Integration of water pit heat storages in energy systems

Denmark is the international frontrunner on large scale application of renewable energy systems. In the last four years, more and more Danish district plants have been equipped with large heat storages in the form of water pits with the aim to increase flexibility and stability of the energy system. The large scale heat storages are designed and operated based on limited experiences from the past and on learning by doing. Research is needed in order to optimally integrate and operate the heat storages in district heating systems with a large share of renewables.

Financing of the project:
Sino-Danish Center for Research and Education + Danish Energy Agency EUDP project +Department of Civil Engineering, Technical University of Denmark

International collaborations:
The project will be carried out in close collaboration between Department of Civil Engineering, Technical University of Denmark and Institute of Electric Engineering, Chinese Academy of Sciences, Vestegnens Kraftvarmeselsskab I/S, Høje Taastrup Fjernvarme a.m.b.a., PlanEnergi, Ea Energy Analyses.

The proposed PhD project aim to include the following technical challenges:
• Gather experience from practice based on operation and monitoring of existing large scale water pit heat storages in Denmark and in China
• Develop simulation models of large scale heat storages with improved prediction accuracy on thermal performance
• Design optimization of heat storages for integration in a hybrid renewable energy system with focuses on system flexibility, reliability and profitability under Danish and Chinese conditions
• Characterization of demand response, thermodynamics behaviors and the interplay of energy production, storage and load
• System coupling over different time scales
• Forecasting based on smart operational strategies for use of large scale heat storages considering both heat and electricity
• Digital twin and data-driven methods for sustainable energy systems and operation

In China there is a growing interest for solar heating plants inclusive water pits connected to district heating systems. Aalborg CSP A/S is one of the pioneer Danish companies who are actively developing the Chinese market. The boundary conditions on district heating systems, the heat demand, the climate, the energy system and the energy policy are different than the boundary conditions in Denmark. The optimal design and operation of water pits for solar heating plants will therefore be different in Denmark and China. If the Danish industry should benefit from the rapid growth of the Chinese market, the technologies must be carefully investigated and optimized for Chinese conditions.