Electricity security of supply

Mae’r dudalen yma ar gael yn Gymraeg.

Infographic guide: How National Grid matches supply and demand second by second.

National Grid looks at a range of conditions when deciding how much power to procure for the Contingency Balancing Reserves. These include the risk of a colder or warmer than average winter as well as if other European countries don’t export as much power as we would normally expect during high demand periods in the winter.

National Grid procures for the Contingency Balancing Reserves in an economic and efficient way approved by Ofgem. This is the optimal level of protection for consumers, accounting for the costs and value of procuring the services. 

Britain has one of the most reliable electricity systems in the world.

As part of their monitoring, National Grid produce an annual Winter Outlook Report. This contains an assessment of the risks to supplies in Britain over the next winter.

Electricity capacity margins (the average amount of extra electricity available compared to peak winter demand) are tightening in Britain. This is because older and less profitable power stations are closing. However, if needed, National Grid can use extra tools to balance the system in winter 2016/17. 

Our electricity sources

Our electricity is generated from a variety of sources including coal, gas, nuclear and renewables.

Generators and suppliers produce and buy electricity. Additionally, four subsea cables connect Britain to France, the Netherlands and Ireland so we can import and export electricity.

Infographic guide: What makes up our electricity system?

Roles and responsibilities

In GB, National Grid’s job is to manage electricity flows on the grid so that supply matches demand on a second by second basis, even when it is very cold or if power stations break down.

The government sets the long-term direction for energy policy. 

What does Ofgem do?

Our role is to make sure that the electricity market works properly and that there are no barriers to stop companies doing their job.

Each year we run a seminar for industry and stakeholders to discuss different perspectives on the supply and demand outlook, plus the risks and challenges for the winter ahead. Find out more in National Grid Outlook Seminars.

Information and reports we have published on electricity security of supply can be found in the publications and updates list below.

Publications and updates

  • Published: 14th May 2018
  • Open letters and correspondence
  • 1 Associated documents
To ensure that the study by CEPA considers views from GB stakeholders, we’d encourage any interested consumers to provide your views via the survey

  • Published: 17th Jul 2015
  • Reports and plans
  • 1 Associated documents
Ofgem’s commentary on the first three winters of National Grid’s Future Energy Scenarios for electricity security of supply. Our assessment is based on data from National Grid accompanied by our own analysis.

  • Published: 17th Jul 2015
  • Factsheets
  • 0 Associated documents
Frequently asked questions explaining how we assess the risks to the security of electricity supply and what it means for consumers.

  • Published: 30th Jun 2014
  • Reports and plans
  • 2 Associated documents
This document is our annual report to the Secretary of State assessing how secure GB’s electricity supplies are for the next five winters.

  • Published: 21st Feb 2014
  • Decisions
  • 1 Associated documents
In November 2013 we published a consultation to seek views on the general approach for assessing the risks to electricity security of supply for the 2014 Electricity Capacity Assessment report.

  • Published: 28th Nov 2013
  • Closed: 9th Jan 2014
  • Consultations and responses
  • 11 Associated documents
Our Electricity Capacity Assessment report aims to illustrate the risks to electricity security of supply in Great Britain (GB) over the next five years. The 2013 report highlighted that the risks to security of supply are increasing faster over the...

  • Published: 27th Jun 2013
  • Reports and plans
  • 1 Associated documents
This report investigates the correlation of tight periods in the electricity markets in GB and its interconnected systems in the past. It is provided here as a complementary document to the Electricity Capacity Assessment Report 2013.

  • Published: 27th Jun 2013
  • Reports and plans
  • 1 Associated documents
This document is Ofgem’s Electricity Capacity Assessment Report 2013 to the Secretary of State.

  • Published: 27th Jun 2013
  • Agendas, minutes and presentations
  • 1 Associated documents
This presentation provides a historical price differential analysis between GB and its interconnected systems.

  • Published: 19th Feb 2013
  • Agendas, minutes and presentations
  • 1 Associated documents
A lecture given by Alistair Buchanan, Ofgem's CEO on 19 February 2013.