Sarah Lokenauth
We’ve all seen lightning streak through the sky on a stormy night. What we may not know is how that lightning works. In short, the lightning that we see is the product of an electrical charge generated by the water molecules present in the fluffy, white clouds in the sky. What makes it special, though, is that these same water molecules present in humidity are now being explored to harness their conductive capabilities as a potential source of clean energy for the future.
The development of technology which uses the water molecules in the air can be traced back to the year 2020, when there were mentions of this technology in Nature. In an article published in 2020, University of Massachusetts Amherst researchers developed what they called the Air Generator (Air-Gen), a device that used water in the air to generate electricity. A key component of the device’s design utilizes protein nanowires made from a microbe called Geobacter. The set-up of the generator involves a film from the nanowires placed between two gold electrodes.
Protein nanowires are nanowires developed from organic material which are more sustainable than traditional nanowires, and can be used to conduct electricity. Researchers detailed how the thin-film devices that were created from the protein nanowires were absorbing moisture from the air and forming a charge gradient, which then was able to produce power. This was a significant improvement from similar generation devices that tried to use moisture in the air, which could only produce power for about short 50 second bursts.
In previous experiments in this field, strategies included using a liquid water source to aid in electricity production; however, realistically it’s difficult to scale up that method if there is no liquid water source nearby. However, in the 2020 experiment, the researchers tried a different approach by creating a generator from “a thin film of protein nanowires” that was able to literally pull water from the air, which produced a continuous current for 20 hours before needing to recharge. The voltage produced by the generator was only about 0.5 volts, but considering that this was from a film only 7 micro-metres thick, it immediately raised the question of how increasing the film’s size could impact energy generation and efficiency. Another key aspect of this experiment was that it was reproduced with other machines of the same film thickness and these machines gave uniform voltages. It was also seen that lack of UV light didn’t impact energy production, which boded well for the potential of this technology to be used in the real-world. Initially, the experiment did face challenges as there was a limited supply of protein nanowire, making it difficult to scale up. However, out of adversity comes creativity and researchers began to utilize E.Coli, a more popular microorganism, to generate the nanowire. This was a significant improvement in humidity-based electricity technology and also highlighted how in order to form a sufficient moisture gradient the device benefited from having a high frequency of nanopores.
Present day this research remains relevant as the same researchers at the University of Amherst are making more discoveries related to the Air-Gen. Recently, they have discovered “that almost any material can be used to create an Air-Gen device,” which is significant as it expands the possibilities of production as it gives access to a greater variety of resources. The only really important requirement for the material is that it will need to be pierced with nanoholes, as nanoholes are big enough to let water molecules through while still touching the material as they move through. The water droplets then subsequently touch the upper layer, increasing its charge and creating a charge imbalance between the upper and lower layers of the machine. The fact that this machine can then be created using any material increases the possible methods of production and implies that we can use a material specific to a certain environment or purpose, which could help with the impact on the environment. However, it must be considered that designerse would still need to use materials that can be easily pierced with nanoholes because if an overly difficult material is chosen, the costs of production will rise and the device will become much less efficient and much more expensive. Also, when talking about the space required for the Air-Gen device, the devices can be stacked in vertical layers to generate significant amounts of electricity. This is a positive feature as in the future, the Air-Gen may be able to replace current fossil fuel energy sources without taking up much space.
Sustainability
Sustainability, not only of the technology but of the manufacturing and materials, is always important to consider when discussing clean energy and sustainability. This is essential because the principles of green chemistry and sustainable development force us to consider both the effects of the technology and the by-products generated and production processes used. In this way, this technology is even more incredible as it opens the door to being able to use affordable, eco-friendly materials since the only requirement is that the material have nanopores.
Overall, this new development in the technology and the potential of the technology opens many new avenues for the potential expansion and scale of clean energy using moisture in the future.
References:
Ferriera, B. Scientists Working to Generate Electricity From Thin Air Make Breakthrough (2023). Available at: https://www.vice.com/en/article/93kade/scientists-working-to-generate-electricity-from-thin- air-make-breakthrough (Accessed: 31 July 2023).
Liu, X et al. Power generation from ambient humidity using protein nanowires. Nature 578, 550–554 (2020). Available at: https://doi.org/10.1038/s41586-020-2010-9 (Accessed: 31 July 2023).
Lovley et al. “Protein Nanowires: The Electrification of the Microbial World and Maybe Our Own.” Available at: Journal of Bacteriology 202, no. 20 (2020). https://doi.org/10.1128/jb.00331-20 . (Accessed: 31 July 2023).
Gault, M. This Device Generates Electricity from the Air Using a Strange Microbe (2023). Available at:https://www.vice.com/en/article/pkezmv/this-device-generates-electricity-from-the-air-using-a-strange-microbe (Accessed: 31 July 2023).