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Gross out

When Gordon Hughes gave evidence to the House of Commons Science and Technology COmmittee the other week, I was struck by the vehemence with which his evidence was denounced as "balderdash" by Grantham Institute policy wonk Robert Gross. Unfortunately, Dr Gross's explanation of precisely why he thought this eluded me, as his subsequent narrative seemed to me to be little more than handwaving.

Being an inquiring sort, I decided to delve a little bit into Dr Gross's positions on wind power and started to read some of his publications. While I haven't got to the bottom of the dispute with Prof Hughes over the effect of wind on carbon emissions, I did find some interesting bits and pieces about just how you reduce intermittency of wind power by installing lots of turbines - a "wind carpet" in the jargon.

This has been the subject of a dispute between Gross and energy consultant James Oswald. In 2008, Oswald published a paper in Energy Policy which looked at this question and concluded that although there was some smoothing of supply, the effect was not nearly enough:

Although the aggregate output of a distributed wind carpet in the United Kingdom is smoother than the output of individual wind farms and regions, the power delivered by such an aggregate wind fleet is highly volatile. For example, had 25GW of wind been installed, with full access to the grid, in January 2005, the residual demand on the supporting plant would have varied over the month between 5.5 and 56GW.

As readers here probably know, if you balance your load with gas, this will mean much ramping up and down of output, with a concurrent loss of efficiency, so this is pretty bad news. However, Oswald went further and analysed the scope for balancing demand with supply from a wider area, but again found that this was not a plausible solution:

Wind output in Britain can be very low at the moment of maximum annual UK demand (e.g. 2 February 2006); these are times of cold weather and little wind. Simultaneously, the wind output in neighbouring countries can also be very low and this suggests that intercontinental transmission grids to neighbouring countries will be difficult to justify.

As his figure 13 shows, the correlation between different European countries can be striking:

The paper was clearly a serious blow aimed at the wind industry and elicited a response from Gross and some of his colleagues, and Grantham's men launched a strong counterattack:

Oswald et al. contend that their findings ‘significantly undermine the case for connecting the UK transmission grid to neighbouring grids’. This is because they argue that there is little potential for geographical distance to smooth wind farm outputs, because weather fronts create common wind conditions across large areas. Indeed Oswald et al. describe very large correlations in wind farm output across a wide geographical area based upon Met Office wind speed data. This finding is at odds with other empirical work, which finds that correlations between power swings from operating wind farms drop off markedly as distance
increases (Holttinen, 2005; Holttinen and Pedersen, 2003). We note that the sites chosen run in a line from north to south that for some reason neglect important offshore sites in the south-east. Moreover, other recent studies use data from operating wind farms and extrapolate as appropriate rather than using raw Met Office data alone (Ilex and Strbac, 2002). One reason for this is that geographically ‘low resolution’ wind speed data are not always a good indicator of local wind conditions and wind output. Future analysis needs to consider why it is that Oswald et al. appear to have found data that run counter to the established
view that distance between wind farms reduces correlations in output.

Interesting, I thought - a direct contradiction. Oswald finds a strong correlation between wind speeds across different areas, while Gross, citing Holttinen apparently says these "fall away" quickly.

The Holttinen papers are readily available on the web. Holttinen 2004 is a study that tries to estimate reserve requirements for systems with different proportions of wind in the energy supply mix, looking chiefly at hourly swings in supply and demand. On the face of it then, it doesn't even speak to the same point that Oswald is making, namely that we can get periods where the wind is not blowing strongly anywhere in Western Europe. Even on its own terms, the paper doesn't seem to support Gross's case. It says in its abstract that "Large geographical spreading of wind power will reduce variability, increase predictability, and decrease the occasions with near-zero or peak output." However, nowhere is there an analysis of how wind speeds correlate with each other over different geographical distances. In the text, there is this though:

When wind power comes from geographically distributed wind farms, the total production never reaches the total installed capacity and is hardly ever totally calm. From the combined production in the Nordic countries, production over 50% of rated capacity is rare in summer and production over 75% is rare in winter. The lowest hourly production was 1.2% of capacity for the Nordic wind power production time series.

Again, this hardly seems to make Gross's point.

Holttinen and Pederson is even worse. Although Gross claims to be discussing empirical studies, in fact this paper is purely theoretical, being a simulation of how a thermal energy system would react to the addition of large amounts of wind power to the grid. And since the system studied is the West Denmark grid rather than a wider geographical area, it again completely fails to address the point Oswald makes.

Perhaps I am missing something here?

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Reader Comments (31)

Wind is not a continuous power. Did they not ever read the rhyme of The Ancient Mariner. This is why the warmists are in the doldrums.

