How energy harvesting tech could power wearables and the internet of things

It’s all very well talking about the evolution of wearable computing and the internet of things, but something has to power these thin and/or tiny devices. For that reason, it’s a good thing that so many ideas are popping up in the field of energy harvesting and storage.

Some of these ideas were on display this week at the Printed Electronics Europe 2013 event in Berlin, which took in a variety of sub-events including the Energy Harvesting & Storage Europe show. The concepts ranged from the practical to the experimental, so let’s start with the practical.

Here’s Perpetuum‘s Vibration Energy Harvester (VEH), being carried around (appropriately) on a model train.

Perpetuum train sensor

The VEH is a wireless sensor that gets attached to rotating components, such as wheel bearings, on trains. Cleverly, the device both measures and is powered by mechanical vibration. It also measures temperature, and it wirelessly transmits the results to the train’s operator so they can immediately spot a failure in its early stages.

It’s a simple, low-maintenance idea (there’s no battery that needs replacing) that promises big savings, as Perpetuum CEO Roy Freeland told me, referring to an unnamed operator:

“The user has achieved a very fast payback because the system has enabled him to delay maintenance on the bearings until the fleet was due for a major train overhaul.”

Perpetuum is part of an EU-funded consortium called Wibrate, which aims to introduce this kind of self-powered vibration monitoring technology into a variety of industrial systems.

Meanwhile, a similar principle was at play in Cherry’s energy-harvesting switch.

Cherry wireless switch

The light you see in that picture can be wirelessly turned on and off by a switch that does not itself require any external powering: the act of pressing the switch creates enough mechanical energy to briefly power its wireless transmission capabilities. This is somewhat preferable to wiring up switches, in terms of both effort and flexibility, and who knows? Perhaps the principle could be employed in certain internet-of-things scenarios, too.

Then there’s good old photovoltaic technology, which may soon find itself woven into a new generation of smart fabrics. Another EU-funded project called Powerweave aims to create two kinds of fiber – one for harvesting solar energy and the other for storing it – that can be woven together into one self-contained system. This could theoretically be used to power soft sensors in clothing, but there are far more large-scale applications in store.

PowerWeaveLindAccording to Christian Dalsgaard, founder of consortium member Ohmatex, the goal is to create a fabric that can generate 10W per square meter. Once that is achieved, he noted, there are “no limits how big such a fabric can be made”, and a 100m2 piece of fabric would in theory be able to generate a kilowatt of power. Commercial applications could range from flexible roofing, tents and sun awnings to a new generation of autonomous airship (balloon manufacturer Lindstrand is also in the consortium). The fabric could even be a valuable part of aid packages, Dalsgaard noted:

“The end fabric should be foldable, so you can fold a large fabric – 100m2 – into a package. It’s not enough to roll it up… The requirement is to fold it, put it in a package and drop it from an airplane.”

Powerweave isn’t quite there yet, though. While a lot of progress has been made on the solar cell and storage fibers, “the challenge is to ensure the solar fibers are on top of the fabric and battery fibers are beneath, and that there is a supporting layer to provide strength,” Dalsgaard added.

But what about fabrics that can harvest energy from movement, rather than light? Yep, people are working on that idea too, although problems remain. As Steve Beeby of the University of Southhampton said at the conference: “Textiles offer a good opportunity for energy harvesting… but clothes are designed for [comfort], not to resist your movement.” And don’t forget, any flexible electronics built into the fabric of clothes need to be machine-washable, too, connectors and all.

And finally, a less technically interesting but nonetheless worthwhile little gadget that was on show: the Clicc.


These dinky little solar panels can be clipped into tiny units that store the captured energy for charging mobile devices — I wouldn’t expect vast amounts of charge, but it’s handy in a pinch — or they can be chained as the picture shows, to increase the total amount of energy captured. Unfortunately the firm behind them, Sonnenrepublik, hasn’t yet come up with a unit to store and output that aggregated power, but it’s a nice thought nonetheless.

In the end, all ideas that take us closer to sustainable energy use are welcome.