Triboelectric Nanogenerators: Energy from Friction

The renewable energy sector has been booming in recent years, especially with the public’s heightened awareness of the global warming crisis. In fact, oil giant BP predicts a 400% increase in green energy by 2040 and the Yale School of Forestry and Environmental Studies recently published a report detailing the growth of solar energy globally in 2017 by an astounding 29.3%. Even China, a country notorious for pollution and environmental violations has jumped onto the bandwagon, notably becoming the world’s largest investor in renewable energy all while repressing the behemoth that is the Chinese oil and coal industry. Notwithstanding the current state of the environment and relentless demagoguery by extremists, the outlook appears bright for a completely clean powered America in the near future, as demonstrated by the Department of Energy’s projection that by 2050, renewable energy will meet 80% of the nation’s needs.

Despite the rapid hike in renewables worldwide, the thriving market remains dominated by a few main contenders—solar, wind, and hydropower—and the renewable sector experiences few new developments. Although essential and paramount technologies, these innovations possess several severe limitations. Solar energy relies on bright, strong sunlight and suffers in cloudy or stormy weather, not to mention being completely useless at night. Wind turbines disrupt local environments, cause noise pollution, and are burdensome to consistently maintain due to their remote locations and towering heights. Hydroelectric generators literally change the courses of natural water flow and destroy delicate aquatic ecosystems by damming key waterways and altering water movement. However, recent breakthroughs in the emerging field of nanotechnology have produced a new opportunity, triboelectric nanogenerators, that holds great promise in addressing the weaknesses and flaws of its predecessors.

First introduced by Professor Zhong Lin Wang at Georgia Tech, the triboelectric nanogenerator (TENG) sounds like something straight out of Star Wars. Albeit not some futuristic spaceship powering device, the triboelectric nanogenerator may well be the next renewable energy miracle. Triboelectric nanogenerators convert mechanical energy into electricity through the triboelectric effect, as the name suggests. The triboelectric effect comes into play when two objects charge each other through friction. One famous example of the phenomenon is the classic rubbing balloon on hair experiment, which nearly every student in America has conducted at least once in their school career. Besides the triboelectric effect, electrostatic induction is another essential element in the TENG. Simply put, it is when electrical charges are redistributed in an object due to outside electrical influences. Together, the triboelectric effect and electrostatic induction create a novel way of electricity generation based on friction between materials, which leads to many exciting applications in the real world.

Thanks to their flexible nature, TENGs can be utilized in an unlimited number of scenarios, from harvesting energy from the movement of the human body, a concept currently being studied at the University at Buffalo and the Chinese Academy of Sciences, to self powered medical devices like pacemakers. One radical new proposal by Professor Wang is to harness abundant wave energy through extensive networks of TENGs placed underwater, coined “blue energy”. The network consists of many little balls which contain an even smaller ball inside. When the waves push and pull, the inner ball rolls inside the outer ball and builds up a charge. (imagine a hamster running in a wheel) Unlike sunlight and strong winds, waves consistently push and pull regardless of the circumstances, rendering them a much more reliable source of energy. Furthermore, the TENG “nets” will have a minimal effect on aquatic biomes and may even serve as artificial environments to help support marine life, e.g. coral reefs. Yet another application for triboelectric nanogenerators is the desert. Constantly blowing sands and shifting dunes provide a valuable opportunity for energy harvesting. Rapidly moving sand particles instigate friction, a driving factor in TENG, and the massive quantities of sand in the Sahara could potentially be harnessed to generate tremendous amounts of electricity. Conversely, TENGs could also be applied to great success in locations with heavy rainfall; Mawsynram, India receives an average of 467 inches of rain annually. TENGs can get energy from falling rain droplets hitting their surface. Subsequently, the climate of Mawsynram renders conventional solar power techniques ineffective. However, TENGs can be adapted to provide clean alternative energy regardless of sunshine.

However propitious this new technology may be, full scale implementation of triboelectricity into American energy infrastructure is still a ways off. Scientists in the United States and China are still studying the properties and effects of TENGs and researching optimization methods of harvesting energy. It may take decades before TENGs can be sufficiently refined to become a strong contender with the current clean energy giants.

A promising new technology, triboelectric nanogenerators are a viable, emerging form of clean energy for their many applications and reliability. From powering a phone, to providing energy to entire countries, triboelectricity may soon be a household name just like solar and wind. Avoiding many of the pitfalls and consequences of other green energy methods, triboelectric nanogenerators will undoubtedly be at the forefront of the energy revolution.





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