Carbon intensity at 181 gCO2/KWh across August’s grid, as power prices break records


Low power demand, CCGT outages and increased availability of French nuke-sourced imports push carbon intensity to a near-record low for electricity last month, National Grid ESO has revealed. 

Meanwhile, wholesale prices for winter supply are soaring to record levels.  Decarbonisation plays a part.

August’s average of 181 gCO2/kWh generated was ‘close to’ record achievements, NG-ESO reports in its latest monthly Electricity Report. 

In previous years August has seen absolute peaks in decarbonisation performance, such as 2020’s then-record for wind at just short of 60%, and an 85.1% total from all zero carbon sources on 17 August 2019. 

Though not as exceptionally carbon-free, August 2021 still maintained the trend of drastic reductions in carbon-based power.  Coal was feedstock for 2% of the nation’s electricity last month; five years ago that share stood at 17%. 

The middle of the month included periods of almost 75% carbon free electricity, driven by occasions of high wind output.

Averaged across August, zero-carbon sources accounted for 41% of power, says NG-ESO.  Friday 13th at 2:00pm was the greenest moment, with zero carbon sources providing 73.89% of output.

Overall, gas sourced 36% of Britain’s power in August, followed by wind at 18%.  Both tied on 15% were UK-sourced nuclear, and imports, the latter largely from EDF’s French reactors, their passage eased by an additional 1 GW potential provided by NG-ESO’s new shared IFA-2 link.

“Ultimately, more interconnection with our neighbours means better network resilience, and better security of supply for everyone”, commented Isabelle Haigh, NG-ESO’s head of national control.

More NG-ESO data on carbon intensity here. 

Meanwhile the summer’s continued rise in wholesale prices shows no signs of slowing.  

On Monday baseload power prices reached a record high of £230/MWh. Weighted across leading bourses EPEX and NordPool, closing prices for the day stood at their highest since mid-January. 

Analysts EnAppSys put the shortage down to shortage of generation, coupled with high carbon prices.    To blame are the late return of some Edf reactors after summer maintenance, including three units still out at Heysham, Lancashire.    

Analysts at LCP pointed to exceptionally low wind outputs – as low as 97% down on outputs achieved over the past twelve months – contributing to contracts pushing earlier this week towards £500/MWh. 


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