Abstract
Electricity demand and supply imbalances have resulted in recurrent load shedding in South Africa. The industrial sector, despite its contribution to the country’s gross domestic product, is not spared of the load shedding. To reduce the frequency of outages in South Africa, and curtail the impact of load shedding on the economy, several demand-side management approaches have been implemented within industrial processes.
Among the demand side management approach is load shifting, a type of flexible demand-side management. Load shifting is the ability of a consumer to increase or decrease consumption. The ability of industrial customers to voluntarily shift their on-grid demand during a constrained period on the grid as a demand-side management approach has not been fully explored in South Africa.
This study explored the potential for flexible demand-side management on the grid using a South African steel plant as a case study. Energy-intensive industrial processes with high base load process equipment are constrained to the extent they can implement a flexible DSM. Such is the case of many of the process operations of the steel plant investigated. However, industrial processes with a batch operation such as the electric arc furnace of the steel plant can participate in flexible demand-side management. However, the extent of participation depends on how the load shifting of an upstream process affects the downstream processes and product quality assurance.
In this study, primary data of a steel plant processes and the number of process equipment, their power demand and energy consumption were obtained and analysed in Microsoft Excel. Scenarios simulation in Microsoft Excel and PVSyst was conducted to assess the potential of flexible demand side management within the steel plant. It was concluded that the electric arc furnace operation and subsequent downstream process operation could be shifted during the peak period without affecting the quality of the product. This is because intermediate products produced during the period of load shifting can serve as raw material to the electric arc furnace when it is back to operation. Daily throughput of the plant will be lower during days of load shifting, however, annual throughput can still be achieved if load shifting is for a short duration. Besides load shifting, the study found that distributed energy resources can also be explored to reduce the steel plant on-grid demand. Approaches were proposed for industrial customers to assess possible flexible demand-side management within their plants.
Keywords: Demand side management; electricity; industrial process; distributed energy resources