Enhanced Desorption System for Atmospheric Water Capture

Because the atmosphere is a vast source of fresh water (estimates put it at around six times more than the combined total in lakes and rivers), atmospheric water harvesting (AWH) is being pursued as a viable tool to meet future global water challenges. There are various AWH devices including fog capture, desiccant-based (adsorber) and refrigeration-based systems. Fog-based systems are limited by elevation and geographical locations. Refrigeration-based systems face challenges in lower humidity regions and/or with lower relative ambient temperatures, making them unsuitable in arid regions. Desiccant-based systems are promising as they absorb water moisture regardless of temperature or humidity levels. However, they are limited by the energy required to heat up the desiccant to desorb and recover the adsorbed water, as well as the cooling needed for adsorption and condensation.

 

Researchers at Arizona State University have developed a novel system to provide simultaneous heating and cooling to enable continuous water production from a compact desiccant-based AWH system. Because this system is more energy efficient than simple electric resistive heaters, it is inherently more efficient than existing desiccant-based AWH systems. Furthermore, the simultaneous heating and cooling means that while heating is applied to the desiccant to desorb water vapor for subsequent condensation, cooling is provided to continue adsorbing water vapor from incoming air. This results in a compact, AWH system that can be run on batteries, solar power, or grid power and is suitable for arid regions and portable or emergency water generation needs.

 

This technology promises enhanced desorption, reduced energy consumption and improved performance in many different environments.