UK carbon intensity is the amount of CO₂ emitted per kilowatt hour of electricity, measured in grams of CO₂ per kWh (gCO₂/kWh).
What Carbon Intensity Means
Carbon intensity provides a straightforward answer to the question: how clean is the electricity right now?
It measures the emissions produced for each unit of electricity, typically shown as grams of CO₂ per kilowatt hour (gCO₂/kWh). A lower number indicates cleaner electricity, while a higher number suggests a greater reliance on fossil fuels.
It’s one of the quickest ways to understand the environmental impact of the electricity system at any given moment.
Why it changes
Carbon intensity isn’t fixed. It fluctuates constantly because the energy mix is always changing.
Low-carbon sources like wind, solar, nuclear, and hydro lower the number. Gas increases it. Coal, which is now rare in the UK, would push it up even more.
Imports also matter because electricity from other countries reflects their energy mix, not just the UK's.
So, the number you see is really a snapshot of everything happening on the grid at that moment.
Patterns through the day
Like demand, carbon intensity follows patterns, but they aren’t always clear.
A windy afternoon can have very low carbon intensity, even if demand is normal. A cold, still evening might be much higher because the system needs more gas to keep up.
Solar reduces the number during the day, especially in spring and summer, but disappears completely after sunset.
That’s why live data matters—the grid can look very different from one hour to the next.
What makes it low (or high)
- renewable output (especially wind) is strong
- demand is manageable
- fossil fuel use is low
In the UK, wind is often the biggest factor. When it generates well, it can supply a large portion of demand and significantly lower carbon intensity.
Nuclear provides a steady low-carbon base, while solar adds a daytime boost.
Higher-carbon periods usually happen when demand is high and renewable output is low. Gas-fired power stations are flexible and fill that gap, but they produce higher emissions.
Why it matters
Carbon intensity isn’t just an interesting number; it can actually be useful.
If you can adjust when you use electricity—like charging an EV, running appliances, or heating water—you can sometimes shift that usage to cleaner periods.
It may not always align with the cheapest times, but it can reduce your overall impact.
More broadly, it also shows how the grid is changing. As more renewable and low-carbon sources are added, the system should spend more time at lower intensity levels, but there will still be moments when fossil fuels are necessary.
On this page
The chart here shows how carbon intensity has changed over the last 24 hours, allowing you to compare current conditions to recent trends.
To understand why it’s high or low, it’s best viewed alongside demand, generation, and imports—either through the links on this page or by returning to the main dashboard.
Return to the live UK electricity dashboard
Page freshness signal: live data checked Mon, 04 May 2026 11:00 BST.