“Air Generator” on “Nature”: The bacteria produce protein, the Sahara desert can also generate electricity,

A 15-year-old discovery has finally been made available. Recently, a department of electrical and computer engineering, department of microbiology, chemistry, A team of researchers from the Institute of Applied Life Sciences and the Department of Biochemistry and Molecular Biology has developed an “air generator” called Air-gen.

The device, which generates electricity from a natural protein produced by bacteria, uses moisture in the air to generate electricity, with significant impacts on renewable energy, climate change and medicine.

On February 17, 2020, local time, Nature published the research team’s “Power generation in a humid environment using protein nanowires” wires) paper.

Harvesting protein nanowires from the site

It is well known that some of the current generation technologies, such as solar cells, thermoelectric devices and mechanical generators, have certain environmental requirements, which in fact limit their potential for continuous power generation.

At the same time, while the power generation technology based on moisture in the air provides us with a new idea, it can only produce intermittent energy bursts for no more than 50 seconds at a time due to the lack of a continuous conversion mechanism.

Based on this, the team harvested protein nanowires from Geobacter Sulpedins.

The so-called dystolucobacteria, or dicoccus bacteria, is a very important alienation Fe (III) reduction bacteria, widely distributed in Fe(III) reduction environment, such as freshwater sediments, organic matter or heavy metal pollution of groundwater deposits, etc. , has important biological restoration functions.

Fifteen years ago, Microbiologist Derek Lovley, one of the paper’s lead authors, discovered that the bacteria can transfer electrons from organic matter to metal compounds such as iron oxides. In fact, many bacteria can create protein nanowires that transmit electrons to other bacteria or their environment, and it is this electron transfer that creates tiny currents — a discovery that could be said to lay the foundation for the development of Air-gen.

According to the paper, the team made air-film edited air-based devices using protein nanowires harvested from the bacillus, which generated continuous power in the surrounding environment — generating a continuous voltage of about 0.5 volts on a 7 micron-thick film with a current density of about 17 microa an ounce per square centimeter. If multiple thin-film units are connected and voltage and current are linearly amplified, power can be supplied to electronic devices.

Specifically, the bottom of the protein nanowire film is located on the electrode, while the smaller electrode covering only a portion of the nanowire film is located at the top. It is the conductivity and chemical properties of the protein nanowires that are coupled with the fine holes in the membrane nanowires to establish the conditions for generating current between the two electrodes.

The following image shows the transmitted electron microscope image and its structure of the protein nanowire device.

Best for air humidity of 45%

In 2018, team member Liu Xiaomeng found that sometimes isolated nanowires spontaneously generate current. Later, Liu Xiaomeng and his mentor, Yao Jun, another lead author of the paper, found that when the nanowire film is sandwiched between two gold sheets that act as electrodes, it can generate at least 20 hours of current.

They then found that when they placed nanowires in an environment with low humidity, the current decreased significantly. So this suggests that air humidity contributes to the release of electrons. So the team applied the discovery to the development of Air-gen, which was driven by the gradient of the naturally formed humidity in the membrane when the film was exposed to air.

The figure below records the voltage (black curve) and ambient relative humidity (blue curve) of the unit generating electricity continuously for more than two months (1500 hours).

It’s worth noting that studies show that Air-gen power generation works best when the air humidity is 45%.

As shown in the figure below, when the relative humidity is approximately 45%, the continuous current output of the cling film is covered at the top of the unit and will be interrupted (black arrow) and will continue this state (grey area) until the cling film is removed. When the cling film is removed, the current size returns to the original value (blue arrow).

At the same time, the new technology is pollution-free, renewable and low-cost, and can generate electricity in areas with very low humidity, such as the Sahara Desert, and can even work indoors. Jun Yao, one of the authors of the paper, also mentions:

We’re actually using thin air to generate electricity, and Air-gen can produce clean energy 24 hours a day. This is the most amazing and exciting application of protein nanowires to date.

Start a new era of protein-based electronic sedevices

In addition, researchers say the current generation of Air-gen devices can power small electronic devices, and they hope the invention will soon go into commercial use. Their next step is to develop a small Air-gen “patch” that will power electronic wearable devices such as health and fitness monitors and smartwatches, reducing their need for traditional batteries. They also want to apply Air-gen to their phones so that users can avoid the hassle of charging regularly.

Ultimately, however, the team’s goal was to build large-scale systems. Jun Yao indicates:

For example, incorporating Air-gen into wall paint to support home power, or developing separate aerodynamic generators to power the grid. Once our wire production reaches industrial scale, I hope we can create large-scale systems that can make a significant contribution to sustainable energy production.

At the same time, Derek Lovley and his team have recently developed a new microbial strain that can produce protein nanowires in large quantities faster and cheaper to continue to advance the practical application of Bacillus:

We’ve turned E. coli into a protein nanowire factory, and with this new scalable process, protein nanowire supply will no longer be a bottleneck.

As mentioned above, the research team members come from different backgrounds, so this is an unusual interdisciplinary collaboration that is an important step forward in the direction of creating new energy sources. However, as Jun Yao says:

This is just the beginning of a new era of protein-based electronic sedevices.

Resources:

https://www.nature.com/articles/s41586-020-2010-9

https://phys.org/news/2020-02-green-technology-electricity-thin-air.html

https://www.sciencemag.org/news/2020/02/electric-bacteria-create-currents-out-thin-and-thick-air