Dam meets mining Innovative combined power plant in the Harz Mountains as the key to energy transition and climate adaptation

Technology transfer project launched for an integrated system that combines energy storage, high and low water protection, drinking water security and multiple use of mining infrastructure.

The energy transition will only work with large storage facilities for green electricity. At the same time, climate change, with increasing extreme weather events such as floods and droughts, is posing ever greater problems for regional water management. In view of these challenges, the Harz Energy and Water Storage Facility (EWAZ) with its numerous dams must be made fit for the future. This is the goal of the multi-million-pound ‘EWAZ Transfer’ project, in which five universities, including Technische Universität Braunschweig, and five commercial enterprises are participating. The future regions of southern and south-eastern Lower Saxony are funding the joint project with European Regional Development Fund (ERDF) funds. Lower Saxony’s Minister for Europe and Regional Development, Melanie Walter, presented the funding approval on 18 September at the dam wall of the Okertalsperre reservoir in the Harz Mountains.

“With the EWAZ Transfer project, we are sending a strong signal for climate protection and municipal services,” emphasised Minister Walter at the event. “The intelligent connection of energy and water systems creates new jobs, promotes regional value creation and protects against the consequences of climate change. We are focusing on innovative and tailor-made solutions that will benefit people in the western Harz region and far beyond, throughout Lower Saxony. This project impressively demonstrates how science and industry can work together to develop sustainable solutions for the challenges of tomorrow.”

Under the leadership of Clausthal University of Technology, the project is based on the transfer of know-how from the EWAZ preliminary scientific study, which will be completed in 2022. “We are delighted that this project, which has implications for society as a whole, is being continued. On the one hand, Clausthal University of Technology can contribute its unique expertise in the field of mining cavities, and on the other hand, the reuse of existing underground infrastructure is precisely in line with the concept of sustainability that we address with our key topic of the circular economy,” said University President Dr.-Ing. Sylvia Schattauer and Professor Jens-André Paffenholz, Director of the Institute of Geotechnology and Mineral Resources (IGMR) at Clausthal University of Technology, in unison. The new transfer project takes up the system concept and develops it into a flagship project for the implementation of a pilot for a so-called combined power plant. “We are looking at two intensive years of project work, during which we will now take concrete steps towards the implementation of combined power plants. Geotechnical investigations and simulations, among other things, will play a decisive role in this,” says Professor Thomas Ulrich (IGMR, Department of Geosciences).

“Due in part to the consequences of climate change, with increasing hydrological extremes, adjustments to existing systems are necessary to achieve greater flexibility in water management operations. Combined power plants are a useful addition not only for storing and generating energy, but also for improving aspects of flood protection, ecological water discharge and drinking water supply,” explains Professor Kai Schröter, Head of the Department of Hydrology and River Basin Management at the Leichtweiß Institute for Hydraulic Engineering (LWI) at Technische Universität Braunschweig, which is supporting the project with simulations of the water management effects of storage operations.

The specific project approach is to connect existing mining cavities with the existing dams in the western Harz Mountains. In this way, new capacities for pumped storage power plants can be created with minimal additional impact on the environment. By combining energy management and water management functions, combined power plants are created that can be used both for storing renewable energy and for water management functions such as drinking water supply, flood protection and low water level elevation.

Such structures are not only new in the proposed concept in the western Harz region: on the one hand, they represent an adaptation measure to climate change in the context of the energy transition in northern Germany, and on the other hand, they serve to provide public services in the future-oriented regions of south-eastern and southern Lower Saxony. In particular, the following aspects are addressed:

• Systemic consideration of the various locations as a combined energy and water management network
• Adaptation of the energy and water management infrastructure to climate change
• Design and preliminary investigation of the first innovative combined power plant
• Development, implementation, simulation and optimisation of the operational management of the combined power plants in combined and individual operation
• Provision of system services for high and low water protection, drinking water extraction and storage of renewable energies

The energy and water management network system to be developed is highly innovative and is being worked on with cooperation partners from the water and energy industries. They are supporting the project through integrative collaboration and co-financing, which underlines the high practical economic relevance of the topic. In addition to TU Clausthal, four other universities are involved in the interdisciplinary project network: TU Braunschweig, Ostfalia University of Applied Sciences, the University of Göttingen and Leibniz University Hannover. There are also five partners from industry: Harzwasserwerke, Uniper, Harz Energie, VGH Versicherungen and Öffentliche Versicherung Braunschweig.

The project will run for two years and has a total budget of just under 2.4 million euros. Of this, just under one million euros will be funded by ERDF funds from the participating future regions. The required co-financing share of around 1.4 million euros will be mainly covered by the industry partners, whose strong commitment is a key prerequisite for the implementation of the project.