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Copyright @ CSIR 2017 www.csir.co.za
Climate change implications of large-scale
seawater desalination plants in coastal cities of
South Africa
IAIA 2017
Annick Walsdorff, Greg Schreiner , Claire Davis, Elsona van Huyssteen, Thomas Roos, Rebecca Garland
Dr Rolfe Eberhard
CSIR - Environmental Management Services
Box 320 Stellenbosch, 7599
Tel +27 21 888 2661
Slide 2 © CSIR 2014 www.csir.co.za
1. What are the Drivers of SWRO in South Africa?
2. What are the Concerns of SWRO in South Africa?
3. Case Study – What are the assumptions?
4. What are the steps toward a sustainable use of desalination?
Slide 3 © CSIR 2017 www.csir.co.za
Drivers: Why use SWRO technology?
1. Climate change: General drying pattern over SA (short to medium term 2021 to
2050)
Increase in extreme events (dry spells (south-west), heavy and extreme rainfalls (east))
Currently 100 days left of water in Cape Town
Cape Town NMBM
eThekwini
Cape Town NMBM
eThekwini
Slide 4
Drivers: Why use SWRO technology?
2. Increasing water demand: Population to grow to 53 million by 2025, industrial and
agricultural growth. Average consumption in SA: 200 to 260 l/p/day (Europe 100-
150 l/p/day and USA 400 l/p/day)
3. Stress on Water Management Areas: Diminishing water quality in catchments,
ageing infrastructure, poor management structures - WWTWs etc.
4. Fewer traditional sources: intensive use of existing freshwater
sources, many of the country’s dams have been built
Slide 5
© CSIR 2011 www.csir.co.za
5. The Australian ‘revolution’: Laying the foundations of a national approach
6. Implementation of small-scale plants in South Africa: Municipal and private sector
developments
7. SA National policy drive: Reconciliation Studies
Increasing interest in large scale SWRO
(in particular in eThekwini, Cape Town and NMBM)
• SWRO: Not a new concept. Global installed desalination capacity in 2016 was 88 900
Ml/day (67% RO)
• BUT energy intensive in a coal dominated energy mix
Contribution to GHG emissions
Drivers: Why use SWRO technology?
Slide 6 © CSIR 2011 www.csir.co.za
0
10000
20000
30000
40000
50000
60000
2010 2015 2020 2025 2030 2035 2040 2045 2050
MW
In
sta
lled
Year
coal 2016 coal 2010 coal legacy
nuclear 2016 nuclear 2010 nuclear legacy
peakers 2016 peakers 2010 peakers legacy
renewabl. 2016 renewabl. 2010
IRP 2010 vs Draft IRP 2016
SOUTH AFRICA ENERGY SITUATION
Slide 7 © CSIR 2011 www.csir.co.za
KEY IMPACTS
COAL RENEWABLE ENERGY
GHG emissions: 1.07 kg CO2 eq/kWh 0.06kg CO2eq/kWh
Other atmospheric emissions
Dust, particulate
matters, heavy metals
None
Water usage 1.42 L per kWh
electricity
None
Terrestrial and aquatic ecology
Fragmentations, loss of
biodiversity, etc. (larger
areas impacted)
Fragmentations, loss of
biodiversity, avifauna
Noise and visual Yes (dependant on
location)
Yes (dependant on location) -
mitigable
Solid Wasters Coal sludge and fly ash None
Slide 8
• Synergies: Coupling with renewable energy? Abundance of renewable resources, increasingly competitive cost Commitment to 55 GW of renewable energy in South Africa by 2050
Energy-climate nexus: Sustainability
Slide 9 © CSIR 2011 www.csir.co.za
Slide 10
Desalination plant capacity: 300 ML/day in Cape Town
• Water usage: Approximately 45% recovery (~2.2m3 seawater required to
produce 1m3 freshwater)
• New technology and affordability: Energy consumption 3.5 to 4kWh/m3
• Run on base load – Base energy demand: ~43 MW (3.5 kWh/m3)
• Under optimum conditions, one would require: 30-40 MW solar plant (Annual solar resource 1900-1950 kWh/m2) 100-110 MW wind farm + additional renewable energy for downtimes (e.g. biogas/biomass)
• Approximately 20% excess solar/wind – sold back to municipality?
© CSIR 2017 www.csir.co.za
CASE STUDY – CAPE TOWN
Desalination plant CAPEX (Million
US$/MLD)
O&M
(US$/m3)
Water Produced
(US$/m3)
Mediterranean Sea 1.2 0.35 0.98
Arabian Gulf and Red Sea 1.5 0.5-0.6 1.3
KwaZulu Natal (Umgeni) 2.0-2.2 0.6 1.03
Slide 11
• GHG emissions 1.07kg CO2eq/kWh (municipality electricity) 0.06kg CO2eq/kWh (renewables)
Coupling SWRO plant with supply from renewable energy would lead to
carbon savings of approximately 1000 tons of CO2eq per day
• Assuming use of 1.42 L of freshwater (coal-fired power stations) to produce 1 kWh 1 491 m3/day water savings
• Power supply: 0.62 ZAR/kWh for solar/wind power
• Municipal electricity range from 1 to 2 ZAR/kWh
• 20 to 40% savings in electricity = 10-20% O&M costs savings
© CSIR 2017 www.csir.co.za
CASE STUDY – CAPE TOWN
Perth, 450 Ml p/d
Slide 12
• Panacea to water scarcity in South
Africa?
• Growth and climatic changes will result in
increasing number of SWRO plants
• Fundamentally, SWRO should be
understood within a holistic national
approach to water supply
• Nexus: Environmental impact, energy,
greenhouse gases, water consumption
and cost
• RED? Nuclear coupling?
Discussion
Copyright @ CSIR 2014 www.csir.co.za
Thank You
Questions
Annick Walsdorff
CSIR - Environmental Management Services
Box 320 Stellenbosch, 7599
Tel +27 21 888 2661