Continuous clean energy: Scientists are pulling power out of thin air

In a groundbreaking study from the University of Massachusetts Amherst, engineers have demonstrated the potential to produce clean energy continuously from humidity in the air. The secret is a porous structure at the nanoscale that can be incorporated into virtually any material. 

The research, which is published in the journal Advanced Materials, could revolutionize the renewable energy sector and pave the way for a more sustainable future.

The lead author of the paper, Xiaomeng Liu, is a graduate student at UMass Amherst’s College of Engineering. Liu expressed his excitement about the discovery: “We are opening up a wide door for harvesting clean electricity from thin air.”

The atmospheric electricity that is exploited with this new technology is abundant. Study senior author Professor Jun Yao compared it to a cloud which, he noted, is essentially a mass of charged water droplets. 

“The air contains an enormous amount of electricity,” said Yao, “Each of those droplets contains a charge, and when conditions are right, the cloud can produce a lightning bolt. What we’ve done is to create a human-built, small-scale cloud that produces electricity for us predictably and continuously so that we can harvest it.”

The remarkable mechanism, referred to as the “generic Air-gen effect,” is an expansion of earlier work by Yao and co-author Professor Derek Lovley that was published in 2020. The study demonstrated that electricity could be continuously harvested from the air using a specialized material made of protein nanowires, derived from a bacterium named Geobacter sulfurreducens.

According to Yao, the team realized after making the Geobacter discovery that the ability to generate electricity from the air – which they called the ‘Air-gen effect’ – is a generic process that any material can perform, given one specific property. The key characteristic is a porosity with nanopores smaller than 100 nanometers (nm), which is less than a thousandth of the width of a human hair.

This condition relates to a parameter known as the “mean free path,” which refers to the average distance between the single molecules of a substance. In this case, water in the air travels before it collides with another molecule of the same substance. In the context of air humidity, this distance is approximately 100 nm.

This realization allowed Yao and his team to design an electricity harvester based on the mean free path. The device features a thin layer of material replete with nanopores smaller than 100 nm, facilitating water molecules’ movement from the top to the bottom. 

Because of the tiny pore size, the water molecules collide with the pore’s edge, creating a charge imbalance akin to that in a cloud, with the upper part of the layer amassing more charge-carrying water molecules than the lower part. This essentially results in a continuously running battery, as long as there is humidity in the air.

Yao described the idea as “simple,” but noted its novelty and the potential it opens for the future. “It’s never been discovered before, and it opens all kinds of possibilities.” 

The wide range of materials that could be used to construct the harvester means that it can be adapted for different environments and made cost-effective. The continuous generation of electricity, regardless of the time of day or weather, addresses some of the challenges faced by renewable energy sources such as wind or solar power that depend on specific conditions.

Another advantage of the technology lies in its scalability. Given that air humidity diffuses in three-dimensional space and the Air-gen device’s thickness is just a fraction of a human hair’s width, thousands of these devices could be stacked on top of each other. 

The ability to layer devices without significantly increasing their footprint could greatly enhance energy production without requiring additional space. Such an Air-gen device has the potential to generate power at the kilowatt level, sufficient for standard electrical utility usage.

Yao is optimistic about the possibilities this technology can bring, envisioning a future where clean electricity can be accessed anywhere. “Imagine a future world in which clean electricity is available anywhere you go,” he said. The universal nature of the Air-gen effect could transform this vision into reality, making renewable energy more accessible than ever.

This promising research was made possible thanks to the support of several organizations, including the National Science Foundation, Sony Group, Link Foundation, and the Institute for Applied Life Sciences (IALS) at UMass Amherst. The IALS is an interdisciplinary collaboration, drawing expertise from 29 departments on the UMass Amherst campus, committed to translating fundamental research into practical innovations for human health and well-being.

More about clean energy

Clean energy, also referred to as renewable energy, is produced by sources that don’t deplete natural resources or significantly harm the environment during their operation. Here are some common types of clean energy:

Solar energy

Generated by harnessing the power of the sun, solar energy has become increasingly popular due to falling solar panel costs. Solar panels convert sunlight into electricity, which can be used immediately or stored in batteries for later use. Solar farms can generate large amounts of electricity, while smaller installations can power individual buildings or homes.

Wind energy

Wind turbines capture kinetic energy from wind and convert it into electricity. Wind farms can be onshore or offshore, and the latter often produces more energy due to stronger and more consistent wind at sea.

Hydroelectric power

This form of energy is generated by the flow of water, often from dams. The water’s flow drives turbines, which generate electricity. Although hydroelectric power is renewable and produces no direct emissions, building dams can have significant environmental impacts.

Geothermal energy

This type of energy utilizes the Earth’s internal heat. Steam or hot water from beneath the Earth’s surface is used to drive turbines and generate electricity. Geothermal energy is constant and doesn’t depend on weather conditions, unlike solar or wind power.

Bioenergy

Energy derived from organic materials, such as plants and waste, is known as bioenergy. This can be in the form of solid (wood, dried plants), liquid (biofuels like ethanol, biodiesel), or gaseous (biogas) forms. While the burning of biomass does produce carbon emissions, it’s considered carbon-neutral if the rate of biomass consumption is sustainable.

Tidal and wave energy

These types of marine energy capture the movement of the ocean. Tidal energy uses the regular rise and fall of coastal tides to drive turbines, while wave energy harnesses the power of ocean surface waves.

Nuclear energy

While technically not a form of renewable energy, nuclear power is sometimes included in discussions of clean energy because it produces electricity without releasing carbon dioxide. However, it does produce other types of radioactive waste, which require careful management.

In the transition to a sustainable future, clean energy plays a pivotal role. Innovations, like the one from the UMass Amherst team that can harvest electricity from air humidity, represent exciting advancements. The development and adoption of these technologies have the potential to reduce our dependence on fossil fuels and mitigate the impacts of climate change.

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