(ORDO NEWS) — It sounds like something from a sci-fi movie, but the recently shown Shadow Effect Power Generator (SEG) is a working prototype. A fascinating concept can help us change the way we produce renewable energy indoors.
SEG uses the contrast between darkness and light to generate electricity. It consists of a series of thin strips of gold film on a silicon wafer placed on top of a flexible plastic base.
Whereas shadows are usually a problem for the production of renewable solar energy, here they are actually used to generate electricity. According to the developers, a technology that is cheaper to produce than conventional solar cells generates a small amount of energy and can be used, for example, to charge mobile devices.
“Shadows are ubiquitous, and we often take them for granted,” said materials specialist Tan Soo Ching of National University of Singapore (NUS). “In conventional photovoltaic or optoelectronic generators, where a constant light source is used for power, the presence of shadows is undesirable because it degrades performance.
“In this work, we took advantage of the contrast of lighting caused by shadows as an indirect source of energy. The contrast in the illumination induces a voltage difference between the shadow and the illuminated areas, which leads to the appearance of an electric current. This new concept of collecting energy in the presence of shadows is unprecedented. ”
It is this contrast between shadow and light that really makes the SEG device effective: when shifting shadows, an energy generator with a shadow effect is twice as effective as conventional solar cells in the same conditions.
When the SEG is completely in the shade or completely in the light (when the voltage across the bands is the same), it produces very little electricity or nothing at all.
The team demonstrated that with passing shadows – possibly caused by clouds or tree branches, or simply by the movement of the Sun – the device is capable of generating enough energy (1.2 V) to start a digital clock. Performance may be improved in the future.
“We also found that the optimal surface area for power generation is when half of the SEG element is lit and the other half in the shade, because it gives enough room to generate and collect the charge, respectively,” says physicist Andrew Wi of NUS.
SEG also acts as a sensor: it can detect shadows passing over it, recording the movement of objects passing by. This can have various applications, for example, in connected smart home devices, and can even be used to create self-powered sensors.
However, much work remains to be done – researchers now want to lower the cost of their SEG, perhaps by replacing the gold film with another material.
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