About the project
RESTORE project focused on revolutionising district heating and cooling networks to make them 100% renewable. The project combines two cutting-edge technologies: thermochemical energy storage (TCES) and a reversible Organic Rankine Cycle (rORC). These innovations enable district energy systems to efficiently store and utilise renewable energy and waste excess heat from diverse sources, radically improving environmental sustainability. The development, testing, and validation of these prototypes represent a critical step in demonstrating the feasibility of the RESTORE concept.
Description of success
RESTORE achieved a significant milestone with the successful development and testing of its rORC prototype. This innovative system is designed to store renewable energy when it is abundant and generate power when energy demand is high.
The rORC prototype, created through a collaborative effort by Enerbasque, Politecnico di Milano (POLIMI), TU Wien, and National Renewable Energy Centre (CENER), was optimised using advanced simulations to ensure efficiency and flexibility. The system’s unique design uses a twin-screw volumetric machine, which allows it to operate as both a compressor and an expander, depending on the direction of operation. This dual functionality enables efficient energy use for heating and electricity production. The rORC can be integrated into district heating and cooling systems to minimise waste and allow operation throughout the year at a range of temperatures.
Figure 1: Construction of the rORC prototype at the Enerbasque Facility
The prototype adopts Novec 649, an environmentally friendly heat transfer fluid that was selected for its safety and minimal global warming potential. The rORC was constructed by Enerbasque and transferred to the labs of POLIMI, where it was installed and connected to a hydraulic system, and integrated with real-time data monitoring. Initial tests validated its ability to work in both heat pump and organic Rankine cycle mode.
Figure 2: Installation of the rORC plant at POLIMI laboratory
Highlights
Designed and tested a flexible rORC system capable of harnessing a wide variety of energy sources and waste heat at diverse temperature levels.
Validated the system’s ability to operate as both a heat pump and a power plant during lab tests.
Created a collaborative design and testing process, ensuring the prototype meets all technical requirements including the compatibility for future coupling with an innovative thermochemical energy storage.
Established a scalable model for integrating a wide variety of renewable energy sources and waste excess heat into district heating and cooling networks.
Outputs
Construction and shipping of the rORC demonstrator with installation at the labs of POLIMI
As well as developing and testing the rORC prototype, RESTORE has written and published peer reviewed articles
Impact
RESTORE demonstrates how district heating and cooling networks can be supplied with up to 100% renewable energy sources, making them cleaner and more sustainable. The rORC system uses excess renewable energy and waste heat during low-demand periods to store it in a TCES and efficiently generates electricity and heat when demand rises.
This technology reduces greenhouse gas emissions, lowers reliance on fossil fuels, and supports cities in achieving their climate goals. The success of RESTORE’s innovative prototype offers a practical roadmap for adopting renewable energy solutions in district energy systems, contributing to a cleaner, greener future for communities worldwide.
Lessons
Creation of the final demonstrator involved the development of two different prototypes that needed to be individually tested and then coupled to form the final product.
Fostering a team that unifies all partners and allowing the fluid exchange of information facilitated the development of the prototypes.
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