Use your body to generate power -

One of the gizmos spotted at CES is a device that charges your phone using the movements you make as you walk, or even stagger to your local for a swift half.

Tremont Electric has made the nPower PEG, which is short for "personal energy generator" and is  made up of a weight, a spring, coils and a battery. If you shove it in your pocket it moves as you do and generates electricity in the coils.

Apparently it gradually charges up the battery. You can then transfer that power to your phone or MP3 player via a microSD port and an adaptor cable.

Unless you are the sort who is always on the move and spends most of their life getting jiggy with it you will not get a lot of charge out of it.

According to nPower 15 to 30 minutes of walking will only give a smartphone user a minute of call time. Some users would be fairly breathless during that minute too. Still it is good for emergencies we guess.

If you use an MP3 player you should get a minute of time for every minute you walk, which makes it good for the jog in the park.

If you want juice in a hurry you shake the peg but given this looks a bit rude we don't recommend it in mixed company.

The cost of the best is $160 and it has just started shipping.

Tremont Electric says it has some difficulty meeting demand.