Reversible ORC prototype system of the RESTORE project, ready for testing and validation

In the frame of the EU-funded research project “RESTORE”, an innovative rORC prototype was recently developed. The rORC prototype’s subcomponents were meticulously designed, manufactured and assembled. Then, the prototype was transported to the POLIMI facilities for testing and performance validation under conditions defined for the RESTORE system.

Milan, March 2025 – The HORIZON 2020 RESTORE project, coordinated by CENER (the National renewable Energy Centre of Spain), aims to develop a solution that allows integrating a wide variety of renewable energy sources in district heating and cooling networks, enabling them to be 100% renewable to radically improve their environmental sustainability. The core of this solution lies in the combination of two key innovative technologies: A thermochemical energy storage (TCES) and a reversible organic rankine cycle (rORC). The construction and validation of prototypes for these technologies, encompassing detailed design and manufacturing and intensive testing, is hence pivotal for the project.

In a collaborative work led by Enerbasque and the Politecnico di Milano (POLIMI), with contributions from TU Wien, and CENER, a rORC prototype has been successfully manufactured following a comprehensive design process. The operating conditions for the rORC system were selected by POLIMI based on an ad hoc numerical model, which also included an intensive investigation to select the most appropriate working fluid.

Enerbasque designed in detail all the components of the system with particular care on the heat introduction and heat rejection heat exchangers that must be compatible with all testing facilities and reversible operation. The rORC prototype’s subcomponents were meticulously manufactured and assembled, ensuring correct operation. The rORC prototype is engineered for flexibility, capable of harnessing a wide variety of energy sources and waste heat at diverse temperature levels. A key component of this prototype is the reversible volumetric machine based on a twin-screw compressor/expander, allowing operating the cycle as a heat pump or as an ORC based on rotational direction.

In the end of June 2024 the prototype was transported to the POLIMI facilities for testing and performance validation under conditions defined for the RESTORE system. After initial tests of the rORC unit, the unit has been connected to POLIMI lab of Laboratory of Energy Conversion and Storage. With the support of Enerbasque, an extensive experimental campaign will be carried out aiming to quantify the system performance under various off-design conditions and to evaluate the efficiency of the components at steady-state.

As the project advances, performance test results from POLIMI will be released, providing critical insights into its operational efficiency. The successful completion of the test plan will validate the rORC machine for both operation modes, charging and discharging, demonstrating the potential of the technology. In addition, this step will unlock the next phase of the project, the relocation of the rORC to TU Wien, where it will be connected to the TCES Prototype with the aim of validating the RESTORE overall concept. This step is expected to be done soon, in early 2025.

The RESTORE project involved the participation of eleven partners spread over Europe: CENER, coordinator, y Enerbasque (España); Technische Universität Wien, Andritz y Simtech (Austria); Politécnico Milano y Turboden (Italy); Aalborg CSP (Denmark); Steinbeis (Solites y Steinbeis Europa Zentrum, Germany); Universitatea Babes Bolyai (Romania) y Prospex Institute (Belgium).

The project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101036766.

More information about the RESTORE Project at: https://www.restore-dhc.eu/