Electricity generation from thin air is now possible.
Updated: May 29, 2020
Scientists from Massachusets university have developed a way to create electricity from thin air. This could be the step towards constant renewable energy that environmentalists have been searching for, for years. A device called Air-gen is now making air generated electricity a reality.
Electrical engineer Jun Yao and microbiologist Derek Lovley at UMass Amherst have developed an air-powered generator, or as they call it Air-gen. Loosely following a discovery by researches at MIT, this device uses moisture in the air to create an electrical charge that can then be harvested for electronic devices.
What MIT discovered
Nenad Miljkovic, a researcher at Massachusetts Institute of Technology and his team discovered, in 2013, that droplets on a superhydrophobic surface will jump away from the surface, thus creating a small electrical charge. This jump only occurred occasionally and spontaneously but did happen on its own accord, needing no external energy source.
What are Superhydrophobic surfaces?
Superhydrophobic or ultrahydrophobic surfaces are extremely hydrophobic. This means that they are incredibly hard to get wet and do not absorb liquids. The contact angles of a water droplet on an ultrahydrophobic material exceed 150 degrees which disallow the water from spreading over its surface. This is also known as the lotus effect as the same superhydrophobic angles are found on the lotus flower.
Another way to easily understand this is how water droplets sit on pieces of grass. Due to the large number of micro-fibers, the surface area angles of the grass are increased and therefor make it highly hydrophobic.
Creating energy from moisture
In order to use this phenomenon to create electricity, the researchers made use of conductive plates, alternating between water-repelling copper oxide and water-attracting copper. As the water droplets separate from one another they gain a charge and travel to the opposite plate. This movement between plates created electricity.
Although this was a groundbreaking discovery, the amount of power generated by this reaction was not immense. During initial testings, it was found to only created 15 picowatts per square centimeter of metal plate. The researchers believed that this is easily increased to one microwatt per square centimeter but this was directly related to the size of the plates and the amount of moisture in the machine.
At that rate, a generator about the size of a camping cooler could fully charge a cellphone in approximately 12 hours.
A paper on this technological advancement can be found in the journal: Applied Physics Letters.
Carrying around a cooler just to charge your phone is not ideal, and to give power to a house in this way would need multiple home-sized generators. However, it was this research that allowed Air-gen to become possible.
How is Air-Gen different from the MIT generator?
As explained above, the generator created at MIT used hydrophobic metals with opposite charges to encourage water droplets to move.
This method was presented with two main problems. 1. The surface area required to create a sufficient amount of electrical charge was too large in comparison to the output of electricity. This made it inconvenient and not yet possible for commercial use as it was in no way efficient.
2. The temperatures between the outside of the generator and the internal plates would need to have a significant difference in order to create condensation on the plates within. This made it difficult to use in non-humid areas and where the outside temperatures were too mild.
Air-Gen, however, does not make the use of external temperature to create charges but instead uses protein nanowires, also known as bacterial nanowires or microbial nanowires to build its own moisture between the two electrodes.
What are bacterial nanowires?
Microbial nanowires are electrically conductive appendages created by certain bacteria. Geobacter is the most commonly know conductor but protein nanowires are not limited to them.
Some bacteria make the use of electrically charged 'arms' to transfer electrons for various purposes, one of which is respiration. This is seen most commonly when bacteria evolve to take energy from metals such as iron or manganese. To do this they donate electrons to the metal in order to break it down into a less toxic or a more easily metabolized state.
A longer explanation of how nanowires work in bacteria can be found at newsmedical.net
Bacteria such as Geobacter also make use of sharing electrons between their adjacent microbes. It is this protein nanowire that is made use of to generate electricity out of water in the air.
How does Air-Gen work?
The air generator works in such a way that protein nanowires between two electrodes produce a harvestable electrical current.
A thin film of microbial nanowires (less than 10 microns thick) is placed on top of an electrode, while another smaller electrode partially covers the top of the film. The nanowire absorbs water vapor from the air, creating conditions that produce electrical charges between the two plates. This is done with a combination of surface chemistry and electrical conductivity where the pili of the bacteria transfer electrons from the water between themselves.
Is Air-gen efficient?
According to UMASS, the researchers say that the current generation of the device is able to power small electronics and that they are planning to bring Air-gen to a commercial-scale soon.
“The ultimate goal is to make large-scale systems. For example, the technology might be incorporated into wall paint that could help power your home. Or, we may develop stand-alone air-powered generators that supply electricity off the grid" says Jun Yao.
This is still a few steps away as the researches claim that their next goal will be to develop small "Air-gen patches" that could be placed on wearables such as sports watches and health monitors, thus allowing the discontinuation of common batteries. They also wish to use this patch to charge devices such as mobile phones in order to eliminate periodic charging.
Furthermore, this power generation can be done in low humidity climates. Some as dry as the Sahara Desert.
"We are literally making electricity out of thin air,” says Yao. “The Air-gen generates clean energy 24/7."
This new technology claims to be non-polluting, renewable, and low-cost. This product is not conditional like wind and solar energy, which allows it to create renewable energy non-stop.
Could this be the sustainable energy source that the world has been waiting for or will it turn out to be another high polluting "green energy" like the other renewables that are sold to us? We will have to wait and see what progresses from this but the way forward looks promising in solving a major environmental problem that we are currently facing.
To read the published paper on this new technology you can find it at nature.com
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