Water drawn from solar cell
A new type of solar panel can generate water as well as electricity.
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 design could become part of a sustainable, low-cost strategy to improve food and water security for people living in dry-climate regions.
The system, called WEC2P, involves 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 hydrogel absorbs water vapour from ambient air and releases the water content when heated.
The waste heat from solar panels when generating electricity is used to drive absorbed water out of the hydrogel. The metal box below collects the vapour and condenses the gas into water.
Additionally, the hydrogel can be used to increase the efficiency of solar photovoltaic panels by as much as 9 per cent by absorbing the heat and lowering the panels’ temperature.
The team conducted a plant-growing test by using WEC2P in Saudi Arabia for two weeks in June, when the weather was very hot.
They used only water 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 (which measured 60cm x 30 cm), 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 2 litres of water were condensed from the hydrogel over the two-week period.
“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,” says Professor Peng Wang from 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.
“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.
“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,” Dr Wang says.
“I hope our design can be a decentralised power and water system to light homes and water crops.”