Climate change implications of large-scale seawater ... · Slide 4 Drivers: Why use SWRO technology? 2. Increasing water demand: Population to grow to 53 million by 2025, industrial

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

[email protected]

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?


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


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



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


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 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?


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


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

[email protected]

Climate change implications of large-scale seawater ... · Slide 4 Drivers: Why use SWRO technology? 2. Increasing water demand: Population to grow to 53 million by 2025, industrial

Documents