Water and the energy crisis – Impact and solutions
South Africa, like many parts of the world, is in the throes of a very difficult electricity shortage. The impact on our daily lives of now regular load shedding and concomitant disruptions of equipment, machinery and appliances that comprise our toolboxes for functionality at home and at work is high, and frequently tests even the most developed sense of humour.
At a structural level, the water business and our ability to deliver quality water services is highly energy dependent. To summarize, energy is the critical enabler at every touch-point in the water delivery chain. This begins with energy driven abstraction, either pumping water for irrigation, domestic or industrial purposes from either surface or groundwater to transporting the water to the point of treatment or direct use. This continues with energy powered water treatment for use, and eventually for wastewater treatment post-use. More recently, and more frequently, energy is being used in freshwater production from brackish or sea water through desalination. Energy is the critical input factor that powers water delivery for all uses and in all environments.
A shortage of power has the net effect of compromising the entire water services value chain for the period of its absence. We have seen this having a major impact in South Gauteng recently with the compromise of two major pumps during to an electrical outage triggered by cable theft. The intermittent supply of the energy service also has other potential challenges to both the pumping machinery that have been designed for continuous, uninterrupted operation without unplanned shutdowns, and the corresponding start-up surges. In addition, we have to examine the impact of interrupted flow in our pipelines and the impact of the introduction of air pockets to both the flow regimes and the corrosion of the piping infrastructure.
Water is also a major player in the electricity value chain. It has the character of a generator in the form of hydroelectricity and wave power. It is also the critical growth additive in the production of biofuels, and biogas is an important by-product of wastewater treatment. It functions as an energy carrier in steam turbines and functions as a hydraulic tool to unleash energy sources like in the hydraulic fracturing or fracking of shale gas. There is last but by no means least the function of cooling energy generators. The relation between water and energy is an intimate one with the highest level of co-dependency.
In this vein, it is clear to see that water can be a major player in alleviating the energy crisis. Water is a major water use and there is a positive correlation between the amount of water used and its energy demand. An up-scaling of our water conservation and demand management interventions will have the impact of lower water consumption and a corresponding decrease in energy demand. The Water Research Commission has in its research portfolio developed a multitude of effective WC/WDM measures and interventions that will realise this impact. In addition The WRC has published a compendium of case studies of successful WC/WDM interventions that have been used successfully on the ground. These include technical and technological solutions, financial interventions, institutional measures and behavioral changes. An example is the implementation of intelligent pressure regulation in Sebokeng/Evaton which not only achieved a water saving of 33%, but a complementary energy saving of 14 million kWh/year and a Greenhouse Gas emissions reduction of 12 000 tonnes.
This has been complemented with a compilation of best practice in efficient energy use in the water sector. In a country where the current energy demand envelope for wastewater treatment is 200-1800 kWh/Ml and the reticulation energy use is anywhere between 0 and 350 kWh/Ml depending on the situation; the opportunity for greater energy efficiency is large. South Africa’s our non-revenue water sits at around 37%, with 25% being in the water leaks domain, the potential for water savings and the related energy saving, therefore, is substantial.
In addition, we are seeing promising results emerging in the WRC portfolio with regard to new micro- and pico- hydroelectricity options utilizing the potential energy stored in the water reservoirs in our towns and cities. The WRC teams are working with our partners to get this technology operational in our towns and cities at scale. This may have the potential of water providing a major component of its own reticulation energy needs in the future.
Water conservation and water demand management together with appropriate investments in water based power generation can become a cornerstone of South Africa’s future energy security for the water sector and beyond.
Author: Mr Dhesigen Naidoo, CEO of the Water Research Commission