Growing demand for electricity forces suppliers to expand their generation capacity. Financing these expansion programmes results in electricity cost increases above inflation rates. By reducing electricity consumption, additional supply capacity is created at lower costs than the building of conventional power stations. Therefore, there is strong justification to reduce electricity consumption on the supplier and consumer side. The mining and industrial sectors of South Africa consumed approximately 43% of the total electricity supplied by Eskom during 2012. Approximately 10% of this electricity was used to produce compressed air. By reducing the electricity consumption of compressed air systems, operating costs are reduced. In turn this reduces the strain on the South African electricity network. Previous energy saving projects on mine compressed air systems realised savings that were not always sustainable. Savings deteriorated due to, amongst others, rapid employee turnover, improper training, lack of maintenance and system changes. There is therefore a need to improve projects that have already been implemented on mine compressed air systems. The continuous improvement of equipment (such as improved control valves) and the availability of newer technologies can be used to improve existing energy saving strategies. This study provides a solution to reduce the electricity consumption and operating costs of a deep level mine compressed air system. This was achieved by modernising and improving an existing underground compressed air saving strategy. This improvement resulted in a power saving of 1.15 MW; a saving equivalent to an annual cost saving of R4.16 million. It was found that the improved underground compressed air DSM project realised significant additional electrical energy savings. This resulted in ample cost savings to justify the implementation of the project improvements. It is recommended that opportunities to improve existing electrical energy saving projects on surface compressed air systems are investigated. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Large cooling systems consume up to 25% of the total electricity used on deep level mines. These systems are integrated with the water reticulation system to provide chilled service water and cool ventilation air. Improving the energy efficiency of these large cooling systems is an important electrical demand-side management initiative. However, it is critical that the service delivery and system performance be maintained so as to not adversely affect productivity. A novel demand-side management strategy, based on variable water flow, was developed to improve the energy efficiency of large cooling systems like those found on deep mines. The strategy focuses on matching the cooling system supply to the demand through the use of modern energy efficient equipment, such as variable speed drives. The strategy involves the modulation of evaporator, condenser, bulk air cooler and pre-cooling water according to partial load conditions. A unique central energy management system was developed to integrate the proposed strategies on large cooling systems. The system features a generic platform and hierarchical network architecture. Real-time energy management is achieved through monitoring, optimally controlling and reporting on the developed strategy. The system is robust and versatile and can be applied to various large cooling systems. The feasibility of the strategy and energy management system was first investigated through the use of an adapted and verified simulation model and a techno-economic analysis. The strategy was then implemented on four large mine cooling systems and its in situ performance was assessed as experimental validation. The results of the Kusasalethu surface cooling system are discussed in detail as a primary case study while the results of the Kopanang, South Deep South Shaft and South Deep Twin Shaft cooling systems are summarised as secondary case studies. The potential to extend the variable water flow strategy to other industrial cooling systems is assessed through an investigation on the cooling system of the Saldanha Steel plant. Results indicate that, over a period of three months, average electrical load savings of 606-2 609 kW (29.3-35.4%) are realised on the four systems with payback periods of 5-17 months. The average electrical load saving between the sites is 33.3% at an average payback period of 10 months. The service delivery and performance of the cooling system and its critical subsystems are not adversely affected. The potential to extend the method to other large cooling systems is also shown. The developed variable water flow strategy is shown to improve the energy efficiency of large cooling systems, making a valuable contribution towards a more sustainable future. This thesis is presented as a detailed discussion of the entire research process. The key results have also been summarised in a series of five research articles attached as independent annexures. Three articles have been published in international scientific journals, one has been presented at and published in the proceedings of an international conference and one is still under review. / Thesis (PhD (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013

