Browsing by Author "Auret, Christina"

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    Scenario modelling for short to long term rollout of Concentrating Solar Power (CSP) in South Africa
    (Stellenbosch : Stellenbosch University, 2015-03) Auret, Christina; Gauche, Paul; Dinter, Frank; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: South Africa is currently in the process of greatly expanding its electricity generating infrastructure. A significant portion of the new capacity will be made up out of renewable energy systems. The aim of this study was to investigate potential benefits and pitfalls of introducing concentrating solar power (CSP) into the South African electricity generating system, by making use of spatio-temporal modelling. Government policy for the expansion of the generating fleet is defined in the Integrated Resource Plan for electricity (IRP). A draft update of the IRP that describes a number of possible scenarios for the composition of the generating fleet was released in 2013. Three of these were selected and modelled for the 2030 and 2050 fleet composition and projected demand for the purpose of this study. The effect of implementing a two tier tariff designed to incentivise electricity production during evening peak by CSP plants was also investigated. All modelling was done on an hourly basis. Spatio-temporal modelling was used to model wind, photovoltaic and CSP electricity production. The balance of the generating system was modelled using a behavioural model. The system performance was compared across scenarios by using the following system adequacy measures: electricity shortfall, open cycle gas turbine capacity factor and coal plant capacity factor. Comparing CSP plants that were optimised to be remunerated under a two tier tariff with plants that were optimised to minimise levelized cost of electricity showed that imposing the tariff had a significant impact on plant configuration and electricity production. Using CSP plants that were under a rigid two tier tariff was also found to have a negative impact on system adequacy measures in a system with a high renewable energy uptake. The results were reasonable for a system with a moderate uptake in renewable energy and good for a system with a low uptake. For example: acceptable levels of electricity shortfall in a projected system would be equal to 20 GWh per year. With the two tier tariff in place the low uptake scenario averaged 32.9 GWh, the moderate uptake scenario 99.6 GWh and the high uptake scenario 5059.7 GWh for 2050. Results for the two higher uptake scenarios were improved significantly by redeploying a large portion of the CSP plants as base load units that were responsive to system needs. The results for a system with a high uptake of renewable generating capacity was still not at acceptable levels (e.g. 844.52 GWh shortfall), but the moderate uptake system performed well. This may indicate that the higher the uptake is of renewable energy, the more flexible the electricity output of the CSP will have to be for optimal overall system performance. While this flexibility is technically feasible, according to this study a rigid remuneration structure will not incentivise the CSP plants to act on this capability.