How was 2024 for carbon intensity in Scotland? Another year of progress and record setting.

Zero carbon days

Most noteworthy of these was that North Scotland generated zero carbon electricity for 236 full days last year. That's 64% of the year with no emissions because wind and hydro provide electricity in combination meaning that it's really not usual for North Scotland to be at almost 100% renewables, well 64% of the time to be precise.

Lowest average annual carbon intensities

South Scotland saw a reduction from 29.8 grammes in 2023 to 24.6 grammes in 2024 while North Scotland saw a reduction from 35.1 grammes in 2023 to 29.9 in 2024.

This brings both of Scotland's main grid areas to an annual average below 30 grammes (just!).

The fact that North of Scotland achieved 236 full days of zero carbon electricity and South of Scotland achieved none raises some questions. How can the South of Scotland have a lower carbon intensity over the course of the year while the North of Scotland is producing so much zero carbon electricity? South of Scotland simply has more diversity of low and no-carbon generation sources and uses less gas for electricity generation than the North. 92% of North Scotland's electricity comes from wind (75.8%), hydro (14.6%) and nuclear (1.7%). Solar is a mere rounding error (unfortunately), so when that wind doesn't blow gas takes over and really raises the daily intensity averages. This results in many days, often weeks, at 0 gCO₂/kWh followed by spikes that reach into the high 200s of gCO₂/kWh.

On the other hand, in South Scotland, slow and steady wins the race. Again, wind makes up the majority of generation at 55.8% and fossil fuel gas makes up only 4.8%. The next big player is nuclear at 29.1%. Hydro, biomass and solar all take up a few percent each.

Slow and steady with a dose of geothermal

So what's the answer to bring these two grid areas more into alignment. More solar and storage is definitely needed in both regions. More hydro would benefit South and more pumped storage, the North. One glaring omission is geothermal which is sadly very lacking across the UK. While is it on the cards more and more for heat networks (and that's great), deep geothermal for electricity generation is very much absent and could make a huge dent in the remaining decarbonisation of the grid that needs to be done.

Where both regions shine is in their adherence to the "low carbon" classification of being under 35 gCO₂/kWh and under 30 grammes for 2025. Using the < 35 metric we can see that both regions are with in this range about 80% of the time. In 2024, North Scotland had 299 full days under the "low carbon" classification while South Scotland achieved 291.

If we project forward to the end of 2025, the same data would result in North Scotland having 296 days under the more stringent target of 30 gCO₂/kWh. South Scotland would drop a bit further to 276 days < 30 grammes. I look forward to comparing 2025's end of year results and seeing further progress towards decarbonization.

What about other areas and their results?

North and South Scotland broke their own records, but they didn't achieve the lowest carbon intensity in GB; that prize goes to North East England despite an increase this year from 15.7 grammes in 2023 to 22.1 grammes in 2024. North West England also gets an honourable mention as the only other sub 50 grammes region this year at 48.3 grammes.

For context, the next closest was North Wales & Merseyside coming in at an average annual carbon intensity of 76.6 grammes CO2 / kWh. The full league table including percentage changes from 2023 is given below. The two highest emission areas saw only single digit drops in their carbon intensity, but several of the mid-range regions saw > 20% drops in their emissions.