Bishop Hill Overoptimistic
Nov 18, 2014 Energy: grid Here's an interesting little detail from the National Grid report on capacity margins that I wrote about a few weeks back.
It seems we have windfarms with a nameplate capacity of 7.6GW. National Grid obviously then have to derate this capacity for planning purposes. As we all know, it's perfectly normal for the whole of the UK to simultaneously experience very low windspeeds (or no wind at all), and this has been known to happen even in the depths of winter, for example the very cold winters of 2009/10 and 2010/11. I had therefore assumed that the Grid would have to plan on the basis that they might get nothing from windfarms at all, but in fact they do nothing of the sort. According to Table 16, the grid assumes that they will get 23% of nameplate capacity, or some 1.7GW.
The explanation in the text makes no sense to me at all:
173. For wind power stations, Equivalent Firm Capacity (EFC) is used. This is a measure of how much 100% reliable generation would be required to replace the installed wind generation whilst maintaining the same level of system security.
174. This wind modelling approach combines the risk from wind variability with the other conventional risks, e.g. high demand or low availability of conventional generation. When the installed wind is a small proportion of total generation the main risk to system security comes from the conventional risks and the EFC is very close to the mean load factor for wind generation. In the coming years, as the installed wind capacity grows as a proportion of total generation, the risk that the variability of the wind will affect system security grows as well as wind’s contribution to system security, which will have the affect of decreasing EFC.
This footnote also appears:
Equivalent Firm Capacity is a model output from a Monte Carlo simulation. For further information explaining the theory behind the EFC, see paragraph 173 and http://pio.sagepub.com/content/226/1/33.
Perhaps there is something in that paper that can justify what appears on the face of it to be a rather reckless assumption, but the abstract doesn't fill me with hope:
This paper describes a new probability theory of the capacity value of additional generation in electrical power systems. A closed-form expression for the effective load carrying capability or equivalent firm capacity of a small additional capacity is derived. This depends on the mean and variance of the distribution of available additional generation capacity, and the shape of the distribution of the difference between available existing capacity and demand, near zero margin. The theory extends naturally to the case where the pre-existing background and additional resource are not statistically independent.
The theory may be used to explain and confirm the generality of various well-known properties of capacity value results, as is illustrated using Great Britain examples. Of particular note is the common observation that if the distribution for demand is shifted so as to increase the calculated risk, then the capacity value of additional generation increases. The new theory demonstrates that this is not true in general, but rather is a consequence of the shape near zero margin of the probability distribution of the margin of existing generating capacity over demand.
Incorporating an assumption that we would get 1.7GW from windfarms, the net forecast margin was 2.3GW. Without it then, the margin would be 0.6GW, or 1%. And as noted at the time the National Grid report was published, the figures that were published excluded the loss of the Heysham and Hartlepool nuclear reactors. In other words the true margin may have been negative.
Put that in your pipe and smoke it.
I do hope they are unmothballing a lot of power plants.
Reader Comments (89)
I can't lay my hands on the 2013 Winter Outlook report, but I wonder if the assumption of 23% for windfarms is a new thing.
I recall, but cannot find, a report by NG a few years ago that showed historical data showing about four times a year the wind output was zero and that in winter this would correspond to a period of high demand. It makes total sense to assume ECF is zero for peak winter demand. Can anybody else find that report?
Since the ECF of 23% is close to the average load factor for wind, it appears that they are assuming that
which is not true anymore.As I recall, the figure from multiple studies by DECC etc, whether offshore or onshore, that comes up as an average measured consistently over a significant time period is 26%. Its been a bit lower this year but rule of thumb for our part of Northern Europe is one day in four for generated capacity.
