Great Britain's electricity system flexibility is key as solar and wind break records

Still (almost) no coal – Great Britain’s coal-free run continued throughout May and beyond, giving the first full calendar month of electricity generation without a contribution from coal since the industrial revolution.

So said National Grid ESO (NGESO) in June – a month that was heading to be coal-free as well until coal generation crept in again mid-month.

While April was a month of record highs for solar generation, May brought some equally record lows for carbon, adds NGESO. Low demand on the electricity system continued to present its control rooms engineers with a unique challenge – particularly with two May bank holiday weekends within two weeks reducing already low demand even further.

The afternoon of Sunday 24 May we saw the grid at its all-time greenest, with a new record low carbon intensity of 46 gCO2/kWh (carbon produced for every kWh of electricity used), helping May to become the greenest month ever seen on the GB electricity system.

NGESO is clear that the weather (and to a lesser extent the lower demand) is the leading factor in these records and trends. While May’s sunshine did not power a record solar high, overall solar share was up from April – with periods where solar was comfortably the top power source, sometimes making up a third of the country’s electricity generation mix.

Looking back to the first quarter of the year for a moment, analysis conducted by academics from Imperial College London for Drax Electric Insights shows how volatile the country’s electricity system was in the first three months of 2020. And also how a variety of energy technologies rose to the challenge.

Output from wind farms soared, by 40% compared to Q1 2019, as severe storms meant Britain experienced its wettest and windiest February since records began. But flexible power stations, and action from businesses able to reduce their electricity usage, helped prevent blackouts during cold, calm spells.

Dr Iain Staffell of Imperial College London said: ‘Britain’s electricity system is under pressure like never before, with both the country’s weather getting more extreme and a global pandemic testing its resolve. So far in 2020 we’ve seen companies reducing their demand for electricity to help keep the grid stable when supply from wind power rapidly decreased, and then the COVID-19 lockdown caused many businesses to shut up shop, reducing electricity demand and creating new challenges with oversupply of power.’

‘Having flexibility within the power system at these critical moments is crucial to keeping Britain’s lights on,’ concluded Staffell.

The report shows that:

• When output from wind power fell sharply on cold, calm days, the stress to the system increased and in one incident created a higher chance of blackouts, with just 0.2 GW of spare capacity available.
• Flexible technologies like biomass, pumped storage and gas were able to increase their output to fill the void on some occasions when wind power reduced.
• An evening peak in demand was also managed with factories and supermarkets reducing their electricity usage.