While generating green energy, solar panels usually create excess heat that goes unused. But with a new, innovative design, scientists have found a way to harness those precious leftovers to give the power producers a second purpose: pulling water out of thin air.
Basically, the self-contained system lays solar panels on a special gel that can collect airborne water vapor. As soon as surplus heat coming from the panels touches the gel, the substance releases a sort of mist into a metal box. Within that container, the gas gets condensed into droplets of water.
The team's motivation is to provide energy and water that's cheap, clean and off-grid to residents of remote and especially dry-climate areas.
"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," Peng Wang, an environmental engineer at the King Abdullah University of Science and Technology in Saudi Arabia, said in a statement. Wang is the senior author of a study on the invention published Tuesday in the journal Cell Reports Physical Science.
In producing H2O nearly on-demand, these panels are addressing several pressing worldwide health concerns. A 2019 report from Our World In Data indicated that unsafe water results in a startling 1.23 million deaths per year, especially among those living in poverty. And as of 2020, the site notes, one in four people still did not have access to clean drinking water.
Beyond that, the climate crisis has introduced a dramatically heightened risk of drought in drier regions, directly imperiling farming practices. Late last year, the United Nations brought attention to crop devastation in Madagascar that resulted from intense drought, and even suggested the disaster could lead to the world's very first climate change-induced famine.
"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 said. "I hope our design can be a decentralized power and water system to light homes and water crops."
Collecting airborne water
Wang's solar panel system involves a few layers.
First, a solar panel is placed atop a hydrogel, a substance known for its water retention ability. Contact lenses, for instance, are also made with hydrogel. The soft, pliable plastic-like material helps keep the film on the lens moist -- that way, your eyes don't get irritated.
For their invention, the researchers developed a specific type of hydrogel that can suck in water vapor from surrounding air, hold it in, then, when heated, let go of it. The heat source in this case is the solar panels' excess, typically "wasted" energy.
Once heated up, the gel starts releasing water vapor and a large metal box below collects the gas and condenses it into true water droplets. As a bonus, the study says the hydrogel increases solar panel efficiency by up to almost 10%. That's because in soaking up the panels' excess heat, it lowers their temperature.
For proof of principle, the researchers built a prototype version of their system and put it into action for two weeks in Saudi Arabia during a time when the weather was very hot.
Approximately the size of a classroom desk, the solar panel they used generated a total of 1,519 watt-hours of electricity, which, for context, is around enough to drive a Tesla seven miles. It also created about two liters of water from air.
Those two liters were used to irrigate 60 water spinach seeds planted in a plastic box. According to the researchers, 57 out of 60 sprouted and grew to a regular 7 inches (18 centimeters). Next, Wang and colleagues intend to scale up their model so it can produce even more electricity and water content.
"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," Wang said. "Our design makes water out of air using clean energy that would've been wasted and is suitable for decentralized, small-scale farms in remote places like deserts and oceanic islands."