Inside a lab at the Massachusetts Institute of Technology (MIT), Sangtae Kim has been tinkering with a paper-thin device the size of a stamp. Kim is interested in harvesting energy from humans (though not the kind that turns people into batteries in the movie, The Matrix). He wants to harness motions, such as walking and running, to power sensors and wearable gadgets.
“It provides a new way of harvesting human energy,” Kim says of his prototype device, which he described recently in an article co-authored with his adviser, Prof Ju Li and other researchers.
“Any motion is possible to harvest, but you wouldn’t want clothes full of harvesters. I would target the soles of shoes – that’s where the most energy is located,” says Kim.
The idea of using movement to generate electricity isn’t new, though it’s far from commonplace. There are stationary exercise bikes with motors to turn sweaty workouts at the gym into energy. But portable energy harvesters that use human motion haven’t hit the market, partly because they have yet to generate enough energy, says Harry Zervos, an analyst with market research firm IDTechEx.
The human energy concept is promising. Using energy that would otherwise be wasted is appealing at a time when plans to fight climate change include using less energy or energy with lower carbon emissions.
Kim is targeting a growing consumer electronics market. Shipments of wearable electronics worldwide are estimated to increase from a predicted 111m devices in 2016 to 214.6m in 2019, according to IDC, a market research firm. IDTechEx expects the annual wearables sales to jump from $20bn in 2015 to nearly $70bn in 2025.
Quest for smaller more powerful batteries
Wearables collect and communicate data wirelessly, like mobile phones, and prolonging battery life is one of the big technical challenges for designers. And just like mobile phones, they are on their way to becoming thinner and more sophisticated. Designers of wearables – such as Apple Watch, Google Glass and fitness and health wristbands – are hunting for technology that could keep those gadgets running for longer in between charging. This means batteries that can pack more energy into smaller space or devices that could otherwise provide an energy boost without needing to plug into the wall.
Lithium-ion batteries, which also power the majority of consumer electronics such as laptops, are the go-to power source for wearables. But their performance declines when they have to shrink to fit tighter spaces, according to Christine Ho, CEO of Imprint Energy, a battery developer in California.
“It’s a conundrum for product designers, who are starting to realise they need to think more creatively,” Ho says. “New batteries have the opportunity to meet the demand.”
Gadget makers, such as Samsung, are experimenting with batteries that are thinner and flexible so that they can more easily fit into wearables that wrap around the finger, wrist and ankle. Imprint Energy is developing ultra-thin and flexible zinc batteries, which can store more energy in a given volume than lithium and are safe and non-toxic, says Ho.
But those emerging battery technologies tend to be expensive and hard to mass produce. Sales of ultra-thin and flexible batteries for wearable devices are expected to reach $300m by 2020, says Tony Sun, an analyst with market research firm Lux Research. The sales could jump to a whopping $4bn by then, he predicts, but only if those batteries can come down in price to the levels of lithium-ion batteries. This would require significant investments for technical breakthroughs, Sun adds.
Source: The Guardian