The sole electricity supplier in South Africa, Eskom, currently has an electricity supply crisis. The supplier requires additional available electricity urgently, particularly during the evening peak period between 18:00 and 20:00. This electricity shortage is due to a steady increase in the demand for electricity, which exceeded the increase in supply capacity, and the inefficient utilisation of electricity. In order to address this problem, Eskom introduced a Demand Side Management (DSM) programme. The aim of DSM projects is to reduce the load of consumers without negatively affecting consumers. Demand Side Management is beneficial for both Eskom and the client. The client benefits from a lower electricity bill and new equipment, while Eskom benefits from a reduced power demand. Various DSM strategies are implemented in different sectors, such as mining and residential. These projects are managed by Energy Service Companies (ESCo). The ESCo is responsible for the identifying, implementing, and maintaining the DSM project. Any identified DSM project is presented to Eskom, which agrees to fund the project depending on the proposed power saving. The mining industry, which has been selected as a candidate for DSM projects, as it is a major consumer of energy with numerous DSM opportunities, is examined in this dissertation. Because compressors are major consumers of electricity on the mines, significant DSM opportunities exist on compressed air systems. The purpose of this research project is to investigate and implement sustainable DSM projects on the compressed air systems of the mining industry. The focus is on automatically controlling the underground demand for compressed air. Reducing the demand for compressed air will result in lower power consumption by the compressors. / Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2009.

South Africa experienced a severe shortfall in electricity supply during 2008. Eskom, the national electricity supplier, implemented several strategies to alleviate the situation. The Power Conservation Programme set the mining sector a mandatory target to reduce its annual power consumption by 10%. The quickest way to achieve these savings is by optimising the largest power consumers on the mines. Compressed air is one of these, constituting approximately 40% of total electricity consumption on platinum mines. Several methods to reduce power consumption on compressed air systems were investigated. The investigation revealed that centrifugal air compressors on the mines are typically manually operated at a fixed delivery output. Attempts to reduce electricity consumption by reducing air demand will therefore not necessarily lead to savings. A control system that will enable the compressor to automatically match the supply with system demand is required. An optimised control strategy was then developed and implemented on three compressed air systems. Measurements demonstrated savings between 13% and 49%. With the Eskom tariffs proposed for 2010, this implies a total saving of R 46 million per year for these three case studies. This will achieve, and may even exceed, the mandatory reduction in electricity consumption of the mines. These results demonstrate that one of the quickest ways to reduce energy consumption on South African mines is by implementing optimised compressor controls. / Thesis (M.Ing. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2010

The sole electricity supplier in South Africa, Eskom, currently has an electricity supply crisis. The supplier requires additional available electricity urgently, particularly during the evening peak period between 18:00 and 20:00. This electricity shortage is due to a steady increase in the demand for electricity, which exceeded the increase in supply capacity, and the inefficient utilisation of electricity. In order to address this problem, Eskom introduced a Demand Side Management (DSM) programme. The aim of DSM projects is to reduce the load of consumers without negatively affecting consumers. Demand Side Management is beneficial for both Eskom and the client. The client benefits from a lower electricity bill and new equipment, while Eskom benefits from a reduced power demand. Various DSM strategies are implemented in different sectors, such as mining and residential. These projects are managed by Energy Service Companies (ESCo). The ESCo is responsible for the identifying, implementing, and maintaining the DSM project. Any identified DSM project is presented to Eskom, which agrees to fund the project depending on the proposed power saving. The mining industry, which has been selected as a candidate for DSM projects, as it is a major consumer of energy with numerous DSM opportunities, is examined in this dissertation. Because compressors are major consumers of electricity on the mines, significant DSM opportunities exist on compressed air systems. The purpose of this research project is to investigate and implement sustainable DSM projects on the compressed air systems of the mining industry. The focus is on automatically controlling the underground demand for compressed air. Reducing the demand for compressed air will result in lower power consumption by the compressors. / Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2009.

