The EIHP team has finalized the activities within the REHEATEAST pilot project with HEP Toplinarstvo Zagreb and other local project partners.
The Zagreb pilot, “Pre-feasibility evaluation of solar PV potential and development at the HEP Toplinarstvo Zagreb site”, had the objective of analysing the feasibility of an alternative heat supply.
The initially regarded pilot idea investigated the optimization of heat supply in summer period for a specific city district, supplied from DH network. It was based on the metering of heat consumption with loggers, to get accurate patterns and seasonal profile, and implement best regulation. However, the response from stakeholders and the timeframe could not assure the desired results, so the EIHP team with ASP had switched to other pilot project concept within Zagreb DH plant.
The targeted solution, which was finally selected for the alternative pilot project, has examined the installation of an integrated photovoltaic plant at the site of the heating substation, combined with thermal storage tanks and electric heaters.
Integrating photovoltaic panels would provide efficient space heating and domestic hot water preparation, reducing dependence on grid, while decreasing heating costs. It also supports decarbonization and less energy losses.
The pilot was promoting the principles of sustainable energy supply: an optimal system sizing, and using locally available heat resources. Initially, an inclusion of a heat pump was considered, but the availability of local abundant sources of high-temperature waste heat has eliminated that concept. It was concluded that the heat from the return flow of the DH network should be used directly, with additional heating for peak loads. Although not strictly considered as the waste heat, the lower-temperature return flow of the DH network provides abundant thermal supply which, integrally, increases the efficient use of energy within the whole system.
The concept analysed here is basically a hybrid heat supply system, combining electricity from RES, efficient use of available return heat, reheating and thermal energy storage. Such integrated system should be highly scalable and adaptable for various DH-supplied consumers.
An analysis of technical solutions and regulatory viability was performed in scope of that. Key activities performed by EIHP, with support from ASP:
- analysis of the present situation on-site and assessment of space and resources
- development of the concept
- PV plant configuration with variants
- stakeholder communication and reporting.
