Demand side management in South Africa at industrial residence water heating systems using in line water heating methodology

The South African electrical utility, ESKOM, currently focuses its demand side management (DSM) initiatives on controlling electrical load between 18:00 and 20:00 each day, which is the utility’s peak demand period. Funding is provided to energy service companies (ESCo’s) to implement projects that can achieve load shifting out of this period. This paper describes how an improved in line water heating concept developed in previous studies was implemented into several real life industrial sanitary water heating systems to obtain the DSM load shift required by ESKOM. Measurements from a selection of these plants are provided to illustrate the significant load reductions that are being achieved during 18:00–20:00. The measured results also show that the peak load reduction is achieved without adversely affecting the availability of sufficient hot water to the persons using the showering and washing facilities served by the water heating system. A very good correlation also exists between these measured results and simulations that were done beforehand to predict the DSM potential of the project.The in line water heater concept provides an improved solution for DSM at sanitary water heating systems due to the stratified manner in which hot water is supplied to the tanks. This provides an improved hot water supply to users when compared to conventional in tank heating systems, even with load shifting being done. It also improves the storage efficiency of a plant, thereby allowing the available storage capacity of a plant to be utilized to its full extent for load shifting purposes.