Design, build and operation of the CHESTER system

Kurzfassung

Within the framework of the European Union's H2020 project CHESTER, a first laboratory scale Carnot Batterie prototype has been developed and built. This so-called CHESTER-system expands the functionality of a Carnot Batterie by coupling it with a renewable district heating supply and a seasonal thermal energy storage. The CHESTER-system built at DLR Stuttgart is the first of its kind to use a Rankine-based heat pump cycle for the transformation of electricity into heat and an organic Rankine cycle for the re-transformation of heat into electricity, which are connected to each other as an exergetically optimized overall system via a cascade of high-temperature latent heat storage and 2-tank pressurized water storage. The technological design of the plant towards the combination with a seasonal heat storage is unique. It allows the plant to operate in a completely decoupled mode in terms of time and a partially decoupled mode in terms of energy. In sum, this results in a storage and energy management system that is able to absorb electricity and heat independently of each other in terms of time and quantity during charging, store both - heat even seasonally - convert both into each other as needed, and provide both again independently of each other in terms of time and quantity in a completely demand-oriented manner. This contribution will provide insight into the design process, the technical challenges faced in building the system, and will show for the first time the operational results obtained during experimental operation.