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Hot weather, effects on electricity demand and production
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adam2
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Joined: 02 Jul 2007
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Location: North Somerset

PostPosted: Sun Jul 28, 2019 7:55 pm    Post subject: Reply with quote

The recent very hot weather has again increased electricity demand beyond the summer norm.
Demand reached over 40Gw which I suspect to be a new record for summer.
This is not yet a matter of much concern as the winter peak demand at about 50GW still significantly exceeds the summer peak of about 40Gw.

Also the winter peak occurs in the early evening with no PV input, whereas the summer peak is earlier in the day when at least 2Gw of PV can be counted upon.

Wants watching for the future though, remember Auckland !
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BritDownUnder



Joined: 21 Sep 2011
Posts: 628
Location: Hunter Valley, NSW, Australia

PostPosted: Sun Jul 28, 2019 9:11 pm    Post subject: Reply with quote

adam2 wrote:
The recent very hot weather has again increased electricity demand beyond the summer norm.
Demand reached over 40Gw which I suspect to be a new record for summer.
This is not yet a matter of much concern as the winter peak demand at about 50GW still significantly exceeds the summer peak of about 40Gw.

Also the winter peak occurs in the early evening with no PV input, whereas the summer peak is earlier in the day when at least 2Gw of PV can be counted upon.

Wants watching for the future though, remember Auckland !

Indeed so. But Auckland was also a catalogue of failures in management of cables, repair and maintenance etc. Someone thought that you could just as much electricity along three cables as you could four when the fourth failed and again that you could get the same electrical current along two as four when the third failed.

It would be interesting to calculate whether the overhead lines are similarly stressed on a 38 degC day at 40GW as they are on a 0 degC day at 50GW. I remember that the specs for overhead lines in Australia always give two maximum current values, one at 0 degC on a windy night which is about 50% higher than the other spec for a 40 degC day at midday with no wind.

All of the slack was taken up by gas so it seems - no coal was used and wind didn't come to the party. Perhaps the price of gas was cheap. I appears on Thursday and Friday the UK even exported power to the damn Frogs and the unspeakable Dutch. Lets hope they paid well for it.

No one appears to have thought of any form of energy storage - solar hot water, batteries etc - or even demand shifting.
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adam2
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PostPosted: Sun Jul 28, 2019 11:47 pm    Post subject: Reply with quote

Auckland was indeed a classic c0ck up.
A popular joke at the time was

Q, what did Aucklanders use for lighting before candles ?
A, electric lights !

Another one featured a cartoon drawing of two young children staring in wonderment at the electric lights at a remote rural farm "poor little things, they are from Auckland and have not seen electric lights before" Says the farmers wife.

More seriously, cables and overhead lines in the UK do have "summer" and "winter" ratings, both of which can be exceeded for short term emergencies.
I doubt that the large capacity high voltage grid lines in the UK were unduly stressed by the recent hot weather. The system was designed largely in the coal burning era to transmit power in bulk from power stations in the coal fields, down to South East.
These days the power comes largely from natural gas power stations which are spread around the country, and in summer daytimes, also from PV which is well spread around but more prominent in the South.

I would be more concerned at the local distribution network at 11Kv/33Kv/66Kv in the London area, and at transformer temperatures at these voltages.
Nothing significant did blow up THIS TIME but there have been some memorable blow-ups in past, and these will no doubt occur in the future.

And yes, we did export power to the French, and I suspect that something unexpectedly broke/blew up/tripped in France. At one point we were running expensive gas gobbling OCGT plant in order to export to France.
That suggests urgency, had the need been known an hour in advance, then extra CCGT plant could have been run. Or given longer notice coal burning capacity could have been used.
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