Honda FCX Clarity. The car that emits only water from its exhaust pipe!

This week, Honda's zero emission, hydrogen fuel cell cars have started to roll off the production line. After 19 years of development, this car marks the beginning of a new era of cleaner motoring.

The car uses a fuel cell stack - a device that uses an electrochemical reaction between hydrogen (H2) and oxygen (O2) to convert chemical energy into electrical energy to power a motor that drives the car's wheels. Honda's FC stack simultaneously generates electricity and water, emitting no CO2 or other harmful emissions.

Next year, Honda's more affordable hybrid car goes on sale in the UK. So as the technology becomes cheaper more people will be able to adopt it, consequently reducing global car emissions.