The impact of reducing mine chilled water supply during periods of low production

As part of the Demand Side Management (DSM) initiative, Eskom partially funds load management and energy efficiency projects. Large industries are therefore willing participants in the Eskom funded electricity savings programme that hold benefits for all parties. One such industry is the mining sector. The refrigeration and pumping systems used in these sectors are two of the major electricity consumers. As part of DSM initiative, an electrical energy savings project was developed and implemented in the deep mines´ chilled water systems. The chilled water system is optimally controlled to reduce underground water usage during certain periods of the day. This ensures that less water is pumped out by the dewatering system, reducing electrical energy usage on the pumps. The study showed that there are positive and negative effects on the mining systems with reduced chilled water use. The financial and thermal impact was determined and compared to the average annual system´s cooling output. In some cases the cooling system components showed a combined decrease in cooling effectiveness of 3 to 4 percent of the total average annual cooling output, but also resulted in electrical energy savings.