Walk and Charge

Consider this scenario. You’re out on a morning walk, and
as you walk, your shoes generate power by which you can run your cellphone,
handheld, Walkman or MP3 player, without batteries. Sounds out of a James Bond
movie? It’s now in the realm of the possible.

Two technologies have been tested so far to convert energy
used in walking into electrical power, and more are on the anvil. The first one
uses piezoelectric material, which is either incorporated in discrete devices
within the boot, or is an integral part of the structure of the boot. This gets
compressed while you walk and generates a substantial voltage, which when
combined with appropriate electronics, can be used to charge a mobile phone
battery.

The other one involves placing small electro-mechanical
devices, such as a dynamo, in the heel of the shoe. The dynamo spins every time
your heel strikes the ground, thereby generating a small amount of current.

The piezoelectric device generates about 150 milliwatts of
power as of now, which is not sufficient to run a cellphone, but would be enough
to charge the battery slowly. The dynamo technology has the potential of
generating much more power than this, but the design would be more complex, and
hence more costly.

The boots were tested by Trevor Baylis–the inventor of a
radio that ran on windup technology–and a companion, in a trek across the
Namib desert. The trek was in support of a British anti-land mine charity. A
pouch was built on the outside of the boots, which held the PCB with the
electronics and connector for a cellphone battery and wired this directly to the
device in the heel that generated electricity. By the end of the walk, Baylis,
who wore the piezoelectric boots, was able to generate enough power to place an
international call to Richard Branson–the head of the Virgin empire–in
London.

The future outlook is for the boots to generate about 1-3 W
of power, so that they can power future microelectronic devices, like MP3
players, Global Positioning Systems, etc. More technologies will be tested for
this, and the issues of how much power can be generated, and how it can be
stored and distributed, will be addressed.

More information is available at the Website of The Electric
Shoe Company–www.theelectric shoeco.com–which is exploring the commercial
possibilities of the technology.

So, here’s to a future where you can listen to music on
your morning walk, or catch up with calls on your cellphone, without worrying
about dying batteries.