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Power loss a blow to wind farm

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Published Date: 13 August 2006
By EMILY DENNIS
ONE of the UK's biggest offshore wind farms is producing less than a third of the electricity it should be, a new report has found.
The 30-turbine Scroby Sands wind farm built off the coast of Great Yarmouth, Norfolk, has generated only 28.9% of the power it was built to provide, according to the government's first annual report into the £67m development.

The report from the
Department of Trade and Industry shows that the wind farm experienced numerous mechanical problems which significantly lowered production.

Between January and December last year, 27 intermediate speed and 12 high speed gearbox bearings needed replacing, along with four generators.

The report states that after extensive investigation "work is now at hand to resolve these issues" but that they had "serious implications for resources, costs and downtime".

According to the report, the wind farm's capacity factor percentage - the amount of electricity compared with what it would be if the turbines were turning 100% of the time - reached a peak in January, 2005, with 48.9%. But by June it was 20% and it never again went higher than 30%, giving an average over the year of 28.9%.

Jason Scagell, director of E.ON UK, which owns the wind farm, said that lessons would be learned from the development.

"We were very happy with Scroby's performance in the first half of the year, particularly as the operation was in its infancy, but the second half was less satisfactory due to a number of defects with the gearboxes and generators," Scagell said.

"Scroby Sands was and remains a pioneering project from which lessons will be learned.

"We're certainly keen to continue working offshore and have four projects in various states of advancement that will allow us to use the lessons from Scroby in larger developments."



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1

Climate Sceptic,

London 13/08/2006 09:47:06

THis article is factually incorrect. The prediucted capacity factor for Scroby Sands was 30-35% so a factor of 28.9% is actually just under 90% of predicted output not one third as described in this article.

2

Harbinger,

Wales 13/08/2006 11:20:23

Congratulations on keeping the glass half full, but it still means less than thirty percent of rated output, not a very good return on a massive investment and particularly unreliable in terms of supplying the grid.

3

Henry Gray,

Scottish Borders 13/08/2006 15:46:49

As usual just a lot of WIND

4

Yale,

13/08/2006 16:47:58

Dennis of Wale wrote:
"... it still means less than thirty percent of rated output ..."

This is one of the most persistent misunderstandings about wind turbines.

They are DESIGNED to produce an average of 1/3 of "rated" maximum. Predictictions of annual generation for planning and financing, is based on the AVERAGE, not maximum capacity.

Consider this analogy.

Your automobile may have an engine rated at 100 horsepower (or "hp").

Yet, when cruising the roads, you may only be using 10 hp. Then why not use a 10 hp engine? Because you need the extra horspower in bursts for accelerations from a stop or to pass other cars.

That "extra" 90 hp is essential.

Likewise, occasional and seasonal winds greater than the average carry vast amounts of energy. A wind turbine rated for 100% maximum power in the average wind would be an engineering and financial stupidity.

A wind turbine generating 1/3 of its maximum potential output may , in fact, be running 100% of the time, and be performing exactly as required.
How else could it capture the energy of high winter winds if it ran at full maximum in summer calm?

This is different than a nuclear reactor. They are designed to run either 100% maximum or not at all. A typical UK reactor running with an apparently favorable 80% capacity factor is, in fact, cold and dead for two and a half MONTHS out of a year, unreliable and requiring vast amounts of wasteful backup reserve generators.

The article by Emily Dennis was totally confused and totally wrong. Due to early mechanical problems in a new system, the output was short of desired, not the 2/3s claimed, but only 10%.

I hope that The Scotsman corrects its error.

Thank you, Yale

5

Agent 99,

Scottish Borders 13/08/2006 20:00:56

If we are to take Yale [4] at face value, we don't just need one correction from the Scotsman, but a whole cartload.

