily preserving the original generation technology.
New Installation Will Not Produce Nuclear Energy but Will Store Grid Electricity
Although it occupies the site of a decommissioned nuclear plant, the battery will not generate electricity through nuclear reactions. Instead, the equipment will receive energy from the grid and store that electricity for later use.
Thus, the installation will serve a different function than that of the former plant. While the nuclear facility produced energy, the new system will allow for the transfer of part of the available electricity from one period to another.
Additionally, the storage may help balance the electrical system during times of variability in renewable generation. However, performance will depend on operational conditions, battery availability, and the needs of the grid.
Therefore, the transformation of Brunsbüttel does not signify a return to nuclear generation. The project marks the repurposing of an industrial area for new energy infrastructure.
1,000 MWh Battery Can Provide Maximum Power for Nearly Four Hours
Two figures illustrate the scale of the venture: 254 MW of power and up to 1,000 MWh of storage capacity.
The megawatts indicate the power that the equipment can deliver at any given moment. Meanwhile, the megawatt-hours represent the amount of energy that the system can store.
By dividing the energy capacity by the rated power, we arrive at a theoretical duration of approximately 3 hours and 56 minutes of discharge at maximum power. However, operational conditions and system losses will affect the actual performance.
Thus, the battery will not operate like a power plant that produces electricity continuously. Instead, the system will receive energy at specific periods and can return it to the grid when needed.
Moreover, the discharge duration varies based on the power used. If the system provides less energy per unit of time, it could extend its operation while respecting the technical limits of the equipment.
Storage Will Help Manage Fluctuations in Solar and Wind Energy
This technology is gaining importance as the share of variable renewable sources, particularly solar and wind energy, increases.
When these sources generate excess electricity, the batteries can absorb part of the supply. Later, operators can use the stored energy to help balance the system.
Additionally, the equipment provides flexibility in situations where renewable generation does not coincide with peak consumption times. In this way, storage can help manage the differences between supply and demand.
Advancements are also evident in other industrial initiatives. In a report by CPG, Roberta Souza presented the construction of a 1.6 GWh battery on a former coal power plant site in Germany, a project by HyperStrong with 400 MW of grid connection.
Although the projects have different stakeholders and characteristics, both demonstrate how old conventional generation complexes are now receiving investments in energy storage.
Vattenfall Expands 700 MWh Project to Up to 1,000 MWh Before Final Decision
The decision announced in September 2026 represents an important evolution regarding the company’s previous plans.
On December 5, 2025, Vattenfall reported that the Brunsbüttel municipal council had approved the urban planning necessary for the project’s advancement.
At that time, the company anticipated 254 MW of power and 700 MWh of storage. Additionally, it expected to begin operations by 2028.
However, in the final investment decision, the company presented a larger configuration. The project now envisions up to 1,000 MWh of energy capacity, while maintaining the 254 MW of power.
This change added 300 MWh to the original plan, an increase of approximately 42.9% in the announced storage capacity.
Consequently, the battery will sustain its rated power for a longer duration than the previous configuration. Thus, the expansion increased the amount of energy that the project can deliver during each operational cycle.
Company Did Not Disclose Investment Amount or Number of Jobs
Although it confirmed the final investment decision, Vattenfall did not disclose the financial value of the project in the consulted statement.
Therefore, the available data does not allow for a specific budget confirmation for the project. Additionally, the company did not provide employment figures for the construction or operational stages.
Thus, the technical data enables the project’s scale to be defined, but does not support estimates of job positions or financial figures that the company has not disclosed.
The announcement also does not detail the chemical technology of the cells that will be part of the system. Thus, it is impossible to state which battery composition the company will use without further information.
However, Vattenfall has already confirmed the main parameters of the project: 254 MW of power, up to 1,000 MWh of storage, and an expected completion by the end of 2028.
Company Will Build Substation and Connect Battery to the 380 kV Transmission Network
In addition to the battery, Vattenfall will develop the necessary infrastructure to integrate the project into the German electrical system.
According to the company, the project plans to connect to the transmission network of 380 kilovolts (kV) operated by 50Hertz.
The German statement also outlines plans for a new substation, which will be part of the connection infrastructure. Additionally, Vattenfall aims to complete the battery and its connection to the electrical system by the end of 2028.
This structure will allow the project to receive electricity to charge its batteries and return energy to the grid at other times. In this way, the system will be able to participate in electricity market operations and provide flexibility according to supply and demand conditions.
Consequently, the connection represents an essential step in the project. After all, the battery will need the transmission infrastructure to move large amounts of electricity.
Battery Expansion in Europe Follows Growth of Renewable Sources
Germany is not facing the challenge of integrating increasing volumes of renewable energy into the electrical system alone.
In another article from CPG, Roberta Souza explained how storage projects of 362 MWh in England, 790 MWh in Greece, and plans for 3 GWh in other European countries demonstrate the expansion of industrial-scale batteries.
However, these projects have different timelines and stages of development. Therefore, it is not accurate to treat all the announced capacities as installations that are already operational.
Despite these differences, the projects reflect a common transformation: companies have begun to incorporate large batteries into the planning of electrical infrastructure.
Moreover, the expansion of storage accompanies the growth of sources whose production depends on weather conditions. In this way, battery systems offer alternatives to manage variations in generation and consumption.
Vattenfall Could Nearly Double Its Battery Portfolio with the New Project
The Brunsbüttel project will also expand Vattenfall’s commercial strategy.
According to the statement, the company has 150 MW of batteries in operation and another 120 MW under construction. Together, these two categories represent a portfolio of 270 MW.
