Infographic: Energy security

Publication date
28th May 2020
Information types
Policy areas

See for a plain-text version of this infographic.

We recommend using Google Chrome to view infographics on the Ofgem website. If you have difficulties accessing the information in this infographic, please contact us.

Energy security infographic - plain-text

Facts and figures on Britain's energy use and supply. Information correct at April 2020.

Security of supply in Great Britain

Britain has a reliable energy system and its gas and electricity supplies come from a diverse range of sources. Though in an uncertain world, no system can be completely free of risk. That is why Ofgem works together with the Department for Business Energy and Industrial Strategy and National Grid, the system operator, to ensure the industry effectively manages these risks.

What affects our demand for gas and electricity?

Demand is influenced by a number of factors:

  • Consumer activity
  • Energy efficiency
  • Weather
  • Economic activity.

Demand is generally higher in winter than in summer, particularly for gas which is used for the majority of heating. A typical domestic household consumes:

  • Gas: 12,000 kWh
  • Electricity: 3,100 kWh

Between October and March, around 70% of annual household gas use happens and around 54% of annual household electricity use.

But for supplies to remain secure, Britain must also be able to manage peak demand on a cold winter day. This can be more than three times as much as average consumption.  

What supplies Britain's electricity?

It's generated using a mix of:

  • Coal (2.3%)
  • Gas (41.9%)
  • Renewables (29.4%)
  • Nuclear (18.4%)
  • Interconnectors (7.6%)
  • Other sources (0.4%)

2019 data - January to December. Source: BEIS Energy Trends.

Electricity generation sources will vary from day to day and year to year. Some factors that influence this are:

  • Cost of gas and coal
  • Environmental policies  
  • The availability of renewable energy
  • Our electricity price relative to countries we are interconnected with. 

Britain's electricity interconnectors link us with France, Belgium, the Republic of Ireland, Northern Ireland and the Netherlands.

They provide an import capacity of:

  • France (IFA) - 2GW
  • Republic of Ireland (East West) - 0.5GW
  • Northern Ireland (Moyle) - 0.5GW
  • Netherlands (BritNed) - 1GW
  • Belgium (Nemo Link) - 1GW

Our ‘Cap and Floor’ regime sets upper and lower limits on the returns interconnectors can earn for the investors.

Interconnectors can lower the cost of electricity for consumers  by letting us import power at times when it is cheaper in other countries. They are good for security too. We can import from a diverse range of energy sources from other countries, particularly  when demand is higher in winter. Equally, when demand is low, we can export our power to a wider market.

Proposed links under Ofgem's 'Cap and Floor' regime:

  • Norway (NSL) - 1.4GW
  • France (FAB Link) - 1.4GW
  • France (IFA2) - 1GW
  • Denmark (Viking Link) - 1.4GW
  • Ireland (Greenlink) - 0.5GW
  • Norway (NorthConnect) - 1.4GW
  • France (GridLink) - 1.4GW
  • Germany (NeuConnect) - 1.4GW

Two further planned interconnectors linking Britain with France have not requested a cap and floor arrangement. ElecLink (1GW) has been approved by Ofgem and the French regulator, CRE, and is currently under construction.

The current situation for electricity security of supply

The Capacity Market, introduced by the Government, is designed to ensure that there is sufficient capacity available on the electricity system. It does so by running annual auctions for capacity contracts.  

Generators and demand-response participants compete in an auction for contracts where they are paid to generate electricity, or reduce their demand for electricity when required.

There have been twelve capacity market auctions so far to deliver from 2017 to 2024. Each auction has attracted around 50 GW of capacity. Of these, six have been smaller auctions, two of which were held only for demand side response, and four of which were T-1 auctions procuring capacity for one year ahead. The remaining six auctions have been either T-4 or T-3 auctions, which have attracted around 50GW of capacity each.

Gas security of supply

Around half of Britain’s gas supplies come from our own North Sea gas fields. The remainder is imported from a variety of sources including pipelines linking us with Europe, and liquefield natural gas (LNG) shipped in from around the world. We don't depend on one single infrastructure source for our security of supply. 

There is also considerable space in the market for supply, even with the withdrawal of Rough (Britain's largest gas storage facility).

In a similar way to electricity interconnectors, our ability to import through pipelines and via LNG is dependent on price signals.

We have:

  • Pipelines connecting us with the UK Continental Shelf and Norwegian gas fields
  • Two interconnectors linking us with continental Europe (the Netherlands and Belgium) and one with Ireland.
  • Three terminals that import liquefied natural gas (LNG)
  • Gas storage sites.

Behind the numbers

You can find fuller historical data and information on how Britain's energy market is structured, larger supplier prices and profits, energy bills and customer switching via the following links:

Terms explained

Who are the larger energy suppliers?open key term pop-up |  Dual Fuel (DF)open key term pop-upWholesale costsopen key term pop-upNetwork costsopen key term pop-upSupplier operating costsopen key term pop-upEnvironmental and social costsopen key term pop-upPre-tax marginopen key term pop-upSwitchingopen key term pop-up

Who are the larger energy suppliers?

The "Big Six" is the name sometimes collectively given to the six larger energy companies who supply most of Britain's gas and electricity. Each of them generate electricity, and deliver both gas and electricity to our homes and businesses. They are:

- Centrica plc (three retail brands: British Gas, Scottish Gas and Nwy Prydain in England, Scotland and Wales respectively)
- Scottish and Southern Energy (SSE)
- RWE npower
- ... more

Dual Fuel (DF)

A type of energy contract where a customer takes gas and electricity from the same supplier (or two affiliated suppliers).

Wholesale costs

This is the amount energy companies pay to buy gas and electricity which they then sell to you. They may buy from the wholesale market, have a contract with an electricity generator, or be part of a company generating its own energy. Wholesale gas is often bought in advance. If suppliers don't buy enough, they may have to buy more which can be at a higher price depending on the market.

Network costs

These include the costs to build, maintain and operate the gas pipes and electricity wires run by the network companies who transport energy to your property. 

Suppliers are charged by network companies for this, and pass on this cost to their customers. We limit network costs carefully though price controls. This is because you can't normally choose which network company you use. You can find out more at more

Supplier operating costs

These are the costs associated with running a retail energy business, including sales, metering and billing.

Environmental and social costs

These are the costs of government programmes to save energy, reduce emissions and encourage take up of renewable energy. They also include the cost of social programmes like the Warm Homes Discount.

Find out more about these at Environmental programmes

Pre-tax margin

This is the difference between the money an energy company receives from their customers and the costs they have to deliver that energy. The ‘margin’ is not just the profit energy companies make. This is because they must pay tax and fund debt payments plus other obligated costs from this money. 


The process of changing gas or electricity supplier, or changing to a new tariff with the same supplier.