Australia’s drinking water supply relies heavily on rainfall, which is a concern since precipitation levels have been dropping across the continent since 1994. However, desalination of seawater from Australia’s extensive coastal areas using reverse osmosis membrane technology can potentially supplement deficiencies in supply, as occurs in the Desalination Plant servicing Sydney that presently meets up to 15% of the city’s drinking water. Unfortunately, the desalination process is energy-intensive, also returns supersaturated salt solution or ‘brine’ to the ocean, which damages the local marine environment. This study investigates how pressure-retarded osmosis (PRO) system can be integrated into the Sydney Desalination Plant, which harnesses the salinity difference between brine and water with lower salinity to produce water flow for generating clean, emission-free electricity. This approach could help reduce the heavy energy burden that desalination imposes on national power grids, while also minimizing the environmental impact of both desalination and wastewater treatment.