The demand for electricity in South Africa has grown faster than the increase in generation capacity. However, it is expensive and time consuming to commission new power stations. Another approach is to reduce electricity demand through the implementation of energy efficiency projects. This alternative is usually less expensive. Compressed air on South African mines is a large electricity consumer with a reputation of wastage. This allows significant potential for electrical and financial savings. A typical mine compressed air system consists of multiple compressors at various locations, surface connection networks, underground distribution systems, thousands of users and leaks. The size, complexity and age of these systems provide a major challenge for electricity saving efforts. Simulating such an intricate system is difficult as it is nearly impossible to accurately gather all the required system parameters. Some initiatives focused on subsections of mine compressed air systems. This is not the best approach as changes to one subsection may adversely affect other systems. A new approach to simplify mine compressed air systems was developed to identify saving opportunities and to assess the true impact of saving efforts. This new approach enables easier system analysis than complex simulation models. Techniques to gather critical system information are also provided. A new implementation procedure was also developed to integrate different energy saving strategies for maximum savings. An electrical power saving of 109 MW was achieved through the implementation of the integrated approach on twenty-two mine compressed air systems. The savings is equivalent to a reduction of 0.96 TWh per annum that relates to a saving of 0.4% of South Africa’s total electricity consumption. Average compressor power consumption was reduced by 30%. The power consumption reduction relates to an estimated annual electricity cost saving of R315 million. A saving of 0.96 TWh per annum is equivalent to a carbon dioxide emission reduction of 0.98 million tonne. The implementation of the integrated approach could be applied to other industrial compressed air systems. A reduction in electricity consumption of 30% on all industrial compressed air systems has the potential to reduce global electricity demand by 267 TWh per annum. That is more than the total amount of electricity consumed in South Africa. / Thesis (PhD (Electrical Engineering))--North-West University, Potchefstroom Campus, 2013

In 2011 South Africa's main electricity supplier, Eskom, experienced a peak electricity demand of 89% of their total installed generation capacity. The high utilisation rate makes it difficult to perform essential maintenance on the system. Eskom implements Demand-Side Management (DSM) projects in various industries, in order to reduce the demand and to ensure sustainable electricity supply. The mining sector consumes 14.5% of the total amount of electricity generated by Eskom. Mine compressed air systems can consume as much as 40% of a mine's total electricity requirements. This makes mine compressed air systems an ideal target for DSM. Electricity load seems to be reduced, but many DSM savings are not sustained throughout the project lifetime. An existing project feedback method of a specific Energy Services Company (ESCo) includes the manual collection of data from the mines and manual generation of reports. These reports show energy savings of the DSM projects to help the ESCo and their clients to improve and sustain the performance of the projects. A great amount of man-hours is used which results in large time delays in the feedback-loop. In order to address this, the need for a new automatic feedback reporting system was identified. This study mainly focusses on the development and implementation of a new method to monitor DSM savings on mine compressed air systems. It includes the reliable collection of data from mines, processing and storing of the data in a central database and generating savings reports. This is done automatically on a daily basis. In order to complete the feedback-loop, the reports are verified and emailed to clients and ESCo personnel on a daily basis. The new reporting system is implemented at a number of mines. Four of these project implementations are used as case studies to measure and interpret the effectiveness and value of this system. It saves a significant amount of man-hours and proves to be of great value in the sustainability of DSM project savings. Both Eskom and mining companies benefit from the efficient monitoring of mine compressed air savings. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

Rising South African electricity prices and reduced sales following the 2008 economic recession have led cement manufacturers to seek ways to reduce production costs. Prior research has shown that reduced electricity costs are possible by shifting load from expensive Eskom peak pricing periods to lower cost times. Due to the complex considerations and variables in cement production, this is not typically implemented. Several simulation and optimisation models are available in literature to schedule plant operation in an electricity cost effective manner. However, these models have not been implemented in practice. The simulation models are reviewed and evaluated for the task of scheduling cement production on South African factories. A model is identified to be implemented, and the requirements for implementing this model on a cement factory are investigated. A computerised management system is designed to automatically incorporate the required information and data to implement the optimisation model on a practical level. An interface is also designed to allow factory personnel access to the optimised production plan. The system is implemented and evaluated through system level testing. Four case studies are presented within which the system is implemented on South African cement factories. The performance of the system is evaluated over a nine month period, within which a total cost saving of R8.6-million is reported. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

