In the sun-scorched landscapes where freshwater is a precious commodity, a novel desalination technology is emerging from the shadows, promising to revolutionize the way we quench the world’s thirst. This isn’t your average desalination plant; it’s a hybrid system that marries the power of the sun with a cutting-edge process called Forward Osmosis (FO). The brainchild of Sultan Ahmed, this innovative approach could reshape the energy sector’s role in water production, particularly in arid regions.
At the heart of this technology lies Concentrated Solar Power (CSP), which harnesses the sun’s energy to drive the FO desalination process. Ahmed, whose affiliation is not specified, has been exploring two types of CSP systems: Parabolic Trough (PT) and Linear Fresnel Reflector (LFR). The former focuses sunlight onto a fluid-filled tube, while the latter uses an array of flat mirrors to concentrate sunlight onto a linear receiver. Both systems have their merits, but the real magic happens when they’re paired with FO.
Forward Osmosis is a natural process that occurs when water moves from a low-concentration solution to a high-concentration solution through a semi-permeable membrane. In this context, seawater is the low-concentration solution, and a special draw solution, in this case, Dimethyl Ether (DME), is the high-concentration solution. The DME draws water out of the seawater, leaving behind salt and other impurities. The DME-water mixture is then heated using the CSP system, causing the water to evaporate and leaving behind pure DME, which can be reused in the process.
Ahmed’s study, published in the journal ‘Frontiers in Water’ (translated to English as ‘Frontiers in Water’), evaluates two operational scenarios: batch-mode operation without Thermal Energy Storage (TES) and continuous operation with TES. In the batch-mode scenario, the FO system operates for 8 hours per day, with the CSP system defocusing during the remaining hours to prevent overheating. This results in excess unused solar energy, but it also keeps costs down. “The batch-mode operation is more economically viable,” Ahmed notes, “but it limits system efficiency and results in unused solar energy.”
The continuous operation scenario, on the other hand, uses TES to store excess solar energy, allowing the FO system to operate 24 hours a day. This significantly increases the system’s capacity factor, but it also raises costs due to the high price of TES. “TES enhances operational stability,” Ahmed explains, “but it introduces prohibitive storage costs.”
So, which scenario is more viable? It depends on the context. In regions where land is abundant and cheap, the batch-mode operation might be the way to go. But in densely populated areas where land is at a premium, the continuous operation scenario could be more attractive, despite the higher costs. Moreover, the study highlights the significant impact of FO module costs on the Levelized Cost of Water (LCoW), with thermal energy operational expenditures dominating cost composition in TES cases.
The implications for the energy sector are profound. As the world grapples with water scarcity, desalination is becoming an increasingly important source of freshwater. And as the price of solar energy continues to fall, CSP-FO hybrid systems could become a viable alternative to conventional desalination technologies, such as Reverse Osmosis (RO) or Multi-Effect Distillation (MED). But to make this a reality, further research is needed to reduce TES costs, explore hybrid CSP-PV-FO configurations, and enhance FO membrane efficiency.
This is where the energy sector comes in. By investing in research and development, energy companies can help drive down the costs of CSP-FO hybrid systems, making them more competitive with conventional desalination technologies. And by partnering with water utilities, they can help bring this innovative technology to market, creating new revenue streams and contributing to a more sustainable future.
As Ahmed puts it, “The future of desalination lies in sustainable, solar-driven technologies. CSP-FO hybrid systems have the potential to revolutionize the way we produce freshwater, but we need to overcome the challenges of cost and efficiency to make this a reality.” The energy sector has a crucial role to play in this journey, and the time to act is now. The sun is shining, the technology is ready, and the world is thirsty. It’s time to make CSP-FO hybrid systems a reality.
