In the quest to integrate more renewable energy into our daily lives, researchers have been exploring innovative solutions to store excess energy generated during peak production times. A recent study published in *Zhileng xuebao* (translated to *Journal of Civil Engineering*) introduces a semi-analytical model that could revolutionize large-scale water-pit thermal energy storage (PTES) systems, offering a promising avenue for enhancing the efficiency of district heating systems.
The lead author, Zhu Meisheng, and his team have developed a model that addresses the limitations of existing numerical and analytical models. “Our model is designed to be both accurate and computationally efficient,” Zhu explains. “It separates the water and soil domains and couples them through the pit sidewall, bottom temperature, and boundary heat fluxes, providing a more dynamic and precise simulation of water temperature.”
One of the standout features of this model is the “three-zone” approach for analyzing heat transfer in the water domain. Unlike simple one-dimensional models, this method divides the cross-section into central, transition, and edge zones, considering horizontal water flow for a more accurate representation. “This approach allows us to capture the complexities of heat transfer more effectively,” Zhu notes.
For the soil domain, the researchers improved the finite cylindrical source model, commonly used in ground-source heat pumps, to better suit PTES systems. The model’s accuracy was validated using 10 years of measured data from a 60,000 m³ PTES in Denmark. The results were impressive, with average temperature errors ranging from 0.233% to 1.27%, all well below 1.5%, demonstrating the model’s high accuracy and reliability.
The implications of this research for the energy sector are significant. Large-scale water-pit thermal energy storage systems can play a crucial role in increasing the share of renewable energy sources in district heating systems. By providing a more efficient and accurate model, Zhu and his team have taken a step forward in optimizing these systems, potentially reducing costs and improving performance.
As the world continues to shift towards renewable energy, innovations like this semi-analytical model will be vital in ensuring that excess energy can be stored and utilized effectively. “Our hope is that this model will contribute to the broader adoption of PTES systems, helping to create more sustainable and efficient energy solutions,” Zhu says.
With the publication of this research in *Zhileng xuebao*, the civil engineering community now has a powerful tool to enhance the design and operation of large-scale water-pit thermal energy storage systems. As the energy sector continues to evolve, this model could shape future developments, paving the way for more reliable and efficient district heating systems.