Solar Panels that can Capture Water Vapour to Grow Crops in Desert

Scientists in Saudi Arabia developed a solar-powered system that successfully grows spinach by drawing water from the air while producing electricity using a novel hydrogel. The proof-of-concept design, published March 1 in the journal Cell Reports Physical Science, provides a sustainable, low-cost strategy for improving food and water security in dry-climate regions.

WEC2P System

"A fraction of the world's population still lacks access to clean water or green energy, and many of them live in rural areas with arid or semi-arid climates," says senior author Peng Wang, an environmental science and engineering professor at King Abdullah University of Science and Technology (KAUST). "Our design extracts water from air using clean energy that would otherwise be wasted, and it is suitable for decentralized, small-scale farms in remote places like deserts and oceanic islands."

The WEC2P system consists of a solar photovoltaic panel mounted on top of a layer of hydrogel, which is mounted on top of a large metal box to condense and collect water. Wang and his colleagues previously developed the hydrogel, which can effectively absorb water vapour from ambient air and release the water content when heated.

The researchers used waste heat generated by solar panels to drive absorbed water out of the hydrogel. The vapour is collected and condensed into water in the metal box below. Alternatively, by absorbing heat and lowering the temperature of the panels, the hydrogel increases the efficiency of solar photovoltaic panels by up to 9%.

The team used WEC2P to conduct a plant-growing experiment in Saudi Arabia for two weeks in June when the weather was extremely hot. They irrigated 60 water spinach seeds planted in a plastic plant-growing box using only water collected from the air.

During the experiment, the solar panel, which was about the size of the top of a student desk, produced 1,519 watt-hours of electricity, and 57 of 60 water spinach seeds sprouted and grew normally to 18 centimeters. Over the course of two weeks, approximately 2 litres of water were condensed from the hydrogel.

"Our goal is to create an integrated system of clean energy, water, and food production, particularly the water-creation component in our design, which differentiates us from current agro-photovoltaics," Wang says. The team intends to develop a better hydrogel that can absorb more water from the air in order to turn the proof-of-concept design into a commercial product.

"Making sure everyone on Earth has access to clean water and affordable clean energy is one of the United Nations' Sustainable Development Goals," Wang says. "I'm hoping that our design can be a decentralised power and water system for lighting homes and watering crops." The King Abdullah University of Science and Technology provided financial assistance to the researchers.

(Source: Cell Press)