Past reports are available here
Last years assumptions:
Nuclear 84%
Hydro generation 79%
Wind EFC (base case) 25%
Wind EFC (max interconnector export) 29%
Coal + biomass 85%
Oil 87%
Pumped storage 97%
OCGT 95%
CCGT 86%
Let me explain. Imagine the power system is represented by a person. And wind is a pair of boots. Well what this report is saying is that if the system needs to it can pull very very hard on the boot laces and they will just fly away to cloud cuckoo and live happily ever after on their retirement fund.
What doesn't help is that the coldest days have the most demand and you get the coldest days when you have a high pressure system with little or no air movement.
TerryS
Thanks. In 2009/10 National Grid was using a figure of 27%
The citation is to this paper, which doesn't appear to be online. I'm intrigued by the term "capacity credit", which suggests to me a number that is being calculated for a different purpose.
I see there's no mention of STOR, the National Grid's dirty (& expensive) secret?
"In the coming years, as the installed wind capacity grows as a proportion of total generation, the risk that the variability of the wind will affect system security grows as well as wind’s contribution to system security, which will have the affect of decreasing EFC"
Does this mean the more we rely on wind power, the less wind power % we can actually rely on?
Or in other words...do they imply there is an optimum amount of wind power to install, and that to install more of it would actually make things worse?
The public can be very sympathetic in a crisis. When something extraordinary happens they don't expect the authorities or the utilities to meet every possibity. BUT. They won't have much understanding for an unforseen period of stillness during a cold snap. They'll each be little wind generation experts and say 'why didn't they predict periods of no wind? Even I know that.' The authorities won't even be able to claim they weren't warned.
This article at the REF seems to set things out a bit more clearly and, moreover, suggests that National Grid previously had a more cautious approach.
Bring on a cold and frosty one.
Where would we be without computers?
Its pretty clear that some kind of probability programme has been used to obtain this unrealistic but perhaps delusional assumption.
I watch the grid on line during the winter and I would say that wind very often fails to reach 1.7Gw. Indeed, during those cold, still, high pressure periods wind tends to almost slip off the bottom, at 0.2 to 0.4Gw of the plot, sometimes for days on end.
We need 40,000 more turbines if we are to rely upon wind, and these need to be on shore and everywhere, even if this destroys tourism in places like the Lake District. Failing this (and I hope we do) then I suggest that there will be a crisis where millions are off line for days or even weeks. Then, perhaps, will this foolishness (criminal negligence) may begin to fade away.
Unchecked, Greens will, ultimately, kill more than Hitler, Stalin and Gengis Khan put together.Perhaps not intentionally(?) but through naive optimism, dogma, and blind 'ambition'.
It's a massive problem for the engineers. What do you do? You know that wind energy is infinitely variable. You know that you cannot possibly know the future weather patterns in sufficient detail BUT you have to make an estimate of generating margin by law.
What do you do? Well, you guess but an educated guess. It is still a guess.
The germans who of course control the EU, just build more really dirty coal plants. The idiots in charge of the rest of europe continue blindly toward the cliff's edge.
@omnologos
...Or in other words...do they imply there is an optimum amount of wind power to install, and that to install more of it would actually make things worse?..
I don't know whether they are implying it or not, but it is perfectly true, and has been recognised in some quarters since at least 2007.
The document to read in this regard is Eleanor Denny's impressive PhD Thesis on the cost-benefits of wind power with worked examples based on the Irish Grid. She finds, IIRC, that the cut-off point is around 20% wind power penetration. It can be found here:
A Cost Benefit Analysis of Wind Power
I have been trying to make this paper better known on the blogs for the past few years, but without success. It's advantages are:
- it provides a real worked example
- Eleanor Denny got an EU award for teaching - her work is very readable and instantly understandable
- This is not only peer-reviewed, but an actual PhD thesis - so it has been heavily scrutinised
Hope this helps...
