New Tech Uses Shadows To Produce Renewable Electricity

A little darkness may soon help power your devices. Scientists have developed a new technology that can generate electricity from shadows, a progress expected to expand the sources of renewable energy. 

The Shadow-Effect Energy Generator (SEG), described in the journal Energy & Environmental Science, relies on the contrast between darkness and light to produce electricity. It promises to help address the problem with renewable solar energy production where shadows are usually a problem. 

"Shadows are omnipresent, and we often take them for granted," Tan Swee Ching, materials scientist from the National University of Singapore (NUS), said. "In conventional photovoltaic or optoelectronic applications where a steady source of light is used to power devices, the presence of shadows is undesirable, since it degrades the performance of devices."

The device, still a prototype, is made of a series of thin strips of gold film on a silicon wafer and a flexible plastic base and can support mobile gadgets. Developers said in its current form SEG is cheaper to manufacture than a typical solar cell, ScienceAlert reported.

It produces energy through the illumination contrast caused by shadows. SEG is placed between shadow and light to capture the contrast that then creates an electric current.

The device produces very low amounts of electricity or nothing at all if placed completely in shadow or fully in the light. However, in the right place between shadow and light, SEG works twice as effective as conventional solar cells, the developers said.

During tests where the team put SEG under passing shadows, caused either by clouds, tree branches or the movement of the Sun, the device generated 1.2 V of energy, which was enough to run a digital watch. Developers said that could be increased in the future. 

"We also found that the optimum surface area for electricity generation is when half of the SEG cell is illuminated and the other half in shadow, as this gives enough area for charge generation and collection respectively," Andrew Wee, a physicist from NUS, said. 

Another important feature of SEG is that it can record shadows and other objects passing by. That gives the device the potential to be used in self-powered sensors.

The developing team plans to enhance SEG with new materials and reduce the cost of production. 

"With its cost-efficiency, simplicity and stability, our SEG offers a promising architecture to generate green energy from ambient conditions to power electronics, and as a part of a smart sensor systems, especially in buildings," the team said in their report. 

SEG The novel shadow-effect energy generator developed by NUS researchers uses the contrast in illumination between the lit and shadowed areas to generate electricity. Royal Society of Chemistry

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