• Does buying your electricity from a 100% renewable ‘green’ supplier mean the carbon footprint of your electricity is zero? 

     

    The short answer, unfortunately, is no. Unless you have your own renewable generation (e.g. solar panels), connecting directly into your building, then your electricity comes from the same national grid as everybody else. 

     

    For a more detailed explanation of this, see the Ethical Consumer’s guide to eco-friendly energy companies.

     

     

     

     

    All tariffs burn fossil fuels at the same rate

     

    Whatever company you buy from, the most important thing to be aware of is that the electricity you use has the same carbon footprint. For example, in the UK in 2024 this was 0.26 21 kg CO2e per kWh (according to the UK government).

     

    As Ethical Consumer explains :


    “If you are on a green tariff and you turn your kettle on… if the amount of electricity being
    used across the grid at the time is higher than what is being supplied by renewables, a gas-
    fired power station will still need to be turned up. In other words, your turning your kettle on can cause a gas-fired power station to be turned up to supply it, just the same as when anyone else does it.

     

    The electricity system is ultimately a shared thing. Most of the decisions about it are being made at the governmental level, and the cost of decarbonising it is being shared between everyone in the country.

     

    So while it is good to buy from one of the companies that is making more of an effort to help, the key thing is to keep minimising your energy use, and push for political action."

     

    This lines up with official UK Government guidance. According to the guidelines on how organisations should report their carbon footprint (page 48 of this document), the correct method is to use “location-based grid average emission factors to report the emissions from electricity”. In other words, the electricity (or gas) coming into your building has all been mixed together in the national grid and we should use the average carbon footprint of that mix to work out our emissions, regardless of who our supplier is. 

     

    In the GCC carbon calculator, we are trying to follow best practice, and so we calculate everyone’s electricity footprint based on their local supply. Although it may seem unfair to pay for a green tariff and then not be able to count it against your carbon footprint, there are good reasons for this guidance, and some benefits too – see below for more details.

     

     

     

     

    What’s the benefit then of using a renewable supplier?

     

    There are definitely positive reasons to choose a green energy supplier:

    • If you don’t choose a reputable renewable supplier, you may be helping to subsidise dirty energy. Most big energy companies still make most of their money from fossil fuels, and even those who offer a “green” tariff (such as E-on, British Gas or Shell) don't ringfence your money for renewables so your bills help them still ship and sell more coal, oil or gas.
    • Some UK renewable suppliers aren’t directly involved in generating any energy, they just buy the right amount of special renewable energy certificates (called REGOs) to match the amount of electricity you buy from them. This allows them to certify your tariff as “green”, but it has little real impact on the energy markets. 
    • However, some renewable companies go the extra mile and actively build new renewable energy generation themselves, or directly support those who do. If you use these suppliers, more of your money is going towards supporting new renewables, which is certainly a good thing.

     

     

     

    What are the different renewable companies doing?

     

    The following list is based on research by Ethical Consumer. Check out their recent guide to ethical energy suppliers for more details on all these companies, and their assessment of the non-renewable suppliers too. If you’re outside the UK, please let us know of any similar references for energy companies in other countries and we’ll share them here.

     

    • Ecotricity is actively building new renewable capacity in the UK.

      comesIt supplies a significant amount of electricity to the UK grid from its own wind turbines and solar panels, and it also has some direct power purchasing agreements (PPAs) with other renewable generators. This gives those generators extra financial stability. 

    • Good Energy and 100Green (previously Green Energy UK) both match all of

      the electricity they sell via PPAs from renewable generators, directly supporting the renewables industry and community renewable projects.

    • Octopus Energy are one of Europe’s largest investors in renewable energy. In December 2022, they claimed to operate £4 billion worth of green generation projects across 7

      countries. They don’t directly operate any fossil fuel facilities and seem to be serious about expanding renewable energy to replace them. However, one of their major investors, Origin Energy, does operate coal and gas plants in Australia , although they claim to be planning to phase them out. 

    • Co-op Energyis supplied by Octopus Energy - see above.

    • Ovo Energy used to buy REGO certificates, but now their renewable tariff is based on PPAs with UK renewable energy generators. They have taken a firm public stance against the REGO market and called out the “100% renewable electricity” claims of other companies as “greenwash ”.

    • Ripple has a different – and interesting – model. Rather than signing a standard supply contract, they ask customers to directly invest in a new renewable generator (e.g. a wind turbine), as part of an energy co-operative. The more you invest, the larger your ‘share’ in the turbine will be, and the bigger the discount on your bills. Any extra electricity you need (if you didn’t invest enough to cover all your bills from the wind turbine) will be supplied by 

      your choice of their partner companies (which include Octopus and Good
      Energy)

    Ethical Consumer classifies four of the above companies as their ‘Best Buys’ for supporting green energy in the UK.  These are: Ecotricity, Good Energy, 100Green and Ripple.

