Solar-powered desalination can be a cost-effective way to manage the salty waste streams produced by desalination plants and oil and gas operations, according to a new study. The research, published in Progress in Energy, developed a modelling platform to compare strategies for handling brine and produced water, and found that pairing photovoltaic panels with reverse osmosis is the most economical solar option for desalination brine, while zero-liquid-discharge systems could be attractive for highly saline oilfield wastewater.
Desalination produces fresh drinking water from seawater but leaves behind a concentrated brine that is difficult and expensive to dispose of. Deep-well injection, which pumps the waste underground, is a common but costly approach. Oil and gas production generates similarly saline wastewater, known as produced water, which is often managed the same way. The new framework, developed by Kurban A. Sitterley and colleagues, evaluates whether it is cheaper to dispose of these waste streams or to treat them further and recover additional water using solar-powered technologies.
The researchers applied their model to two case studies in the United States: the Kay Bailey Hutchison Desalination Plant in Texas, a large inland facility, and produced water from the Permian Basin, one of the country’s most productive oil regions. They compared a range of desalination technologies, including reverse osmosis, which uses membranes to separate water from dissolved salts, and thermal methods that use heat to evaporate and recover water. Solar technologies included photovoltaic panels that generate electricity and solar thermal systems that provide heat.
For desalination brine, the most cost-effective solar-powered option was photovoltaic combined with reverse osmosis. Solar-thermal desalination remained relatively expensive because of the cost of solar collectors and heat storage. For highly saline oilfield wastewater, zero-liquid-discharge systems, which recover almost all of the water and leave behind solid salts, could be economically attractive because they reduce or eliminate costly brine disposal.
The findings suggest that renewable energy could help make desalination and wastewater treatment more sustainable, particularly in water-stressed regions. By identifying cost-effective ways to increase water recovery and reduce brine disposal, the work could support wider water reuse and potentially enable valuable minerals to be recovered from waste streams rather than discarded. The study offers a practical tool for evaluating when solar integration makes sense, depending on the salinity of the waste stream and local energy costs.
As demand for fresh water grows and oil and gas operations continue to generate large volumes of produced water, the ability to treat and reuse these streams could become increasingly important. The research highlights that no single solution fits all cases, but that solar-powered technologies can play a role in reducing the environmental and economic burden of waste disposal.
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