Is my energy tariff really green?

By Lottie Leigh-Browne

Electricity from renewables such as solar or wind power known as ‘green energy’ is becoming favoured as people become more aware of their energy sources. This increasing demand puts pressure on companies to produce ‘green energy’. But how do we know whether our electricity is from a renewable source? Renewable Energy Guarantee of Origin or REGO certificates are assigned to the electricity produced from renewable sources, guaranteeing their origin. This renewable energy with REGO certification is entered into the national grid alongside energy from fossil fuel sources. Energy companies are often sourcing REGO certificates to prove their energy units have been sourced from renewables. Unfortunately, there has been recent evidence that energy companies have been able to obtain electricity with REGO’s attached despite being sourced from fossil fuels. This means companies can falsely claim their energy is sourced from renewables, leading to ‘green washing’ (deceptively displaying something as more environmentally friendly) of consumers.

To prevent green washing of energy sources from providers, it is recommended that energy is sourced from companies that produce their own renewables with Power Purchase Agreements (PPAs), a contract between the electricity generator and the user, or from independent producers of energy. This energy is not sold to the national grid and therefore avoids the issue associated with REGOs. Previous research by Bristol Energy Network (BEN) suggested that Green Energy, Good Energy and Bristol Energy Ltd. were energy companies that accurately displayed their energy sources with 100% from renewable energy. Although now outdated, these companies still hold true. Here, we aim to update this list.

To understand which companies can now be added to the list of companies providing 100% renewable and not green washing their customers we relied on an organisation who aims to do just that. Big Green Switch displays recommended energy suppliers that meet their specific criteria including those who guarantee that 100% of their electricity sold is matched by energy from renewables. Other criteria include providing Ofgem’s requirements for renewable tariffs , which requires suppliers to demonstrate ‘additionality’, ‘transparency’, and ‘evidence of supply’. They also do not list clean tariffs where the supplier’s definition of clean energy includes (a) oil, coal and gas; (b) nuclear or (c) large-scale virgin biofuels, such as those burned at Drax, monitor the customer service of the provider as well as refusing to list tariffs selling electricity matched by REGOs that are sourced outside of the UK.
Further information on their tariff selection can be found here.

From these criteria, Big Green Switch displays these energy companies on their website;

However, BEN wanted to know if there are energy suppliers excluded from this list that still meet 100% renewable energy sourcing with REGO’s true to their source. Below are companies which we believe to source 100% renewable energy. The suppliers were contacted by email to confirm their sources.

Green Energy UK

Green Energy UK is not displayed on Big Green Switch’s website but source their energy from water, solar, wind and organic material to provide their customers with 100% renewable energy. Green Energy UK was ranked number 3 green energy in the UK and provide information on their renewable energy sites on their website. Alongside renewable electricity, Green Energy also supply 100% green gas. The location of energy sources is not provided and any indication on whether this is generated by the company themselves is not given.

Tonik Energy

Tonik Energy promises customers cheaper bills and greener energy. This supplier ‘sells only 100% renewable electricity tariffs’, with the option for their customers to include 10% green gas in their tariffs produced from animal and vegetation waste. Tonik’s website states their renewable energy sources are 9% from wind and 91% from solar. Tonik however does not display its renewable energy plant locations on its website. Tonik does not produce its own renewable generation.

Pure Planet

Another renewable energy provider Pure Planet, states on their website that they provide 100% renewable electricity, with 80.5% from wind and 19.5% from solar (taken from March 2019). They don’t generate any renewable energy themselves but instead buy from renewable ‘generation heroes’ backed by REGO’s. Locations of their solar and wind farms can be found on their websites; however.  They also provide gas that is 100% carbon offset. BP has a 24% share in PurePlanet and buys renewable and carbon offset gas on their behalf. As PurePlanet doesn’t generate its own renewable energy or have contracts to buy it directly from generators, there is a concern that they are ‘greenwashing’ their tariffs while not supporting new renewable electricity generation.


This company was actually bought by Octopus Energy in January and will therefore meet the criteria set by Big Green Switch.  Previously Engie’s overall fuel mix was 34% renewable but Engie customers are now being switched to Octopus, meaning it will become 100% renewable (Link). Octopus energy provide 100% green energy as well as offering carbon offset gas.

So, in addition to those listed on Big Green Switches website, Green Energy UK, Tonik Energy, Pure Planet and Engie provide 100% renewable energy. As a note of caution, the fact that they do not all provide their energy plant locations should be taken into account when choosing an energy provider. Companies that buy directly from wind or solar farms, listing their locations and providing transparency seem to be those that are most reliable for their energy source. This website compares companies’ green credentials and was used to check results found by BEN.

For more information on REGOs: here

For further questions or queries, please contact:


For a limited time, you can also see Caroline and Lottie talking about this at the Sustainablish Festival on the 14th May 2020. We are 34mins into the Open Mic Session. Click here to view!