Scientists in search of methods to amp up the capabilities of solar energy turbines have found a way that may enhance their effectivity by an element of 15.
The breakthrough lies in a singular, laser-etched “black metal” developed by researchers over the past five years, which they now hope to make use of in photo voltaic thermoelectric turbines (STEGs).
STEGs are a kind of solid-state digital gadget that converts thermal vitality into electrical energy by way of the Seebeck impact — a phenomenon that happens when the temperature distinction between supplies displaces charged particles and creates an electromagnetic drive (EMF), or voltage.
A STEG accommodates semiconductor supplies sandwiched between a “hot” and a “cold” aspect. When the recent aspect is heated — both by the solar or one other thermal vitality supply — the motion of electrons by the semiconductor materials creates an electric current.
The challenge with existing STEGs is that they are hugely inefficient, converting less than 1% of sunlight into electricity. This stands in contrast to the photovoltaic solar panels you’ll typically find attached to people’s homes, which convert around 20% of the light they receive into electricity.
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However, in a new study published Aug. 12 in the journal Light: Science and Applications, researchers used laser-treated metals, also known as “black metal” due to their deep, inky-black appearance, to boost the energy efficiency of a solar thermoelectric generator by a factor of 15.
Laser treatment
The method involved blasting a piece of tungsten with extremely fast and precise laser pulses to etch microscopic grooves into its surface. These “nanoscale etchings enabled the tungsten to absorb more thermal radiation and hold onto it for longer.
The laser pulses also have the effect of turning the surface of any metal pitch black, increasing their capacity to absorb heat. The researchers then covered the black tungsten with a piece of plastic to create a “mini greenhouse” that trapped even more heat.
For the cold side of the STEG, the scientists took a piece of regular aluminum and again blasted it with laser pulses. The tiny etchings in the metal created a “super-high-capacity micro-structured heat dissipator” that the team claimed was twice as efficient at dissipating heat versus a typical aluminum heat sink.
To test the system, the researchers used it to power an LED under simulated sunlight. A typical STEG couldn’t illuminate the LED even when exposed to light 10 times stronger than normal sunlight. With both sides treated using the black metal, however, the device lit the LED at full brightness under light five times stronger than normal sunlight — equating to a 15-times increase in power output.
While it likely won’t be replacing solar farms any time soon, the technology could eventually be used for low-power wireless Internet of Things (IoT) sensors or wearable devices, or serve as off-grid renewable energy systems in rural areas, the researchers said in a statement.
“For many years, the analysis group has been specializing in enhancing the semiconductor supplies utilized in STEGs and has made modest positive aspects in total effectivity,” Chunlei Guo, examine co-author, professor of optics and physics, and senior scientist at Rochester University’s Laboratory for Laser Energetics, stated within the assertion.
“In this examine, we don’t even contact the semiconductor supplies — as a substitute, we targeted on the recent and the chilly sides of the gadget as a substitute. By combining higher photo voltaic vitality absorption and warmth trapping on the sizzling aspect with higher warmth dissipation on the chilly aspect, we made an astonishing enchancment in effectivity.”