Optimization of seasonal storage for community-level energy systems: status and needs

Abstract

The status and needs relating to the optimal design of community seasonal energy storage are reported. Thermal energy storage research has often focused on technology development and integration into buildings, but little emphasis has been placed on the most advantageous use of thermal storage in community energy systems. Depending on the composition and characteristics of a community, the most appropriate community thermal storage may differ from that for a single building. District energy systems usually link thermal users to cold supplies and/or heat supplies (e.g., solar thermal energy, geothermal energy from ground-source heat pumps or geothermal hot zones, industrial waste heat, thermal energy from cogeneration or trigeneration). It is demonstrated that the optimal integration of these technologies can be enhanced through the use of appropriate seasonal thermal energy storage and that community-level seasonal storage can facilitate the development of smart net-zero energy buildings and yield efficiency, economic and environmental benefits. Issues that need to be resolved to allow optimal solutions to be attained are described. Advanced tools are required for modeling, simulation, analysis, improvement, design and optimization, which incorporate advanced methods like exergy analysis. The most appropriate scale, number and type (e.g., sensible, latent, thermochemical) of thermal storages in a community need to be better assessed, and the appropriate time duration capacities for each determined in an optimal manner. This is particularly important since a combination of short-, medium- and long-term storage is sometimes required to yield the most benefits from community energy systems.