Carbon intensity
Checks on this page
Each feed is judged by the age of its newest data against its own timetable: “late” means the last check found nothing newer. Settlement period now: SP–.
GB’s carbon intensity turns the live fuel mix into one number — grams of CO₂ per kWh — judged against bands that shift each year as the grid cleans up. This page tracks it against its forecast, in your area and fuel by fuel.
Carbon intensity over the last 24 hours
NESO · half-hourlyLow-carbon share
How much of GB generation came from sources that emit nothing at the point of generation, over the last 24 hoursYour area
NESO regional · forecast, half-hourlyPick a region or enter your postcode area to see how clean the electricity is where you are, and why.
Every fuel, in detail
Latest reading, its 24-hour range, and what it costs in carbonThe last 30 days
Daily averageAbout these figures
This figure and its limits · bands that move · fuel mix and carbon
This figure, and its limits
Carbon intensity is the average grams of CO2 released for each kilowatt-hour of electricity on the GB grid this half hour. It is an average across the whole system, not a property of your supply: a green tariff does not change what is running, and neither does living next to a wind farm. It measures how clean the country’s electricity is at this moment.
⚠ Half the time, the current figure is a forecast. NESO’s actual for a half hour does not exist until that half hour has finished, so a figure for “now” is a prediction. This page labels which one you are looking at, every time, because a forecast presented as a measurement is the most common error in this subject.
⚠ The bands move, and almost nothing says so
NESO redraws the boundaries between “low”, “moderate” and “high” as the grid decarbonises. A reading that earned “low” a few years ago earns “moderate” today without a single gram having changed. The scale above is this year’s.
So comparing band labels across years compares two different rulers. To know whether the grid got cleaner, compare the grams. The label says how today’s reading stands against today’s expectations — useful, but a different question.
Fuel mix and carbon, two boundaries
The same fuels are measured two ways on this page: as a share of the electricity and as a share of the emissions. They do not line up. Gas is routinely under a third of the generation and most of the carbon; nuclear and wind are the reverse.
The two strips in the 24-hour panel are drawn to the same scale so the mismatch is visible, and Every fuel, in detail gives both shares for each fuel, with the emission factor applied.
This is why “renewables hit a record share” and “carbon intensity was unremarkable” can both be true of the same day. What decides the intensity is not how much clean generation ran, but how much gas had to run alongside it.
The factors are NESO’s published set, live where the feed answers. The interconnector row is a blend of the three published import factors and is labelled as one: the real carbon content of an import depends on what the neighbouring market was running, which nobody publishes in real time.
How figures are marked. A figure with no mark is measured; an estimate is hatched; a forecast is dashed. A total or a share with the solar estimate inside it says so: incl. est. solar.
More in the methodology: carbon intensity, and a ruler that moves →