A backpack-like device that can harvest the side-to-side motion generated as you walk could be used to charge up electronic devices.
Designed by researchers from Canada, the device is intended for people who work in remote areas while wearing backpacks — like soldiers or disaster relief workers.
As the wearer walks, the 11 lbs (5 kg) backpack’s contents — represented by a weighted plate in tests — drives an electricity-generating pendulum.
With a 20 lbs (9 kg) plate, the backpack generated enough power to operate a small electronic device such as a GPS handset or an emergency beacon.
Heavier carried weights can produce more power — to generate enough power for your smartphone, however, you would need to carry at least 55 lbs (25 kg).
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A backpack-like device that can harvest the side-to-side motion generated as you walk could be used to charge up electronic devices
Engineers Jean-Paul Martin and Qingguo Li of Queen’s University, Canada, designed their energy harvesting device for people who work in remote areas, without access to the electrical grid, and routinely carry heavy backpacks.
Such people might include soldiers, members of scientific expeditions, disaster relief workers or even long-distance hikers — all of whom use portable electronic devices like GPS navigation systems, phones, emergency beacons or radios.
For journeys over a certain length, however, it may become impractical to carry enough batteries to keep such devices powered.
‘The ubiquity of portable electronics, and our reliance on them, are limited by maintaining a continual power source for their operation, Mr Martin and Professor Li wrote in their paper.
To address this, the researchers’ device is designed to harvest the energy generated as the mass in a backpack sways from side-to-side while the wearer walks.
To demonstrate the principle, the team created a prototype device in which the backpack contents are represented by a weighted plate, which is attached to a pendulum whose motion generates electricity.
The whole set up is contained in a frame that the user can wear like a conventional backpack, weighing in at 11 lbs (5 kg).
In testing the device, the researchers experimented with seven different damping conditions for the pendulum to find the best one for energy harvesting.
When the user walked with a 20 lbs (9 kg) weight standing in for their backpack’s contents, the device generated around 0.22 Watts of electricity — enough to power smaller portable electronic devices like GPS handsets or emergency beacons.
‘Modelling predicts that an increase in electrical power production could be achieved by increasing the weight carried,’ the researchers wrote.
‘If generating over 1 W of electrical power was desired for powering higher demand devices, such as talking or browsing the internet with a cellphone, our model indicates that over 20 kg (44 lbs) of weight would be need to be carried.’
Engineers Jean-Paul Martin and Qingguo Li of Queen’s University, Canada, designed their energy harvesting device for people who work in remote areas, without access to the electrical grid, and routinely carry heavy backpacks — like soldiers
The main advantage of the researcher’s energy harvester is that it not only acts as a renewable source of power, but that it also does not require dedicated efforts — unlike, for example, hand-crank generators, which require deliberate turning.
Instead, wearers of the backpack device need merely to walk around as they likely would otherwise have been doing.
Moreover, the energy harvesting came with no extra physical demands on the wearer beyond that of carrying the weight of the device itself.
Furthermore, unlike solar panels, the harvester can work whatever the weather.
Prospective users of the device might include soldiers, members of scientific expeditions, disaster relief workers or even long-distance hikers (pictured) — all of whom use portable electronic devices like GPS navigation systems, phones, emergency beacons or radios
The device can also be tuned to reduce the side-to-side swaying forces experienced by the wearer while carrying weight in their backpack by around 27 per cent.
‘This means that the sharp increases in loading an individual normally feels when carrying weight in a backpack will be reduced using our device, increasing user comfort and potentially reducing injury,’ Mr Martin told MailOnline.
‘Future work should consider reducing the mass of the energy harvesting backpack system to reduce carrying costs associated with walking with the device,’ the researchers wrote in their paper.
The full findings of the study were published in the journal Royal Society Open Science.
