Development direction of tunnel energy storage

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?

Besides their structural purpose, energy tunnels can be used to inject, store and extract heat from the ground by means of a heat carrier fluid circulating through an integrated pipe system embedded within them.

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).

Can underground heat exchangers be used as energy storage systems?

This work focuses on tunnels equipped with ground heat exchangers, typically called energy tunnels, to serve as seasonal, medium-temperature underground thermal energy storage systems (UTES).

Are tunnels an energy geostructure?

Tunnels are probably the least investigated energy geostructure ( Barla & Perino, 2014 ). However, they could play a fundamental role in the current challenge of addressing the increasing need for clean and renewable sources of energy.

Does convection affect storage performance of energy tunnels?

Specifically, this work addresses the storage performance of energy tunnels in different subsurface environmental conditions influenced by convection through 3-D thermo-hydraulic finite element simulations validated against full-scale experimental data. The results of this study are described in detail by Schaufelberger et al. .