Every time plans for a wind farm are announced the media reports the capacity of the installation and then, presumably in an attempt to allow Joe Public to understand, translates this into the number of homes that can be supplied. Since the boilerplate capacity of the proposed installation is always used in the calculation, we should now expect a retraction from the Scotsman [amongst others] publishing the real, adjusted figure based on Yale's proposal. One would then see that wind farms aren't quite the panacea that they are claimed to be.

Not that the staff reporters can be blamed for these inaccuracies. Who would, after all, expect them to be experts on electro and mechanical efficiencies of turbine technology? No, they have simply swallowed the press release from the developer. Among others "facts" in almost every wind farm Environmental Statement is a guide to how many tons of CO2 can be saved by consenting the proposal. These untruths are based on a projection of how many conventional fossil-fuel burning power stations can be shut down as a result of implementing this white hot glowing technology.

We have recently learnt that Scotland has passed the target set by the Executive for renewable energy by 2010. One would expect that the combination of all the promises of the various wind farm developers would have resulted in one or two or the coal-burning monsters being retired. How many have actually shut down? Sorry, didn't hear that reply, again please? Oh, None, you say.

When will the so-called wind "industry" admit that their crop is not energy production but ROCs and government-sponsored funding? Take away the subsidy and I predict the whole gold rush will collapse like a deck of cards.

This antiquated technolgy doesn't deserve further investment. The Dutch were using these things more tha

6

Colin, Glasgow,

Glasgow 13/08/2006 23:05:00

Richard (#5) I think it is fairly likely that the media takes the electricity generation and carbon saving figures from the likes of the BWEA.

http://www.bwea.com/edu/calcs.html

It's asking a bit much for journalists to work this out for themselves.

The BWEA figure does take the loading into account (0.3 of the rated power output).

However I tend to agree that this is a bit misleading. Clearly a windfarm that can supposedly power 1000 homes, say, isn't powering them all the time.

The cost figures don't always take into account the fact that a substantial amount of conventional plant is sitting idly depreciating when it is held in reserve as backup for wind generation.

But the most misleading error in the BWEA figures is the carbon saving. They take the saving based on replacing the output of coal power stations. It is my understanding that coal stations tend to provide base load electricity rather than load-following as the BWEA suggests. It is more likely that the wind farm will replace output from gas powerstations, which produce less than half the carbon of coal.

At least the BWEA freely admit that their turbines do not replace nuclear electricity (which is base load).

7

Yale,

USA 14/08/2006 00:28:01

As Colin points out, Richard is incorrect. As I had pointed out originally, the output of wind turbines are in fact specified to the average, not the maximum capacity.

I disagree with Colin however, where he states that claiming that a wind turbine supplies the power of a thousand homes may be misleading, because the supply is not continous. If that is misleading, then the same point must be applied to a nuclear plant, which is typically dead in the water more than 2 months per year.

Colin's point about baseload vs loadfollowing coal is only partially true. Coal is used in the UK for BOTH, and wind output should be credited against coal emissions from load following.

In practice, however, the utilities may use wind to displace gas, because that is so very expensive. That is a economic, not a technical choice.

In any event, gas power may be as nasty as coal from a greenhouse gas perspective, rather than strictly a carbon consideration. Methane from natural gas is a MUCH more damaging emission, and a great deal escapes from leaky transmission, distribution and consumption. CO2 is also stripped from the raw gas at the well and dumped in the air.
Actual coal vs gas damage is not a simple matter.

In any event, neither coal, gas, nor wind produce plutonium.

yale

8

Yale,

USA 14/08/2006 02:52:37

Looks like the BBC caught the error in the story and corrected it.

