Improving existing DSM initiatives on mine refrigeration systems for sustainable performance
Nel, Andries Johannes Hendrik
MetadataShow full item record
South Africa, as a young developing country, is dependent on a sufficient electricity supply for ongoing economic development. With an increasing gross domestic product and an alarming growth rate attributed to the abundant resource endowments, and historical low coal and electricity prices, emphasis is placed on the main economic drivers for sustainable growth. South Africa has the largest reserves of gold, platinum and coal in the world. It therefore comes as no surprise that mining is considered as one of the main, if not the cornerstone of economic development, contributing up to 14% of South Africa’s electricity usage. The global electricity paradigm is highlighted by the staggering demand increase projected for South Africa. The national power utility, Eskom, is currently busy with large capital expansion projects for increasing the supply as a last condonable effort to satisfy the current and growing demand. The electricity price has increased dramatically over the last few years to aid the utility’s supply expansion projects. The gold mining sector, however, is under immense pressure to reduce operational costs, especially with increasing labour unrests and stringent governmental policies. The daunting reality imposed on mines is subsequently to mine more efficiently without affecting production adversely. Since mining is done at great depths in South Africa, refrigeration systems was identified as one of the largest electricity consumers on mines. The general operation, control and equipment stance of the refrigeration systems are, however, inefficient and overdesigned. As a result, several demand-side management (DSM) initiatives have previously been implemented on mine refrigeration systems, which notably reduced not only the electricity usage but also the operational costs. Furthermore, the DSM initiatives contributed positively towards the feasibility of mines to stay competitive in a global market. Although significant electricity cost savings were realised as part of the DSM initiatives, project deterioration occurs over time, eroding the viability of sustained electrical cost savings. It is therefore critical to identify the factors affecting the performance of DSM initiatives to develop a strategy that includes measures to improve the existing DSM initiatives on mine refrigeration systems for sustainable and optimised performance. Implementing such a performance strategy will ensure effective and efficient use of the existing DSM initiatives on mine refrigeration systems. The strategy will ensure that the electrical cost savings and optimised performance of the refrigeration system are maintained by including detailed monitoring, control and reporting measures of key performance indicators. The feasibility of such a strategy was proved using case studies by analysing the post-implementation effects on two underperforming deteriorating refrigeration systems, situated at two separate gold mines, with existing DSM initiatives. The study validation has shown that a sustainable average daily power saving of 1.8 MW was achieved during the course of 15 months for Mine A; with a sustainable average daily power saving of 1.62 MW over the course of 17 months for Mine B. As a result, the average electrical cost savings amounted to R11.9 million for Mine A and R12.1 million for Mine B. In order to fully appreciate the results, the average electricity reduction was quantified as a percentage for both mines, achieving a combined reduction of 24%. The developed performance strategy therefore improves existing DSM initiatives on mine refrigeration systems for sustainable performance.
- Engineering