Harvesting Clean Energy from Thin Air, 24/7
A “generic Air-gen effect” says that nearly any material can be engineered with nanopores to harvest cost-effective, scalable, interruption-free electricity. A team of engineers at the University of Massachusetts Amherst recently demonstrated that nearly any material can be turned into a device that continuously harvests electricity from humidity in the air. The secret is in peppering the material with nanopores less than 100 nanometers in diameter. Their research appeared in the journal Advanced Materials.
The team, in effect, created a human-built, small-scale cloud that produces electricity predictably and continuously. This same team showed that electricity could be constantly harvested from the air using a specialized material made of protein nanowires grown from the bacterium Geobacter sulfurreducens in 2020. From this, they realized that they could generate electricity from the air, that literally any material can harvest electricity from the air, as long as it has a specific property. It needs to have holes smaller than 100 nanometers (nm) or less than a thousandth of the width of a human hair.
This is based 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 single molecule of the same substance. Water molecules suspended in the atmosphere have a mean free path of about 100 nm.
The harvester is made from a thin layer of material filled with nanopores smaller than 100 nm that would let water molecules pass from the upper to the lower part of the material. However, since water molecules easily bump into the pore’s edge as they pass through the thin layer, the upper part of the layer is bombarded with many more charge-carrying water molecules than the lower part. This creates a charge imbalance, like in a cloud, as the upper portion increases its charge relative to the lower part, effectually creating a battery—one that runs if there is any humidity in the air. Given that humidity is ever-present, the harvester would run 24/7, solving one of the major problems of wind or solar solutions, which only work under certain conditions.
Many thousands of these harvesters can be stacked on top of each other, scaling up the amount of energy without increasing the device’s footprint. An air-gen device could deliver kilowatt-level power for general electrical utility usage.