Monday December 17, 2018
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Your body could soon power wearable devices

The study described a small tab (1.5 centimetres long, by one centimetre wide). It delivered a maximum voltage of 124 volts, a maximum current of 10 microamps and a maximum power density of 0.22 millwatts per square centimetre.

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The tab consists of two thin layers of gold, with polydimethylsiloxane (also called PDMS — a silicon-based polymer used in contact lenses, Silly Putty and other products) sandwiched in between. Wikimedia Commons
The tab consists of two thin layers of gold, with polydimethylsiloxane (also called PDMS — a silicon-based polymer used in contact lenses, Silly Putty and other products) sandwiched in between. Wikimedia Commons
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Researchers have developed a metallic tab which, when connected to a human body, is capable of generating electricity from bending a finger and other simple movements.

According to a research project led by the University at Buffalo, New York, and Institute of Semiconductors (IoP) at the Chinese Academy of Science (CAS), the tab — a triboelectric nanogenerator — can convert mechanical energy into electrical energy for electronic devices.

“The human body is an abundant source of energy. We thought: ‘Why not harness it to produce our own power?’” said lead author Qiaoqiang Gan, associate professor at the University at Buffalo.

The tab was detailed in the journal Nano Energy. Triboelectric charging occurs when certain materials become electrically charged after coming into contact with a different material. Most everyday static electricity is triboelectric.

Also Read: Scientists Use Pocket-size Device to Map Human Genetic Code

The tab consists of two thin layers of gold, with polydimethylsiloxane (also called PDMS — a silicon-based polymer used in contact lenses, Silly Putty and other products) sandwiched in between.

The tab was detailed in the journal Nano Energy. Wikimedia Commons
The tab was detailed in the journal Nano Energy. Wikimedia Commons

One layer of gold is stretched, causing it to crumple upon release and create what looks like a miniature mountain range. When that force is reapplied, for example, from a finger bending, the motion leads to friction between the gold layers and PDMS.

“This causes electrons to flow back and forth between the gold layers. The more friction, the greater the amount of power is produced,” said Yun Xu, a professor at the IoP.

The study described a small tab (1.5 centimetres long, by one centimetre wide). It delivered a maximum voltage of 124 volts, a maximum current of 10 microamps and a maximum power density of 0.22 millwatts per square centimetre.

Also Read: Mitra: An Indian Robot That Greets You With A ‘Namaste’

That is not enough to quickly charge a smartphone, but it lit 48 red LED lights simultaneously. The team is planning to use larger pieces of gold, which when stretched and folded together are expected to deliver even more electricity.

The researchers are also working on developing a portable battery to store energy produced by the tab. They envision the system serving as a power source for various wearable and self-powered electronic devices. (IANS)

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Clean Water And Clean Power Through Algae

It’s an entire cycle where you’re dealing with not only a water pollution problem.

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biodiesel from microalgae
A biochemist shows different types of microalgae for the study and manufacture of a biofuel in high displacement diesel engines for reducing emissions of gases and particulate matter in Santiago, Chile. VOA

“Nature sometimes isn’t pretty,” said University of Maryland environmental scientist Peter May, grabbing a clump of slimy green-brown gunk.

That gunk lines the bottom of what’s called an algal turf scrubber at the Port of Baltimore. The meter-wide, shallow channel runs the length of a football field alongside one of the port’s giant parking lots.

“Actually, it’s always pretty,” May corrected himself. Even the gunk. Because that gunk is removing pollution from the Chesapeake Bay. Plus, May’s colleagues are turning it into clean, renewable electricity.

The Chesapeake needs the help.

Algal feast

Like many waterways around the world, the bay is polluted with excess nutrients from farm fertilizer runoff, city wastewater and other sources. Algae feast on those nutrients, triggering massive growth that chokes out other aquatic life. Last summer, algal growth left an average of 4.6 cubic kilometers of the bay without oxygen.

A third of the pollution reaching the bay literally falls out of the sky.

Fossil fuels burned in power plants, cars and elsewhere create nitrogen oxide air pollution, which ultimately ends up in the bay, either attached to airborne particles or dissolved in rainwater.

Forests would soak up that pollution. But like many urban areas, the Port of Baltimore has a pavement problem. There’s not a tree to be found at the entire 230-hectare Dundalk Marine Terminal, where the algae scrubber is located.

So regulators require the port to remove as much pollution from the bay as its parking lots allow in. That’s where the algal turf scrubber comes in.

Algae
Algae is seen near the City of Toledo water intake crib, Aug. 3, 2014, in Lake Erie, about 2.5 miles off the shore of Curtice, Ohio. VOA

Putting algae to work

The scrubber is like “a controlled algal bloom on land,” May said, “which puts the algae to work pulling nutrients out of the water.”

The city of Durham, N.C., is planning to build another scrubber to clean up a local reservoir. A pilot study found it would cost about half as much as typical pollution control measures, such as constructed wetlands, and much less than retrofitting existing systems. Others are up and running in Florida.

The algal turf scrubber creates one big challenge, May said.

“What do we do with that algae? You have to have an end use or else you’re going to pile that algae up very quickly,” he said.

It’s high in protein and omega-3 fatty acids. It’s been turned into animal feed. It can be fermented into biofuels. Some of May’s colleagues have used it to launch a fertilizer business.

But here at the Port of Baltimore, they’re turning it into electricity.

Baltimore, Algae
Containers are unloaded from a ship at the Port of Baltimore, Oct. 24, 2016. The port uses an algae scrubber to remove pollution from the Chesapeake Bay. VOA

Digesting for power

May works with University of Maryland colleague Stephanie Lansing, an expert in a process called anaerobic digestion. It’s not much different from our own digestion.

“You have bacteria in your gut that break down food. We’re doing that same process in an anaerobic digester,” Lansing said. “We’re breaking down the material, and we’re producing energy in the process.”

In this case, the microbes digesting the algae produce methane biogas. The biogas runs a fuel cell.

“The fuel cell is actually a very efficient way to use the energy,” she said. This small, pilot system produces a modest amount of electricity.

Also Read: India’s Floating Solar Panel a Gateway To Clean Energy For Asia

“You can use it to charge batteries. You can use it for lights. You can use it for fans,” she added.

The Port of Baltimore plans to build a larger system that will cover about a third of a hectare, which could produce a few hundred kilowatts — still modest, but not bad, when you start with just polluted water and algae.

“It’s an entire cycle where you’re dealing with not only a water pollution problem, but an air pollution issue,” Lansing said. (VOA)