Germany’s Uniper and NGEN to deploy 100MWh BESS at retiring coal plant

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German state-owned legacy plant operator Uniper will install a 50MW/100MWh BESS at a soon-to-be-decommissioned coal facility in partnership with NGEN, an energy storage operator and technology provider based in Slovenia.

The companies will build the 2-hour battery energy storage system (BESS) at the Heyden 875MW hard coal power plant site in Petershagen, with a commercial operation date (COD) expected in 2025.

The Heyden plant, one of the most powerful in Germany, will be decommissioned by Uniper on 30 September, 2024. Decommissioned power plant sites provide excellent locations for new clean energy projects with substantial existing grid infrastructure and interconnections which can be re-utilised.

The new BESS will comprise of 26 energy storage packs, so around 3.85MWh each. In an interview with Energy-Storage.news in September 2023, NGEN CEO Roman Bernard said the company had primarily used Tesla Megapacks for its projects to-date, including the largest BESS facilities in Slovenia, Austria and Croatia. Tesla’s Megapack’s have an energy storage capacity of 3.9MWh.

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NGEN is a developer and operator of those projects but also describes itself as a provider of energy solutions, with its own energy management system (EMS) platform, Energy Smart Grid Platform, which can aggregate numerous technologies into virtual power plants (VPPs). As part of the move into Germany the company will open an office in Frankfurt.

Uniper was formed through the spin-off of German multinational energy company E.On’s electricity generation businesses from its retail utility operations, after the split became effective at the beginning of 2016.

Uniper is aiming to be carbon-neutral by 2040, and for 80% of its generating capacity to be zero-carbon by 2030. This includes growing its renewable and clean energy portfolio but also converting its legacy gas plants to alternative gases like hydrogen and biomethane.

Germany’s grid-scale energy storage market has picked up in the last few years with the right market and policy signals incentivising investment in large-scale projects. Energy-Storage.news has recently reported on BESS projects of around 230MWh being launched by developers Eco Stor and Nofar.

Transmission system operator-led (TSO) ‘grid boosters’ are also underway, with system integrator Fluence recently starting to ship BESS for TransnetBW’s and TSO Amprion getting its project approved by the regulator.

15 September 2026
Berlin, Germany
Launching September 2026 in Berlin, Energy Storage Summit Germany is a new standalone event dedicated to Germany’s energy storage market. Bringing together investors, developers, policymakers, TSOs, manufacturers and optimisation specialists, the Summit explores the regulatory shifts, revenue models, financing strategies and technology innovations shaping large-scale deployment. With Germany targeting 80% renewables by 2030, it offers a focused platform to connect with the decision-makers driving the Energiewende and the future of utility-scale storage.
6 October 2026
Warsaw, Poland
The Energy Storage Summit Central Eastern Europe is set to return in September 2025 for its third edition, focusing on regional markets and the unique opportunities they present. This event will bring together key stakeholders from across the region to explore the latest trends in energy storage, with a focus on the increasing integration of energy storage into regional grids, evolving government policies, and the growing need for energy security.

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