The Cost Implications of Operating a Coal-Fired Power Plant in a Cycling Mode

High penetration of non-dispatchable wind and solar to the electricity grid forces the base-loading units to cycle on and off or ramp up and down as per electricity demand. This paper analyses the implications of cycling operation, relative to base-load operation, on the resource and maintenance requirements and costs of operating Majuba coal-fired power plant. Majuba power station's extent of cycling within the Eskom generation fleet has been excessive. In 2016, Majuba experienced 69 starts due to cycling operation. The increased boiler tube failures, fuel oil, coal, water and cost were reviewed for 2016. 60% of the boiler tube leaks experienced at Majuba were caused by cycling operation. 61 % of fuel oil used was due to cycling operation. Cycling operation also resulted in high forced outage rate, and excessive revenue loss caused by loss of production during forced outages. The cost for cycling incurred by Majuba power station during 2016 was at least R156 919 million, without revenue loss due to the loss of production, when repairing boiler tube leaks caused by cycling operation. When including the revenue loss of R776 314; the total cost for cycling operation was R933 million. The cost of cycling per GWh was R280 676. The plant is also ageing fast due to the consequential damages.