CarbonDiem, a personal carbon calculator that won the Prague/Czech Republic regional prize in the European Satellite Navigation 2007 Competition, sponsored by ESA’s Technology Transfer Programme. It uses satellite navigation data to track distance and method of travel every time a journey is made, calculates the generation of carbon dioxide (CO2) as a result of the travel and displays the data on a mobile phone giving details of the carbon footprint. Travellers can then easier optimise their travel method to reduce the amount of carbon dioxide released into the atmosphere.