Is desalination becoming Australia’s most reliable water source?

With climate uncertainty rising, desalination is emerging as Australia’s most reliable, climate-independent water source. Building resilience means diversifying supply. That’s why keeping desalination firmly on the table is more important than ever.

The AWA Desalination Specialist Network promotes awareness and adoption of desalination technologies, shares information among sector professionals, encourages research, and supports education to enhance Australia's water management through desalination solutions.

Desalination Specialist Network Chair and Veolia Australia and New Zealand Manager Operations Excellence Scott Murphy said within the ‘all options on the table’ approach to water management, desalination has become the reliable, climate-independent element in the mix of potential sources.

“What makes desalination unique is its climate independence and its reliability,” he said.

“We see in all the capital cities, where desalination plants have been providing that climate-independent source of water reliably for over a decade in this country.”

Murphy said the Millennium Drought was the catalyst for everything, instigating a flurry of plants built on the east coast: “We pumped out quite a few billion dollars’ worth of assets in that period”.

But now, desalination is not just a drought solution, it’s considered now in many scenarios to support growing industry and communities.

“We had a hiatus, at least on the east coast, because of rain. But now, desalination is seen not only as something for drought, but as a flexible and reliable water supply option in general. That next pipeline of plants is definitely coming,” he said.

“All of the east coast plants are looking at increasing their capacity within the next few years. Over in the west, they’re already expanding. And it’s all needed based on population growth and water security.”

Easy way in

When it comes to getting the mix of alternative sources right, Murphy said it’s important to understand the benefits and restraints of desalination and recycled water – both are important sources, but desalination is proving less challenging.

"Recycled water is circular, it’s closed. We’re not adding to the system, by the very nature of being circular. If there's more demand, you can’t create new water if you’re putting it in a circle. Recycled water doesn’t introduce new water into the cycle, but desalination does,” he said.

"Within the water community, we’re all sold on recycled water safety. The broader public is mostly sold on it, too. But our political colleagues are not. There is a real fear of what it means to introduce potable recycled water into a water system.

"But we don't have that challenge with seawater desalination. We are starting from a source that isn’t nearly as challenged as wastewater. With desalination, we haven’t had to have that water literacy fight.

“But it’s interesting to contrast with California. Over there, they’re really accepting recycled water, and desalination is struggling to get approvals from an environmental and energy perspective.”

Continual improvement

Here in Australia, desalination has been widely adopted, leading to a lot of gains within the research and development space. Murphy said the improvements in reverse osmosis (RO) have been unfolding consistently since the sector transitioned from thermal processes.

"There are fundamental thermodynamics at play in RO; there’s a physical limit to how low you can go with energy consumption. We’re not a huge way away from that limit,” he said.

“All of our improvements in the last decade have been incremental. No big step-change in energy efficiency, just nibbles of the cheese to improve our position.

“There is the issue of brine discharge. And then there’s the question of where your energy is coming from. But here in Australia we are doing very well.”

Murphy said all desalination plants constructed in Australia are either directly offset, or, in places like South Australia, are generating electricity behind the meter to use on site.

"In terms of brine management, when desal first came to Australia, we just didn’t know what would happen if we took water out of the ocean, removed half the fresh stuff, and put the brine back,” he said.

“But all the large municipal plants have rigorous monitoring programs that show minimal impact. In some cases, we’ve actually seen improvements, as new marine structures can increase biodiversity.”

Where to next?

Murphy explained that desalination will continue to improve as adoption expands across multiple sectors.

“The industrial market, particularly green hydrogen and mining, is going to be significant. There just isn’t enough water for those industries. If green hydrogen grows like projections suggest, we’ll need a lot more water in our system,” he said.

“People talk about nine litres of water per kilo of hydrogen, but that’s just the stoichiometric ratio. You need to cool the electrolysers, too. The real figure is much higher.

“We’ve already brought energy consumption down. Early desal plants used 3.6–4 kWh per kilolitre. The latest ones in the Middle East are under 3 kWh/kL, that’s a big step.

“This improvement has come from better design, reduced pressure losses, improved membrane fluxes, and more of that nibbling at the cheese.”

Murphy said the other big influences are machine learning and AI in achieving more efficiency.

"The improvements in efficiency we can achieve with AI will probably never end. RO will be around for quite a bit longer; we don’t see any big new treatment tech coming soon. So it’ll be about getting closer and closer to that thermodynamic limit,” he said.

Interested in learning more about the AWA Desalination Specialist Network? Take a look at what’s on the agenda here.