Evaluating the efficiency benefits of DSM on mine compressed air systems

Deep level gold and platinum mine compressed air systems contribute significantly to the total mine electricity consumption. Insufficient compressed air supply will lead to production losses. Many mines often counteract this risk by ensuring that an oversupply of compressed air is always available, resulting in increased production costs. Significantly higher electrical energy costs and a generally more competitive market require energy consumers to pay more attention to the introduction of various cost savings measures. Energy savings achieved must be quantified in order to evaluate the true impact, not only on the national electricity grid, but also on the costs savings realised from the reduction in electricity consumption. Mining operations and schedules are continuously subject to change, causing frequent variations in compressed air supply and demand. These variations, combined with complex compressed air systems, make it difficult to quantify energy savings. Performance assessment is the process through which a post project implementation energy profile is compared to the original energy baseline prior to any intervention. Compressor electricity savings are not always easily detectable on the total mine electricity bill. This leads to the misconception that energy savings achieved on compressor DSM projects do not result in electricity cost savings. In order to quantify achieved DSM savings, mine production data was compared to compressed air consumption. By comparing data, taken over a period of five years, a decrease in the average compressed air consumption per ton of ore broken was shown. From these comparisons, it was possible to investigate the actual effect of compressed air DSM projects on the energy consumption of the mines. This alternative approach confirmed that energy saving projects resulted in improved compressed air system efficiency without adversely effecting production.