Does soil thermal conductivity affect borehole thermal energy storage?

Core Ideas Borehole thermal energy storage is studied with a 3D transient fluid flow and heat transfer model. BTES heat extraction efficiency increases with decreasing soil thermal conductivity. BT...

What is borehole thermal energy storage (BTES)?

Borehole thermal energy storage (BTES) is an innovative renewable energy technology for building heating and cooling. The lack of studies about BTES in unsaturated soils acts as a barrier to further implementation.

Why are borehole thermal energy storage systems located in unsaturated zones?

Borehole thermal energy storage systems are probably located in unsaturated zones, in part to take advantage of the lower thermal conductivity with degree of saturation (Smits et al., 2013).

How does soil thermal conductivity affect BTES efficiency?

BTES heat extraction efficiency increases with decreasing soil thermal conductivity. BTES efficiency decreases with convective heat losses associated with high soil permeability. Borehole thermal energy storage (BTES) in soils combined with solar thermal energy harvesting is a renewable energy system for the heating of buildings.

Can soil and groundwater be used for heat storage?

Using soil and groundwater for heat storage offers an opportunity to increase the potential for renewable energy sources. For example, solar heating in combination with high temperature storage, e.g., using ducts in the ground, has the potential of becoming an environment friendly and economically competitive form of heat supply.

How does soil thermal conductivity affect energy injection?

Energy injection into the soil decreases for lower soil thermal conductivity values, but the ability to extract energy showed slight increases. The development of the thermal plume for low and high thermal conductivity soils is shown in Fig. 11. In both cases, the thermal plume grew outward despite the system being in a heat discharging state.