THE MICRO WIND-TURBINES OF THE NUL

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Bigger, is not always better! In fact, in the world of science, it is often the smallest that calls the shots.

This is especially true when it comes to a micro wind-turbine developed by Mr Lerato Chapile, the National University of Lesotho (NUL) graduate from the Department of Physics and Electronics working under his supervisor Dr Moeketsi Mpholo.

The ingenious micro wind-turbine will charge cell-phones for people in rural areas. It is also good for clean energy enthusiasts, in whatever corner of the world they may live.

This shrewd idea was deemed worthy of winning the award in the recently held Boliba Pitch Competition—for good reasons. Lerato’s design has some fascinating features. For instance, one version has a sensor that helps its rotor (the rotating part of the turbine, including blades) to change direction so that it can always face the direction of the wind, automatically.

Further, as the electricity is produced, the micro wind-turbine has a capacity to store energy such that cellphones can be charged in real-time or after batteries are full. This device is a system that can even monitor wind speed, wind direction and how much electricity is being produced at any moment in time, in a computer.

But it is a small, a very small wind turbine. In fact, comparing Mr Chapile’s design to the humongous industrial wind turbines is no more different from comparing a mature human being to a mere ant. It is the story of David and Goliath right there! Yet, in life, the fastest do not always win the race.

What matters, they say, is not the size of the dog in the fight— it is the size of the fight in the dog.

“I have always wanted to make this kind of a wind-turbine,” Lerato said. “So when I met Dr Mpholo we sat down and developed this idea and through lots of experiments, we finally got it right.” At this point, you may be wondering, what, exactly, is a wind turbine?

Within the scientific realm, they are widely known as aerofoil-powered generators. In the real world, our world, we call them wind turbines. Although they are often taken for granted in some quarters of the world, they are truly intriguing objects. They convert wind’s kinetic energy into electrical power! It sounds simple.

However, it is not that simple. Wind, as we all know, is air in motion. Wind has energy. Sometimes it has lots of energy. If you have ever experienced the overwhelming power of hurricanes (khanyapa), and tornadoes, no doubt you have felt the power of wind in action. That display of power is no laughing matter when you happen to be on its receiving end.

So Mr Chapile’s idea is to harness the same wind power, but for a far more peaceful purpose—to charge your cellphone. How that energy is harnessed is deceptively simple. But, in that simplicity, lays the ultimate sophistication! How so?

First the wind turbine is made such that its blades are carried and pushed around by wind. “We make two versions of the turbines: horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs),” Lerato pointed out. In the first model, the wind blades face the direction of the wind.

This is a more efficient alternative since the turning speeds of the blades are always faster than the speeds of the winds pushing them, thus maximizing energy.

However, since the rotor has to face the direction of the wind, Lerato has made sensors that first sense the wind direction following which the machine is automatically steered towards the direction of the wind.

The second model, VAWT, has blades revolving around a vertical pole (called must). The VAWTs have an advantage in that they work irrespective of the wind direction and the design of their blades are not always complex. However, they have inherently low speeds—many times the blade speeds can’t go beyond the speeds of the winds pushing them.

The really mystical part of the device is in how it transforms wind into electric power. The magic was discovered by Michael Faraday some two centuries ago. As he passed a magnet back and forth through a stationary coil of wire, the coil produced electricity. Electromagnetism, an elite word, was born.

At that very moment, the world was to witness the birth of an electric generator with wide implications for development of the human race, to this day. Wind turbine generators follow in the same steps.

Little did the genius Faraday know that two centuries later, Lerato Chapile, and his supervisor Dr Mpholo, will still be using the same principle to address the problem of the poor in their country and, possibly, across Africa, and the developing world!

 

This blog post was originally written by NUL Research and Innovations

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