Aug 28, 2012 at 6:04 PM | Unregistered CommenterPeter whale

You know that you are not supposed to look at the references cited in support of climate science, this is a typical "denier" trick. You are supposed to take ex cathedra statements from the "chosen ones" as the "truth".

Aug 28, 2012 at 6:05 PM | Unregistered CommenterArthur Dent

He has research funding from the Carbon trust and BP.

And BWEA and Greenpeace.

Aug 28, 2012 at 6:11 PM | Registered CommenterPaul Matthews

Gross uses the tried and tested system when dealing with politicians of "masking" references (Quasimodo et. al. 2010) Making up references ( Cyrano de Bergerac et. al. 1998) and generally using BS derived from Fred Flintstone, Rubble and associates (2009) secure in the knowledge that no politician will ever look them up. (Yeo,Deben and Huhne 2008). Class Act.

Ivor Ward.

Aug 28, 2012 at 6:20 PM | Unregistered CommenterDisko Troop

Teleconnections have been used as an excuse for reducing the number of stations for measuring temperature & averaging temperature anomalies over long distances. Why should it come as a surprise that wind strength is correlated over long distances.

Aug 28, 2012 at 6:22 PM | Unregistered CommenterRogue

OK, there is plenty of actual wind experience in other countries. We should not need to guess at this nor debate it. Anybody at the party ought to be coming armed with real operational experience. No ifs buts and maybes. If they cannot so inform thenselves they should be excluded.

Aug 28, 2012 at 6:25 PM | Unregistered CommenterRhoda Klapp

Reports by Poyry to the Committee on Climate Change show that for the projected UK wind turbine distributions necessary to meet 2050 targets for renewables, wind power output could vary from ~ 90 Gigawatts down to ~ 5 Gigawatts and back to ~ 90 Gigawatts within a matter of hours. Actual data shows that the statistical benefit of widely distributing windfarms is less than has been hoped.

Poyry has also argued that the fact that the wind operation is unpredictable over long time periods, means that the demand for otherwise reliable OCGT and CCGT backup power stations becomes equally unpredictable, and consequently uneconomic in operation.

So the wind-turbines must be subsidised because they are uneconomic, and the necessary backup gas-fired power stations will have to be subsidised because they are rendered uneconomic. Subsidies-on-subsidies for two parallel generating systems, when greater operating efficiency, reduced costs and probably negligible difference in emissions could be achieved by CCGT alone.

Wind energy is "free" ? - but you have to pay the equivalent of over 30 years dependable electricity supply in a lump sum, up-front, to benefit from this unreliable resource.

One of the major economic advances of the 19th century was the development of steam-powered ships, enabling international trade to be break free from the vagaries of wind and tide. Now we are well on the way to a wind-powered economy, led by similar financial wizadry to that which gave us the 2007 financial crisis.

In contrast, France, over the last 30 years has developed CO2-free nuclear power and correspondingly zero-emission high-speed electric trains. Perhaps the French know something we don't.

Aug 28, 2012 at 6:26 PM | Unregistered CommenterMalcolmS

The Bonneville power Authority has the greatest experience because it has the ideal hydro mix. It is 3 times the are of the UK and Ireland. It frequently suffers near dead calms. this man gross appears to be a dangerously deluded extremist.

Aug 28, 2012 at 7:14 PM | Unregistered CommenterAlecM

The important thing to remember in comparing Oswald (and Stuart Young and Hugh Sharman) with theoretical studies such as Holtinnen is that Oswald et al are referring to OBSERVATIONS, not models. In fact Oswald is referencing data stretching back over several years.

And really Oswald is only confirming what we can 'see' for ourselves when we watch those winter TV forecasts during periods of high pressure across the whole of the UK - there's no wind anywhere, or not much to speak of. So we're not surprised when someone tells us the bleeding obvious (no disrespect to Oswald intended - it needs saying).

But what is less obvious is another conclusion of Oswald's and that is that these high pressure lulls can be near pan European. This may not be obvious to many, but anyone used to picking up forecasts for avaition will also know that pan European wind lulls are not rare birds. So greater European grid interconnection isn't going to provide a complete fix to wind intermittancy.

Aug 28, 2012 at 7:31 PM | Unregistered CommenterCapell

"Perhaps I am missing something here?"

Correlation is likely to fall due to "local" turbulence - where "local" is an artefact of the geography. Another way to think of this is the eddies and flows caused by obstructions to the wind. E.g. "local" around a house is perhaps 100m. Local around a set of mountains could be 10-100miles.

On top of this is superimposed the longer term and spatially wider variability of weather pressure systems. These tend to be hundreds of miles across and takes hours to days to pass.

