Abstract for: Modelling the Raw Water Demand of a Dry-Cooled, Coal-Fired Power Plant: A System Dynamics Approach

South Africa is a country with limited and deteriorating quality of fresh water resources. Eskom, being the key supplier of electricity to the country, is the single, largest user of these precious water resources. Consequently, it is imperative that the organisation fully understands its long-term water supply and demand; with regards to quantity, accessibility and quality; for planning purposes to ensure that the security of water for electricity needs is met and to respond appropriately to the water crisis in South Africa. In modelling the long-term raw water demand, a system dynamics approach was favoured as a result of the ability to model, to an optimum level of complexity, the dynamic trends in water demand over life of the plant, without losing the ability to follow causality between system parameters with time delays. Water mass balances for a 4,800 MW dry-cooled, coal-fired power plant were constructed across every process utilizing water and, every water source and sink. Upon varying rainfall; coal quality; thermal efficiency; auxiliary power consumption; demineralized water recovery and consumption rates; third party water usage and, employing flue gas desulphurization technology and other water saving measures, efficient use of water at the plant to reduce raw water demand was simulated.