"They have developed a completely passive system that is based on a foam-like material that draws moisture into its pores and is powered entirely by solar heat."
> The current version can only operate over a single night-and-day cycle with sunlight, Kim says, but “continous operation is also possible by utilizing abundant low-grade heat sources such as biomass and waste heat.”
It can operate for multiple days, but it only generates water once a day. At night the foam absorbs moisture, and then sunlight provides energy to release it as water.
Why can it only un for a single day on solar?