Abstract
This paper performs a techno-economic assessment in deploying solar photovoltaics to provide energy to a refrigeration machine for a remote underground mine. As shallow deposits are rapidly depleting, underground mines are growing deeper to reach resources situated at greater depths. This creates an immense challenge in air-conditioning as the heat emissions to mine ambient increases substantially as mines reach to deeper levels. A system-level design analysis is performed to couple PV with a refrigeration plant capable of generating 200 tonne of ice per day to help to mitigate this issue. Generated ice can directly be used in cooling deep underground mines via different types of direct heat exchangers. State-of-the-art technology is used in developing the model which aims to decrease the size and cost of a conventional refrigeration system run on a diesel generator. Costs associated with deploying a solar system are computed as per the recent market value. Energy savings, carbon emissions reduction, and net annual savings in employing the system are quantified and compared to a diesel-only scenario. In addition, two different energy storage strategies: an ice storage system and a battery storage system, are compared. A detailed economic analysis is performed over the life of the project to obtain the net cash flow diagram, payback period, and cumulative savings for both systems. Moreover, a sensitivity analysis is proposed to highlight the effect of solar intensity on solar system size and the area required for installment. The study suggests that the use of solar PV in mine refrigeration applications is technically feasible and economically viable depending on the sun-peak hours of the mine location. Additionally, the economics of deploying an ice storage system compared to the battery storage system has a better payback period and more cumulative savings.
Highlights
Industrial energy usage accounts for 40% of the overall global energy demand in 2018, greater than any other end-use sectors [1]
This paper proposes a strategy to manage the peak cooling demand of a remote underground mine using ice cubes generated from a solar photovoltaics (PV)-driven refrigeration system
Since most of the remote mines are located in high solar intensity zones, this solar irradiation intensity is considered as a standard number and is used in analysis hereafter
Summary
Industrial energy usage accounts for 40% of the overall global energy demand in 2018, greater than any other end-use sectors [1]. Mining is the second most energy-intensive industry after construction, draining 6.2% of the global energy share [2]. 30–40% of a deep underground mine’s total energy expense [3]. Mines are going deeper and deeper to meet global consumer needs. In ultra-deep mines (2500 m or deeper), gravitational compression of the intake air sinking in the downcast shaft and geothermal heat acting on the mine ambient can cause a substantial increase in the temperature in association with the depth (auto-compression). Virgin rock temperature in such mines could be as high as 65 ◦ C [4] due to the geothermal gradient
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