Dr John Etherington addressed this in 2006, nothing changes, except we have more of a problem with more wind turbines: http://goo.gl/o67Ybw
In 2005, the Eon-Netz Wind Report revealed the problems of ever increasing wind turbine presence in the grid. It can be found here: http://www.nerc.com/docs/pc/ivgtf/EON_Netz_Windreport2005_eng.pdf
"In order to also guarantee reliable electricity supplies when wind farms produce little or no power, e.g. during periods of calm or storm-related shutdowns, traditional power station capacities must be available as a reserve. This means that wind farms can only replace traditional power station capacities to a limited degree.
As wind power capacity rises, the lower availability of the wind farms determines the reliability of the system as a whole to an ever increasing extent. Consequently the greater reliability of traditional power stations becomes increasingly eclipsed. As a result, the relative contribution of wind power to the guaranteed capacity of our supply system up to the year 2020 will fall continuously to around 4%.
In concrete terms, this means that in 2020, with a forecast wind power capacity of over 48,000MW (Source: dena grid study), 2,000MW of traditional power production can be replaced by these wind farms."
Wow.
I have just checked Gridwatch (10am, 18th November).
Current demand is about 50GW. Wind is supplying 1.52 GW. Brilliant!!!, only 0.2(approx) BELOW THE ASSURED SUPPLY. Now if it were very cold and we had a persistent cold low pressure area across the UK....now remind me again, exactly how does the reality stack up with pressure to buy electric cars and an abundant green energy future?
...Now if it were very cold and we had a persistent cold low pressure area across the UK....now remind me again, exactly how does the reality stack up with pressure to buy electric cars and an abundant green energy future?...
It will be fun to watch.
Note that practically everything depends on a reliable supply of electricity. You can't unload tankers carrying oil or gas without it, and you can't fill your car at the garage without it. You can't mine coal without it. You can't even generate more electricity without it.
Once a first-world country runs out of electricity it will be a very difficult exercise to start it up again. As far as I know, this has never actually been done. Perhaps we will be privileged to have a ringside seat for the first attempt...
I can sort of see the government thinking over reducing the margin. It’s wasteful and expensive to have capacity you don’t regularly use. But having sufficient electricity isn’t like making sure that there’s enough turkey for everyone at Christmas. You can’t make up for a shortage with something else. People won’t think ‘I should have bought mine sooner’. You don’t allow customers to make alternative arrangements (barring buying a generator which could lead to a whole load of problems). Electricity is not a luxury and in some cases it’s essential to life.
It would be interesting to know if they’ve done the cost analysis of both brownouts (damaging equipment) and full on shortages. If a blackout happened because of something unlikely (like a strike or massive storm) that’s one point but where do planners stand if people die during a foreseeable power cut due to a lack of wind? Would the city sue for an interruption in supply?
TCO2: The powers that be will mandate that the blackouts will be restricted to rural areas. They can't afford to have blackouts in the City of London or any other major city, since foreign investors would flee the country and there would be widespread rioting, looting and other civil unrest.
I thus have my own generator, a full log store and a full oil tank.
I agree with all the points made, but please let's be realistic, if there is a shortage then it won't be the public who'll have their electric cut off, as we all know there are existing mechanisms to cut demand at large industrial users. It will doubtless cause some financial grief if people are laid off, but that's not the same as no electricity.
"...a Monte Carlo simulation..."
The roulette-wheel method.
Remember, this has either a single or double-zero.
Indeed IanH the solution to throttle back demand on the days when the wind farms fail to deliver has been the case all along. An alternative would be to blame the lack of supply on maintenance and hide the pea that way.
ERCOT, the grid management organization for Texas, has the one of the largest wind capacities to deal with in the United States. Their view of wind seems to have improved lately as well.
Using anything much over 15% seems to be madness
Here is the daily output of wind:
http://www.ercot.com/gridinfo/generation/windintegration/2014/10
Note the many days with low single digit wind capacity output.
