UK Electricity Grid Report 2018
In 2018, Great Britain generated 298 TWh of electricity. Gas was the biggest single source at 38.6%. Renewables (wind, solar and hydro) supplied 22.9%, or 28.3% counting biomass, and each unit generated averaged 214gCO₂ per kWh. That made 2018 cleaner than 2017: carbon intensity fell 25.7 g on the year.
Automated summaryIn 2018, Great Britain's electricity grid generated 298.32 TWh, with gas remaining the largest single source at 38.6%, followed by nuclear at 20.3% and wind at 13.2%. Low carbon sources accounted for 48.6% of generation, while renewables including wind, solar and hydro reached 22.9%, rising to 28.3% when biomass is included. Coal contributed just 5.2%, with the grid running coal-free for 1,844 hours, helping to bring the average carbon intensity down to 214.3 gCO2/kWh. The average wholesale market index price stood at £58.38/MWh, with nine hours of negative prices recorded across the year.
Renewables share
22.9%
28.3% incl. biomass
Low carbon share
48.6%
renewables + nuclear
Carbon intensity
214 g
per kWh · low 61 g, high 410 g
Generation
298 TWh
incl. estimated embedded wind and solar
Coal share
5.2%
1,844 coal-free hours
Peak wind output
12.1 GW
highest half-hour average
The 2018 generation mix, fuel by fuel
share of GB generation- Gas38.6% · 115.23 TWh
- Nuclear20.3% · 60.65 TWh
- Wind13.2% · 39.4 TWh
- Imports7.4% · 22.04 TWh
- Biomass5.4% · 16.1 TWh
- Coal5.2% · 15.4 TWh
- Solar3.8% · 11.39 TWh
- Hydro1.1% · 3.21 TWh
- Storage0.8% · 2.37 TWh
- Other0.2% · 0.72 TWh
Wholesale prices in 2018
market index (MID), volume-weighted across APX and N2EXThe average UK wholesale electricity price in 2018 was £58.38 per MWh on the market index (MID) basis. Prices were negative for 9 hours across the year. The most expensive half hour came on 1 March 2018 (settlement period 38) at £320.75 per MWh; the cheapest, £-24.62, came on 18 September 2018.
Average price
£58.38
per MWh, volume-weighted
Highest half hour
£321
1 March 2018, period 38
Lowest half hour
£-24.62
18 September 2018
Negative price hours
9
price below £0/MWh
Electricity supplied, 2009 to 2026
TWh per year, generation basis incl. estimated embedded wind and solar- 2009329 TWh
- 2010335 TWh
- 2011322 TWh
- 2012324 TWh
- 2013322 TWh
- 2014310 TWh
- 2015305 TWh
- 2016303 TWh
- 2017301 TWh
- 2018298 TWh
- 2019292 TWh
- 2020276 TWh
- 2021285 TWh
- 2022290 TWh
- 2023275 TWh
- 2024281 TWh
- 2025289 TWh
- 2026151 TWh
Britain supplies markedly less electricity than it did in 2009, even as the economy has grown: efficiency, LED lighting and offshored industry all pushed demand down while the mix decarbonised.
How 2018 compares
- Versus 2017: renewables +2.5 points, carbon intensity -25.7 g.
- Versus 2009, the first year on record: renewables up 19.5 points (from 3.4%), and each unit of electricity 51.8% cleaner (445 g to 214 g).
- Explore the neighbouring years: 2017 · 2019 or the full year-by-year table.
Cite this report
You are welcome to reuse the figures on this page with a link back. Suggested citation:
Purely Energy, "UK Electricity Grid Report 2018", purelyenergy.co.uk/grid-report/2018. Derived from NESO historic generation mix data.
2018 grid questions, answered
How green was UK electricity in 2018?
In 2018, wind, solar and hydro supplied 22.9% of GB generation (28.3% including biomass), low-carbon sources supplied 48.6%, and the average carbon intensity was 214 gCO2 per kWh.
What was the biggest source of UK electricity in 2018?
Gas was the largest single source in 2018, supplying 38.6% of GB generation. The full fuel-by-fuel breakdown is on this page.
How much coal did the UK burn for electricity in 2018?
Coal supplied 5.2% of GB generation in 2018 (15.4 TWh), and the grid ran coal-free for 1,844 hours.
What was the average UK wholesale electricity price in 2018?
The average UK wholesale electricity price in 2018 was £58.38 per MWh on the market index (MID) basis, volume-weighted across the year's half-hourly trading.
How many hours were UK power prices negative in 2018?
UK wholesale power prices (market index basis) were negative for 9 hours in 2018.
Use the data
Every figure on this page, as a CSV you can drop into a spreadsheet.
Basis: NESO historic generation mix (GB transmission generation plus estimated embedded wind and solar), aggregated by calendar year, energy-weighted. Renewables is NESO's wind + solar + hydro measure; the biomass-inclusive share is shown alongside. See the live version of this data on our real-time grid map and today's prices on wholesale market data.
Data comes from the Elexon Insights Solution (BMRS), the NESO Data Portal and the Carbon Intensity API, a project by the National Energy System Operator and the University of Oxford Department of Computer Science. Contains BMRS data © Elexon Limited copyright and database right 2026.
Energy decisions for the grid of 2026
The mix above sets the shape of wholesale prices. We turn it into procurement strategy for businesses across the UK, from fixed contracts to flexible purchasing.
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