South Africa has been facing significant challenges in meeting demands in its water and energy sectors in recent years and planning for both sectors has mostly been done separately. The City of Cape Town has started to supplement its dwindling conventional freshwater supplies with groundwater, wastewater and seawater, in light of the drought that commenced in 2015. The Cape Flats Aquifer in Cape Town represents an important resource whose yield could be increased to 85 000 m3/ day through artificial stormwater recharge in the Zeekoe Catchment alone. The abstraction and treatment of this water would require significant amounts of energy and thus this paper explores the links between energy usage in the water sector and its carbon footprint. The three alternatives investigated were ‘centralised’, ‘desalination’ and ‘decentralised’ approaches. The former two are centralised treatment mechanisms to produce potable water utilising existing and new treatment infrastructure, respectively, and the latter proposed minimal treatment for non-potable end-users. The energy intensities of the alternatives were evaluated by identifying energy-intensive components and carrying out a preliminary design of the networks and the required treatment mechanisms. South Africa’s future potential electricity mixes were used to conceptualise the significance of the associated energy demand. The centralised approach’s energy intensity was found to be the lowest of the three, ranging from 1.16 to 1.57 MJ/m3, while those of the decentralised and desalination approaches ranged from 3.57 to 7.31 MJ/m3 and 7.41 to 9.62 MJ/m3, respectively. The Western Cape Water Supply System has an installed capacity of 47.6 MW which could potentially increase by at least 2.7%, 5.7% and 12.3% through the centralised, decentralised and desalination options, respectively. This paper contributes to a growing knowledge on the water–energy nexus in South Africa.
South Africa is an arid country, where water supply is often obtained from a distant source. There is increasing pressure on the limited water resources due to economic and population growth, with a concomitant increase in the energy requirement for water production. This problem will be exacerbated by the onset of climate change. Recently, there have been concerns about negative impacts arising from the exploitation of energy resources. In particular, the burning of fossil fuels is significantly contributing to climate change through the emission of carbon dioxide, a major greenhouse gas. In addition, fossil fuels are being depleted, and contributing to decreased energy security. As a result of this, the international community has initiated various interventions, including the transformation of policy and regulatory instruments, to promote sustainable energy. With this in mind, South Africa is making policy and regulatory shifts in line with international developments. Renewable energy is being promoted as one way of achieving sustainable energy provision in the country. However, some issues require scrutiny in order to understand the water footprint of renewable energy production. Due to the large gap that exists between water supply and demand, trade-offs in water allocation amongst different users are critical. In this vein, the main objective of this study was to investigate and review renewable energy choices and water requirements in South Africa. Data were acquired through a combination of a desktop study and expert interviews. Water withdrawal and consumption levels at a given stage of energy production were investigated. Most of the data was collected from secondary sources. Results show that there is limited data on all aspects of water usage in the production chain of energy, accounting in part for the significant variations in the values of water intensity that are reported in the literature. It is vital to take into account all aspects of the energy life cycle to enable isolation of stages where significant amounts of water are used. It is found that conventional fuels (nuclear and fossil fuels) withdraw significant quantities of water over the life-cycle of energy production, especially for thermoelectric power plants operated with a wet-cooling system. The quality of water is also adversely affected in some stages of energy production from these fuels. On the other hand, solar photovoltaic and wind energy exhibit the lowest demand for water, and could perhaps be considered the most viable renewable options in terms of water withdrawal and consumption.
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