Supplier Fuel Mix Update 2021 – The Big 6

The electricity we use every day can be generated from a range of different fuels such as coal, gas, nuclear and renewable sources (wind, water and solar power).

Different suppliers use different combinations of these fuels to make up the energy that they supply to our homes and businesses. The combination of these fuels make up the supplier’s fuel mix.

What Does This Mean for Suppliers?

Under The Electricity (Fuel Mix Disclosure) Regulations 2005 all suppliers have to publish the details and breakdown of the fuels they use to generate their supply, along with the environmental impact their choices have. The fuel mix is represented through percentage breakdowns. The environmental impact is usually published as ‘CO2 Emissions’, this means the amount of Carbon Dioxide emitted for every kilowatt-hour (kWh) of energy generated.

A useful analogy for this is food companies having to disclose how much sugar, salt, fat etc is in their products. From this, you as a consumer can make an informed decision about whether you buy the product. The same is true for deciding which energy supplier you use.

What Should You Look Out For?

Coal emits the most carbon in the UK, whereas nuclear and renewable power generates no CO2 emissions. So, suppliers who’s fuel mix contains higher percentages of nuclear and renewable energy are considered to be making greener choices. This does not mean that nuclear power has no detrimental impact; the fuel statement from suppliers will usually detail the long-lasting impact of nuclear power on the environment.

No energy source has zero impact on the environment, but as you can see from the table below the severity of the environmental impact of different fuels varies a lot.

Fuel Type Potential Environmental Impact
Oil Ocean spills, toxic waste, release of toxic chemicals into the air
Coal Emits the highest amount of CO2, extracting is can be disruptive
Natural Gas Releases greenhouse gasses into the air
Solar Panels Can have a ‘large land footprint’ and installation can damage the surrounding environment
Wind Turbines Noise and Sight pollution concern local communities, installation can damage the surrounding environment


Below is a breakdown of last week’s electricity generation in the UK.

  • RED – CCGT

    fuel mix pie chart
    fuel mix pie chart


You can keep up to date with these breakdowns by following the above link.


Who Does it Well?

Which providers handle their environmental responsibilities the best? We’re going to look at ‘The Big Six’ aka the 6 biggest energy suppliers, and how they differ in their approaches to providing energy.

SSE – Mostly Renewable Energy


Energy Source SSE UK Average
Coal 3.5% 3.9%
Natural Gas 9.3% 39.4%
Nuclear 0 16.6%
Renewables 51.9% 37.9%
Other Fuels 0 2.2%
CO2 Emissions 178 g/kWh 198 g/kWh
High-level Radioactive Waste 0 0.0012 g/kWh


British Gas – Mostly Renewable Energy


Energy Source British Gas UK Average
Coal 4% 3.9%
Natural Gas 29% 39.4%
Nuclear 9% 16.6%
Renewables 56% 37.9%
Other Fuels 2% 2.2%
CO2 Emissions 157 g/kWh 198 g/kWh
High-level Radioactive Waste 0.0006g/kWh 0.0012 g/kWh


EDF – Mostly Nuclear Energy


Energy Source EDF UK Average
Coal 0 3.9%
Natural Gas 9.3% 39.4%
Nuclear 66.6% 16.6%
Renewables 20.5% 37.9%
Other Fuels 0.1% 2.2%
CO2 Emissions 70 g/kWh 198 g/kWh
High-level Radioactive Waste 0.0047g/kWh 0.0012 g/kWh


Who Does it Less Well?

Most of The Big Six does have a high proportion of renewable and/or nuclear energy, however, these suppliers still rely heavily on non-renewable sources. Due to their fuel mix including a balance of renewable and non-renewable sources, their carbon emissions are still lowe


E.on – Mostly Renewable Energy

but the high consumption of Natural Gas. Their carbon emissions are higher than the UK average, as a result.


Energy Source E.on UK Average
Coal 3.7% 3.9%
Natural Gas 42.2% 39.4%
Nuclear 4.8% 16.6%
Renewables 46.3% 37.9%
Other Fuels 3% 2.2%
CO2 Emissions 221 g/kWh 198 g/kWh
High-level Radioactive Waste 0 0.0012 g/kWh


Who Does it Badly?

These suppliers heavily rely on non-renewable fuel source, thus they also have the highest CO2 emissions and hence the worst impact on the environment.

npower – Mostly Natural Gas

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This fuel mix is not very sustainable. Coal use and carbon emissions are also high.

Energy Source npower UK Average
Coal 6.2% 3.9%
Natural Gas 71.2% 39.4%
Nuclear 8.1% 16.6%
Renewables 9.3% 37.9%
Other Fuels 5.1% 2.2%
CO2 Emissions 373 g/kWh 198 g/kWh
High-level Radioactive Waste 0.0006 g/kWh 0.0012 g/kWh


Scottish Power – Mostly Natural Gas


Though there is a high percentage of renewables. The carbon emissions are high.

Energy Source Scottish Power UK Average
Coal 4% 3.9%
Natural Gas 50% 39.4%
Nuclear 6% 16.6%
Renewables 36% 37.9%
Other Fuels 4% 2.2%
CO2 Emissions 264 g/kWh 198 g/kWh
High-level Radioactive Waste 0.0004 g/kWh 0.0012 g/kWh


Hopefully, now you have a better idea of what a fuel mix is, why it is significant, and (out of The Big Six) which suppliers have the best, and the worst, fuel mixes.

For more information about this post and how Energy Solutions can help with your Electricity, Gas, or Water, click on the links, or check out the contact details at the bottom of the page.