The increasing electricity demand in South Africa has lead to a shortage in electricity supply. In response to this problem Eskom has introduced multiple capacity expansion programs. Unfortunately the electricity shortage is expected to continue until Eskom’s capacity expansion programs are completed. Demand Side Management (DSM) is widely accepted as an immediate solution to the high electricity demand of South Africa. Numerous DSM projects implemented by ESCo’s have been successful, but over the years have not been sustainable. Without regular maintenance from the relevant ESCo, many projects have failed to achieve sustainable savings. After the implementation of DSM projects, all installed equipment and software becomes the property of the client. Experience has illustrated that some mines did not always have the expertise or available resources to monitor and maintain the projects. As a result the electrical energy savings of the project would gradually deteriorate. A feasibility study was conducted to determine whether the re-instatement of redundant and debilitated mine DSM projects could be marketed as the “low hanging fruit” of the industry. A key driver for this study, was the fact that costs involved for re-instatement of such DSM projects are generally considerably lower than those of new projects, yet still producing lucrative electricity savings. Three major mining entities discussed in this dissertation have neglected to realise a collaborative cost saving of R 55,5 Million per annum. This loss of opportunity can mainly be attributed to a lack of maintenance and monitoring of operational DSM projects on their mining sites. Three DSM projects related to the water reticulation system of the mine were investigated. It was discerned in all three cases that the successful re-instatement of DSM projects are indeed possible, but only when subjected to continuous monitoring. The maintenance performed on two of the three projects, respectively realised approximately R2,7 Million and R 750 000. This was achieved through the process of load shifting, over a period of one year. Maintenance on the third project realised approximately R1,5 Million through energy efficiency over a three month period. This dissertation illustrates that attractive savings in electricity and cost can be realised when re-instating redundant DSM projects in the mining industry. It also demonstrates the cost and time effectiveness of implementing such projects, compared to the focus on new DSM installations. / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.

Global climate change and the electricity supply constraints could possibly be one of the utmost strategic issues facing businesses and consumers of all sizes currently in South Africa. Energy Efficiency is the ability to produce the same output but with less energy. The implementation of Energy Efficiency strategies is pivotal in order to sustain the climatic conditions as well as mitigate the supply constraints the South African utility Eskom is experienced. The aim of this study was to reiterate the importance of energy efficiency strategies and to identify the barriers and challenges companies face towards implementing energy efficiency and energy management strategies. This dissertation identified incentives and rebate schemes available to promote energy efficiency strategies and discussed the policies and strategies the South African Government implemented towards realising the energy efficiency target of 12%.The literature review conclude with discussing best practices indentified by implementing corporate energy efficiency strategies. The level of preparedness and progress in implementing an energy management system and strategies between the different companies were assessed. The target population includes the high intensity user group (HIU), listed and SME companies in the different industry sectors in South Africa. The study concludes that there are still multiple challenges facing companies in implementing sustainable energy efficiency strategies. Although government and multiple stakeholders are initiating incentive and rebate models to promote the implementation of energy efficiency measures, industry still lacks the commitment to change their behaviour toward implementing energy management strategies. / Thesis (MBA)--North-West University, Potchefstroom Campus, 2013.

A rapid growth in the national electricity demand is placing an ever-increasing demand on the national electricity supply utility, Eskom. Projections show that the load demand in South Africa may exceed the installed capacity by as early as 2007. This is mainly due to the increase in demand in the residential sector as a result of the electrification of rural and previously disadvantaged communities. However, the industrial and commercial sectors also have a role in this increase. In an attempt to reduce the demand for electricity Eskom has adopted its Demand Side Management (DSM) initiative. This initiative is aimed at lowering the electricity demand in peak times through energy efficiency (EE) or load shift, out of peak demand times. Eskom is implementing the DSM strategy by financing Energy Service Companies (ESCOs) to reduce the demand load of major electricity end-users during peak times. Buildings consume a large percentage of the total energy supply in the world. Most of the energy consumed in buildings is used by the heating, ventilation and air-conditioning (HVAC) systems, as well as lighting. However, a large potential for energy savings exists in buildings. Studies have shown that up to 70% of the electricity consumption of a building can be saved through retrofit studies. However, to capitalise on these opportunities, the ESCOs require tools and procedures that would enable them to accomplish energy savings studies quickly and efficiently. It should be a holistic approach to the typical ESCO building audit. A study of current available software programs showed the lack of holistic tools aimed specifically at retrofit audits, and therefore also the need for such a program. The building simulation program most suited to the retrofit study was chosen and it was used in a retrofit audit. By emulating a retrofit audit with this software, its performance in the field, both positive and negative, could be established. With the experience gained from the retrofit study, as well as input from ESCOs in the industry, a need for such a retrofit tool was established. The simulation program that was tested in the retrofit study is the tool Quickcontrol, as well as the newer version of the program, entitled QEC. The case study showed that even though these packages are well suited to ESCO work, they have certain drawbacks in view of the holistic project approach. The ESCOs require a simple, fast, and integrated procedure for energy audits. This procedure should be embodied in a software program. This study proposes a new integrated procedure for energy audits and the analyses of buildings, in the form of a software tool. This new tool is geared towards the ESCO building audit, in both South A6ica and internationally. It is designed to enable a diplomate engineer to accomplish a building energy and retrofit analysis in two weeks, leading the user through all the main project steps, from data acquisition to writing of the final project report. This is a significant improvement, since it normally takes 50 man-days for an experienced and trained engineering team to complete a full building audit. This tool was used in a case study to test its validity and accuracy. It was found that certain situations would arise in which the criteria that were set for the program would not be adequate. The results from the case study were favourable and satisfied the criteria that were set for the procedure. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2004.

