worked on experimental and numerical tests, focusing on their comparison, and achieved satisfactory results on simulations that had input temperatures from experiments [31]. When it comes to design and operation of porous media storage systems, two important parameters ought to be highlighted: the rate of heat transfer between fluid and solid domains, and the power necessary to run the heat transfer fluid through the system. The former determines operating cost, while the latter is directly related to storage capacity and rate. Besides, other case-specific factors can directly impact the outcome of the system. Hence, it is crucial to fully comprehend the porous structure of the rock bed domains and how important they are for the design of heat storage systems. Some studies have focused on evaluating influential parameters. Optimizing the heat transfer rate between the fluid and solid domains has been demonstrated to be a key factor to achieve a good performance on TES systems [32]. [PERSON] et al. [8] and [PERSON] et al. [33] investigated, in detail, both numerically and experimentally, the performance of sand and rock beds, which allowed for the impact of several design and operating conditions, as temperature and HTF velocity, to be evaluated on thermal energy storage performance. Air mass flow has been shown to enhance interphase heat transfer rates, decreasing charging time [4], while some have suggested that air density would not directly affect said heat transfer [29]. It has also been stated that volumetric heat capacity would play a major role on overall system performance [28]. Regarding insulation, a thickness of about 16-20 cm was found to be enough to retain low energy losses for intermediate temperatures [16]. Studies have also shown that for short-term (diurnal) cycles, a 95% overall thermal efficiency is achievable [7]. Another study was performed to evaluate rock suitability for use on TES, regarding chemical, mechanical, and thermophysical properties, and it found that some rocks which are not thermally stable (like foliated rocks) could be unsuitable. Finally, it has been stated that there is no absolute optimum design to a rock-bed TES system, meaning every unit needs to be planned and directed towards the requirements for cost and performance of the specific application. It is important to note that the majority of experimental data available in literature focuses on lab-scale models. Not many studies exist in literature investigating the heat transfer phenomena on large-scale rock-bed TES as the ones with potential for implementation in mining applications. Only recently has thought been put into uses of rock beds, such as cooling/heating of intake air in underground mining sites and block-caved mine ventilation systems [21; 24]. It is very important to investigate pressure drop on those systems, as significant additional fan power is required to pump the air through the bed [34; 35], which leads to meaningfully high costs that could affect the viability of the system. Even though several studies have modelled heat transfer and fluid flow in a packed bed of rocks, most of them present restrictions, including a dimensional reduction to a 2D, 1D, or quasi-1D model, neglecting heat transfer in at least one of the three special dimensions. Others have employed simplifications from interphase energy balance (obtained by the local thermal non-equilibrium method (LTNE)) to a less realistic local thermal equilibrium (LTE). A few even neglect pressure differentials. This study focuses on a TES system being charged by a stream of hot air, the product of the exhaust from a local power plant. The novel approach proposed here is the use of large rocks (possibly waste rock from mining operations) as storage medium while using streams of hot gases (such as those from exhaust) as the heat source of the thermal energy storage system. The latter contains energy commonly discarded to the ambient air at establishments employing diesel-based power plants, such as the ones present on remote communities in Canada [15; 17].