E.ON Energy has one green tariff which is a Green Energy Supply certified tariff:

Go Green offers customers green source electricity as well as a carbon offset element for their gas consumption. It is available to dual or single fuel customers. The company matches 100% of the electricity you use with a supply of renewable power back into the electricity grid and purchases credits from the non-profit organisation Climate Care, which invests in environmentally friendly projects around the world. The tariff costs an average £24 or 2% per year more than their standard tariff, based on a typical household using 20,500 kWh of gas and 3,300 kWh of electricity.

Go Green customers will also be able to use tools such as carbon calculator and annual energy efficiency check to understand their energy consumption and carbon footprint. E.ON Energy also offers customers discounts on energy saving products such as lightbulbs and energy efficient kettles as well 500 Tesco Green Clubcard Points per fuel each year.