Choosing a green energy tariff

What is green energy?

A green energy tariff works by the supplier promising to match all or some of the electricity and/or gas you use with renewable electricity or biogas, which it feeds into the National Grid or gas network. The more people who sign up to a green energy tariff, the higher the percentage of green energy in the national supply.

What does buying 100% renewable electricity mean – and is it green?

To offer a 100% renewables tariff, suppliers need to ensure they either supply to the grid at least as much renewable electricity as their customers on these tariffs consume (either through their own generation or by way of contracts with renewable generators) or they need to purchase REGO (Renewable Energy Guarantees of Origin) certificates to an equivalent amount. REGO certificates are sold by renewable energy generators who have supplied electricity from renewable sources to the National Grid. A further consideration in assessing the Green-ness of a 100% renewables tariff is where suppliers offer 100% renewables tariffs, though their overall fuel mix is not 100% renewable. In some cases suppliers are actively growing their renewables business, but in others it appears to be simply robbing Peter to pay Paul; for every new 100% renewables customer they get, they just give less renewables to their other customers.
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What is the impact of buying 100% renewable electricity?

With a typical supplier’s fuel mix (see pie chart), annual CO2 emissions from the generation of electricity to serve a UK average household (consuming 3100 kWh electricity) could be approximately 700 kg; around 10% of household CO2 emissions {Ref 1}.
High-level nuclear waste would be 4.34g per year. [ ] Although the operation of any energy generation technology and the National Grid with their associated services, are not carbon neutral, the reduction in CO2 emissions simply from choosing a 100% renewable electricity tariff, is significant; typically a 10+% CO2 saving.

{Ref 1:  Buchs, M. and Schnepf, S.V., UK Households’ Carbon Footprint: A Comparison of the Association between Household Characteristics and Emissions from Home Energy, Transport and Other Goods and Services, IZA Discussion Paper No. 7204, February 2013  available at}

Is there sufficient renewable electricity generation to ensure my supply is 100% from renewables?

Yes. In the last 5 years the capacity of green energy sources, like solar power, wind energy and biomass, tripled, while the capacity of fossil fuels has fallen by a third. More than 29% of Britain’s electricity comes from green sources, exceeding the current demand from customers opting for 100% renewable electricity tariffs. Renewable capacity will increase further as suppliers seek to meet both EU climate change targets and rising consumer demand.

Will supply of 100% renewable electricity cost more?

“Not always.” [ Money Supermarket ]

“The cheapest renewable tariffs tend to cost more than the cheapest standard tariffs, so it really is a question of your personal politics. However, if you can afford to go renewable, then it’s a help to the environment, and all the main comparison services allow you to compare renewable tariffs.” [ ]

You can easily compare typical costs of energy supply tariffs – see the ‘Help with Switching Energy Supplier’ section below.

Comparing Suppliers

There are lots of different ‘environmentally friendly tariffs’ available, with different shades of greenness. Some commit to a proportion of your fuel coming from green sources, others promise 100% will be from renewables. Fuel mix graphs for electricity suppliers are available at

For a comparison on both environmental and ethical criteria, Ethical Consumer magazine/website provides scores. You can customise scoring criteria through the link at Other criteria for selecting a supplier should be considered e.g. customer service.

Ofgem provide general advice on switching energy supplier at including a list of accredited price comparison websites which may also offer a direct switching service. Please bear in mind these websites earn commission, so may not include all available tariffs. Some certainly do not include Ecotricity or Good Energy.

The Citizens Advice comparison service at compares costs for ‘all UK suppliers’ including a filter to only show ‘green plans’.

On the Money Saving Expert ‘Cheap Energy Club’ search results page, you can apply a ‘100% Renewable’ filter – see

Green energy comparison and switching services include:

Energy suppliers have a cooling-off period of 14 days, which starts from the date you submit your switch, so no action is taken until this period is over.
The new company you are switching to will then contact the old supplier. Most suppliers should now switch your contract and billing in 3 weeks. Suppliers are supposed to keep you updated on your switch (via letter/phone/email – keep an eye on your junk/spam folder). You can contact them for an update.

This may help you consider whether, to typically achieve 10% savings in a home’s CO2 emissions, it is worth switching to a 100% renewable electricity tariff. We have listed some examples of renewable energy suppliers on a separate page. (These are not recommendations, just given without prejudice).