If it helps, I often take screen shots of the BM Reports site, and from them, I've extracted some "Lows" over the last couple of years:
11-12-2012 @12:10GMT = 184MW
03-02-2013 @22:00GMT = 29MW
02-08-2013 @22:15GMT = 74MW
08-08-2013 @08:20GMT = 62MW
09-09-2013 @09:55GMT = 122MW
23-09-2013 @15:20GMT = 75MW
28-11-2013 @11:30GMT = 291MW
13-03-2014 @17:10GMT = 111MW
13-03-2014 @19:35GMT = 98MW
20-01-2014 @12:25GMT = 486MW
20-01-2014 @15:35GMT = 236MW
04-09-2014 @17:40GMT = 248MW
I also took a shot of a pressure chart on 30th of June this year, showing the entire UK sitting in the middle of a slack area of moderately low pressure. There was one isobar running down the North Sea, and another just cutting across Bodmin Moor, and up through Ireland. Unfortunately I didn't note the wind power then, but I think we can all guess how low it would be...
That figure is just too convenient. It is almost as if some green minion at DECC supplied it to show that wind generated electricity is more useful than it really is.
As it stands that figure has no place in the real world and from an engineering perspective never will.
And of course on these cold still days there will be an electrical demand from some of the wind farms to maintain various functions and stop them freezing solid, has a figure for this type of demand ever been disclosed?
Dodgy Geezer on Nov 18, 2014 at 10:24 AM
"Note that practically everything depends on a reliable supply of electricity. You can't unload tankers carrying oil or gas without it, and you can't fill your car at the garage without it. You can't mine coal without it. You can't even generate more electricity without it."
Most shops, including supermarkets, close when the electricity supply fails, because their computer systems stop. They would also need to take evasive action to save their frozen foods in display cabinets. Those without computer systems, usually the smaller shops, would need people with skills in arithmetic to add up the bill. Restaurants and cinemas would be affected, but with traffic lights out of action, some roads might even flow more easily. Much of the railways would have been OK, but they are being electrified! And who needs radio, radar and landing lights at airports?
Anyone can look at the figures for themselves. If you want to see the history over days.months, years (back to 2009) you can download a snapshot of the grid status every 5 minutes from this website here:
http://www.gridwatch.templar.co.uk/download.php
I've just downloaded the last 12 months. Load it into a spreadsheet and sort the rows by wind (column H). After 41 null rows of missing data there are over 200 rows where the wind generation was below 100MW.
Just one example is 31 May 2014 where wind generation dipped below 100MW at 08:25 in the morning and stayed under 100MW until 10:50. If you pick a higher threshold you can find longer periods of non-contribution.
rules of thumb here: about 1Mgbpound per MW installation investment required ,plus 1M maintenance over 20y.
sooo, 8 GW => 16 B GBpound invested.
return: say 1.5 GWatts * 7000H= 11G Kwh
1KWh = 10p? => 1.1 B per year
5p => 0.6B per year
This NEVER going to pay itself off. Let alone bring any "carbon dividend" in its lifetime.
This is a scam. And a very dangerous one, IF CO2 were in any way to be harmful.
A complete misfocus of our efforts and invesmtnet. A derangment of wise policies.
in other words: liberal retardism to the max
"Would need people with skills in arithmetic to add up the bill"
Good luck with finding them!
"Much of the railways would have been OK, but they are being electrified!"
Even a "Heritage" Deltic or steam loco like Tornado is going to be in trouble if the signalling system doesn't have a reliable back up.
" And who needs radio, radar and landing lights at airports?"
Airports will have back up generators to power essential services, but how many of the approach lights will be included I don't know. These can stretch some distance out from the airfield boundary, and may be powered by local supplies.
Re: IanH
> if there is a shortage then it won't be the public who'll have their electric cut off, as we all know there are existing mechanisms to cut demand at large industrial users.
Except that peak demand is between 6 and 9pm in the evening. Unless the large industrial users are running shifts or operating in anything other than standby mode, then asking them to shut down wont make that much difference.
Does anyone know how accurate gridwatch is? http://www.gridwatch.templar.co.uk/
For some time now it shows that there is 6 gig of wind power capacity which is wrong.
