ASSESSING LARGE SCALE SEAWATER DESALINATION AS A REGIONAL WATER SUPPLY OPTION Steve Gillham General Manager: Engineering & Scientific Services Umgeni

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1 ASSESSING LARGE SCALE SEAWATER DESALINATION AS A REGIONAL WATER SUPPLY OPTION Steve Gillham General Manager: Engineering & Scientific Services Umgeni Water South Africa

2 Conventional Water Resource Options Surface water Direct River Abstractions Dams Lakes Groundwater Boreholes Wells

3 Why even consider seawater desalination as an option? Conventional water resources Close resources already utilised More developments and limited space Longer conveyance distances Increased pumping costs Increased treatment costs Environmental compliance more difficult

4 Why even consider seawater desalination as an option? Seawater desalination Technology costs decreasing Efficiencies increasing Electricity requirements decreasing Operating costs decreasing Capital costs decreasing Conventional resources Capital costs increasing Operating costs increasing

5 For seawater desalination to be a competitive alternative Applicable to coastal strip Availability of an energy source Optimal site location for plant Optimal marine conditions Operational competence

6 (Ref: GCD Alliance) What is regarded as large scale Capacity large enough to serve a region rather than a single community (> 30 Ml/day) vs Sedgefield Desalination Plant 1.5 Ml/day Gold Coast Desalination Plant 125Ml/day

7 Primary components of a seawater desalination plant Intake pipeline from sea/beach to plant Desalination plant (Pretreatment & Treatment processes) Brine discharge pipeline to sea/beach Potable water reservoir Pump station and pipeline to connect to supply network

8 Desalination technologies Thermal distillation: multi-stage flash multi-effect mechanical vapour compression thermo-vapour compression Membrane: electrodialysis reverse osmosis

9 Energy requirements Operational energy consumption average of 4kWh per kilolitre Require about 30 MW of power to supply 150Ml/day Provides % of the Energy

10 Site selection criteria for a desalination plant Primary selection criteria based on potential impact on financial or environmental costs : Distance from the shoreline Elevation above sea level Distance to bulk potable water supply infrastructure Distance to bulk electricity infrastructure supply Existing/planned developments

11 Site selection criteria for a desalination plant.continued

12 Site selection criteria for a desalination plant.continued

13 Site selection criteria for a desalination plant.continued

14 Site selection criteria for a desalination plant.continued Site conditions Flood impacts Geological Environmental sensitivity at, or near, the desalination site Botanical Estuarine Social

15 Site selection criteria for a desalination plant.continued Distance from the shore to Intake and Outlet Marine bathymetry Sea bed geology Beach geology

16 Site selection criteria for a desalination plant.continued Marine infrastructure HDPE Pipe anchored on seabed Tunnel through surf zone Sheet piling or pier through surf zone

17 Site selection criteria for a desalination plant.continued Environmental sensitivity - sea Intake and Outlet Plume dispersion modeling

18 Site selection criteria for a desalination plant.continued Sea current direction and magnitude

19 Site selection criteria for a desalination plant.continued Seawater quality Seawater temperature Continuous sampling of: salinity turbidity temperature chlorophyll water currents Discreet sampling of over 60 other determinants

20 Costs capital and operating Capital costs Infrastructure size linked to efficiencies Corrosion resistant materials Construction cost of 150Ml/day plant ~R3.5 billion Operating costs Energy (74%) Operation & Maintenance (10%) Chemicals (10%) Membrane replacement (4%) Staff (2%) Operating cost of 150Ml/day plant ~R450 million/year

21 Institutional arrangements OPTION Prelim design Design Construction Commissioning Operation Finance Permits Asset ownership DBB Utility Utility Utility Utility Utility Utility Utility Utility DBB+O Utility Utility Utility Utility Private Utility Utility Utility DB Utility Private Private Private Utility Utility Utility Utility DB+O Utility Private Private Private Private Utility Utility Utility DBO Utility Private Private Private Private Utility Utility Utility DBO alliance Utility Shared Shared Shared Shared Shared Utility Utility BOT n/a Private Private Private Private Private Private Utility

22 Implementation Programme

23 Conclusions Seawater desalination is becoming a more financially viable alternative as the cost gap between it and conventional resources narrows Large scale seawater desalination plants require very specific site conditions to minimise capital and operational costs Specialised assessments are required to ensure a workable, and environmentally acceptable solution Pre-Treatment processes are the cornerstone to a sustainable plant Selection of the appropriate institutional arrangement is important To ensure financial sustainability the desalination plant needs to be integrated into long-term water supply plans as opposed to a shortterm drought solution.

24 THANK YOU