Solar Photovoltaics are used in Water and Food Production in dry climates

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 concept and design offers a sustainable, low-cost strategy to improve food and water security for people living in dry-climate regions.

The system is composed of a solar photovoltaic panel placed on top of a layer of hydrogel, which is then mounted on top of a large metal box to condense and collect water. Peng Wang, a professor of environmental science and engineering at the King Abdullah University of Science and Technology (KAUST), and his team developed the hydrogel in their prior research. The material can effectively absorb water vapor from ambient air and release the water content when heated.

The researchers used the waste heat from solar panels when they generate electricity to drive absorbed water out of the hydrogel. Then metal box below then would collect the water vapor and condense the gas into water. Alternatively, the hydrogel increases the efficiency of solar photovoltaic panels by as much as 9% by absorbing the heat and lowering the panels' overall temperature.

The team conducted a plant-growing test by using this system in Saudi Arabia for two weeks in June, when the weather was very hot. They used the water solely collected from air to irrigate 60 water spinach seeds planted in a plastic plant-growing box. Over the course of the experiment, the solar panel, with a size similar to that of a student desk, generated a total of 1,1519 watt hours of electricity. 57 out of 60 of the water spinach seeds sprouted and grew normally to 18 centimeters. In total, about 2 liters of water was 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." says Wang. 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.

"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," Wang also says, "I hope our design can be a decentralized power and water system to light homes and water crops."

Agrivoltaic systems help conserve natural resources. They have been shown to be especially beneficial in dry areas, where plants under panels require less water, and fruit production is increased. With warmer temperatures likely to become status quo due to climate change, agrivoltaics could be the key to protecting small-scale outdoor farms. For farmers, the money from an agrivoltaics project could be livelihood saving, especially with solar power becoming more cost-effective and more accessible. The Farmers of 2030 may be our tomato & green salad source and a critical piece of independent electrical grids.

Citations & Resources: Science Daily; Cell Press. "These solar panels pull in water vapor to grow crops in the desert." https://www.sciencedaily.com/releases/2022/03/220301131056.htm. Agrivoltaics: Mel Smith; A Win-Win for Food Production and Solar Energy; https://www.greenbuildermedia.com/blog/agrivoltaics-a-win-win-for-food-production-and-solar-energy