University of Cape Town
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Water Energy Nexus - Reports

posted on 2019-10-18, 10:38 authored by Fadiel Ahjum, Bruno MervenBruno Merven, Adrian Stone
This research focuses on incorporating a representation of water supply and infrastructure costs into an energy systems model (SATIM-W) to better reflect the interdependent nature of the energy-water nexus in South Africa and the water supply challenges facing the energy system. The research methodology developed embeds the various water supply options in a least cost optimization energy planning tool, so that the cost of water is captured. A key feature of the developed SATIM-W model is that it regionalizes power generaation, refining, and energy resource supply, thereby introducing a spatial dimension to the water demands of the energy sector. It also contains a regionalized structure of the basins and delivery infrastructure that would be required to supply the energy sector and assesses the impact of meeting those needs on the cost of supplying water. The results of this investigation demonstrate the process and type of tools that can be employed to examine the energy-water nexus in a national level planning context, and the insights that can be gained from water-smart energy planning. A number of relevant policy scenarios in South Africa were explored, and the results show that specific energy sector policies can have significant implication for both new investment in water supply infrastructure and in some cases can lead to stranded energy and water investments, reinforcing the importance of planning these sectors through a nexus approach. This case study is the first time the cost of water supply has been assessed in a sector wide energy supply expansion plan. By documenting the methodology, the authors aim to help energy sector planners and modelers properly incorporate water constraints in their work.



The interdependency between water and energy is growing in importance as demands for both water and energy increase. Several regions of the world are already experiencing water and energy security challenges, which adversely affect sustainable economic growth. In addition, the world’s population is expected to grow, which will in turn increase demand for water and energy, especially in fast-growing developing countries. The project aims to represent the evolving cost of water to the technologies represented in an energy system’s planning model, ERC’s SATIM model, by representing the planned augmentation schemes for key water supply regions to 2050 and their projected costs and capacities. This will thus be a water-smart energy planning model (SATIM-W) which is hoped will give powerful insights into infrastructure decisions when combined with climate scenarios.


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