OT: Renewable bollox. and gridwatch

[Paul]

There's an example of a windmill power curve here.

It puts out the rated power, at only one point on the curve.

The resource planning people should only be quoting "average system net", to make the figures seem realistic. If the average day makes 10GW and outstanding day makes

13GW, then quoting 10GW might be fair. Quoting number_of_towers times max_output_power, would be pointless, as that's never going to happen.

Paul

[T i m]

<snip>

Interesting if not unexpected, however it does raise the question of the validity of Turnips statement:

"(ii) The difference between 'max output' and 'overspeed', in a gust, is so narrow that turbines that might develop full output are routinely shut down for safety."

According to the graph, 'max power' is at 50 km/h and 'overspeed' is

100km/h and so I wouldn't call a 'narrow' wind speed range (even considering gusts)?

Just how fast can a turbine of that size react to a gust in any case?

He might know a bit about databases and nuclear but I'm not sure I'd take his word for much outside that, especially when included in one of his campaigns.

I'm guessing they would use MPPT/C devices to maximise the output like they do with PV?

Like P.M.P. on HiFi (well, it might happen but the numbers are pointless). ;-)

Cheers, T i m

[Fredxx]

Sadly without quoting which make/model, and not indicating how typical the curve is.

Quite, but TNP's claim suggests either the curve in your link is atypical or we never attain anything like rated speed.

Some real performance data for real turbines is needed.

[Chris B]

I'm late to this party but this site

allows you to select and compare your make/model, and I found that 3 of the bigger models on that site give > 7000kw for wind speeds > 12 ish m/s and it stays constant output up to 20 m/s which is a fairly wide power band. Does not by any means imply that the same rule applies for all, esp the major grid generators.

[Pancho]

How did ships ever sail?

Realistic numbers, current, average, maximum, variance.

15GW maximum is actually an astonishing amount of power, average 6.2GW is just as surprising. It's just a shame we at least an order of magnitude more, probably 20 times more.

[John Rumm]

Intermittently, and not always in the ideally desired direction!

Probably a good deal more than that if you are going to try and do it all with renewables and storage.

[The Natural Philosopher]

Badly, slowly, dangerously and expensively. Just like wind turbines

*Average* speed of a freightship was 5-7mph Crew needed at least 40. Compare a tramp steamer with a crew of 10 and an average speed of 7-10mph that replaced it

Same reason piston engined airliners vanished overnight. Massive maintenance and slow - less passengers per year on a fixed interest loan to purchase = higher fares than jets

Thank f*ck we are not. £1000 a month electricity bills for an unreliable supply I can do without.

[Pancho]

Could you do a yearly break down grouped by energy generation categories.

Quote: "Wind power contributed 24.8% of UK electricity supplied in 2020"

cites:

So 6.236 GW avg wind implies 25.15 GW avg total generated. Looks a bit low to me. I guess they are excluding imported electricity, from France etc. So it would be interested to see yearly breakdowns by source.

If you can do it.

[The Natural Philosopher]

I could...45 minutes later...

These are actual average MW flows - remember exports will show as negative

total demand: 29709.861625072732 coal: 499.60661429872493 nuclear: 5396.223768594414 ccgt: 10817.110560868245 ocgt: 19.323002049180328 french_ict: 988.316019656952 ifa2: 0 irish_ict: -35.716188524590166 dutch_ict: 465.3759866423801 pumped: 170.31197821797207 hydro: 491.32829576502735 wind: 6235.664408773528 solar: 1263.5740662525375 oil: 0.009116955069823922 biomass: 2048.4459338949605 other: 167.60802785367335 nemo: 552.5707821038251

1 row in set, 1 warning (0.36 sec)

Or as percentages

demand: 100% coal: 1.4% nuclear: 18.9% ccgt: 35.4% ocgt: 0.1% french_ict: 3.3% ifa2: 0.0% irish_ict: -1.2% dutch_ict: 1.5% pumped: 0.5% hydro: 1.6% wind: 21.7% solar: 4.1% oil: 0.0% biomass: 7.0% other: 0.6% nemo: 1.8%

I hope I got the queries OK

trusted on anything to do with energy or climate change

That is slightly more reliable, but if you drill down into 'official' figures you end up with a circular argument. "We *predict* that the capacity factor of wind will be x therefore the amount generated is Y which validates our capacity factor!"

There is a bit of 'embedded' wind that just shows as a drop in grid demand, so my figures for wind *and* demand might need upping by a GW or so

so from 6236->7236 and 29709 -> 30709 gives us 23.5%

As I say them problem is embedded stuff like unmetered wind and solar - you can pretend that its much bigger than it really is with 'models'

I guess they are excluding imported electricity, from France

The problem is of course that you can cherry pick stuff to get the politically correct answer

And remember, I am looking at GB figures. The Irish grid runs NI and that is part of te UK

[Pancho]

Thank you.

The items sum to 29,080, 630 less than the total demand.

The percentages sum to 96.7 which is too different to just be due to rounding.

Is it possible total demand (29,709.86) includes this?, where as the sum of the items (29,080) doesn't. It might be coincidental but if we assume the item amount missing (630) is entirely from wind, making wind = (6,866), and exclude inter connector stuff from the total = (27,739)

We then have wind % = 6,866 / 27,739 = 24.8%.

A lot of guess work, but their 24.8% looks ballpark right, if we accept you are undercounting wind, for the reason you give, and they are excluding foreign generated demand.

Thanks for gridwatch figures. It is always nicer to see stuff before it has been spun by biased/interested parties.

[Vir Campestris]

I'm even later to the party, but...

has wind speed records for the computer lab in Cambridge. The speeds are in knots, so I converted:

12m/s is about 23kts, 20 ~=38.

I pulled down the data, and if I have it right it was over 23kts 569 times, and under 429,359 times.

Negligible. I won't worry about the occasional >20 m/s.

OK, so that's the middle of a city, but there's a wind farm up on a hill not far away. Let's assume that the wind up there is double.

The wind in Cambridge is over 11.5kts 25k times. About 6%. Better.

So well over 90% of the time these turbines don't have enough wind.

I can also tell you from observation most of the time at least one of them is parked when the others are running.

Andy

[Chris B]

If I understood it correctly the debate was about the small margin between Max power and having to be shut down due to excessive wind. The data you have shown above seems to show that getting max power is rare, but being shut down due to excessive wind is extremely rare. Being shut down due to maintenance is something else entirely.

[T i m]

<snip>

That was a Turnip statement yes. Turns out the difference between those can be 100%.

Quite.

And an order of difference to how much valuable land covering the world is 'locked-out' for a very long time if any generation solution (specifically nuclear of course) 'goes wrong'.

And as we all know, 'What can go wrong, will go wrong'.

Cheers, T i m

[The Natural Philosopher]

There are several reason why a windmill or windfarm may cease to operate

- its broken

- its being *paid* to shut down because the grid cant handle the power transfers

- its gusting towards overspeed and the loss of income is less than the cost of lost turbines. As far as the frequency of events goes, I have noticed that the best generation happens when the whole of the UK has a 'good stiff breeze' Once the winds get more than that, then generation actually drops.

As a more realistic counterpoint to 'the wind is always blowing somewhere (it isn't by and large) we can say that the wind is never blowing perfectly everywhere.

Zero wind days are just as likely (if not more so) than perfect wind days

[tony sayer]