Can energy tunnels store thermal energy?

This study indicates storage efficiencies of energy tunnels of up to about 70%. Therefore, energy tunnels have marked potential to store massive amounts of thermal energy in the shallow subsurface for subsequent reuse.

Can energy tunnels be used as heat exchangers?

Energy tunnels can serve single buildings and city districts as thermal energy storage means. This paper presents an unprecedented investigation of the thermal energy storage potential of underground tunnels used as heat exchangers, often called energy tunnels, with a focus on seasonal, medium-temperature thermal energy storage applications.

How efficient are energy tunnels for energy storage?

The rationale behind this work is that Rotta Loria recently highlighted promising storage efficiencies of up to 70% for energy tunnels characterized by favourable subsurface conditions for storage applications (i.e., lacking convection heat transfer).

Why are energy tunnels important?

A significant feature of energy tunnels, similar to other underground infrastructures, is that they are characterized by a relatively low surface-area-to-volume ratio [ , , ] – a valuable attribute for the effective storage of thermal energy.

Does subsurface temperature affect thermal energy storage performance of underground tunnels?

The findings indicate a positive influence of subsurface temperature rises on the thermal energy storage performance of underground tunnels. Meanwhile, the findings indicate a generally detrimental role played by convection heat transfer for the performance of such systems.

How do energy tunnels work?

In fact, through diverse shapes in contact with the ground (e.g., prisms with cylindrical, egg-shaped, squared, or rectangular cross-sections), energy tunnels and other underground infrastructures involve an unchartered energy performance for heat storage.