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Buying green electricity

Carbon-free electricity 

child running through a wheatfield towards a wind turbine

In the UK, more of our electricity comes from low carbon and renewable sources all the time. Between January and May 2019, Britain generated more power from clean energy than from fossil fuels for the first time since the Industrial Revolution. In 2018, carbon-free sources of electricity, including nuclear and renewables, accounted for almost 50% of total electricity production in the UK.

Coal-fired power plants are in decline, with only six remaining operational in the UK. Only around 3% of our electricity comes from coal today – whereas it was around 30% of all electricity generated only ten years ago.

Wind farms provide the highest percentage of renewable energy, with new offshore wind farms adding to the creation of renewable energy in recent years. Biomass fuel and Solar PV also make a significant contribution to renewable energy generation.

In 2018 one third (33%) of the UK’s electricity came from renewable sources. This is up from 29.7% in 2017.

Green tariffs

With electricity from low carbon sources making up an ever larger percentage of our national grid, we are all likely to be using some sustainably generated electricity, whatever tariff we’re on. Currently, electricity suppliers are obliged by Government to buy some renewable electricity in the mix of sources, so what is the benefit of a green tariff in particular?

Choosing a green tariff shows the demand is there. It sends a message to your supplier and the wider industry that you wish to avoid electricity generated from fossil fuels. The increasing numbers of green tariffs available shows the industry is listening. This is a valuable contribution, whichever green tariff you choose.

A green tariff means that some or all of the electricity you buy is 'matched' by purchases of renewable energy that your energy supplier makes on your behalf. These could come from a variety of renewable energy sources such as wind farms and hydroelectric power stations. Some green supply tariffs are also nuclear-free.

Your supplier should let you know what sources are included in the mix, and also what proportion of your supply is renewable. Some tariffs will be ‘100% renewable’, others will offer a percentage of the total.

Green and not so green tariffs

pencils in different shades of green and brown

We’d recommend taking a close look at how your supplier operates when it comes to putting together your green tariff. Some are definitely greener than others in terms of how much they support the renewables industry in the UK. This is because of the way the renewable energy market works.

For every 1 MWh of renewable electricity created by a solar farm or other renewable energy generator, OFGEM (the energy regulator) issues an accompanying certificate, known as a REGO. There are two ways for a renewable generator to make money from this energy:

  1. Selling the electricity itself
  2. Selling the REGO certificate.


The certificate and the electricity won’t necessarily be sold together. Some suppliers will buy the renewable electricity but not the REGO certificate (for example large commercial customers that aren't worries about proving where their electricity comes from). This means there can be lots of REGOs left over that other suppliers can buy to make their power appear green, when in fact they're supplying brown (non-renewable) electricity on the wholesale market. 

The greenest tariffs

When your energy supplier buys renewable (green) electricity and its accompanying certificates directly from generators, such as UK wind or solar farms, this provides a clear benefit to the UK renewable industry. Most energy suppliers that work this way will be transparent about the source of their electricity and list it on their website.

We’ve identified the following suppliers who all clearly list the renewable sources of their energy on their websites. We think these tariffs are as green as they get. Other suppliers may meet the same standard of sourcing direct from UK renewable energy generators but we couldn’t identify this from their websites at the time of our investigation.

We last checked in February 2020.

Moderately green tariffs

Some larger electricity suppliers will own or have partnerships with a mixture of green (renewable) and brown (regular fossil fuel) generators. Their standard tariff will provide electricity from a mix of sources, while the green tariff will be backed up by the REGOs from their low carbon electricity sources.

That is fine as far as it goes but growing numbers of people on their green tariff won’t necessarily mean they buy more renewable energy. Instead, they can just divert a higher percentage of the green energy they source to the green tariff and make their standard tariffs dirtier. So increased demand for these tariffs doesn’t necessarily lead to increased support for renewable generation.


Some electricity suppliers, including some who claim to supply 100% renewable energy, will do so simply buying up excess REGO certificates. These certificates are cheaply available from times of excess production across the EU and these tariffs do little to encourage the generation of renewable energy in the UK.

Green funds

A green fund usually involves paying a premium to contribute to a fund that will be used to support new renewable energy developments. Under this option, the existing electricity supply continues as normal, but your involvement could help to alter the mix of energy sources in the future toward renewable sources (depending on the type of tariff).

The new generation projects supported will probably also receive support under existing government support schemes.

The importance of energy saving

wind turbines and solar panels against a blue sky

We can't say whether switching to a green tariff will have an impact on global carbon dioxide emissions or not. Some people argue that all the renewable generation in the UK is already supported through government led schemes, which are paid for by all of us, and green tariffs don’t provide any incentive for companies to build more new generation than they would have anyway. Others argue that, as genuinely green tariffs grow in popularity, they will build up to a significant additional incentive which will help to accelerate decarbonisation.

Either way, if you choose to sign up to one of the greener tariffs around, you will be sending a clear message to the government and the electricity industry that you care about the carbon content of your electricity, and you would like them to do what they can to reduce it.

Wind and solar farms feed the electricity they generate into the UK’s electricity grid, as do coal and gas-power stations. The electricity itself doesn’t look any different wherever it came from – you just use what you use. The less electricity you use, the less has to come from gas and coal, and the less carbon dioxide is emitted. And this is true whatever tariff you are on. So if you run your washing machine at a lower temperature, for example, you’ll save just as much carbon dioxide whether you’re on a green tariff or not.

That’s why it’s so important to reduce the electricity you use wherever possible. We’ve got lots of advice and tips to help you do that on this website.

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