Solar panels grow crops in desert by pulling in water vapour

Using a unique hydrogel, scientists in Saudi Arabia have created a solar-driven system that successfully grows spinach by using water drawn from the air while producing electricity. The proof-of-concept design, published in Cell Reports Physical Science, claims to offer a sustainable and low-cost strategy to improve food and water security for people living in dry-climate regions.

“A fraction of the world’s population still doesn’t have access to clean water or green power, and many of them live in rural areas with arid or semi-arid climate,” said senior author Peng Wang, a professor of environmental science and engineering at the King Abdullah University of Science and Technology (KAUST), “Our design makes water out of air using clean energy that would’ve been wasted and is suitable for decentralised, small-scale farms in remote places like deserts and oceanic islands.”

The system, called WEC²P, is composed of a solar photovoltaic panel placed atop a layer of hydrogel, which is mounted on top of a large metal box to condense and collect water. The material can effectively absorb water vapor from the air and release the water content when heated.

Last summer in Saudi Arabia, over the course of two “very hot” weeks, the researchers were able to grow spinach with a crop survival rate of 95 percent. Over the course of the experiment, the solar panel, with a size similar to the top of a student desk, generated a total of 1,519 watt-hours of electricity, and 57 out of 60 of the water spinach seeds sprouted and grew normally to 18 centimetres. In total, about two litres of water were condensed from the hydrogel over the two-week period.

“Our goal is to create an integrated system of clean energy, water, and food production, especially the water-creation part in our design, which sets us apart from current agrophotovoltaics,” said Wang. “Making sure everyone on Earth has access to clean water and affordable clean energy is part of the Sustainable Development Goals set by the United Nations. I hope our design can be a decentralised power and water system to light homes and water crops.”

To turn the proof-of-concept design into an actual product, the team plans to create a better hydrogel that can absorb more water from the air.