With the 254 MW planned for Brunsbüttel, the total capacities could reach approximately 524 MW, considering the completion of the projects and without accounting for any future changes.
Therefore, the new system will nearly double the considered portfolio capacity. However, the company still needs to complete the construction and start operations at the German facility to achieve this result.
In addition, the expansion strengthens the company’s interest in large-scale storage systems. Thus, Brunsbüttel plays a relevant role in Vattenfall’s growth strategy.
New battery will operate independently of solar and wind power plants
Another important detail involves the operational model of the equipment.
Most of the batteries that Vattenfall currently owns accompany solar and wind projects. However, Brunsbüttel will follow a different strategy.
The company will develop a standalone battery with direct connection to the transmission system. This way, the facility can receive electricity from the grid without relying solely on the production of a specific renewable power plant.
Additionally, this model allows the company to develop storage strategies based on the operational and commercial conditions of the electrical system.
Consequently, the installation can perform various flexibility functions, respecting its technical limits and market rules.
Vattenfall also aims to expand its services of optimization and commercialization of batteries owned by other investors.
Company sets goal to manage up to 1,500 MW of batteries by 2029
The strategy announced by Vattenfall goes beyond building its own equipment.
The company aims to increase its participation in the management, optimization, and commercialization of third-party storage systems. Through these services, it will seek to manage the commercial operation of batteries owned by other investors.
According to the announcement from September 2026, the company has set a goal to manage a portfolio of up to 1,500 MW of batteries by 2029.
However, this does not mean that Vattenfall will build or own all these systems. After all, the goal also includes third-party capacities that may hire the company’s optimization services.
In practice, this model allows battery owners to turn to specialized companies to define storage and electricity commercialization strategies.
Thus, Vattenfall intends to expand its operations both through its own projects and by providing services to other investors.
Energy prices and operating costs will influence the profitability of batteries
Although storage offers new commercial opportunities, various factors influence the profitability of the projects.
These include energy prices, operating costs, equipment availability, and the rules of the electricity market.
Furthermore, charging and discharging strategies depend on market conditions. Therefore, a battery does not guarantee positive financial results simply because it has a large storage capacity.
Similarly, the growth of Vattenfall’s commercial portfolio will depend on securing new services and the evolution of the projects.
Thus, the 1,500 MW represents a corporate target for 2029, not a capacity that the company already fully manages.
Germany projects over 80 GW of large batteries by 2040
Vattenfall’s decision comes during a period of expansion for electric storage in Germany.
According to the company, German transmission network operators expect that the installed capacity of large-scale batteries will exceed 80 gigawatts (GW) by 2040.
However, this number represents a projection for the future. Therefore, it does not correspond to the capacity that the country currently has in operation.
Growth follows the expansion of renewable sources. As solar and wind generation increases, the electric system needs to manage the differences between production and consumption times.
In this context, batteries can offer greater flexibility. The equipment stores electricity during certain periods and returns energy at later times.
Furthermore, the systems can assist in integrating renewable sources. However, their contribution will depend on the network’s needs and the technical characteristics of each installation.
Researchers Also Study Energy Storage in Underground Rocks
Despite the advances in electrochemical batteries, researchers are also exploring other ways to store large amounts of energy.
In a report by CPG, Roberta Souza showed how researchers study porous rocks located between 1,000 and 2,500 meters deep to store renewable energy, using compressed air in underground reservoirs.
This technology operates differently from the electrochemical batteries that Vattenfall plans to install. However, both aim to address a similar challenge: storing electricity to enhance flexibility and facilitate the integration of renewable sources into the energy system.
Additionally, different technologies can cater to distinct needs based on storage duration, required power, and deployment conditions.
Therefore, the growth of batteries does not automatically eliminate interest in other alternatives. On the contrary, the expansion of renewable sources increases the importance of assessing solutions suitable to the characteristics of each electric system.
How Vattenfall’s Project Could Affect the Energy Sector?
The installation in Brunsbüttel combines three important movements for the electricity industry: reuse of energy sites, expansion of large-scale batteries, and integration of renewable sources into the grid.
First, Vattenfall will utilize the land of an old nuclear plant that is still undergoing decommissioning. Furthermore, the 380 kV connection will integrate the storage system with the 50Hertz transmission infrastructure.
The project will also transform the energy function of the site. Previously, the area hosted a facility that generated electricity through nuclear reactions. Now, the company plans to use the land to store energy and return it to the electrical system as needed.
For the sector, projects like this can help manage fluctuations in renewable generation. Additionally, they provide alternatives for operators and market agents to deal with supply and demand discrepancies.
Project Has Confirmed Investment Decision, but Operation Depends on Completion of Works
Although Vattenfall has approved the investment, the project still needs to progress through the implementation and connection stages.
Moreover, the company has not provided specific estimates for savings on electricity bills, actual emission reductions, or the number of homes the system may serve. Therefore, the available data does not allow attributing these results directly to the project.
The announcement confirms the final investment decision made in September 2026. The company plans to install 254 MW of capacity, up to 1,000 MWh of storage, and complete the project by the end of 2028.
If they meet the schedule, Vattenfall will give a new purpose to the old nuclear site in Brunsbüttel and expand its participation in the energy storage market.
Thus, the initiative demonstrates how the electric industry can utilize existing facilities to develop new projects. However, operational and commercial results will depend on the completion of the construction and the effective functioning of the system.
And you: transforming the sites of old nuclear and coal power plants into large battery systems is a path that Brazil should also explore to enhance renewable energy storage?
