Sea water desalination is as old as is nature and so the human engineered desalination approach is from a philosophical perspective engineered biomimicry and nothing else. So why are the critics, mostly not from the water sector, so vocal? From a South African angle these three arguments seem to surface that we can look at objectively:
- It's expensive
Recent projects in the well established desalination regions have seen IWP's (Independent Water Producer) the benchmark drop to USD 0,50/kl (R7,25/kl) which is a contractually guaranteed price. The global average (http://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/WWMay-June2021_desalination.pdf) is reported to be in the region of USD 1,21/kl (R17,55/kl). In South Africa our bulk water production costs by water utilities from traditional dam resources are highly variable due to a complex set of circumstances including state owned monopolies where unregulated pricing absorbs many inefficiencies. Having said that, our prices seem to be in the range of R5,20/kl in 2018 (City of Cape Town "Water Outlook 2018 Report") so probably closer to R7,00/kl in 2021 and Rand Water tariff at R11,66/kl in 2019, so around R14,00/kl in 2021. (https://www.randwater.co.za/SalesAndCustomerServices/Tariffs/Tarrif%20Consultation%20Process%202017-18/All%20customers%20approved%20tariff%202019_20.pdf)
Water price inflation in South Africa has been in double digits for the past decade at least whereas desalination prices are reducing in real terms globally. I would guess, until we have the Independent Water Regulator in place, that our water prices will easily be between R10,00 to R20,00/kl by 2025 by when we would expect utility scale (50 MGLD and larger) desalination pants to start coming online in South Africa.
Using untested but published estimates of capex and renewable energy inputs for South Africa, it looks like we will achieve an initial R10,00 to R11, 00/kl in 2025 which is USD 0,69 to USD 0,76/kl which is still above the global benchmark in 2021 of USD 0,50/kl but not expensive relative to surface water costs.
It is therefore absolutely untrue that SWRO (Sea Water Desalination) in South Africa will be expensive and this is using the first wave of utility scale facilities where in time as we develop more project implementation experience the costs will drop closer to global norms.
- It needs high energy
Two decades ago SWRO needed around 8kWh/kl and now its well below 4kWh with the norm hovering around the 2,5kWh/kl. Theoretical minimum is 0,83kWh/kl which excludes peripherals that will probably get us down to around 1,5 to 2kWh/kl with technology improvements currently being worked on from improved energy recovery systems to membrane mater. so if one looks at this steep reduction in energy required and the consequent price we can safely that the energy required is not high coupled with renewable energy that is infinitely renewable.
- It produces polluting brine
When one looks at the water cycle we have:
- Sea water evaporates and the water component is loaded into the atmosphere globally with the salt or brine staying in the sea.
- Precipitation on land and sea when conditions are ideal takes place.
- Some of the water percolates into the ground and is stored in aquifers.
- The balance of the water eventually finds its way into the sea via rivers, return flows and transpiration
- Most of the water is returned to the sea in time, even the ground water.
SWRO mimics the water cycle, as does the mangrove illustrated, in an engineered manner with exactly the same net effect, how can this from a mass balance perspective be polluting? There is an obvious proviso, SWRO is around 50% efficient and so when removing the 50% water it results in the doubling of the salt concentration in the return flow/brine stream. This brine stream is engineered to be diffused at a distance from the coastal zones where natural equilibrium is rapidly reached as brine diffuses from a higher to a lower concentration naturally and rapidly. Over time with return flows after use by humans the sea water receives the potable water back resulting in a zero net effect. This is how nature works and SWRO is no different in reality, maybe a little faster at times.
Engineered return flows in Australia, that has similar coastal conditions as South Africa, have been closely monitored by independent oversight with only slight improvements in biodiversity observed, hardly polluting at all is the obvious conclusion here.
In conclusion, having water security 100% of the year is surely not a pricing, energy or environmental issue but an economic security matter!
About Benoit
Benoît has in excess of thirty five years of environmental engineering experience concentrating on the Water, Waste Water and Waste fields serving all tiers of government, mining, utilities, SOE’s, automotive, Food & Beverage, Iron & Steel industries. He has been developing and integrating environmental solutions internationally using appropriate technologies via advisory services and the supply &/or co-ordination of specialized technologies. He has also presented training for the water and waste water disciplines to provincial and local government via the Centre for Environmental Management at North West University and various presentations on Water and Waste Water (concentrating on Capacity Building) for the Institute of Municipal Engineers of SA.
Benoît has been involved in water EPCM and O&M projects since 1982 in the industrial, mining and municipal sectors and as such has significant experience in turning around South Africa's collapsing municipal water and sanitation infrastructure.
Current activities are focusing around the revitalisation of the South African water sector with a lead role in the PPGI, Public Private Growth Initiative, coupled with the co-founding role in the establishment of the SA Water Chamber. Both of these initiatives seek to engender water resilience and attract investment back into South Africa.
Benoît has Certificates in Chemistry, Diplomas in Chemical Engineering and Business Management. Identifying and selecting appropriate technologies/solutions for waste and water management with embedded energy harvesting a primary driver in most cases forming the cornerstone of his activities as the Co-Founder and CEO of the SA Water Chamber, CEO Water Shortage SA, CEO of Enviro-One, CTO of Mechanika and Operations Director of Nexus Water Alchemy.
Benoît is an avid believer in that water is not only an economic enabler, but a national priority for South Africa’s economic revival and a general theme globally.
