Report counts the cost of desalination

PERTH company AgritechSmart-Water has commissioned an economic review of its plans to use Wellington Dam as a major new source of water for the South West.

The company is proposing the desalination of Wellington Dam's brackish water by using gravity pressure, as an alternative to the Water Corporation's plan to build a new desalination plant on the coast at Binningup.

Its push for support comes as the new state government conducts a review of alternative water sources.

"Wellington Dam is well and truly on the radar,'' a spokesman for Water Minister Graham Jacobs told WA Business News.

"All possible options for use of Wellington Dam are seriously being considered."

The spokesman said the government had allocated $250,000 to fund an independent review of water sources.

The Water Corporation has focused on the Binningup desalination plant and the Yarragadee groundwater aquifer as the state's best options for future water supply.

Water Corp spokesman Phil Kneebone said it had not been able to make an informed judgement on the AgritechSmartWater proposal.

"They have never come back to use with detail," he said.

"We don't know if it works or not."

AgritechSmartWater has moved to fill the knowledge gap by commissioning Subiaco-based Resource Economics Unit to complete a pre-feasibilty study of its proposal.

REU's principal is economist Jonathan Thomas, former assistant chief of the CSIRO's Division of Water Resources.

His report states that the capital cost of Binningup, at 2008 prices, will be $640 million, nearly quarter of a billion dollars above the already built Kwinana desalination plant and $480 million more than the Wellington Dam gravity fed proposal.

When trunk piping is included, aggregate costs are: Binningup, $680 million; Kwinana $424 million; and Wellington Dam, $242 million.

Potable water output of all three is 45 gigaliters.

This means the cost per kilolitre for Binningup will be $2.18 to Kwinana's $1.74, with Wellington Dam water only costing 57 cents.

Resource Economics Unit's report says: "The [Wellington] project is an example of how Public Private Partnership arrangements can deliver more effective, efficient and environmentally responsible water infrastructure investment, in line with the recent recommendations of the [WA] Economic Regulation Authority proposing the establishment of a new Procurement Authority for water infrastructure in WA."

AgritechSmartWater proposes that brackish Wellington Dam water be piped 21 kilometres, falling 150 metres, in a 1.5-metre pipeline by gravity feed to a desalination plant located on the coastal plain below Collie.

The plant would consume 56GL of the dam's brackish water stock annually and feed 45GL of potable into the Water Corporation's network.

Because AgritechSmartWater's plant would not rely on generated energy, unit outlay per litre is dramatically slashed.

The Resource Economics Unit report says: "A literature review and preliminary assessment suggests that gravity powered reverse osmosis (RO) would have a considerable competitive advantage over seawater desalination due to:

- the use of hydraulic head to drive the reverse osmosis plant, thus minimising power costs; and

- savings in membrane maintenance due to the superior physical and chemical characteristics of Wellington Dam water as compared to seat water, notably the absence of carbonates, which builds up in sea water RO plans and review chemical dosing using sulphuric acid which is returned with the waste stream to the receiving water."

The report says the Wellington Dam proposal can expect operating costs of about $6.8 million ayear compared with $45 million a year for Binningup.

Over a 20-year period, using a 6 per cent discount rate the outcome "is at present value of $86.9 million for Wellington as against a massive $576 million for Binningup".


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