Re: 1GW (sic) Battery Energy Storage Systems

On 30/11/2024 15:51, john larkin wrote:

On Sat, 30 Nov 2024 10:50:07 +0000, Martin Brown
<'''newspam'''@nonad.co.uk> wrote:
 

On 26/11/2024 03:15, john larkin wrote:
>

Having electricity used to be normal.

>
UK power supply is generally way more stable than US.

 How many hours per year is your power out?

Mine personally used to be entirely reliable after they replaced the perished 1950's rubber insulated 3 vertical strands LT with modern aluminium compound cable wiring with a steel hawser core. Prior to that the lights would flicker in storms and burning bits of rubber would fall to the ground under mostly bare copper wires as wet strips of old rubber and canvas insulation touched them with much arcing and sparking.
Apart from half a day a year for preventative maintenance where they cut down overhanging tree branches it was reliable in the old days. Failure is usually because someone has driven into a pole. Hazard of above ground cabling (which is unusual in the UK apart from rural backwaters).
However, since the latest shower cut back on preventative maintenance we got hammered when storm Arwen hit taking down several (rotten) poles. We were down for a couple of days but people around me were down for up to two weeks (not enough poles and/or people and kit to put them in). Their replace on fail policy can't cope with massive systemic failures. Same with a couple of inches of snow and UK grinds to a standstill.
In the cities mains supplies are underground and pretty much reliable apart from that infamous incident that I referred to. However, in a cold winter on a still and cloudy day the margins now are extremely tight at a level where they have to pay some bigger industrial users not to use power.

I'd estimate two total here, on avearge, but a pole on our street
toppled down recently and that took 5 hours to replace

We had that too in my village. Once a tree fell on it and the steel hawser held it but permanently bent all the poles like bananas and the other time the milk tanker on sheet ice totalled a pole on one of the coldest days of the year (Sunday morning). Isolated random incident so the previous power distribution company had us back on by nightfall.
If that happened again today I expect we would get something like :
"Your call is really important to us ... our office hours are 9-5 please call back on Monday with you emergency power outage <naff music>".

Large-region power failures are very rare here, between major
earthquakes.

They are in the UK too. We don't have earthquakes (well we do notice the odd one every few years but they are tiny compared to real earthquakes).

The public consultation was yesterday. It really is 1GW injection power
and 4 hours so a 4GWhr battery farm (40x bigger than the largest system
currently in the UK and being built by a startup with no track record!).
>
It will have ~900 container modules of batteries as close together as
they dare (half the US regulation spacing) and in double lines of 50.
>
SO that makes me wonder how big is a 1GW transformer operating at 400kV?
And how much does one cost?

 Big utility transformers are made to order, and that can take years.
The hazards there are obvious.

That is what I thought. I'm trying to put bounds on the lead time. I'm more impressed with their sales pitch than I expected to be. My back of the envelope calculations suggest an air of unreality about their claimed/intended GW injection capacity. Availability of supergrid line is not in doubt two main corridors run close by. You can light up a fluoro tube stood on end under them. Indeed an artist did just that!
https://www.industrytap.com/florescent-bulbs-unplugged-and-shinning-tapping-electromagnetic-fields/1763

>
I'm guessing the secondary to handle 2500A will have to be (30A = 2mm^2
so 3000A ~ 200mm^2 = 16mm diameter) and at a 40:1 stepdown the low side
will have to be 40x bigger cross section 6x linear size hollow core?).
Are these guesses approximately right? How many turns on each?
>
How much soft iron core does it require (approximately)?

 It takes special gear to measure the inductance of a utility-scale
transformer. A handheld meter won't do.

Granted.

The location chosen is very cunning. They will get paid not to produce
electricity by intercepting the payments (to not produce electricity)
currently made to wind farm owners in Scotland and off the NE coast.

 Hey, I know how to not produce electricity.

You also have to possess the requisite kit to get paid for not doing it.
(UK infrastructure is a complete mess after decades of under investment)
Another question for my education approximately what is the current rating of a modern UK 400kV supergrid line (I presume limited by sagging or softening from thermal expansion). Likewise for 132kV and 33kV.
Wiki says ~2GW/circuit at 400kV (seems far too low to me)?
--
Martin Brown