Did you know you can make electricity from a screw? Yes, a screw! That’s what two students from the National University of Lesotho (NUL), Kabelo Moketo and Salang Malelu, did. They took an old idea, the Archimedes screw, and used it to make real electricity from flowing water.
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Brought to you by NUL Innovation Hub; Where Academia Meets Industry & MILCO, a store that sells only Lesotho products at Sefika Complex. MILCO was founded by NUL Innovation Hub.

Long ago, the Archimedes screw was invented to lift water for farming. Farmers would turn the screw, and water would climb up. But Kabelo and Salang asked themselves: “What if we flip it around? What if we let water turn the screw, instead of us?”

That’s how their science adventure began.

They didn’t have fancy tools or expensive parts. Instead, they built their screw from things you’d see every day. The blades? Cut from an old 20-liter plastic container. The main body? A simple PVC pipe. They added a thin metal rod to keep it strong, and they used four small gears to connect it to a generator—the little machine that turns spinning into electricity.

It wasn’t shiny, but it was smart.

Then came the fun part—testing! The students poured water down the screw and waited to see what would happen. And guess what? The screw began to turn, just like they hoped.

But they didn’t stop there. They wanted to know which angle worked best. So they tested four different slopes: 25°, 30°, 40°, and 55°. (Think of how steep a slide is—some slides are gentle, some are very steep!)

Here’s what they found:

• At 25°, the screw was too flat. The water moved slowly, and the power was weak.

• At 55°, the screw was too steep. Water rushed through without turning it properly.

• At 30°, it was just right! The screw turned smoothly and made the most power.

That’s how they discovered the “golden angle.”

Now, how much electricity did it make? Not a lot—just 4.4 milliwatts. That’s too small to light your classroom. But here’s the important part: it proved the idea works. If a tiny plastic screw can do it, imagine what a big, strong one in a real river could do.

As Salang said: “For our first try, with scrap materials, this was a huge success.”

So why is this screw special? Well, most big power plants need huge dams that block rivers and can hurt fish. But the Archimedes screw is different. It works in small rivers, with little drops of water. And it turns gently, so fish can swim through safely. That makes it one of the most nature-friendly ways to make electricity.

For a country like Lesotho, with so many mountain streams, this is exciting. A bigger screw could power a school, a clinic, or even help charge phones in a village. All from the water that flows naturally around us.

Of course, the students know there’s still work to do. Their gears were a bit stiff and wasted some of the power. Their generator wasn’t the perfect match either. Next time, they want smoother gears, a better generator, and maybe even a bigger screw.

But as Kabelo said: “What matters is that the principle works.”

So next time you see water rushing down a hill or stream, picture this: a screw turning slowly, sending power to lights, computers, and phones. An old invention, brought back to life by two young Basotho students, helping to light up the future.
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Brought to you by NUL Innovation Hub; Where Academia Meets Industry & MILCO, a store that sells only Lesotho products at Sefika Complex. MILCO was founded by NUL Innovation Hub.