A 20 year forecast of water usage in electricity generation for South Africa amidst water scarce conditions

Being a semi-arid country with limited fresh water resources and also a fossil fuel based energy intensive country, South Africa encounters the added pressure of allocating limited water resources. Roughly 90% of electricity in South Africa is generated from coal fired power plants that are located in semi-arid areas and use a combination of wet and dry cooling techniques. The paper aims to forecast water usage within coal based electricity generation in order to facilitate water management in water deficient parts of the country. Some of the older return to service (RTS) power plants which have been brought back to operation due to electricity shortages are water intensive and are located in water constrained water management areas. These power plants should be phased out gradually and replaced by higher efficiency dry cooled power plants - that are currently under construction – by the year 2020. Total water requirements could reach 370 gigalitres by the year 2021 from current levels of 360 gigalitres. Depending on the retirement of inefficient power plants, total water usage can be reduced by roughly 14%. Results show that management of water resources in the electricity generation sector can result in informed water allocations within water management areas. Proposed gradual retirement of the RTS fleet could result in a savings of 15% of the forecasted shortfall of 234 gigalitres by the year 2025. The deficit in electricity generation output caused by the retirement of the RTS fleet will have to be compensated by the simultaneous commissioning and operation of new build power plants. Such measures will provide much required water relief to water constrained water management areas. Overall increases in water usage until 2035 can be minimised if inefficient wet cooled power plants are gradually retired and if dry cooled power plants are more prominent.