South Africa experienced a severe shortfall in electricity supply during 2008. Eskom, the national electricity supplier, implemented several strategies to alleviate the situation. The Power Conservation Programme set the mining sector a mandatory target to reduce its annual power consumption by 10%. The quickest way to achieve these savings is by optimising the largest power consumers on the mines. Compressed air is one of these, constituting approximately 40% of total electricity consumption on platinum mines. Several methods to reduce power consumption on compressed air systems were investigated. The investigation revealed that centrifugal air compressors on the mines are typically manually operated at a fixed delivery output. Attempts to reduce electricity consumption by reducing air demand will therefore not necessarily lead to savings. A control system that will enable the compressor to automatically match the supply with system demand is required. An optimised control strategy was then developed and implemented on three compressed air systems. Measurements demonstrated savings between 13% and 49%. With the Eskom tariffs proposed for 2010, this implies a total saving of R 46 million per year for these three case studies. This will achieve, and may even exceed, the mandatory reduction in electricity consumption of the mines. These results demonstrate that one of the quickest ways to reduce energy consumption on South African mines is by implementing optimised compressor controls. / Thesis (M.Ing. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2010

In the context of the development of renewable energy sources in the U.K., and of the increase in anthropogenic atmospheric CO2, it is important to develop alternative ways of providing energy to the community. The shift to renewable sources of electricity comes to a cost: variable generation. At present, an important part of the renewable electricity capacity is being curtailed during low demand periods. One way to ensure that electricity supply matches demand is to store excess energy when it is available and deliver it when demand cannot be met by primary generation alone. Compressed Air Energy Storage (CAES) allows this storage. The aim of this project is to build upon existing knowledge on CAES using porous rocks (PM-CAES) to assess the technical feasibility for this storage technology to be developed offshore of the UK. The focus is on inter-seasonal storage. This assessment is undertaken by developing geological and power plant models to calculate the storage potential of offshore UK formations. Modelling of a conceptual aquifer air store enables approximations of the subsurface pressure response to CAES operations. These pressure changes are coupled with surface facilities models to provide estimates of both load/generation capacity and roundtrip efficiencies. Algebraic predictive models can be developed from the results of a sensitivity analysis of the store and plant idealised models. Screening of the CO2 Stored database, containing data on geological formations offshore of the UK (initially developed for CO2 storage), was then performed to estimate PM-CAES potential using the predictive models. The results suggest that there is substantial PM-CAES potential in the UK. Results indicate an energy storage potential in the range of 77-96 TWh, which can be released over 60 days. A geographic information system (GIS) study was then performed to identify the portion of the identified storage potential colocated with offshore windfarm. 19 TWh of the storage potential identified is colocated with windfarm and would be achievable at an average levelised cost of electricity of 0.70 £/kWh.

Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this research is to analyze the overall energy consumption of an industrial compressed air system, and identify the impact of various energy saving of individual subsystem on the overall system. Two parameters are introduced for energy consumption evaluation and potential energy saving: energy efficiency (e) and process effectiveness (n). An analytical energy model for air compression of the overall system was created taking into consideration the modeling of individual sub-system components: air compressor, after-cooler, filter, dryer and receiver. The analytical energy model for each subsystem included energy consumption evolution using the theoretical thermodynamic approach. Furthermore, pressure loss models of individual components along with pipe friction loss were included in the system overall efficiency calculation. The efficiency analysis methods and effectiveness approach discussed in this study were used to optimize energy consumption and quantify energy savings. The method was tested through a case study on a plant of a die-casting manufacturing company. The experimental system efficiency was 76.2% vs. 89.3% theoretical efficiency. This showed model uncertainty at ~15%. The effectiveness of reducing the set pressure increases as the difference in pressure increase. The effectiveness of using outside air for compressors intake is close to the compressors work reduction percentage. However, it becomes more effective when the temperature difference increase. This is mainly due to extra heat loss. There is potential room of improvement of the various component using the efficiency and effectiveness methods. These components include compressor, intercooler and dryer. Temperature is a crucial parameter that determines the energy consumption applied by these components. If optimum temperature can be determined, plenty of energy savings will be realized.