     

    In addition to the above, a new company, Fuse Energy , has launched since Ethical
    Consumer’s last report on this topic. They claim to reinvest all of their profits back into
    building more renewable energy generation, and have a refreshingly honest statement on
    their website about why they don’t claim to supply “100% renewable energy”:


    “At Fuse Energy, we're committed to a real renewable transition, not just buying certificates
    to claim 100% green energy. The reality in the UK is that renewable sources can't always
    meet demand every hour, and many companies buy certificates (REGOs) to appear fully
    green, even if their actual energy mix includes fossil fuels. We believe this is misleading and
    a distraction. Instead, we reinvest all profits into building more renewable energy, ensuring
    the focus remains on creating real-world impact.


    “Our fuel mix reflects this approach. While we receive certificates, we use the proceeds to
    fund more wind and solar projects, not to make unfounded claims. We believe that
    meaningful action, not certificates, will drive the renewable transition.”

     

     

     

    What about “green gas”, offsetting, and other environmental claims?

     

    Some energy companies say they are generating gas from sewage or grass, or offsetting emissions by planting trees. Some of these projects may be positive, others are controversial or unlikely to have much impact. See Ethical Consumer for more information on this. None of them can be accurately measured or verified in terms of their carbon savings, so we don’t count these kinds of measures in our carbon calculator. Overall, we’d recommend choosing a supplier based on their support for renewable electricity, rather those who put forward these harder-to-prove claims.

     

    Supporting an energy company that is genuinely helping to build new renewables is one way we can help reduce our carbon footprints in the longer term. Increasing the amount of renewables in the electricity grid will bring down the average footprint per KWh, which will feed into our carbon calculator and help all of us reach our carbon targets.

     

     

     

     

    Why aren’t green tariffs counted as zero carbon?

    A more detailed explanation:

    1) Buying from a renewable tariff means that the supplier pledges to buy enough renewable energy certificates to match the amount of power it is selling to you. However, all electricity comes to us via the grid - there's no specific cable with 100% clean energy flowing from the green supplier to the customer. No new green power has been ‘switched on’ when you change to a green tariff, all that happens is that some certificates are traded somewhere.
     
    2) The point of green tariffs in the UK was supposedly to increase demand for renewables, helping to boost their growth. However, this isn't really happening under the current UK system. In order to call its emissions ‘renewable’, all an energy supplier needs to do is to purchase the correct number of certificates (called REGOs) from someone who owns some renewable energy generators (e.g a wind farm or hydroelectric scheme). There is currently a large surplus of these REGOs in the market – around 37% of the UK's electricity supply is from renewables, while only 3% of UK households are on green tariffs [2]. So buying from a green tariff isn't stimulating the market in a meaningful way.
     
    This isn’t just true for the UK – a recent study found that green tariffs were not helping to increase renewable supply in Germany, France or Italy either. 
     
    3) Part of the reason for this is that it’s not just our electricity that’s mixed together – our money is too. No matter who our energy supplier is, we’re all helping to support renewables through levies on our energy bills, and via our taxes. Under the current UK system, these funding streams have a vastly bigger impact on the UK’s renewable supply than our choice of energy supplier. New renewable energy developments survive or fail based on a range of factors, but being able to produce REGO certificates doesn’t seem to be one of them [3].
     
    4) From an accounting perspective, if we did decide to count green tariff electricity as zero, that would then mean that everyone else's ‘brown’ electricity would need to be counted as slightly dirtier, because we'd have sliced a bit of renewables out of the shared pool. This would be very difficult to calculate and also not really fair, when – as noted above – the levies and taxes that everyone pays on their bills make a far bigger contribution to producing renewable energy than the amount paid to green suppliers.

     

    There are benefits to reporting electricity footprints using the grid average:

    • If we counted our electricity footprint as zero, there would be less incentive to increase efficiency and reduce energy use. This is important, because while it is possible to power the needs of the world with renewable energy, the sums only add up if those of us in wealthier countries seriously cut down on the energy we waste (as explained in this book and elsewhere). Reducing our energy footprint also saves us money.
    • The average footprint of many electricity grids is set to dramatically fall over the next 10

      years, thanks to the rapid rise of wind and solar power, and the closure of coal plants – see for example this 2024 report from the International Energy Agency. This means that using grid electricity will give organisations a ‘free’ decline in emissions over that period, making it easier to meet any carbon targets.

      

    Research and write up: Danny Chivers, Environmental Advisor, GCC. Many thanks to Dr Chris Jardine of Joju Solar and Josie Wexler and Clare Carlile at Ethical Consumer for their help with writing this piece. I’m also grateful to the work of Scott MacDonald, whose PhD research and subsequent published papers provided key facts and figures.

     

     

     

    Footnotes: 

    [1] There are around 25 countries and territories (including the UK, France, Germany, New Zealand, Ireland, Spain, Sweden, the Netherlands and some US and Australian states) where customers have the choice of purchasing their energy from a ‘green’ supplier. The information in this report is focused mainly on the UK, but the basic principles are similar in other regions where green tariffs are available. If you have specific questions about renewable tariffs in a country outside the UK, please do feel free to contact us and we’ll help if we can.

    [2] & [3] Based on research by Scott MacDonald.