Integration of DSM interventions into bulk water supply strategies

Abstract

Supplying water to communities, industries and agricultural developments within South Africa is a cardinal task undertaken by the Department of Water Affairs (DWA). South Africa is a water-scarce country with an uneven fresh groundwater distribution. This makes the continued supply of potable water an arduous and essential task. Water schemes are spread widely across the country, utilising large dams and pump stations to supply water where needed. These pump stations are energy intensive. The national peak demand for electrical energy has reached Eskom’s total generation capacity. Different ways of reducing this demand are being investigated and executed, until the generation capacity can be increased. Eskom has introduced a time-of-use (TOU) costing method for large energy users. This makes it possible to shift load from national peak times to less expensive ones. To enable load shifting at pump stations within water transfer schemes (WTS), certain factors need to be investigated. The DWA conducts an annual operating analysis (AOA) for its water schemes according to the appropriate catchment area. These AOAs are referred to as the “May-one” rules, as they are released by every first of May. They consist of various forecasted water supply scenarios. These are based on annual rainfall, catchment runoffs, user demands and other variables. A 1000 scenarios are generated stochastically, and then evaluated by genetic algorithms (GA). This determines which scenario best suites the supply and demand of water for a specific water scheme. From the results of the AOA, a set of water supply strategies (WSS) are generated. How these WSS could impact DSM interventions and their savings, and how DSM could impact the execution of these WSS are the subject of this study. Their mutual interactions will be simulated and then verified based on the results from a case study. The case study this dissertation will focus on is referred to as Government Water Scheme-A (GWS-A) in Mpumalanga, South Africa. Load shift projects were implemented by HVACI on multiple stations within this scheme.