I-Corps: Radiative cooling technology for commercial applications of irrigation water recycling

The broader impact/commercial potential of this I-Corps project is the development of a super-efficient greenhouse system providing passive water purification and accelerated water condensation technologies by recycling water from transpiration. Irrigation for agriculture is the largest consumer of fresh water representing approximately 87% of global fresh water consumption.

In particular, greenhouses lose roughly 90% of input water as vapor escaping through ventilation systems. In theory, all lost water could be recycled to realize great savings. However, recycling evaporated water is difficult in practice because it requires the use of a passive technology to recycle ambient-temperature vapor, particularly during the daytime.

New technologies are required to achieve moisture condensation for water harvesting during daytime operation due to elevated temperatures from solar heating. The proposed technology solution may enable water recovery under such conditions with reduced energy requirements. Such a technology may support a more sustainable supply of food by allowing for food production in regions where water is a non-renewable, scare resource.

Enhancement in agricultural water use efficiency is a promising technology in order to enable urban consumption of water, with potential far-reaching impact in arid areas.

This I-Corps project is based on the development of a greenhouse system to recycle irrigation water using sub-ambient cooling and water harvesting technologies. The key water recycling mechanism is through radiative dew condensation, which is a passive technique that does not consume electricity or fuel. Today’s known radiative dew condensation techniques are low in efficiency.

They are only effective during a few hours in the night and the water collected quickly evaporates when the sun rises. Using the proposed electricity-free radiative cooling technology, the aim is to substantially boost the efficiency of dew condensation by permitting operation during daytime. This may provide an inexpensive and sustainable solution for providing fresh water more efficiently and effectively by recycling formerly lost transpired water vapor in greenhouses.

In addition, the technology may allow the development of a super-efficient greenhouse system using passive water purification using radiative cooling-accelerated water condensation technologies to recycle water from transpiration.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.