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UK Electricity Grid Report 2020

In 2020, Great Britain generated 276 TWh of electricity. Gas was the biggest single source at 34.5%. Renewables (wind, solar and hydro) supplied 31.3%, or 37.8% counting biomass, and each unit generated averaged 168gCO₂ per kWh. That made 2020 cleaner than 2019: carbon intensity fell 21.2 g on the year.

Automated summaryIn 2020, Great Britain's electricity grid reached a milestone with low carbon sources supplying 55% of generation, while renewables including wind, solar and hydro accounted for 31.3%, rising to 37.8% when biomass is included. Gas remained the single largest source at 34.5% of the 275.52 TWh generated, followed by wind at 19.9% and nuclear at 17.2%, with coal falling to just 1.6% amid 5,138 coal-free hours. This shift helped bring the average carbon intensity down to 168 gCO2/kWh. The average wholesale price stood at £35.52/MWh, and the market recorded 164.5 hours of negative pricing over the year.

Renewables share

31.3%

37.8% incl. biomass

Low carbon share

55%

renewables + nuclear

Carbon intensity

168 g

per kWh · low 41 g, high 333 g

Generation

276 TWh

incl. estimated embedded wind and solar

Coal share

1.6%

5,138 coal-free hours

Peak wind output

13.8 GW

highest half-hour average

The 2020 generation mix, fuel by fuel

share of GB generation
  • Gas34.5% · 95.09 TWh
  • Wind19.9% · 54.71 TWh
  • Nuclear17.2% · 47.41 TWh
  • Imports8.4% · 23.02 TWh
  • Biomass6.5% · 17.98 TWh
  • Solar4.4% · 12.11 TWh
  • Coal1.6% · 4.38 TWh
  • Hydro1.6% · 4.31 TWh
  • Storage0.5% · 1.49 TWh
  • Other0.5% · 1.47 TWh

Wholesale prices in 2020

market index (MID), volume-weighted across APX and N2EX

The average UK wholesale electricity price in 2020 was £35.52 per MWh on the market index (MID) basis. Prices were negative for 164.5 hours across the year. The most expensive half hour came on 15 September 2020 (settlement period 37) at £510.88 per MWh; the cheapest, £-53.02, came on 22 May 2020.

Average price

£35.52

per MWh, volume-weighted

Highest half hour

£511

15 September 2020, period 37

Lowest half hour

£-53.02

22 May 2020

Negative price hours

164.5

price below £0/MWh

Electricity supplied, 2009 to 2026

TWh per year, generation basis incl. estimated embedded wind and solar

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 2020 compares

  • Versus 2019: renewables +5.5 points, carbon intensity -21.2 g.
  • Versus 2009, the first year on record: renewables up 27.9 points (from 3.4%), and each unit of electricity 62.2% cleaner (445 g to 168 g).
  • Explore the neighbouring years: 2019 · 2021 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 2020", purelyenergy.co.uk/grid-report/2020. Derived from NESO historic generation mix data.

2020 grid questions, answered

How green was UK electricity in 2020?

In 2020, wind, solar and hydro supplied 31.3% of GB generation (37.8% including biomass), low-carbon sources supplied 55%, and the average carbon intensity was 168 gCO2 per kWh.

What was the biggest source of UK electricity in 2020?

Gas was the largest single source in 2020, supplying 34.5% of GB generation. The full fuel-by-fuel breakdown is on this page.

How much coal did the UK burn for electricity in 2020?

Coal supplied 1.6% of GB generation in 2020 (4.38 TWh), and the grid ran coal-free for 5,138 hours.

What was the average UK wholesale electricity price in 2020?

The average UK wholesale electricity price in 2020 was £35.52 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 2020?

UK wholesale power prices (market index basis) were negative for 164.5 hours in 2020.

Use the data

Every figure on this page, as a CSV you can drop into a spreadsheet.

Download 2020 data (CSV)

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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