Browsing by Author "Heinrich, Glen Sean"
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- ItemOpen AccessA comprehensive approach to electricity investment planning for multiple objectives and uncertainty(2008) Heinrich, Glen SeanAppropriate Energy-Environment-Economic (E3) modelling provides key information for policy makers in the Electricity Supply Industry (ESI) faced with navigating a sustainable development path. Key challenges include engaging with stakeholder values and preferences, and exploring trade-offs between competing objectives in the face of underlying uncertainty. As such, a comprehensive framework is needed that integrates multiple objectives and uncertainty into a transparent methodology that policy makers and planners can use to analyse and plan for investment in the ESI, in a way which shapes decision outcomes, and enables confident choices to be made. This thesis is aimed at developing such a framework. As a case study the South African ESI was represented using a partial equilibrium (Energy-Economic-Environment) E3 modelling approach. This approach was extended to include multiple objectives under selected future uncertainties. This extension was achieved by assigning cost penalties (PGPs – Pareto Generation Parameters) to non-cost attributes to force the model’s least-cost objective function to better satisfy non-cost criteria. It was shown that using PGPs is an efficient method for extending the analysis to multiple objectives as the solutions generated are non-dominated and are generated from ranges of performances in the various criteria rather than from arbitrarily forcing the selection of particular technologies. Extensive sections of the non-dominated solution space can be generated and later screened to allow further, more detailed exploration of areas of the solution space. Aspects of flexibility to demand growth uncertainty were incorporated into each future expansion alternative (FEA) by introducing stochastic programming with recourse into the model. Technology lead times were taken into account by the inclusion of a decision node along the time horizon where aspects of real options theory were considered within the planning process by splitting power station investments into their Owner’s Development Cost (ODC) and Equipment and Procurement Cost (EPC) components. Hedging in the recourse programming was automatically translated from being purely financial, to include the other attributes that the cost penalties represented. The hedged solutions improved on the naïve solutions under the multiple criteria considered as well as better satisfying the non-cost objectives relative to the base case (least cost solution). From a retrospective analysis of the cost penalties, the correct market signals could be derived to meet policy goal, with due regard to demand uncertainty.
- ItemOpen AccessAn investigation into the use of froth colour as sensor for metallurgical grade in a copper system(2003) Heinrich, Glen Sean; Bradshaw, DeeIn recent years the development of Machine Vision systems has opened up new possibilities for non-intrusive process performance sensors and process control. There are currently various Machine Vision systems on notation plants worldwide (Metso at Kennecott, Frothcam at Escondida). Extensive research has been done on using froth image analysis in closed loop control (Hyotyniemi et aI, 2000; Kittel et aI, 2001; Holtham and Nguyen, 2002; Cipriano et aI, 1998) and recently plants have been using these systems to control the air or level of a flotation cell as a means of controlling mass pull using the froth velocity output. As yet no flotation plants have reported the use of froth colour in their control strategies, however it is well accepted that an experienced operator can judge the metallurgical state of a flotation cell by the appearance of the froth, using colour as a key descriptor of grade, particularly in the case of copper froths. For this reason an investigation was undertaken to evaluate whether a relationship existed between concentrate grade and the froth colour obtained using a Machine Vision system. This relationship could be used to control reagent addition or for system diagnostics. Both would be invaluable tools for the flotation industry. A Machine Vision system called SmartFroth has been developed at University of Cape Town (VCT) as a research tool to investigate the relationships between froth surface indicators and metallurgical parameters. The relationship between froth colour and % solids was also investigated as it was believed that solids loading could be reflected by froth colour. This work was aimed at evaluating the empirical relationship between froth colour and copper grade in the laboratory and then investigating whether a similar relationship existed on plant. Various colour spaces were examined to find one appropriate for the copper flotation froths in order to allow for accurate colour analysis. It also evaluated the use of calibration objects in the colour analysis of flotation froths. This work also evaluated relating froth colour to % solids on plant. Two batch flotation campaigns were done using different ores as well as a preliminary plant trial.