As the sun shone on millions of solar panels and unseasonable gusts turned thousands of turbine blades last Sunday, something remarkable happened to Britain’s power grid.
For a brief period, a record 70% of the electricity for the UK’s homes and businesses was low-carbon, as nuclear, solar and wind crowded out coal and even gas power stations. That afternoon was a glimpse into the future, of how energy provision will look in 13 years’ time because of binding carbon targets.
On what one grid manager called “stunning Sunday”, the carbon intensity of producing power – a key measure of progress towards climate goals – dropped below the “magic number” of 100g of CO2 per kilowatt hour for the first time. That’s the level that must be the norm by 2030, according to the government’s climate advisers.
Yet last Sunday was just one of a run of striking records for renewable power in Britain that pose profound questions for conventional generators and the companies which manage power grids.
On one Friday in May, solar power briefly eclipsed the UK’s eight nuclear power stations. The grid recently went without coal for an entire day for the first time, and the dirty fuel is now regularly absent from power supply for hours at a time.
These milestones are having tangible effects. Solar cuts power demand for National Grid, reducing prices, while wind power also lowers prices. That led to another first last week, when high wind output pushed down the wholesale price and resulted in negative power prices, which means some conventional power plants had to pay household suppliers like British Gas to take their electricity.
So far, the low prices seen in the UK during renewable output surges were relatively infrequent and had had limited impact, he said. But that will change as such events become more common – records will continue to be broken because of a pipeline of offshore wind farms being plugged into the grid.
In the UK, the rise of renewables is also creating new challenges for the people who manage local and national power grids.
Robert Gross, director of the centre for energy policy and technology at Imperial College, said fossil fuel plants were having to ramp up and down more quickly to adjust to wind and solar output.
“My understanding is that’s not causing any insurmountable problems [for the grid]. The way I heard it characterised is the National Grid control room now finds summer to be more worrisome than January nights. Now it’s the [challenge of] solar and low demand on very sunny days [rather than high demand days in winter].”
His research shows that costs for managing the grid – balancing supply and demand as the energy supply becomes more variable – will not rise prohibitively until the UK has at least twice as much wind and solar power as it does now.
The UK isn’t done with records this year yet, Burt thinks, suggesting solar could go higher and carbon intensity might go even lower than the 90g CO2 per kWh last Sunday, to as low as 80g. “I think we will beat them several times this summer.”