This reminds me of the Financial world that almost universally used Gaussian statistics to model risk for all sorts of financial instruments. Even though it was well known that the real world typically produced returns that were not Gaussian (higher peaks, longer tails). The ease of doing analytical work under Gaussian assumptions outweighed the problems associated with the apparently small differences in the distributions. Most users of the outputs of these models did not appreciate the dangers, particularly in calculating the probability of apparently very rare events occurring. We all know where that ended up.
So they are relying on a Monte Carlo model…. fine, but the model will rely on "random" inputs drawn from a particular distribution. What is that distribution? And how accurately does it replicate the real world? As various readers have pointed out, periods of effectively zero wind production are not that rare and there is certainly some correlation with periods of maximum demand.
Don't let the theory blind you. Make sure it really does effectively represent the variability that we can all observe thanks to the public availability of the data.
"Would need people with skills in arithmetic to add up the bill"
Good luck finding them!
"Much of the railways would have been OK, but they are being electrified!"
Even a "Heritage" Deltic or steam loco like Tornado is going to be in trouble if the signalling system doesn't have a reliable back up supply.
" And who needs radio, radar and landing lights at airports?"
Airports will have back up generators to for essential services, but how many of the approach lights will be included I don't know. These can stretch some distance out from the airfield boundary, and may be powered by local supplies.
That is odd, I thought Wind Generation was now up to over 9GW.
ECF is cloud cuckoo land thinking, typical of Davey and co, they just do not live in the real world.
As they keep saying the wind is always blowing somewhere, but not necessarily anywhere in the UK.
Bitter&Twisted, wishing for old people to die of hypothermia just to prove a point isn't a very charitable attitude, in my view.
Anyways, when the wind stops blowing, houses get less drafty, so a good jumper is all you need! and consumption can drop!
Re: A C Osborn
Its 7.7GW onshore and 4GW offshore. You can get the data here. It also includes details of sites that are under construction or have had consent to build.
Letter published in Telegraph 11 months ago:
Sir
Your leader today questions whether wind power can add to Britain's energy
security. Unfortunately today it cannot. Whilst wind power contributes to
the national generating capacity on an average basis over time, security
effectiveness can only be measured at the moment when the "threat" exists;
i.e. at times of peak demand.
Based on publicly available data from the national grid, during the past
three years during periods when demand was between 95% and 100% of that
peak, wind power was able to satisfy just 1.5% of the demand, less than the
margin of accuracy with which demand can be predicted. This is no doubt
related to the periods of coldest weather in winter being often associated
with areas of high pressure and low wind speeds.
Whilst the contribution of wind power averaged over a year is around 5 - 7%
of demand, unfortunately it fails the energy security test; it cannot be
relied upon at times of peak demand.
Jonathan Paget
When will the numpties in DECC realise that "spare capacity" is not a luxury, but a necessity?
It is like the spare tyre in your car.
You do not need it 100% of the time, but when you do need it, you need it 100%
Conversely, we all know about the press releases by developers, that promise that such-and-such a new wind farm 'COULD (my capitals) power (say) 25000 homes..'
Well - the independent survey releases a few weeks ago (I fail to remember the source) was reviewed on BBC Cambridgeshire, and the presenter came up with this little nugget from the report:
'In the last year, the length of time that the UK wind 'fleet' exceeded 90% of installed capacity was....'
Wait for it....
'Seventeen minutes...'
I know - its a cracker,isn't it..?
Steve ta says "Bitter&Twisted, wishing for old people to die of hypothermia just to prove a point isn't a very charitable attitude, in my view."
That is not my wish- althoough it may well be the Greens wish.
My wish is for the government's lack of joined up thinking to be exposed to the Public in in a dramatic way.
