As part of its ‘progres.nrw’ funding programme, German state North Rhine-Westphalia is providing funding of €200 000 for a technical and economic-evaluation study of the new MAN ETES energy-storage technology. This still-untested technology is said to offer the potential for a carbon dioxide-free alternative to traditional, large-scale, heat supply.
The project partners – RWTH Aachen University, Stadtwerke Aachen Aktiengesellschaft (STAWAG) and MAN Energy Solutions – want to investigate the potential for implementing the technology in NRW. The study will examine the necessary requirements for constructing a research facility in the Aachen area. A?storage system with a capacity of up to 7 MW is planned.
"Today, the process for generating heating and cooling is mainly based on fossil fuels. We must therefore make the growing share of renewable energies available to this sector in order to sustainably reduce emissions," commented Professor Manfred Wirsum, director of the Institute of Power Plant Technology, Steam and Gas Turbines (IKDG) at RWTH Aachen University and co-ordinator of the study.
Dr. Uwe Lauber, CEO of MAN Energy Solutions, said: "With our innovative technology solution, we want to contribute to the planned reduction of fossil fuels in NRW's electricity and heat supply and thus provide concrete support for the structural change of the energy sector in the state. Sector coupling is a decisive step on the way to a climate-neutral future. MAN ETES provides renewable energy – in the form of usable and storable heating and cooling – that can be converted back into electricity as required. The system thus couples the electricity, heating and cooling-supply sectors with unprecedented flexibility."
The basic principle of ETES technology is the reversible conversion of electrical energy into thermal energy, which is stored in the form of hot water and ice in insulated reservoirs. A special feature of the electrothermal process is the added – or even preferable – possibility of distributing the heating and cooling capacity generated to users depending on demand and margins, and accordingly offering the option of converting it back into electricity as an additional usage variant. The technology fulfills two important tasks: on the one hand, it helps with maintaining the grid balance by absorbing large amounts of surplus electricity from renewable energies and feeding it back into the grid when needed; on the other, the system integrates several sectors by generating, storing and providing thermal energy for heating and cooling purposes.
The system's properties are highly relevant for urban regions with a strong industrial base, such as North Rhine-Westphalia, with the traditionally-high energy requirements of its strong industrial sector and the planned phase-out of its coal- based electricity generation. The state supports the research association coordinated by RWTH Aachen University, which will develop a concept for an ETES research facility for an emission-free heating-and-cooling supply based on an evaluation study. Provided that the framework conditions of the energy industry are correct and feasibility can be validated, the construction of a pilot plant with an electricity-to-electricity storage efficiency of arond 50% will take place in 2021.
At the same time, the study will serve as a basis for the further technological development of ETES’ system components. The system is based on heat-pump and heat-engine technologies using carbon dioxide charging-&-discharging cycles, and the storage of pumped heat. ETES innovations include the use of water as a storage medium, as well as toxicologically and environmentally safe CO2 as a working medium for the entire energy-storage system.