Shallow geothermal energy as a strategy to reduce electricity consumption for cooling and heating in Ghardaïa

Abstract

This study analyzes the performance of a 28-meter long Earth-air heat exchanger (EAHE), installed at a depth of 2.3 meters in Ghardaïa, to meet cooling and heating needs in dry climates. The methodology combines on-site experimental monitoring at URAER and laboratory characterization via an equipped box that simulates a continuous heat flow. The high-precision acquisition was carried out using type K thermometers and an Agilent 34972A acquisition. The results show that the strong thermal diffusivity of limestone contributes to the diffusion of heat towards greater depths and gradually, unlike dry sand, which plays the role of a thermal insulator. In terms of energy, the EAHE system allows a significant reduction in consumption, as it relies on a fan with a capacity of only 21 watts for cooling and preheating. The economic analysis reveals an initial investment of 102930.00 DAcompared to conventional systems, for a low operating cost of 80.29 DA per quarter. This shows that the rocky nature of the soil is the decisive factor in the feasibility of the system, as limestone provides ideal conditions for exploiting underground thermal inertia.