Record-breaking 2020 becomes greenest year for Britain’s electricity

2020 was the greenest year on record for Britain’s electricity system, with average carbon intensity – the measure of CO2 emissions per unit of electricity consumed – reaching a new low.

According to our data, last year’s average carbon intensity was 181 gCO2/kWh – continuing a trend which has seen the system decarbonise by 66 per cent in the last seven years.

May 2020 saw both the greenest month on record (average carbon intensity 143 gCO2/kWh) and the lowest carbon intensity ever seen on the system – 46 gCO2/kWh on May 24.

These records underline the progress we're making towards our ambition of being able to operate the system carbon free by 2025

Significant periods of coal-free electricity generation and record-breaking levels of power from zero carbon sources were key factors in reducing 2020’s carbon intensity – while record low electricity demand during the nation’s lockdown also contributed.

During spring Britain saw its longest run since the industrial revolution generating electricity without using coal, stretching almost 68 days (1,630 hours) between April 10 and June 16.


In total the country was powered coal-free for over 5,147 hours in 2020, compared with 3,666 hours in 2019, 1,856 in 2018 and 624 in 2017. Coal generated only 1.6% of the electricity mix in 2020, compared with almost 25% five years ago.

Read our monthly insights in our regular electricity reports

2020 was also a record-breaking year for renewable power sources.

The record for the highest ever level of wind generation was broken several times during the year – most recently on December 18 (17.2GW) – while August 26 saw wind contributing its highest ever share to the electricity mix (59.9%).

Solar power, too, set new records for its highest ever level of generation (9.7GW) and its highest share in the mix (34%) – comfortably providing a third of Britain’s electricity supplies on several occasions in May.

And while not everyone enjoyed a white Christmas, 2020 did bring a green Christmas – with the first ever coal-free Christmas day and zero carbon sources powering over half of our electricity demands.


• Dec 18 – highest ever level of wind power (17.2GW)
• Aug 26 – highest ever share of wind power (59.9%)
• May 30 – highest ever share of solar power (34%)
• May 24 – lowest ever carbon intensity (46 gCO2/kWh)
• May – greenest month on record (143 gCO2/kWh) 
• Apr 20 – highest ever level of solar power (9.7GW)
• Apr 10—Jun 16 – longest ever GB coal-free period 
• Total coal-free hours: 5,147 hours

2020 was also a year of firsts for Britain’s electricity system.

As part of National Grid ESO’s stability pathfinder initiative, Drax’s Cruachan hydroelectric pumped storage plant became the first to provide inertia to the grid in July without generating unnecessary electricity – a key milestone in managing a stable, zero carbon grid in the future.

In September, Tesla became the first user to go live with our new wider access API, marking a significant step in helping smaller power sources more easily access Britain’s balancing market.

And we rolled out the first in a suite of new fast-acting frequency products in October, boosting its control room’s ability to respond rapidly to disturbances in the flow of energy around the grid.


Rob Rome, interim head of national control at National Grid ESO, said:

“2020 has been a record-breaking year for Great Britain’s electricity system. The grid continues to transform at an astonishing rate as we move away from fossil fuel generation and harness the growth of renewable power sources.

“In our role balancing Britain’s electricity supply and demand, we’re continuously innovating with industry to improve the grid’s resilience and make sure it’s ready to exploit the potential of these renewables.

“It’s an exciting time, and the progress we’re seeing with these records underlines the significant strides we’re taking towards our ambition of being able to operate the system carbon free by 2025.

“That 2025 ambition is a stretching target. Last year gave us a flavour of some of the challenges ahead, as our control room worked 24/7 to operate the electricity system in unprecedented conditions.

“But I’m proud to say every action we’ve taken has delivered safe, secure and reliable low carbon electricity at the same time as minimising costs for consumers.”

Follow Britain's electricity mix live through our carbon intensity app.