Fried foods are popular around the world. They are also high in fat and considered unhealthy by many people. Reducing the fat content of fried food may allow for even more growth in their popularity, while allowing for healthier eating. Furthermore, vacuum-frying and frying with nitrogen gas have both been shown to extend the life of frying oil. In this study, the use of novel frying methods as a way to reduce fat content of breaded fried foods was evaluated. A pressure fryer was modified so that fish sticks could be vacuum-fried and fried using external gas (nitrogen and compressed air) as the pressurizing media. These products were compared to those pressure fried and fried atmospherically in terms of crust color, moisture content, oil content, texture, and juiciness. Overall, products fried using nitrogen and air were not found to be significantly different (p < 0.05) from each other. These products were both more tender and lower in oil content than steam-fried fish sticks. The energy to peak load of fish sticks fried with air was 123.10 J/kg, fish sticks fried with nitrogen had an energy to peak load of 134.64 J/kg, and fish sticks fried with traditional pressure frying had a peak load of 158.97 J/kg. The crust oil contents of fish sticks fried with air, nitrogen, and steam were 17.35%, 15.88%, and 23.31% oil by weight, respectively. In other words, using nitrogen or air to fry fish sticks reduced the fat uptake in the crust by 31.8% and 25.6% compared to traditional pressure frying, respectively. The only area where vacuum-frying had a significant effect, when compared to pressure-fried and atmospherically-fried fish sticks, was in juiciness. Vacuum-frying created significantly juicier fish sticks than the other two frying methods. Vacuum-fried fish sticks had juiciness of 43.03% (120oC) and 41.31% (150oC), while pressure-fried fish sticks had juiciness of 30.01% (175oC) and 32.93% (190oC), and atmospherically-fried fish sticks had juiciness of 31.56% (175oC) and 29.38% (190oC). In addition, vacuum-fried fish sticks were more tender than atmospherically-fried fish sticks. The results of this study demonstrated that frying with external pressurizing media can be used to reduce oil content in fish sticks, while also creating products that are more tender than conventionally pressure-fried fish sticks. In addition, vacuum-frying, which has been shown to extend oil life compared to pressure frying because of the lower temperatures involved, can be used to create fish sticks that are comparable to pressure-fried fish sticks, but juicier. / Master of Science

<div>The purpose of this research is to analyze the overall energy consumption of an industrial compressed air system, and identify the impact of various energy saving of individual subsystem on the overall system. Two parameters are introduced for energy consumption evaluation and potential energy saving: energy efficiency (e) and process effectiveness (n). An analytical energy model for air compression of the overall system was created taking into consideration the modeling of individual sub-system components: air compressor, after-cooler, filter, dryer and receiver. The analytical energy model for each subsystem included energy consumption evolution using the</div><div>theoretical thermodynamic approach. Furthermore, pressure loss models of individual components along with pipe friction loss were included in the system overall efficiency calculation.</div><div>The efficiency analysis methods and effectiveness approach discussed in this study were used to optimize energy consumption and quantify energy savings. The method</div><div>was tested through a case study on a plant of a die-casting manufacturing company. The experimental system efficiency was 76.2% vs. 89.3% theoretical efficiency. This showed model uncertainty at ~15%. The effectiveness of reducing the set pressure increases as the difference in pressure increase. The effectiveness of using outside air for</div><div>compressors intake is close to the compressors work reduction percentage. However, it becomes more effective when the temperature difference increase. This is mainly due to extra heat loss. There is potential room of improvement of the various component using the efficiency and effectiveness methods. These components include compressor, intercooler and dryer. Temperature is a crucial parameter that determines the energy consumption applied by these components. If optimum temperature can be determined, plenty of energy savings will be realized.</div>

published_or_final_version / abstract / toc / Medicine / Master / Doctor of Medicine

Electrical energy is commonly used in households and in industry - demand continues to rise due to economic and population growth. This requires that energy suppliers must increase their supply capacity. The result is that end–user energy costs continue to increase, therefore a growing need exists to reduce electrical energy demand in South Africa and internationally. Households account for the majority of electrical energy customers, but they only consume a fraction of the total energy supplied. The industrial sector and mines combined consume approximately 42% of the total electrical energy produced. Approximately 10% of this energy goes into compressed air production. This study focuses on methods of reducing the requirement of compressed air in industry so that the demand for electrical energy can be reduced. Many studies have focused on specific methods of reducing energy usage associated with compressed air production. These methods are categorised into methods of reducing compressed air requirements and methods of increasing compressed air supply efficiency. This study aims to combine these efforts into a single optimised solution. Although this study includes industry in general, the central focus is on the South African mining industry. Two different mining sites are considered and analysed as case studies. Methods of reducing energy required to produce compressed air were applied to each case study. Case Study 1 only allowed limited control of the compressed air system. In Case Study 2 integrated control was realised. Energy usage of compressors was reduced by 18.9% and 42.9% respectively. Results show that system savings can be doubled by combining different methods of reducing energy usage of compressed air. This, however, requires continuous monitoring and control of the air network at each section supplied with compressed air. The study is limited to achieving savings by changing the air system. Additional savings can be achieved by training personnel, altering schedules of production activities and implementing a system designed to locate air leaks. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.