Lucy Wright
Nanomaterials could generate energy by creating the equivalent of tiny thunderstorms.
Air humidity has emerged as a potential source of renewable energy. Researchers have shown that nearly any material can be engineered to harvest cost-effective and interruption-free electricity from humidity in the air. Unlike traditional, intermittent sources such as solar or wind, humidity is continuously available.
In what they describe as the ‘generic air-gen effect’, a team of engineers at the University of Massachusetts Amherst, US, designed an electricity harvester using a thin layer of material peppered with nanopores less than 100nm in diameter.
‘This is very exciting,’ said Xiaomeng Liu, a graduate student in electrical and computer engineering in UMass Amherst’s College of Engineering and the paper’s lead author. ‘We are opening up a wide door for harvesting clean electricity from thin air.’
The technology hinges on the ‘mean free path’ – the distance a single molecule of a substance, in this case water in the air, travels before it bumps into another molecule of the same substance. By creating nanopores smaller than this path, water molecules bump into the pore’s edge as they pass through, creating a charge imbalance across the thin layer.
Jun Yao, Assistant Professor of electrical and computer engineering in the College of Engineering, and the paper’s senior author explained: ‘Think of a cloud, which is nothing more than a mass of water droplets. 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 research builds on a previous study completed in 2020 showing that electricity could be continuously harvested from the air using a specialised material made of protein nanowires grown from the bacterium Geobacter sulfurreducens.
Now, the team have demonstrated that almost any material can harvest electricity, significantly broadening the potential application of the technology. Joe Briscoe, at the Sustainable Engineering Research Centre, Queen Mary University of London, UK, commented: ’This is a really exciting study that shows that energy can be constantly harvested from humid air using relatively simple materials.’
Briscoe leads a research group focused on the use of thin films and nanostructured materials for renewable energy applications. He explained: ‘In the previous study, the widespread use was limited by the complexity and cost of synthesising these films at scale. This is overcome in this work, as they show that actually many simple materials can demonstrate this effect, provided the pores within them are small enough.’
However, Briscoe also noted that more needs to be done to demonstrate the practical use of the technology: ‘One big issue is that the actual useable power levels that the devices produce are not demonstrated clearly – it is possible that the actual level of power produced may be too small to be useful for any practical devices.’
Nevertheless, the authors are excited by the potential their findings have. ‘Imagine a future world in which clean electricity is available anywhere you go,’ says Yao. ‘The generic air-gen effect means that this future world can become a reality.’
Image: Derek Lovley/Ella Maru Studio
Visit Blog
