Adelaide Desalination Plant

South Australia, as the "driest state in the driest (inhabited) continent",[6] has experienced severe water shortages during periods of drought. As drought conditions worsened during 2006-7, reduced inflows into the River Murray lead to the introduction of progressively harsher water restrictions and the future of Adelaide's water supply came to the fore as a political issue.[7]

In light of the drought, South Australian Premier Mike Rann announced on 11 September 2007 that the State Government would fund and build a desalination plant to guarantee Adelaide's water supply. He said the plant would provide an insurance policy against future droughts and cost more than $1.4 billion.[2]

In the leadup to the November 2007 federal election campaign Prime Minister John Howard promised that, if re-elected, his Coalition government would contribute towards the capital cost of a desalination plant to reduce the city's dependence on the River Murray. Then Opposition Leader Kevin Rudd made similar pledges.[8]

The site for the main desalination plant was purchased by SA Water from ExxonMobil in December 2008.[9] Construction commenced in March 2009.

The plant is located on the eastern shore of Gulf St Vincent just north of ExxonMobil's disused Port Stanvac Oil Refinery. It lies within the industrial suburb of Lonsdale within the local government area of the City of Onkaparinga. The residential area just north of the plant lies within the suburb of Hallett Cove (part of the City of Marion).

The plant was originally intended to be capable of producing 50 GL per year and projected to cost almost $1.4 billion.

During late 2008 and early 2009, the South Australian Government was actively considering doubling the capacity to 100 GL/year at an incremental cost of around $450 million. It sought funding from the Australian Government for the full cost of this expansion.[10]

In May 2009 the Australian Government, under Prime Minister Rudd, announced a grant of $100 million to support the initial stage of the project under the National Urban Water and Desalination Plan.[10] This announcement fulfilled Rudd's commitment during the 2007 election campaign.

As part of this announcement, the Australian Government also committed a further $228 million for the expansion to 100 GL/year. The South Australian Government subsequently committed to the expansion in June 2009.

The final capital cost of A$1.83 billion for the Adelaide Desalination Project included:

1. The desalination plant and associated marine works
2. A pumping station and 12 km transfer pipeline to take the desalinated water to the Happy Valley Reservoir Treatment Plant (treated water tanks) where it is blended with treated catchment rainwater and delivered into the SA Water distribution system
3. SA Power Networks electricity supply sub-station
4. Preliminary site works, land and other interconnection work with SA Water's existing facilities.

The SA and Australian governments agreed to make all power used by the plant renewable.

The plant uses 3.47 to 3.70 kilowatt-hours of electricity per kilolitre of water produced.[15]

The plant sources all its electricity from 100% GreenPower accredited Renewable Energy sources from within South Australia. The plant sources its electricity from renewable energy sources provided by AGL Energy under a 20-year contract at an annual cost initially estimated at over $75 million per year (for the first 50 GL plant).[16] Energy supply cost is part of the overall operating cost of the facility which was confirmed by SA Water in December 2010 at $130 million per year (for double the capacity or 100 GL plant). SA Water advised that the $130 million per year would result in one of the lowest operating cost per unit of desalinated drinking water of any desalination plant in Australia. This was possible because of energy efficient technologies and innovations throughout the plant.

The plant's buildings have been designed to maximise natural light during the day and a selection of high thermal materials (e.g. solid precast concrete walls and insulation) to improve thermal properties, thereby minimising energy consumption. More specifically, solar photovoltaic cells have been placed on the reverse osmosis buildings for localised power generation. Each reverse osmosis building has an approximately 100 kW solar cell array providing a site capacity of approximately 200 kW at peak sun hours. The high pressure pumps feeding the reverse-osmosis membranes are the largest consumers of energy in the plant. Energy recovery devices are installed to harness the pressure in the saline concentrate stream and use it to pressurise some of the feed water. As a result, the high pressure pumps are only needed to deliver half of the water feeding the reverse osmosis system, reducing energy consumption in the plant by up to 40 per cent. Likewise, two turbine generators in the outfall tunnel take advantage of the plant elevation 50 metres above sea level. This mini-hydroelectric system is capable of producing 1,290 kW of renewable electricity which is fed back into the plant, reducing energy consumption by approximately 2.5%.

The lack of tidal movement for up to 2–3 days during dodge tides, which occur twice a month in Gulf St Vincent, reduces mixing of the water column. This raised concerns during the planning phase of the project about the potential effects of the brine discharge on benthic flora and fauna.[17][18]

Dodge tides and other local conditions were taken into account in the design of the outfall system. Discharge to the sea occurs via a 1,080 m undersea tunnel, with dispersal through one of 6 specially designed diffusers. Each diffuser has a head consisting of four duck bill valves that assist in maintaining high discharge velocity for optimum mixing, independent of plant operating conditions.

Marine monitoring buoys placed at 100-metre radius from the outfall structures allow real time data monitoring via the plant control system, to assess performance against Environment Protection Agency discharge licence conditions. Monitoring of the surrounding marine environment started before construction of the plant began and will continue into the future to ensure no adverse environmental impact.

The Adelaide Desalination Plant has been controversial as the high cost of construction has contributed to water price increases, even when the plant is not in use. While the plant was used quite intensively between 2013 and 2015, its utilisation has reduced due to greater water availability in metropolitan reservoirs and from the Murray River. This is shown in the table below, which demonstrates that the plant produced around 8 GL in the year from November 2015 to October 2016, compared to over 100 GL between December 2012 and October 2015.

As of January 2016, the desalination plant was continuing to run at around 10 per cent capacity, despite having sufficient reservoir capacity and water allocation from the Murray River.[21][1]

During the course of determining water prices for South Australia, the Essential Services Commission of South Australia (ESCOSA) commissioned expert engineering advice from to assess SA Water's proposal to operate the desalination plant at minimum capacity, rather than place it into 'cold standby'. Based on this advice, ESCOSA allowed for SA Water to recover $4.1 million per year to cover to cost of operating the plant in minimum operation mode (approximately 8 GL/year), noting that doing so:

• may defer capital upgrades elsewhere in SA Water's supply network (though the associated cost savings were highly uncertain)
• could improve security of supply for customers who rely solely on the Happy Valley Treatment Plant for supply
• gives SA Water flexibility to undertake maintenance on other assets
• could allow it to respond to water quality issues arising elsewhere in the supply network.[22]

In November 2019 an agreement was reached between the Australian Federal Government and the South Australian government to significantly increase production of water to supply the Adelaide metropolitan area. The agreement was reached to allow farmers affected by drought to access more water from the Murray River.

Since much of Adelaide's household water supply is sourced from the River Murray, allowing the desalination plant to produce the city's water frees allocation from the river to be used upstream. The river water saved will then be allocated to drought-affected farmers along the river's irrigation area with farmers in this area able to bid for the water at a discounted rate.[23]

The development of a solar farm on 14 hectares of land adjacent to the desalination plant is expected to significantly reduce the plant's electricity bills.[24]

• List of desalination plants in Australia
• Reverse osmosis plant

Wikimedia Commons has media related to Port Stanvac Desalination Plant.

• AdelaideAqua Retrieved 25 August 2011.
• SA Water > What's New > Major Projects > Adelaide Desalination Project Retrieved 25 August 2011.
• Work starts on desal pipe project abc.net.au | 2009-06-12