Investigating demand response potential in a mining group

Eskom issued warnings that the supply of electricity would be under pressure during the winter months of 2013 due to lack of reserve capacity, and planned maintenance that cannot be postponed any further. In addition, Eskom's power buy-back programme on a number of smelters has come to an end in May 2013, which leads to a possibility of increased come-back load from the participating customers. This could result in a substantial shortage of supply from the utility during the domestic peak period (from 17h00 to 21h00). In response, Eskom implemented the hard-wired Demand Response (DR) programme with various end users. One of the users includes a prominent gold mining group in South Africa. Due to the nature of the hard-wired DR programme, the projects investigated will entail the load reduction of larger loads during a peak period of 17h00 to 20h00 [1]. This includes an additional load reduction during the 17h00 to 18h00 timeslot as opposed to standard DSM initiatives. In order to determine the achievable load reduction, numerous tests and simulation models have been utilised. Existing DSM projects already in operation could also be altered to contribute to additional peak period load reduction. However, practical limitations on the hardware available would need to be addressed. Focus was placed on pumping systems, refrigeration plants, process mills, compressed air and winder operations. Overall potential impact of this mining group was determined as 19.4 MW during 17h00 to 18h00 and 19.5 MW during 18h00 to 20h00. This could result in a possible R 4.2 million in incentives for the three winter months of 2013.