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  • Lily Cairns Haylor

Where (and when) are the blockers to net zero?

In the UK, the Easter Bank Holiday Monday set a new record for the lowest national average carbon intensity: 39 grams of CO2 per unit (KWh) of electricity was the national average at 13:00 on 5 April.


An exciting achievement and a sign of great progress in the transition to net zero. However, that "national average" figure is just one part of the picture. In fact, the carbon intensity of power ranged between 0 and 340 grams of CO2, depending on location and time of day. We were curious, so we took a deep dive into National Grid's data:

The graph above shows the carbon intensity of power for every half hour on April 5, broken down across 14 network regions in the UK. Evidently, we have a long way to go before 39 grams is the national norm. Let's pick out some highlights:

  • At 13:00, lowest carbon intensity regions were in Scotland, where hydro and wind supplied 'zero-carbon' power for most of the day.

  • The national average on April 5 (in black) is substantially lower than the annual national average for the past 12 months (grey). This is largely due to seasonal variation: GB needs far less power to function on a sunny bank holiday in April than it does the rest of the year round.

  • At 13:00, the highest carbon intensity was in Yorkshire (100 grams of CO2 per unit of power), where gas and biomass were used to top up the power demand not met by renewable generation sources.

  • On the same day (5 April), the carbon intensity in South Wales peaked at 19.30 in the evening at a little under 350 grams of CO2 per KWh.

What can be done to "smooth the peaks" and maximise the consumption of low-carbon power?


We need to deploy a mix of technologies to support an affordable and effective transition to net zero: hydrogen, storage, wind, PV, etc. The question is "how much do we need?", "where should these be located?", "how should they be integrated with existing systems?" and - in the case of technologies like batteries - "when should they operate?"


These are complicated questions. And this is where systems modelling can help.


At Advanced Infrastructure, we are developing approaches to modelling scenarios with an emphasis on carbon reduction and emission avoidance. From local energy system retrofits to transmission-level constraint management, such approaches can help accelerate the Energy Transition. Models can help answer questions such as "where to locate" and "when to charge" batteries - in order to maximise the consumption of low-carbon power and avoid increasing demand on the fossil fuel generators that cause the "peaks" in carbon intensity.


Its a tricky balance to cut carbon, minimise cost, and ensure the lights are always kept on! April 5 gave us a snapshot of how far the UK energy system has come - and how much work there is left to do.