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Financial risks and environmental concerns associated with fossil fuel dependency are motivating mining companies to improve their energy profile. Diesel generators are vastly used as the main power source in off-grid mining operations located in the cold climate regions of Canada and other northern areas of the globe. However, almost 65% of the heat generated in the combustion chambers of a diesel generator is rejected as waste heat, a sizeable portion of which is discarded through the exhaust. This study presents a techno-economic analysis on the feasibility of recovering waste heat from exhaust streams of diesel generators by identifying their fuel consumption and recoverable thermal energy available in their exhaust. The potential energy and economic savings are investigated by reviewing the performance of the proposed diesel exhaust heat recovery system through a series of parametric studies, especially on temperature conditions, heat exchanger effectiveness, mine size and applications. The analysis shows that an extensive fraction of the heat demand of the mine could be supplied by the system. For pre-heating the mine intake air in cold climate regions, these savings could be as high as several millions of dollars. Consequently, the present work shows how deploying such diesel exhaust heat recovery strategy can lead remote mining towards a more energy efficient, economic and sustainable operation while gradually reducing carbon footprint in the life cycle of mines. [ABSTRACT FROM AUTHOR]

• A zero-carbon heating system for remote underground mines has been established. • A rock-pile seasonal thermal energy storage has been incorporated with exhaust heat recovery system. • A valid analytical model has been presented showing the techno-economic feasibility. • Financial analysis has been conducted; the proposed model has a promising payback period. Millions of liters of diesel or propane are burnt every year in remote mines for pre-heating the intake air, leaving a monumental size of carbon footprint every year. A novel zero-carbon heating model for remote underground mine has been investigated. Both the technical and financial feasibility of integrating a validated seasonal thermal energy storage with an exhaust heat recovery system in the proposed model have been investigated. An analytical model has been developed and inspected along with different set-point temperatures, heat exchanger effectiveness, and vulnerability of fossil fuel price to judge the performance of this integrated approach. Energy savings by the exhaust heat recovery system and the seasonal thermal energy storage have been enumerated separately, and based on that, a rockpile-based seasonal thermal energy storage has been sized reasonably throughout the study. The system reaches the breakeven point in 2.6–4.8 years, depending on the operating conditions. The life cycle assessment compares the amount of carbon emission from different available heating systems for remote mines with the proposed integrated heating system. The present system provides a typical remote underground mining operation with an opportunity to eliminate the entire 15–23 million kilograms of carbon emission for heating purposes. [ABSTRACT FROM AUTHOR]

• A rock-pile waste heat storage is proposed, and its corresponding numerical model is developed. • Both fluid flow and heat transfer are validated against experimental data. • Local Thermal Equilibrium and Non-Equilibrium approaches are compared. • Parametric studies are performed on thermo-physical properties. • Payback time analysis is performed, and the system is economically justified. Remote communities in arctic climates are solely dependent on diesel generators for continuous power supply due to their detached loci from national power gridlines or natural gas pipelines. Moreover, to get along with the harsh, long winters, these communities directly or indirectly depend on fossil-fuel based heating systems. Due to the lower efficiency of the conventional diesel engines, these generators discard a significant amount of heat through the exhaust. Occasionally, during the wintertime, this waste heat from the exhaust is used directly as a heat source after recovery. However, during summer, when the heating demand is lower or nil, this heat is commonly discarded, and its energy potential wasted. A rock-pile based seasonal thermal energy storage is a viable solution that can sustainably resolve this issue. This paper presents a validated numerical study that focuses on the coupling of a waste heat recovery system to a diesel exhaust stream offering a performance assessment of the proposed rock-pile waste heat storage system in a remote, off-grid community located in northern Canada. It examines the impacts of local thermal equilibrium versus non-equilibrium approaches as well as temperature-dependent properties, variation of air mass flow rate, particle size and finally the thermo-physical properties on the proposed model. The presented results show that air should be treated as an ideal gas and that the local thermal non-equilibrium approach should be used for its considerably higher accuracy. Techno-economic assessment of the system resulted in a relatively short payback period of less than six years. [ABSTRACT FROM AUTHOR]