Salt-rejecting passive solar desalination with thin-film condensation
UCSB has developed a passive solar desalinator that overcomes salt-accumulation limitations, enabling continuous freshwater production. By utilizing a unique solar absorber-emitter and thin-film condensation within a microporous membrane, the system achieves 32.9% solar-to-water efficiency and has demonstrated 7 days of continuous operation. This technology is available for licensing to support sustainable water solutions.
Overview
Researchers at the University of California, Santa Barbara, have developed a salt-rejecting passive solar desalinator designed to address global freshwater shortages with high efficiency and durability. Unlike traditional systems that rely on wicking structures susceptible to salt accumulation, this technology enables continuous operation by allowing salt to diffuse away from the membrane. This approach significantly extends the usable lifespan of the device and improves the sustainability of freshwater production, making it a viable solution for industrial water production, agricultural management, and humanitarian water aid.
Technical specifications
- Solar absorber-emitter: Converts sunlight to infrared radiation that is highly absorbed by water.
- Thin-film condensation: Uses a microporous membrane to enhance heat transfer, allowing condensation to occur within the membrane rather than in droplets.
- Efficiency: Achieves a solar-to-water efficiency of 32.9% under one-sun illumination.
- Performance: Demonstrated a record-high continuous desalination and salt-rejection duration of 7 days (168 hours).
- Design features: Thermally isolates evaporation and condensation surfaces to increase vapor pressure; removes the need for solar concentrators, simplifying design and reducing costs.
Technology readiness level
The technology is at a stage of lab validation and prototype demonstration (TRL 4). It has been successfully tested in a laboratory setting, achieving a 7-day continuous operation record under one-sun illumination. The research is published in peer-reviewed scientific literature, and the technology is currently patent-pending and available for licensing through the university.
About University of California, Santa Barbara
UC Santa Barbara is a comprehensive public research university with a collaborative, innovation‑driven culture. Industry partners engage through co‑located cleanrooms and prototyping suites, campus‑wide shared instrumentation, and flexible sponsored‑research agreements coordinated by an industry partnerships team. The coastal campus sits within a Central Coast technology corridor, supporting close collaboration, recruiting pipelines, capstone engagements, and short‑course training tailored to corporate needs. Research is sustained by competitive federal funding from NSF, DOE, DOD, and NIH. A dedicated technology transfer office manages IP, licensing, and startup formation to speed commercialization.
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