Automated demand side management of clear water pumping and storage for shifting load out of Eskom's domestic peak in the mining industry

Pneumatic rock drilling equipment is widely used in the mining industry. These drills get very hot during drilling operations and require constant cooling. This is done by feeding clear, cold water down the shaft from a surface storage dam to underground storage dams. Clear water pump stations are situated on various mining levels to return the used hot water back to the surface. Depending on the depth of the shaft, water is either pumped directly to the surface or to an intermediate dam on a higher level. Fissure water increases the complexity of the water reticulation system and makes it impossible to accurately predict the volume of water that must be pumped back to the surface. Presently, many water pumping stations are manually controlled by pump station operators to ensure correct predetermined dam level capacities. Failure to maintain correct dam capacities can cause flooding resulting in serious financial losses due to equipment damage and loss of production. Some shafts are equipped with sensors that control the dam levels. However, these sensors alone cannot be used to carry out effective load-shifting. In this article, two case studies will show that automation of the pumping system will result in financial savings from reduced maintenance and because pumping is carried outduring selected periods of the day when energytariffs are lower. Partial or total Eskom funding also makes these interventions beneficial to consumers who participate in these projects.