The costs of desalination are dropping in several countries, with the ultimate goal to supply water from desalination plants at a cost of $0.40 a kilolitre.
Trans-Caledon Tunnel Authority (TCTA) strategy advisory senior manager Dawid Bosman told the Water Desalination/Reverse Osmosis Membrane & Wastewater Reuse Conference, in Cape Town, on Wednesday, that the typical range of desalination water exit price was between $0.60 and $1.20 a kilolitre.
Bosman said the Gulf States had embarked on replacement of obsolete thermal desalination plants with Seawater Reverse Osmosis plants on a massive scale of 15 megaprojects in six countries with a combined capacity of more than 7 400-million litres a day.
“The bids received so far are testing the $0.50 a kilolitre price threshold, a price which has not been seen in 15 years.”
He said efficiency gains have stemmed from procurement and risk perceptions by the market. Algeria and Israel in particular had managed to drive down costs, while Australia has built the most expensive plants.
Several factors could help to bring the price down further, including the integration of renewable energy into desalination projects, as well as the potential to integrate artificial intelligence in plant design and operations – an area which remains largely untapped.
Bosman believes seawater desalination by reverse osmosis is a viable prospect and increasingly doable on a large scale in South Africa. He has proposed that South Africa adopt a more circular use of water.
“Water is, but should not be, the scarce natural resource that we are used to.
We shouldn’t waste water, but if we want to develop the economy, we have to change our mindset about water. Water can be an economic commodity with a predictable price, infinitely scalable, where you can have as much as you need.”
He said Umgeni Water’s cost estimates for desalination plants “come in very nicely within the ballpark” while he believes the City of Cape Town should have questioned the costs it was given by its suppliers for desalination plants.
The City of Cape Town paid a premium for its desalination plant near the V&A Waterfront, procured when the city was facing a drought and a looming Day Zero.
“The disadvantage of a Day Zero looming is that the market charges you a premium for desalination.”
Bosman said the timing and staging of a desalination project were key. While expensive to begin with, a large-scale plant could save money in the long run and would be based on the paradigm that future water security requires desalination.
“If we had had enough water through desalination, 30 000 jobs in agriculture would have been saved during the drought,” said Bosman.
He said policy certainty and having a clear desalination strategy would mitigate risk perceptions by developers, contractors and suppliers.
Bosman added that poor timing of a desalination plant could result in supply being mismatched with demand and capital locked up in contingency infrastructure. Technology could also become redundant, while political fallout was also an issue, with changing administrations.
Bosman responded to recent news about the prospect of towing an iceberg the size of Table Mountain to Cape Town, by saying the costs would be about ten times higher than the cost of desalination plants.
Expert marine salvager, Nick Sloane, has said the iceberg would potentially be able to provide pure water every day for a price of five to six cents a litre.
“It sounds reasonable per litre, but if you convert that to kilolitres it’s very expensive – around R50 per kilolitre,” suggested Bosman.