Cost effective control of a platinum mine cooling system using combined DSM strategies

Abstract

The platinum mining industry in South Africa faces various challenges. Increasing labour and energy costs as well as dropping commodity prices threaten the sustainability of the industry. Reducing energy usage and cost will aid the sector in remaining profitable. Refrigeration and cooling of mines are, among others, users of large amounts of energy. Implementation of Demand Side Management (DSM) strategies at these cooling systems will aid in both reducing energy usage and improving system efficiency. A background of platinum mine ventilation and cooling systems were covered to determine the required system parameters that must be adhered to. Existing DSM strategies were studied to determine possible shortfalls of the approaches and likely energy savings. The energy efficiency DSM strategies place a focus on average power usage reduction. Load shifting DSM strategies place focus on the shifting of load from the evening peak to off peak periods. A case study was carried out at a platinum mine with appropriate cooling systems and requirements. Simulations of both independent and combined strategies were carried out to determine the feasibility of implementation. All required hardware and software additions were included in the feasibility study. Simulated savings and control alterations were compared to the proposed cost of implementation to determine viability. Power usage prior to implementation was quantified in order to accurately calculate post-implementation energy savings. Installations were carried out, including hardware and software updates. Initially a single strategy was implemented with the second strategy implemented at a later stage. This was due to a delay in approval from the mine as well as funding requirements. Upon completion of implementation, the actual acquired savings were compared to the simulated savings. The Combined implemented strategy yielded a daily energy saving of more than 44 MWh. The corresponding cost savings were R 22,400 daily. Comparing these values with the simulated savings results showed for an over performance of approximately 25%. As a result, the viability and success of the combined strategy is proven.