I, unlike the Greens value Human life.
ptw on Nov 18, 2014 at 11:46 AM
Using your figures, for a 5 MW wind farm, at 20% load:
The capital cost is £5,000,000
maintenance cost is £5,000,000 over 20 years
With a 20% load, a 5 MW wind farm will produce 1 MW at the domestic socket
Therefore, total costs per MWhr at the socket, are:
£10,000,000 / (20 * 365.25 * 24) = £57
£57/MWhr = 5.7p/kWhr
With the wind blowing in the right direction, this is almost feasible, but it does not allow for any energy loss for energy storage, such as batteries, the load balancing effort required, nor the up front capital costs, just for starters.
Are these figures from a published document?
Do these figures include the costs of transmitting the wind power from remote places such as Scotland or the Dogger Bank?
I remember reading a NG report, probably from about 6-7 years ago, which stated that as UK wind capacity increased, the required backup for windless days would also also increase, and almost proportionally once wind penetration became significant in terms of total grid capacity. There was a formula and I cannot remember the exact figures, but the logic went:
Total 2GW wind capacity - backup required (when no wind) would be almost zero as the existing thermal plants could easily ramp up to cover this shortfall.
Total 5GW wind capacity - backup required when no wind would be about 2GW (of new thermal plant required)
Total 10GW wind capacity - backup required would be about 7GW (of new thermal plant required).
Total 15GW wind capacity - backup required would be about 12-13GW (of new thermal plant required).
and so on...
I can't find this report now nor a link.
All I can find (which may have been mentioned above) is this Ofgem report from 2012 which makes a reference to an EFC of 20-22% on page 68:
Source - http://www.templar.co.uk/downloads/electricity-capacity-assessment-2012.pdf
Dave Ward on Nov 18, 2014 at 12:26 PM
And it all needs to be planned!
In 1981 I was flying to Houston and the area from Victoria to Gatwick lost electrical power. With no trains, I took a taxi from Victoria Station to the airport where we waited until the flight was due to take off. They then walked down the aircraft aisles to count the empty seats, as their computers were not running. There were lots and lots of these because so many passengers were stuck in stranded trains! They had caught earlier trains, to make sure they caught the flight!
Yes, we do need a secure electricity supply.
Sherlock -
I saw that too, but still find it difficult to believe. Surely that was a mistake and it should have been 17 hours or 17 days? It was in a Report published by the Scientific Alliance / Adam Smith Institute iirc, but I don't have a copy.
It is tough choosing who lives and who dies: http://www.popoffsets.com to save the planet.
I believe that wind nameplate capacity is way higher than 7.9GW. On the NETA site wind capacity is shown as 8.4GW and this does not include embedded (in local networks) wind - probably another 1.5-2GW. This would make nameplate capacity nearer 10GW?
To discuss wind farms in the context of capacity margins does them an honour they do not deserve in the first place. They are not there to provide a useful contribution to electricity production so they shouldn't even be considered in those terms. Wind farms are there to make politicians and Greens feel good about themselves and their heroic efforts to save the planet. That is literally the be all and end all of the matter. They do not provide free energy because wind is no more free than any other resource - transforming it into electricity is what costs money just as with coal, oil, uranium, etc. What energy they sometimes generate is not cheap or competitive. They do not save any significant amount of CO2 (plant food) for reasons well known, and it didn't need to be saved in the first place because we are in plant food famine in this age. If anything the end result of wind farming is to increase CO2 production, as in the German example. Not only do they not contribute usefully, they actually render a sane energy policy impossible because the subsidies they require in order to exist (and so defeat market choices) make the construction of real power stations completely unprofitable. Worse still, the rest of the energy industry is increasingly forced to concentrate on compensating for unpredictable surges in wind output resulting in loss of efficiency as more wind farms are built. It is not for nothing that the National Grid chooses to attempt to claim a capacity benefit for wind farms which does not exist. Not to do so would be tantamount to admitting that they are a national scandal on an unprecedented scale. Every last one needs to be scrapped and the subsidies which are their life blood torn up.