Researchers at Flinders University have developed graphene oxide membranes that can desalinate seawater at energy costs potentially 10 times lower than current reverse osmosis technology, though significant challenges remain before commercial application.

The membranes consist of single-atom-thick graphene sheets with precisely engineered nanoscale pores that allow water molecules to pass while blocking salt ions. Water flux through the membranes is about 1,000 litres per square metre per day at pressures below 1 megapascal, compared to 5-8 MPa required for commercial reverse osmosis.

That pressure difference translates directly to energy savings. Reverse osmosis typically consumes 3-4 kilowatt-hours per cubic metre of freshwater produced. The graphene membranes could theoretically reduce that to 0.3-0.4 kWh/m³, though practical systems would likely be somewhat higher.

Dr. Amanda Foster, who leads the membrane research group, said energy efficiency is critical for desalination expansion. “Water scarcity affects millions of Australians, but desalination is energy-intensive and expensive. More efficient membranes could make desalination viable for inland communities that can’t afford current technology.”

Australia has five large-scale desalination plants supplying cities including Sydney, Melbourne, Perth, Adelaide, and the Gold Coast. These plants provide insurance against drought but operate intermittently because desalinated water costs 2-3 times more than water from dams and rivers.

Regional towns experiencing water stress often can’t justify desalination because of high energy and capital costs. More efficient technology could change that calculation, particularly if powered by solar energy, which is abundant in water-stressed inland regions.

The Flinders membranes use graphene oxide rather than pure graphene, which makes manufacturing more practical. Graphene oxide can be produced in large sheets using chemical processes, whereas pure graphene typically requires more complex production methods.

Creating precisely sized pores in the graphene oxide is the technical challenge. Pores need to be about 0.7-0.9 nanometres in diameter, large enough for water molecules but small enough to block sodium and chloride ions. The research team developed a chemical etching process that creates pores of controlled size.

Membrane durability is a major concern. Laboratory tests run for days or weeks, but commercial desalination membranes need to operate continuously for 3-5 years. Single-layer graphene is mechanically strong but also extremely thin, raising questions about resistance to fouling, chemical degradation, and physical damage.

The Flinders team is addressing durability by developing multi-layer membrane structures where graphene oxide layers are supported by porous substrates. This sacrifices some of the theoretical performance but improves practical robustness.

Fouling, where organic matter and other materials accumulate on membrane surfaces, is a persistent problem in desalination. Anti-fouling treatments and regular cleaning maintain performance but add operational costs. Whether graphene membranes are more or less susceptible to fouling than commercial polymer membranes remains unclear.

The research has attracted interest from SA Water, which operates South Australia’s desalination plant. They’ve provided funding and technical advice, and they’re potential customers if the technology matures.

Commercial membrane manufacturers are also watching developments. Desalination is a multi-billion-dollar global industry, and membrane performance improvements directly translate to reduced operating costs. Even modest efficiency gains are worth substantial investment.

However, scaling laboratory discoveries to industrial production is notoriously difficult. Many promising membrane technologies have failed to commercialise because manufacturing processes that work at lab scale don’t translate to high-volume, low-cost production.

The Flinders team is collaborating with manufacturing partners to develop roll-to-roll production methods compatible with existing membrane manufacturing equipment. That pragmatic approach increases commercialisation prospects compared to technologies requiring entirely new production facilities.

Another application for the graphene membranes is in forward osmosis for industrial water treatment. This process uses osmotic pressure differences rather than applied pressure to drive water through membranes, potentially enabling even lower energy consumption.

The research received $4.5 million in funding from the Australian Research Council and the National Water Grid Authority. Additional support came from commercial partners interested in water treatment applications beyond desalination, including mining industry water recycling and agricultural drainage water treatment.

Climate change is increasing water stress in Australia, particularly in the Murray-Darling Basin and southern regions experiencing declining rainfall. Adaptation strategies include water conservation, improved irrigation efficiency, and alternative water sources including desalination and water recycling.

More efficient desalination technology could enable distributed water supplies where small-scale plants serve individual towns or even large farms. Current desalination economics favour very large centralised plants, but that model doesn’t work well for dispersed populations.

Critics of desalination argue that demand management and conservation should be priorities before investing in expensive supply augmentation. They contend that water pricing doesn’t reflect true costs and that desalination enables continued wasteful water use.

Those arguments have merit, but they don’t eliminate the need for alternative water sources in regions where conservation alone can’t bridge the gap between supply and demand.

The Flinders research is still early-stage. The membranes work in laboratory conditions treating synthetic seawater. Performance with real seawater containing organic matter, bacteria, and variable chemistry needs verification. Durability testing under realistic operating conditions will take years.

Pilot testing in actual desalination applications probably won’t begin until 2027 or 2028, and commercial availability likely remains 5-10 years away assuming no major obstacles emerge.

That timeline is typical for advanced materials research. The gap between laboratory proof-of-concept and commercial products spans a decade or more. Many promising technologies never complete that journey.

Still, the potential energy savings from graphene membranes are significant enough to justify continued development. If even half the theoretical performance can be realised in commercial systems, it would be a meaningful advance in desalination efficiency.

Water security is going to be an increasingly important issue for Australia, and technologies that reduce the cost and energy consumption of alternative water sources contribute to resilience.