Power dressing - Jeff Hardy

Is it just me or are there more and more unusual energy related technologies getting into the popular media in recent times? Perhaps it's just a function of my daily news trawl for the National Energy Research Network, but several things have surprised me recently.

It appears that scientists and engineers have been busily devising ways of usefully capturing some of the energy we expend whilst wandering around. The driving force, perhaps unsurprisingly, is the need to charge electronic devices away from the grid – I suspect particularly by the military.

In its simplest incarnation, the idea is to turn us into mobile solar power platforms. For example, backpacks fitted with solar photovoltaic cells and lithium ion batteries are already available. These mainly provide power for mobile phones and other small electronic devices on the move. PV cells are also being fitted to other things, including laptops and mobile phones.

Scientists in Canada and America have developed a knee brace that captures the kinetic energy of walking. The device works in a similar way to regenerative braking in hybrid electric and can generate around 5 watts of electricity at a typical walking pace. This is approximately enough to charge 10 mobile phones simultaneously. It looks like a rather sturdy knee support and currently weighs in at a rather hefty 1.6 kg; however it is a work in progress. The device could potentially be built into prosthetic knees, or other such implants, which could negate the need for further surgery to replace batteries that these devices require.

Not to be outdone, nanotechnologists in America are proposing to make clothes from nanofibres that generate electricity from movement, literally opening the door for power dressing. The technology works through the piezoelectric effect, which converts mechanical energy to electrical energy. The electrical energy is generated when pairs of zinc oxide fibres (one of which has been coated in gold to act as an electrode) rub together. The inventors estimate that up to 80 milliwatts of electricity could be generated per square metre of fabric, which is about enough to power an iPod.

An idea struck me when I was writing this article. I use the gym frequently (although not as frequently as I should…) and I spent a lot of time rowing, cycling and running. Could I be putting all this kinetic energy to use by converting it into electrical energy? Unless you are a genius, then any idea that you have thought of will already have been explored (and then probably rubbished/exploited) by someone else. A quick internet trawl proved this to be the case. The answer to the question is a resounding "sort of". I'll not go into the full details as you can read them for yourself, but in essence, my 10 minute slog on the rowing machine equates very roughly to enough energy to run a light bulb for 30 minutes. I can assure you that it feels like more work than that.

This idea has actually been brought into reality in a Hong Kong gym. Here they reckon that the average person produces around 50 watts of electricity per hour of exercise. They harness this by placing a generator in the machine and storing the electrical energy generated in batteries. The electricity is used to contribute to the gyms lighting and apparently inspires the members to push themselves harder knowing that their efforts are not wasted.

So, will we see people plugging themselves into the grid to sell their daily harvest of electricity anytime soon? Probably not, but it's fascinating to see the ways in which scientists and engineers are approaching energy generation and also that that these inventions are being picked up by the popular press. Is this just a function of energy being such a media buzz word at present or is it an indication that more and more bright minded people are rising to the energy challenge in a variety of novel and unexpected ways?