By Paul Homewood
Little Emily has a scoop:
https://twitter.com/emilygosden/status/1256540336572313600
Her story is behind a paywall at The Times, but this is the gist:
Britain could be at risk of blackouts as extremely low energy demand threatens to leave the electricity grid overwhelmed by surplus power.
National Grid asked the regulator yesterday for emergency powers to switch off solar and wind farms to prevent the grid from being swamped on the May 8 bank holiday, when demand is expected to be especially low.
In its urgent request to Ofgem, it warned of “a significant risk of disruption to security of supply” if the “last resort” powers to order plant disconnections were not granted.
It is of course a problem which I have been warning about for a long time, that when wind and solar power are really ramped up there would be huge surpluses of power at certain times of the year, not to mention days, as well as shortages at others.
In this instance, however, the coronavirus lockdown has suppressed demand, thus bringing forward the issue.
Daily demand this week has fluctuated between about 20 and 30 GW each day. This is probably about 5 GW lower than the same time last year, with the biggest drop seemingly at night time ironically.
http://gridwatch.templar.co.uk/
Although Emily mentions solar power as an issue, it may well be at night when the risk is greatest.
First, let’s have a look at the Univ of Sheffield Solar site for the last week:
https://www.solar.sheffield.ac.uk/pvlive/#
Bear in mind that most solar generation is embedded, that is it is absorbed by local grids rather than transmitted via the National Grid, As such it shows as a drop in demand instead of extra generation. The Sheffield site therefore adjusts the total generation upwards, so as to include the solar contribution.
We can see that total generation drops to around 20 GW at night.
Now if we look at the official grid figures for the last 48 hours (ie excl solar), we see that nuclear is supplying a steady 6 GW, which cannot easily be switched on and off.
Wind is currently under 2 GW, but was up to nearly 6 GW yesterday:
https://www.bmreports.com/bmrs/?q=eds/main
However, we already have 24 GW of wind capacity. If demand drops to 20 GW, and nuclear remains constant, that would mean the system could only absorb 14 GW of wind power, 58% of capacity.
On most days, this would be manageable, but if its a windy day next Friday, all bets are off.
I should not finish without mentioning solar power.
This week it has peaked each day at around 7 GW. At peak solar, ie midday, demand seems to be about 10 GW greater than at night, so on the face of it the grid should cope with the extra generation from solar.
In other words, it is wind power which poses the real problem.
Emily has actually done quite a good job on this one, and her twitter feed mentions that the National Grid are struggling with the legalities of whether they can order generators to switch off. Hence the talk of emergency powers.
What she does not mention is that this will become a regular and much bigger problem in years to come, when wind and solar capacity are expanded.
For instance, under the Committee on Climate Change’s 5th Carbon Budget, the central scenario anticipates 47 GW of wind power capacity and 40 GW of solar just by 2030. (This compares to 24 GW and 14 GW respectively now.)
Even allowing for higher demand for EVs etc, this clearly is not at all manageable at times of low demand.
Even at average loading, 47 GW of wind power would mean an average load of 17 GW, so there would be surpluses on average every night.
Meanwhile 40 GW of solar would probably yield about 20 GW at midday, when the extra demand only appears to be 10 GW.
By 2050, there would need to be much more renewable capacity, of course. The CCC are talking perhaps of 110 to 175 GW of wind/solar.
There is little prospect we could offload any of this to the continent, who would be in a similar position.
Which brings us back to either paying billions a year in constraint payments, or ordering wind and solar farms to switch. Something which radically alter their economics.
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May 2, 2020 at 01:15PM
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