What do you do with a desalination plant when it rains?

Neil Palmer's picture

Despite a few seasons of above average rainfall in most parts of Australia, we still live in the driest nation on the planet. Neil Palmer says that delaying the operation of desalination plants is short-sighted.

SA Water’s Chief Executive, John Ringham, announced on October 4 that Adelaide’s new desalination plant “…may not need to be operated in the upcoming regulatory period after the completion of its 24 month warranty.”

This has been widely interpreted to mean that the $1.83 billion project will be mothballed from 2015 onwards.  This is a result of widespread rain which replenished metropolitan reservoirs and heavy snowfall in the Snowy Mountains which secured ample flow into the River Murray in the immediate future.

Construction of the plant commenced during the Millennium Drought which lasted from 1997 to 2009.  During this drought the Murray River virtually stopped flowing and, with increasing salinity near the inlets to the pumping stations, Adelaide actually came close to running out of potable water.

Water rates have increased steadily since 2007 to cover the financial and fixed costs of the desalination project.  It was argued by the SA Government that the public would benefit from the reduced costs associated with mothballing the plant, even though it meant more water would be taken from the River Murray.

There has been a significant and, I think, unexpected backlash from consumers about the announcement.

The National Centre of Excellence in Desalination Australia was established in 2009 to facilitate desalination research funded over five years by the Australian Government’s Water for the Future initiative. One of the recently completed projects undertaken by three of the Centre’s partners (Deakin University, Victoria University and Murdoch University) involved an extensive Australia-wide survey of community attitudes towards desalination. With 3077 written responses, this survey is an authoritative source.  Conducted after rain had fallen in the eastern states, and the need for alternative water sources had diminished, the researchers found that general attitudes towards desalination in Australia were quite positive.  In fact, 54% of Australians surveyed were supportive of desalination while only 21% were unsupportive.

This provides a key to the consumer backlash in South Australia.  While the media appears to promote the view that desalination is unpopular, this is not supported by the Australians surveyed.  Desalination plants are not constructed to provide water for the next couple of years.  They have a design life exceeding 50 years.

Adelaide is growing and neither the metropolitan reservoirs nor the Murray will deliver more water in the long term.  Then there is variability of weather – CSIRO research is finding that we will get more droughts – and climate change.  The south-western region of Western Australia has experienced an ongoing drying trend over the past 30 years and Perth is now dependent on two large desalination plants for half its water and authorities are discussing further measures needed due to increasing demand.

It also costs a lot of money to “mothball” a desalination plant.  You need chemicals to preserve reverse osmosis membranes and skilled operators to ensure the plant is maintained in a suitable condition so that it is available when needed in the future.

A sensible alternative to “mothballing” would be to operate it continuously at say 10-20 percent of its capacity. In this way, no preservation chemicals are needed, operators and their considerable skills are retained, some value is derived from the plant and less water is taken from the Murray.  The Gold Coast desalination plant, for example, has been operated in “hot standby” mode at 5% of its capacity for the past two years.

There is a danger in thinking desalination plants are like peak load electricity generating plants, to be turned on when we are next short of water.  Nothing is further from the truth.  Water has no market that is equivalent to the electricity market to generate premium prices during shortages.

It is more useful to think of desalination plants more like base load plants, with some of the water stored in reservoirs to be considered as “banked” water for use in peak demand.  With careful management of both stored water and desalinated water, water security (for which consumers are prepared to pay) can be achieved at minimum cost.

In any case, there is no doubt investment in Adelaide’s seawater desalination plant, as a source of climate resilient water, will be understood and appreciated over the life of the plant. 

Neil Palmer has degrees in civil and public health engineering. His career spans 35 years in the Australian water industry, 20 years in Government and 15 years in the private sector.  Neil is currently the CEO of the Australian National Centre of Excellence in Desalination, a partnership of 14 Australian universities and research organizations administering $20m of Australian Government research funding. Neil is a Vice President of the Asia Pacific Desalination Association, a Director of the International Desalination Association and a member of the Institution of Engineers Australia. He is also a Life Member of the Australian Water Association and National Co-convener of the AWA’s Membranes and Desalination Specialist Network.