Harvesting human energy


Fossil fuels are a finite resource. Renewable sources of energy such as sun, wind and sea are constantly being refined. However, it looks as though the human body could turn out to be an important source of energy to power our ever-increasing demand for personal gadgets and enhancements.

Scientists at MIT have announced that they’re working on a paper-thin device the size of a postage stamp, which is designed to live in the sole of your shoe, and collect power as you walk.

The idea isn’t new. There are already gyms which harness the power of stationary exercise bikes and devices such as the Ampy Move, a pack of cards-sized portable battery that translates the kinetic energy of your movement into power for devices. It claims to be able to power a smartphone for up to one hour at standard use and five hours on standby. Smartwatches should be able to get up to 24 hours of power.

But MIT’s discrete solution could mark a new direction for energy harvesting, making power generation part of your daily routine, as natural as breathing.

It works on the principle that applying stress to a standard lithium-ion battery changes the voltage and usually reduces the battery’s capacity. By placing a conducting electrode on either side of a liquid electrolyte, then applying stress, each electrode spits out lithium ions which are then split into lithium ions and electrons by the electrolyte. The electrons travel through a circuit where they’re captured as electricity.

It sounds like a good idea, but the main problem is that it doesn’t yet generate enough power. It will need to boost the amount of mechanical energy it converts to electricity from 0.6% to 6% just to power a wristband.

Not that it necessarily needs to power a device all on its own. Much of the existing thought is going into technology that will enhance the life of an existing battery, rather than powering it outright. And that power could eventually come from a variety of sources. Fabrics are being developed with piezoelectric fibres, which could be woven into clothing and generate tiny amounts of power that could be used to power health sensors, for example. Another group looking at harvesting power for pacemakers has created enzymes that can generate energy through the oxidation of blood sugars.

With so much of our world relying on ever-increasing demands for constant, reliable power, the solution won’t be simple, and it could be that we come to depend on a combination of various technologies to keep our gadgets ticking over day and night.

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