"Dirtiest" hour of generation now cleaner than average hour five years ago

Britain’s power sector has undergone such radical transformation that the “dirtiest” hour of generation in the first three months of 2017 was cleaner than the average hour half a decade ago, new research has revealed.

Carbon emissions were down 10 per cent year-on-year, as coal generation plummeted 30 per cent due to record high wind output and a mild winter.

The most carbon intensive hour over the quarter began at 8.30pm on 16 January, according to the latest edition of Drax’s quarterly Electric Insights report, during which 424 grams of CO2 were released for each kilowatt hour generated.

This compares with an average of 471 grams per kilowatt hour between 2009 and 2013.

The report, which was produced in collaboration with researchers at Imperial College London, found that the average over the first three months of 2017 was just 284 grams per kilowatt hour.

The cleanest hour came on a windy Sunday night in March when the power sector had a carbon intensity of 102 grams per kilowatt hour.  

Iain Staffell from the Centre for Environmental Policy at Imperial College London said: “Coal output – largely driven by the carbon tax – has fallen 82 per cent in the last four years and has been replaced by mid-carbon gas, low carbon biomass and imports, as well as zero carbon wind and solar.

“Together these have driven decarbonisation in line with, or even slightly ahead of, the country’s targets – which are the most ambitious in the world.”

Carbon intensity of the UK power sector and power sources

Source: Electric Insights, Drax and Imperial College London 

The start of the year also saw a flurry of new renewable records.

Wind output rose to 11.3TWh – besting the previous record in 2015 by more than 10 per cent – whilst hydro output hit 1.6TWh – a 20 per cent increase on the previous high water mark. Biomass output increased to 4.4TWh.  

Towards of the end of period solar reached a new peak output of 7.67GW – enough to meet a fifth of all demand at the time – and on the final weekend in March “invisible” behind-the-meter solar generation meant for the first time ever demand on the grid was lower during the daytime than it was overnight.

“How we manage this changing pattern in demand requires a major change in how power stations operate,” said Staffell.

“Solar output is still relatively hard to forecast in advance. Technologies that are flexible and can be turned on and off quickly, such as gas or battery storage will help accommodate these changes.” 

Demand on the grid towards the end of March

Source: Electric Insights, Drax and Imperial College London