Could footsteps ever power Olympics?

Imagine if the energy you used walking down the street could be harnessed and turned into electricity.

It sounds like science fiction but it is a reality for youngsters at a school in Canterbury, Kent, where they are trialling a system of flexible paving slabs that collect kinetic energy from each child's footsteps.

This is then turned into an electrical charge used to light up a bulb.

The installation of just four tiles at the Simon Langton Grammar School shows the potential of the technology.

Head teacher Ken Moffat says: "We've got 1,100 students in the school and you can imagine 1,100 young men running around the place.

"That's about as robust as you get. If you could put something like this in a London Underground station, that would be very exciting."

On that scale, it is easy to see the potential.

And with more corporations and public bodies needing to meet green emissions targets, the tiles - made by Pavegen - could play an important part of the sustainable energy mix.

The company's founder and chief executive Laurence Kemball-Cook explains: "When you stand on a tile it flexes just 5mm in the centre, which is actually imperceptible to users.

"Through our technology we convert that into electrical power and seven watts per footstep is created. The heavier you are, the more energy is created."

And Mr Kemball-Cook's plans are a lot bigger in scale than just schools.

"One of the key sites we're working on is at Westfield, Stratford City," he says.

"This is in the largest urban shopping centre in Europe, right on the edge of the Olympic Park and where we're going to be seeing 14 million people walking through this area over the Olympics.

"Now with that amount of footfall we're actually going to be able to power a large portion of the outdoor lighting within the shopping centre itself."

The tiles work by using an electromagnetic system which creates a current by moving a magnet inside a coil. The energy is then stored in a battery within the paving slab.

It is a process that has been widely used in self-winding wristwatches for many years.

Energy harvesting, as it is commonly known, is sparking the imagination of inventors across the globe.

A number of different methods can be used to generate power - some systems collect heat while others rely on piezoelectric crystals, which generate a small voltage when put under pressure.

But they all have limitations.

Professor Markys Cain, science area leader at the UK National Physical Laboratory specialising in scientific measurement, said the current technology was not able to deliver the watts of power that were needed.

"It's delivering milliwatts - 1,000 times less than is required," he says.

"I think a really good example of how energy harvesting can be used in the consumer environment is to extend the life of batteries so your mobile phone will last three days between charges rather than one, for example."

To put the limitations in perspective - the average person will walk 150 million steps in their lifetime.

In theory, using the Pavegen slabs, that would only be enough to power the average family home for three weeks.