how do you tell where current flows?

[JohnW2]

The "dream", one supposes, is that eventually, there will be so many windmills (or general "renewable" sources), with so much geographic diversity, that the current flowing from the fossil-fired or nuclear-heated power stations will dwindle down, and some of them can eventually be turned off.

Maybe, but how sure can we be that the 'dream' may not turn out to be a nightmare? I know it's pretty fanciful, but if we ever did succeed in extracting a few tens of gigawatts of power from the winds over and around the UK, what on earth would happen to the weather patterns and climate? I haven't got a clue, but suspect that the effect would not be at all trivial.

Kind Regards, John.
Edit: typo corrected.

 

[JohnW2]

As a matter of personal interest, I just looked at the real-time National Grid data. At 10:35 this morning, the situation was:

Total UK demand:.........38,821 MW
TRANSFERS:
Northern Ireland -> GB:.....332 MW
France -> GB:.................1,500 MW
Netherlands -> GB:............620 MW
North -> South:.............10,139 MW
Scotland -> England:.......3,196 MW

Kind Regards, John.

 

[Mikefromlondon]

that is quite intersting john, wonder where you got that site information from?

So i am down in south, heavily dependent on the Northerns! lol

 

[JohnW2]

that is quite intersting john, wonder where you got that site information from? So i am down in south, heavily dependent on the Northerns! lol

That, and a lot more (real-time and historical) data can be found here

Kind Regards, John.

 

[Mikefromlondon]

Thank you JohnW2, that is very intersting and I will be looking regularly into this during extreme cold spells!

 

[JohnW2]

Thank you JohnW2, that is very intersting and I will be looking regularly into this during extreme cold spells!

You don't actually have to wait for cold spells to look. If you go to here, you will find half-hourly demand and transfer figures back to 2001, with more limited data (daily GWh figures) back to 1971. Happy reading!

Kind Regards, John.

 

[SparkyTris]

thanks for that John. very interesting indeed.
I have learnt that Scotland apparently has 22% of its electrical demand supplied by "renewables" (I assume that this is about 99% wind) as of december 2011. the target is 50% by 2020. looking at the NG stats, scotland appears to be a significant net exporter. seeing as there seem to be about gazillion windmills large and small all over orkney and less than 20,000 people living here, perhaps the county is a net exporter!

research continues.

 

[JohnW2]

thanks for that John. very interesting indeed. I have learnt that Scotland apparently has 22% of its electrical demand supplied by "renewables" (I assume that this is about 99% wind) as of december 2011.

Are you sure of that (99%) - what about hydroelectric, doesn't that count as 'renewable'?

looking at the NG stats, scotland appears to be a significant net exporter. seeing as there seem to be about gazillion windmills large and small all over orkney and less than 20,000 people living here, perhaps the county is a net exporter!

I don't know how abstemious or excessive those in Orkney are in their use of electricity, in comparison with the 'UK average', but if you divide the total average UK demand by the UK population, you get a figure of about 670 watts per person. If Orkney folk are similar to that, 20,000 of you would therefore require about 13.4 MW total, which does not sound totally out of the question for a gazillion windmills (provided the wind is blowing!), depending on how large an Orkney gazillion is! - so you could be right!

Of course, if Orkney were already a significant exporter, then that might make more sense of OFGEM's concerns about the possible impact on their cables of further generation in Orkney.

Kind Regards, John.

 

[plugwash]

Something else to consider is that neither generation or demand is constant. What matters when sizing a cable is not the average flow it's the peak flow.

 

[JohnW2]

Something else to consider is that neither generation or demand is constant. What matters when sizing a cable is not the average flow it's the peak flow.

Indeed - and, of course, when (and of what extent) that peak flow arises will depend on all sorts of things. If Orkney always imports at least some electricity, then peak flow (mainland to Orkney) would occur when Orkney's demands were at their highest but there was no wind (hence generation) there. On t'other hand, if it is usually an exporter, then peak flow (Orkney to mainland) might arise when there was optimum wind for full generation in Orkney and the Orkney demand was at its lowest. However, it's also possible that, even if usually an exporter, 'total wind failure' coupled with high Orkney demand could invoke the first of those situations, in which high flow was going in the non-usual direction. In the above, I'm assuming that Orkney has no local 'conventional' generation. If it does, then the impact of demand and wind changes on the flow to/from the mainland would presumably be reduced.

Kind Regards, John.