How much correlation you get would depend not only on the distance, but also over the time period you use. Taken over e.g. "winter", there would be a high correlation across the northern areas. Taken every second, there may be very little correlation between windmills even a few hundred meters apart (if the local topology is far from flat, like a city)

Aug 28, 2012 at 7:32 PM | Unregistered CommenterScottish Sceptic


Excellent comment!

Aug 28, 2012 at 7:32 PM | Unregistered Commenterchris y

In addition, a Garrad Hassan report has shown that long term wind speeds across northwestern Europe are well-correlated. Annual mean wind speeds are well correlated in the UK, northern France, Germany, Holland and Denmark.

Aug 28, 2012 at 7:49 PM | Unregistered CommenterPhillip Bratby

Another snout in the trough- how Gross can you get?!

Aug 28, 2012 at 7:53 PM | Unregistered CommenterDon Keiller

MalcolmS - yes good post except Nuclear is far from CO2 free and there has never been a nuke plant built anywhere that doesn't rely on subsidy. They are just not add affordable.

Nuke emissions can be as much as 288 g CO2e/kWh (Average 66g) Sovacool, B. Energy Policy 36, 2950–2963 (2008).

Billions are being spent building LNG export terminals around the world. If we want to access cheap power we need to start constructing more LNG import terminals now. Cheap gas will be a fungible commodity.

Aug 28, 2012 at 8:04 PM | Unregistered CommenterChairman Al

Bishop Hill: Perhaps I am missing something here?

as to correlation over large areas, please look at, especially the monthly and yearly wind graphs. Note, that these are produced real-time by almost all of the windfarms connected to the UK national grid, 4648 MW, offshore and onshore, across a very large area.
These graphs are very discontinuous in nature, varying dayly from low to high output and sometimes the total UK wind contribution to the grid is close to zero. What more proof do you need that Gross is talking out of his hat?

Aug 28, 2012 at 8:14 PM | Unregistered CommenterAlbert Stienstra

AlecM suggested a good system to use for comparison. Three(?) years ago during the winter Bonneville had a stretch of about 12 days where they never generated more than 3% of their total wind capacity.

They have numerous graphs and data sets linked on this page.

Graph #1 is a real time(5 minute) seven day graph of their wind, hydro, and thermal power generation. Green trace is wind.

Aug 28, 2012 at 8:14 PM | Unregistered CommenterBob Koss

Peter Whale (6.04pm)
The only bit of the Ancient Mariner I remember (and I may not have got it entirely right) is:

The ice weren’t here, the ice weren’t there
Not e’en the Larsen Shelf
The Weddell Sea is turned to pee
Since Monbiot wet ‘isself.

Aug 28, 2012 at 8:20 PM | Registered Commentergeoffchambers

Dont care how many you build or how big you build them you cant make USEABLE Electricity from air.

Denmark, Germany the UK and the Industrial Revolution prove Windmills dont work
France and America prove that Shale and Nuclear does.

Aug 28, 2012 at 9:41 PM | Unregistered CommenterJamspid

"The paper was clearly a serious blow aimed at the wind industry......."


Aug 28, 2012 at 9:43 PM | Unregistered CommenterJoe Public

If Robert Gross has misinterpreted scientific papers then he will no doubt be given a very public dressing down by fellow Grantham Institute employee Bob Ward. After all, it would not do for the Policy and Communications Director to be seen to be unbalanced in dealing out his pen-lashings. Some might be see him as being a defender of dogma rather than scientific standards. :)

Aug 28, 2012 at 10:56 PM | Unregistered CommenterManicBeancounter

Chairman Al

I think you are missing the point - carbon dioxide is good for us! It feeds plants! In fact forget all this Carbon garbage. Likewise wind farms. Why does anyone think that our ancestors gave up windmills when fossil fuels gave us cheap reliable power?

Aug 28, 2012 at 11:15 PM | Unregistered CommenterDizzy Ringo

""From the combined production in the Nordic countries, production over 50% of rated capacity is rare in summer and production over 75% is rare in winter. The lowest hourly production was 1.2% of capacity for the Nordic wind power production time series.""

Gross should show his work.

If production is seldom over 75% rated capacity or 50% rated capacity, that would be true even if it averaged only 15%. Weasel wording?

"The lowest hourly production was 1.2% of capacity for the Nordic wind power production time series." That statement sounds a little more definitive.

