Simple explanation of solar thermal desalination
Solar thermal desalination uses sunlight to heat water until it evaporates, leaving salts and many contaminants behind. The vapor is then condensed back into liquid freshwater. This mimics the natural water cycle — evaporation and condensation — but in a controlled, engineered system.
There are common configurations:
- Solar stills: Sunlight heats a water basin; vapor rises and condenses on a cool surface, dripping into a collection channel.
- Multi-effect distillation (solar-assisted): Solar heat drives a sequence of evaporators and condensers to boost efficiency by reusing latent heat.
- Humidification–dehumidification (HDH): Air carries moisture from a heated saline source to a cooler surface where it condenses.
Advantages:
- Simple, low-tech options (like solar stills) are easy to operate and maintain.
- Thermal processes tolerate high-salinity and some contaminants that foul membranes.
Limitations:
- Thermal systems generally have lower productivity per unit area than high-pressure membrane methods.
- They require large collectors or heat inputs for significant output and often need thermal storage or backup to smooth production.
Solar thermal desalination is best where sunlight is abundant, maintenance resources are limited, and salinity or contamination levels make membrane processes less suitable.