Teams from Australia, Germany and Switzerland have set off from Geneva for what they hope will be the first carbon neutral race around the world.
The aim is to complete the 18,642 mile trip without pumping carbon into the atmosphere, a goal that Louis Palmer, the race organiser, believes can be done.
Palmer should know. Two years ago the Swiss inventor and former schoolteacher completed his own round-the-world trip in a solar-powered taxi without using a single drop of gas.
"There is climate change, the petrol is coming to an end, everybody knows, but we have the solutions like electric cars, renewable energy," he said at the start of the race.
"That's what we want to show to the people all over the world. It runs, it works, we can even make a tour around the world in eighty days," he added.
Participants will charge their vehicles from regular power outlets along the way, offsetting their consumption by pumping electricity into the grid from solar and wind plants back at home.
The race - which will be measured in points for style, technology and popularity rather than speed - will pass through 150 cities, including Berlin, Moscow, Shanghai, Los Angeles and Cancun, the Mexican resort where governments are going to hold a global climate change meeting at the end of November.
