Perth's combined wind energy / Desalination plants , the greatest greenest civil engineering projects ever, anywhere.

Perth ,Western Australia is a growing city of over 1.7 Mn people (annual growth 3%), this oceanside paradise it sits not only on the Swan River (named after the native Black swans) , but on fast dwindling aquifers whose decline has been accelerated by a massive growth in demand by a shift to a hotter, drier shift climate.

The dry winter of 2001 and drier 2002 summer was the worst drought period on record - in 2005, it was confirmed that in the eight years from 1997 stream flows had dropped by a third to an annual average of 115GL/yr from 161GL/yr over the previous 23 years (1974–1997).

It was evident that short term cuts on sprinkler usage, greater groundwater allocation (three bores into the Yarragadee aquifer deep below Perth's northern suburbs and a further nine into the shallower aquifer at Mirrabooka) and A$142 MN spent on more storage was only a stopgap measure even with expenditure of $142m to further augment supply capacity with dams and resevoirs in Samson Brook and Wokalup Creek. ( Perth and South West dams total capacity is 688 gigalitres - they currently(today) hold 140.16 gigalitres, 20.4% of their total capacity.)

Although these measures added some 40GL/yr to the City's integrated water supply system supplying a user base over 2.5 million square kilometres, it was evident that a longer term, 50 year 'Security through Diversity' strategy would need to be adopted. Demand growth calculations showed that by 2010, around 107GL/year of new water will be needed to meet the rising demands of a growing population.

As a result the City fathers and the state owned Western Australia Water Corp. with remarkable foresight, planned, designed, and built a wind farm north of the City, to supply electricity for a massive coastal seawater desalination plant located at Kwinana, 25km south of the city (see Google Earth view) - the capital costs were A$350 Mn and with running costs of A$19 Mn a year . The direct cost of water delivered is A$1.16 per 1,000 litres (Kl).

With an in initial capacity of 140,000m³ and planned expansion to 250,000m³/day, it is the biggest of it's kind in the world and will ultimately supply 17% of the Perth coastal areas needs - some 45 GL/yr.

Drawing water from the Cockburn Sound the Perth Seawater Reverse Osmosis Plant (SWRO) extracts water with an input salinity of 35,000mg/l to 37,000mg/l at 16°C to 24°C (0.02% of the water in the sound being removed per day).

This is initially filtered by the pre-treatement plant then is forced through the spiral wound membrane elements of the Reverse Osmosis treatment trains. This product water is treated with lime, chloride and fluoride, stored and then blended with water from other sources before being pumped into the the municipal integrated supply system.
The filter backwash and concentrate stream is returned to the sound and because the the Cockburn Sound is an area of environmental sensitivity the effluent is strictly monitored and has to meet stringent conditions have been imposed on TDS, temperature, DO and the sediment habitat in the vicinity.The concentrate outflow is about 7% salt, so the the discharge nozzles are designed to act as diffusers, to ensure that salinity falls to less than 4% within 50m of the discharge point.

Electricity for the desalination plant – which has an overall 24MW requirement and a production demand of 4.0kWh/kl to 6.0kWh/kl – comes from the new 80MW Emu Downs Wind Farm, which consists of 48 wind turbines located 30km east of Cervantes about a 3 hour drive north of the City. Developed by Stanwell Corporation, a power generation corporation owned by Queensland Government and Western Australia's Griffin Energy, this facility commenced operation in 2006.

Sydney, another seaside Australian city is expected to commission a plant even larger than Perth's in the next few months and now Perth expects to have built another one by 2011..

Perth was also examining exploiting the The South West Yarragadee aquifer as a water source which was resisted fiercely under their banner :

"The forests and wetlands of the South West Region may die
so Perth's lawn may live."

Their website is a model for ecological activists and well worth a visit.

"Perth's water crisis is not one of lack of supply but one of lack of imagination on behalf of short-sighted politicians and policy makers. The realisation that the continual search for water for unsustainable landscapes is a dead end resulting in a move towards collapse of ecosystems and economies."

The Friends of Yarragadee have obtained some respite and politicians have seen sense, because on May 16th 2007 West Australian Premier Alan Carpenter announced that a second seawater desalination plant powered by renewable energy would be Western Australia's next major water source. The Premier said ;

"The internationally acclaimed wind-powered Kwinana seawater desalination plant has demonstrated that large quantities of water from an unlimited ocean supply can be provided using a clean and green process," ...

"I have asked the Water Corporation to immediately start developing the State's second major seawater desalination plant."

The proposed second combined wind energy / desalination plant is at a Water Corporation wastewater treatment near Binningup - will provide at least 45 gigalitres of water a year which could increase to 100 gigalitres. The capital cost will be A$640 million with a further A$315 million piping / connection costs.

Last week's State Budget allocated $750 million over the next four years for a new water source. An additional $205 million will be allocated in the 2011-12 financial year. Some of the cost will also be met by a A$30 rise in household water bills in 2008-2009 on top of the A$28 rise announced for 20078/8 in the Budget. The new plant is expected to produce water at A$1.90 a kilolitre (qv A$1.16 for Kwinana. Plant operation will require approximately 20 full time employees.

"We can no longer rely on traditional, seasonal climate patterns and rainfall," the Premier said.

As this decision to can the Yarragadee Aquifer development, was due to come on stream in 2009, there are concerns by some vote hungry pols that the winters of 2009/10 could see supply problems and (hot damn) lawn sprinkler restrictions. There are also more individually expressed concerns claiming that better water management may be the key to Perth's water supply.

These are the current mandatory restrictions on water usage in Sydney - Minimum fines for offences A$220.

• Hand-held hosing of lawns and gardens and drip irrigation is now allowed only on Wednesdays and Sundays before 10 am and after 4 pm
• No other watering systems or sprinklers are to be used at any time
• A permit from Sydney Water is required to fill new or renovated pools bigger than 10,000 litres
• No hosing of hard surfaces including vehicles at any time
• No hoses or taps to be left running unattended, except when filling pools or containers
• Fire hoses must only be used for fire fighting purposes – not for cleaning.