Criminal activity, dark photos, lifeless solar panels. Shadows get a bad rap. Now a group of Singapore scientists are chasing—and capturing—shadows. The inventors are using them to generate electricity.
Of course, shadows aren’t really bad. In fact, the Bible speaks of the “shadow of God’s wings” and the “shadow of the Almighty” as places of rest, healing, and safety. Now researchers from the National University of Singapore have found the positive side of shadows too.
The scientists have developed something they call a shadow-effect generator (SEG). Dr. Swee Ching Tan leads the research team.
The two-and-a-half-inch SEG is similar to a solar panel cell. To work properly, part of the machine must lie in shadow. But instead of collecting its energy from light, this technology harnesses the contrast between light and shadow on the device. The SEG converts that contrast into electricity.
When one area is illuminated and the other is in shadow, a voltage difference exists between the two. That difference, Tan says, “[drives] the electrons from the bright side to the dark side, and therefore [creates] electricity.” It’s that energy that the SEG captures. (Isn’t it amazing that God designed electrons to work this way—flowing from light toward darkness! Think about John 1:5.)
SEGs are cost-efficient, simple, and dependable. Current models perform twice as well as some other solar cells do when in shadow.
Tan says SEGs “can be based in [shadowed] areas to harvest obstructed light, for example.” The energy from the light-shadow generator in mild shadow can make an electronic watch tick.
Early SEGs produce about 0.25 volts of electricity. It would take 20 such panels to power a lightbulb or charge a cellphone.
The team predicts other uses for the generator too. By tracking moving shadows, an SEG could one day work as a self-powered sensor to observe moving objects—like a motion detector.
Some locales will benefit more from the shadow-effect generator. Tan says, “The device might come in handy in places like very densely populated cities where skyscrapers are everywhere, where shadows are always persistent.”
Tan and his team are still perfecting the device. Plans include founding a company to make shadow-effect energy available for home use. Researchers say a household SEG could result in more clean, green energy—while running a home’s electronics, including smart sensor systems such as doorbells and alarms.
To be truly useful, SEGs need further development. So far, the devices work only on a small scale. But some day, shadows may emerge from the dark side to help us all.