How much does it cost?

The further you travel, the more CO₂ you emit, so the cost depends on the zone you are flying to.

You can green a return trip within Europe for €4.50 (zone 1), and a trip to Canada or a trip to the US for €11.50 (zone 2).

Costs of a rental car:  The amount of CO₂ emitted per day by your rental car (150 km) is the same as the CO₂ saved by running a windmill in India for 5 minutes. Running that windmill for 5 minutes costs €0.27 (excluding VAT). That’s no money at all for a clean car! And you can green a camper for €10 per 1000 km.