Anyone still feeling environmentally enthused by the weekend's Live Earth event may find the Carbon Hero concept device a smart idea.

The Carbon Hero personal carbon calculator concept device was one of the winning projects of the BSI Sustainability Design Awards 2007. Designed by MA student Andreas Zachariah, the Carbon Hero is a keyring sized device. It can measure the exact carbon footprint of the owner by identifying different forms of transport taken as a user travels, by identifying velocity, relative location and patter of their activity.

Of course, all that bit's still a tad tricky for existing technology to handle at the moment, hence why it's still in the concept stage.

The info generated by the Carbon Hero device can then be downloaded to a user's mobile phone or a PC (the easy tech bit). It'll display the amount of carbon used and how many offsetting credits need to be purchased.

Nice idea, we reckon, though other less glamorous climate-saving technology - such as energy-efficient light bulbs - are a more practical way of keeping it green for the time being.