Aug 29, 2012 at 12:08 AM | Unregistered Commentereyesonu

Bish: If you want a RELIABLE supply of electricity, one needs MORE than wind farms that are generating electricity - one requires the ability to correctly forecast how much electricity they will produce. Limiting power outages due to inadequate generation on one day a year (the British standard) demands 99.7% reliability in one's ability to predict how much wind power will be available until you can fire up a fossil fuel plant to replace low production from wind. Wind power fluctuates dramatically because power output varies with the cube of the wind speed. A 20% reduction in wind speed is a 50% reduction in power output. Right now, the power delivered by wind farms is within +/-50% the company's estimates made 4 hours earlier 99.7% of the time. They are hoping to reduce this uncertainty to +/-30%). The other 50% is backed up by fossil fuel plants operating in spinning reserve, a minor nuisance when wind farms are currently providing only 4% of electric power and the other 96% also requires backup. In 2020, Britain is planning to generate 30% of its electricity from wind. One-half to one-third of that power theoretically will need to be backed up by fossil fuel plants running in spinning reserve mode or reliability will deteriorate. Will the cost and CO2 emissions of this backup power be counted as part of the the cost of wind power? Of course not.

See page 9, item 2.14 from:

Aug 29, 2012 at 12:38 AM | Unregistered CommenterFrank

Gross's thinking reminds me of the charioteer whose horse died. Believing he would win the race if he had four horses, he went out and bought three more dead horses.

Aug 29, 2012 at 1:02 AM | Unregistered Commenterjorgekafkazar

If Dr Gross thinks wind farms are the "answer' and are practical and economic then he should explain why Germany is currently constructing 23 coal fired power stations ( that is not a typo --23 !!) because they now realise that their massive investment in wind and solar is not producing the goods.

Aug 29, 2012 at 5:08 AM | Unregistered CommenterRoss

This will take the sales out of their wind........

Aug 29, 2012 at 7:01 AM | Unregistered CommenterAlecM

Indeed @DizzyRingo , but I think it is you that is missing the point as I agree with everything you say.

My thrust is not whether or not we should justify energy generation on the relative merits of saving CO2. I am cautioning against the notion that "wind is not required because nuclear plants have low CO2". There is no point in justifying nuclear power because 1) the emissions are not as low as you may think, 2) nuclear power is not as reliable as you may think and 3) nuclear power is far too expensive. You may reflect that the draw backs for nuclear power are very similar to the draw backs for wind.

Look around, everyone is shutting down nuclear plants - even the French want to reduce exposure to their cash hungry, nuclear burden. French subsidy to the nuclear industry is said to be a closely guarded secret - I wonder why.

In conlusion, we need cheap reliable gas. Gas is becoming massively surplus in many regions, producers are have been forced to shut in because the price is too low - so now they are searching for new export opportunities. We are going to see increasing volumes of gas being shipped and traded globally - not regionally constrained. If we want to keep the lights on we better start building more LNG import terminals and infrastructure right now. Much cheaper to do this than build nuclear plants or wind farms.

It is said that US manufacturing costs will become 70% less than competitors who have no access to cheap energy from shale gas. We may have access to some shale gas in the future, but we cannot rely on this. Therefore we need to become world leading gas traders, importers and exporters. If we do not do this we will have massively uncompetitive energy costs and the prospect that one day we will switch places with the likes of India. India and other countries will make stuff and prosper and we will provide the call centre jobs. If we get our energy choices wrong our national wealth will decline rapidly and the British will become a nation of migrants searching for a better life elsewhere.

Aug 29, 2012 at 4:20 PM | Unregistered CommenterChairman Al

Not many people have an idea of what correlations of anomalies of wind speed (or wind vector components) are like. In midlatitudes, temporal correlation is generally low and spatial correlation surprisingly high. This sort of information is available and used by the weather forecasting centres to initialise weather prediction models. Local differences due to topography etc. hardly change the big picture.

Aug 29, 2012 at 6:09 PM | Unregistered CommenterCees de Valk

Chairman Al " If we get our energy choices wrong our national wealth will decline rapidly and the British will become a nation of migrants searching for a better life elsewhere."

Quite so. Unfortunately the wrong choices have already been made haven't they? As much as most here agree with each other over the stupidity of current policy, ours and others various efforts appear to cut no ice (ice?) with those in control of the policies. Hardly surprising if blatant conflicts of interest can, apparently, be so easily overlooked.

Aug 29, 2012 at 7:36 PM | Unregistered Commentermiket

"Windcarpet", presumably with magical propoerties?

Aug 29, 2012 at 9:09 PM | Unregistered CommenterDon Keiller

Aug 28, 2012 at 8:04 PM | Chairman Al: MalcolmS - yes good post except Nuclear is far from CO2 free
Agreed, to some extent, because Chairman Al is referring to lifecycle CO2 for nuclear.

Unfortunately, NOBDY takes lifecycle CO2 into account for windmills, especially not DECC. When full lifecycle calculations and cost+emission of backup are taken into account, there is no case for wind energy. and other articles on this site

Aug 30, 2012 at 9:05 AM | Unregistered CommenterAlbert Stienstra

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