“Nanotechnology” is defined by the National Technology Initiative as science, engineering or technology that involves manipulating matter with at least one dimension that falls in the range between 1 and 100 nanometers. A nanometer is one billionth of a meter which is a scale that is almost impossible to comprehend. Jennifer Kahn in an article in National Geographic tried to express this tiny distance on a more human scale by comparing it to the amount an average man’s beard grows in the time it takes him to raise his razor to his face.
Interest in nanotechnology is driven in large part by the fact that properties of materials that are stable and familiar at the macroscale we experience can change radically at the nanoscale. Understanding and harnessing these changes promises to transform our everyday world in ways that may sound like science fiction but may happen in the not-so-distant future.
Here are some recent achievements in the nanotechnology of alternative energy sources.
Producing energy from air pollution
Hydrogen is an attractive alternative source of fuel because burning hydrogen in combination with oxygen produces water, not carbon dioxide and other air pollutants as a “waste product”. The energy needed to create pure hydrogen is a limiting factor in developing hydrogen as a fuel source.
Researchers at the University of Antwerp and the University of Leuven in Belgium have devised an alternative method for producing hydrogen that has the potential to reorient our approach to solving several global environmental problems.
The researchers created a device with two compartments separated by a membrane created from nanomaterials. Air pollutants are broken down in one of the compartments. Some of the chemicals produced as a result of the breakdown are passed through the membrane. The nanomaterials in the membrane extract hydrogen which is collected in the second compartment. This hydrogen can be harvested and stored as a potential fuel source. The device runs on solar power eliminating the burning of fossil fuels that other methods use to produce pure hydrogen.
Imagine how different the world would look if a system based on this technology was operating at scale. Existing air pollution and its negative effects on health and climate change would be reduced. Cleaning the air would produce a clean-burning fuel that reduces the need to rely on the dangerous fuel sources that polluted the air in the first place. The cities with the highest levels of air pollution would become the most abundant sources of clean energy.
Producing energy from motion
How much fun do you have making sure your cell phone is charged every day? How would you like it if all you had to do to keep your phone charged was put it in your pocket? Researchers at Vanderbilt University have built a system that can make this possible by harvesting electricity from human motion.
The researcher’s system uses sheets of black phosphorous that are only a few atoms thick. Bending or pressing the black phosphorous nanosheets produces a small electrical current that can be harvested and stored in a battery.
The nanosheets have two properties that make energy-harvesting clothing possible. The first is that the sheets are so thin they can be incorporated into clothing without changing the look or feel of the material. The second is that they are able to harvest electricity at the low frequencies that characterize human motion.
While piezoelectric techniques for extracting energy from motion generally work best at movement frequencies above 100 Hz (100 cycles per second), human motion normally occurs at 10 Hz or less. The nanosheets are capable of producing an electric current at movement speeds as low as 0.01 Hz (one movement cycle every 100 seconds). This is more than sufficient for harvesting energy from everyday activities such as sitting, standing and walking.
The energy harvested from the nanosheets could power electronic textiles in addition to devices like cell phones. This opens the door to creating clothing with built in sensors to monitor health or fitness metrics, or clothing that uses an app to change patterns and colors.
Researchers at the University of Texas at Dallas and Hanyang University in South Korea have developed an alternative approach to harvesting energy from motion. Rather than rely on sheets of black phosphorous, they spun carbon nanotubes into yarn and tightly twisted the yarn to make it elastic. The yarn was then coated in an electrolyte. When the yarn is stretched, it produces an electric current.
The researchers sewed the yarn into a shirt that produced an electrical signal when the person wearing the shirt breathed. The signal could be used to power a sensor that measures respiratory rate.
They also demonstrated how the yarn could be used to harvest energy from repetitive natural motions such as waves in the ocean. A sinker was attached to a balloon with a 10 cm strand of yarn and placed in the Gyeongpo Sea off the coast of South Korea. The sinker tethered the balloon to the sea floor. Passing waves lifted the balloon which stretched the yarn producing a measurable current.
It’s worth emphasizing that these applications of nanotechnology are not theoretical or “in-principle” achievements. The hardware exists. The problems associated with the tech don’t lie in finding out if it will work, they lie in finding out if it will scale. If and when the scaling solutions are found, the world will look quite a bit different than it does today.
If you found this article interesting, here is another that is part of this ongoing series about nanotechnology.
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