The StoREN Phase 1 project delivered a comprehensive feasibility study for converting the existing thermal power plant at the Holthausen industrial park into a CO₂‑neutral heat‑storage power plant (WSK). The study focused on integrating renewable electricity—primarily solar PV and wind—into the plant’s operation, thereby enabling continuous power and heat supply while reducing fossil fuel consumption. The technical assessment was carried out in five work packages (AP 1–5). AP 3 produced a detailed techno‑economic analysis of mono‑energetic and hybrid plant variants. The analysis showed that a hybrid configuration, combining renewable‑driven heat storage with a small fossil‑fuel backup, delivers the lowest levelised cost of energy for the site while maintaining grid stability. The hybrid option also offers a higher CO₂‑avoidance potential, estimated at several hundred tonnes per year, and a lower risk of supply interruptions during prolonged periods of low renewable output. AP 4 translated these findings into a concrete pilot‑plant concept. The design incorporates a modular thermal storage unit that can be retrofitted onto the existing boiler house, coupled with a power‑to‑heat conversion system that charges the storage with surplus renewable electricity. The techno‑economic model for the pilot plant predicts a payback period of roughly 6–8 years under current electricity price scenarios, and a net present value that exceeds the baseline fossil‑fuel plant by 15 %. AP 5 produced a roadmap for a stepwise transformation of the park’s energy supply, outlining key milestones for demonstration, scaling, and full deployment. The roadmap also includes a risk assessment and a CO₂‑saving cost analysis, confirming that the WSK approach is competitive with other low‑carbon alternatives such as district heating or direct electrification.

The project’s scientific results are supported by a data book and an electricity‑price forecast prepared by r2b energy consulting, which provide the market context for the techno‑economic calculations. The study also identified that the current energy crisis—triggered by geopolitical events and the rapid transition to renewables—has increased price volatility, necessitating a flexible plant design that can adapt to changing market conditions. The pilot‑plant concept therefore emphasizes modularity and the ability to switch between renewable charging and fossil‑fuel operation without major retrofits.

Collaboration among the partners was structured around their respective expertise. BASF Personal Care & Nutrition GmbH and Henkel AG & Co. KGaA, both major users of the Holthausen plant, supplied detailed demand data and operational constraints. The German Aerospace Center (DLR) provided the technical modelling and economic analysis. The project was carried out under a European Union funded programme, with the Phase 1 feasibility study completed in March 2024. The timeline included an initial delay of about one month at project start due to contractual arrangements for confidential information, followed by a further extension to December 31 2023 to accommodate the increased workload in AP 2 and AP 3 caused by the volatile energy market. All five milestones—MS 2.1 through MS 5.1—were achieved, confirming the readiness of the concept for a demonstration project. The report concludes with a set of planned publications and a clear decision framework for the next phase, positioning the Holthausen site as a leading example of industrial decarbonisation through heat‑storage power plants.