The power utility of South Africa, Eskom, expected a supply shortfall of approximately 400MW between February and August 2006 in the Western Cape. The peak of the crisis was in mid-winter (June to August). This shortfall was firstly caused when Eskom experienced a breakdown on the one of the two nuclear supply units. Secondly the remaining of the Koeberg units was due for refuelling which necessitated the shut-down of the reactor. No electricity was therefore generated by both units. It was clear that if electricity demand was not effectively curbed, extensive power outages would be experienced; which was the case. Various demand side management (DSM) programmes were rolled-out to address lighting, switching from electricity to gas for cooking, compensating customers that could generate own electricity, energy efficiency and load curtailment in the education, commercial, and industrial sectors, as well as an extensive energy efficiency campaign. It is shown in this study that the most constrained periods were expected during the evening peak and was a consequence of electricity consumption in the residential sector. The residential evening peak is very prominent and primarily caused by water heating, cooking, space heating, lighting, and appliances. None of the mentioned programmes focused on the residential evening peak. Traditional residential DSM technologies were almost impossible to implement in the short timeframe because there are more than 625,000 residences in the Western Cape. A solution was looked for that could be implemented in a relatively short period to address the residential evening peak. This study focuses on the development, implementation, and performance evaluation of Power Alert – An innovative residential load management system. The need for such a system was identified and the expected impact was determined through a feasibility study. Power Alert was designed to be a link between Eskom and the public through the national television broadcaster. It was operational during the whole Western Cape winter. A methodology to determine the impact of Power Alert was also developed to demonstrate the actual load reductions. The methodology was applied and Power Alert demonstrated that it was a valuable residential load management tool that could be designed and implemented in a much shorter time than conventional residential DSM measures. / Thesis (Ph.D. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.

Demand Side Management (DSM) is one of the most viable and sustainable short term methods to address the shortfall in electricity generation in South Africa. This is because DSM projects can be implemented relatively quickly and inexpensively when compared with alternative generation options. This specifically applies to the mining industry. South African mines presently consume 15% of Eskom-generated electricity. Mine compressed air systems are some of the biggest users, consuming approximately 21% of mine electricity consumption. Electricity savings on compressed air systems are therefore important. With this study, various Energy Efficiency methods on compressed air systems were investigated. These methods include variable speed drives on compressor motors, temperature control of compressor discharge, minimising pressure drops in the air distribution systems, eliminating compressed air leaks, and optimising compressor selection and control. The most efficient strategies were identified, taking into account factors such as financial viability, sustainability, and ease of implementation. The best strategies were found to be the optimised control and selection of compressors, minimising compressed air leaks, and the optimal control of system pressure. These strategies were implemented and tested on large compressed air systems in gold and platinum mines. Savings of between 10% and 35% on the maximum demand of the systems were achieved. In present monetary terms this translates to as much as R108 million savings for the mines per year at the end of 2009 tariffs. If total mine compressed air electricity consumption can reduce by 30%, it will result in nearly a 1% reduction in total Eskom demand. This shows that mine compressed air savings can make a significant contribution to the drive for Energy Efficiency in South Africa. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.