Taking a form inspired by the water lily, HydroLily’s structure consists of a tetrahedron-framed “stem” and a woven wood basket. Within this structure, an active system and passive system work together. Solar panels power a thermoelectric cooler, while the inner basket surface is radiatively cooled using high emissivity materials.
The active system utilizes three thermoelectric cooling (TEC) units, solar panels, and a battery for energy storage. Energy from the solar panels helps power the TECs to create a 70C thermal gradient. This creates a cold surface that reaches a temperature below the local dew point, enabling condensation formation. To increase the rate of condensate, heat sinks help efficiently dissipate heat to widen the thermal gradient. Excess energy collected by the solar panels is stored in the battery, allowing HydroLily to continue working after sunset.
The passive system uses a special polyethylene (PE) film to radiate heat to the night sky. The film’s cooling effects also reduce the surface temperature below the dew point – similar to natural formation of fog and dew. Based on the success of small-scale testing results, HydroLily’s final design also incorporates a layer of fiberglass insulation between the wooden basket weave and the PE film. Insulation helps prevent unwanted heat transfer into the film while it continuously radiates heat.