Assessment of the national DSM potential in mine underground services
ESKOM is moving towards a price structure for electricity which reflects, as far as possible, the real cost of generation. It is called real time pricing (RTP). ESKOM developed this cost structure to coax customers to use more electricity in off-peak periods (low cost of generation) and less electricity in peak periods (high cost of generation). However, many industries do not effectively use these price offerings from ESKOM to the detriment of themselves and ESKOM. In previous research improvements to this situation for the South African mining industry were investigated. ESKOM funded research to find the potential for load shifting on mines using RTP. The RTP investigation focused on the supply side management (SSM) in the mining context of underground services on gold and platinum mines. Elements investigated included the ventilation, cooling and pumping (VCP) systems. (Except for pumps, these plants are generally installed aboveground.) Previous research showed a national RTP and SSM potential to shift 500 MW of electrical load for a period of 5 hours. Through the previous research it became clear that the mines were previously able to react partially to the price signals. However, it was proved by the research that the full load shift potential can only be realised through the use of integrated dynamic simulation and optimisation. An even higher potential exists for load shift and electricity efficiency through demand side management (DSM) on the underground services. Therefore, if underground DSM strategies are combined with SSM strategies, a further and much bigger potential can be exploited to the benefit of ESKOM and the mines. Due to these factors this study was undertaken. Three case study mines were identified for this study. They are Kopanang and Target, both gold mines, and Amandelbult, a platinum mine. The DSM potential on each of these mines was calculated using simulation, calibration, verification and optimisation. These results were presented to mine management to negotiate the implementation of the proposed strategies on one of the mines. Kopanang's management agreed to the implementation of these strategies for a trial period of 3 months after which the success would be evaluated. The results of the implementation, together with the case study results, were used to calculate the national DSM potential in the mining sector through extrapolation. The DSM potential amounts to 650 MW of load per day as well as 5% on electricity consumption. This amounts to a potential saving of R72.1 million per year using current tariffs. This means that ESKOM can save about R5000 million on the building of a new power station to supply the equivalent load to the DSM potential. Now that the national impact has been calculated and discussed, all these findings must be used to motivate the implementation of these strategies throughout the mining sector. A similar project can be undertaken to look at possible DSM strategies in the industrial sector. This might prove to be more difficult as the electricity intensive systems are mostly all linked to the final production. In the mind of management this out-weighs the possible cost savings that can be achieved. ESKOM and the NER will have to rethink their strategy. Through DSM and load shifting actions alone the pending electricity crisis will not be averted. The current tariff structures should be amended to not only reflect the true cost of electricity but also provide incentive for DSM and load shifting. Another problem that must be addressed to achieve the DSM targets set for 2007 is the time that it takes to complete the study as well as the implementation time. Software can easily be created to help in the speeding up of the case study itself, as the process and steps followed, as well as models used, are very generic (at least in the gold and platinum mining sector).
- Engineering