This is the original story as posted by the BBC and The Scotsman:

http://72.14.203.104/search?q=cache:9ASvgLDkorEJ:news.bbc...

at 12:19 UK time:
=====================
"Wind farm at one third capacity

Problems with gearboxes and generators hit the wind farm
One of the UK's biggest offshore wind farms is producing less than one third of the electricity it should be, according to a new report. "
====================

Four hours later, the BBC, but NOT The Scotsman, re-posted the story:

http://news.bbc.co.uk/1/hi/england/norfolk/4786647.stm
16:27 UK Time

This time it got it right:

================

"Performance report into wind farm "
... "That meant we had to carry out an extensive programme of modifications but, despite that, the wind farm still generated 153GWh, which is around 90% of our forecast annual output."
==================
Notice the quote left out of the original story where the underperformance of only 10% is pointed out.

Let us hope that The Scotsman also does the right thing and corrects its misleading story.

Thank you, Yale

9

Colin, Glasgow,

Glasgow 14/08/2006 10:10:59

Yale (#7) I would hope it is obvious that there is a difference between the nature of the variation of supply from a nuclear power station compared to a wind farm. True, nuclear stations do have to shut down occasionally to refuel (with current designs anyway). But when they are running they produce continuous 100% output at their rated capacity for months on end.

This greater degree of predictability means that downtime can be planned months in advance and alternative supply brought online. With multiple reactors on the grid downtime can be coordinated to minimise disruption and cost.

Wind turbines, on the other hand, are subject to the vagaries of the weather. Even when they are running they don’t produce 100% output much of the time.

So to say that a given wind installation will provide enough power for 1000 homes (or whatever) is misleading. It implies a steady and continuous supply. It would be more honest to say “on average it provides 10% of the electricity requirement for 10,000 homes”, or something like that. Sometimes it will provide all the electricity for 3,000 homes, and sometimes only enough for 30.

10

Climate Sceptic,

London 14/08/2006 17:22:20

Sorry to disappoint Colin but a significant number of nuclear downtime is NOT predicted as you imply, witness the recent closure of 40% of Swedens nuclear capacity virtually overnight

http://news.bbc.co.uk/1/hi/world/europe/5241780.stm

On the other hand wind power output can be predicted to an increasing extend. Wind speeds can now be predicted with current models to an accuracy of +/-1.5m/s - not perfect but still largely predictable. The UK grid runs on half hourly gate closure prices - the wind output in the next half hour CAN be predicted with fairly accurate results. Our pumped hydro-storage capacity is currently nearly 6000MW which is over three times our current wind power capacity and can be called on in a matter of seconds - your claim that wind therefore needs fossil fuel backup at current levels is patent nonsense.

When wind capacity reaches higher penetration levels other techniques are available such as demand side management http://www.dynamicdemand.co.uk/index.htm
http://www.responsiveload.com/

and energy storage techniques - which have already been incorporated into wind farms in Japan and Norway.

Of course we could just be negative about wind - but it offers CO2 free electrcity with no need for any fuel - hence is not at risk of geopolitical risks, surging fuel prices and environmental degredation. New inventions have always met with resistance -when steam trains first appeared people said the speed will kill you, or you would be sick and faint travelling on one, when cyclling became popular, coach drivers (the horse variety) often tried running cyclists down, because they thought cyclists would put them out of business. We should embrace wind power for all its benefits and try and work out ways of mini

11

Colin, Glasgow,

Glasgow 15/08/2006 09:04:44

Martin (#10) I don’t want to be wholly negative about wind power. After hydro, it is our best renewable option. I just want the case to be put in perspective – it is not a wonderful panacea.

You are correct that the supply from nuclear stations is occasionally interrupted unpredictably. But I still say it is disingenuous to compare this to the variable output from wind farms. Nuclear stations provide base load power all over the world: this would not be practical if they went out of action every five minutes. Interruptions are uncommon – which is what makes such events newsworthy.

You are also correct that we are getting better at predicting the availability of wind energy. However we still have no control over how it varies.

Hydro is indeed useful for backup. But whether we have hydro or fossil fuel stations as backup, they still cost. And if hydro is the backup for wind then we don’t save as much carbon.

Wind is part of the answer. So is hydro. As is nuclear. They all have shortcomings, but together they provide a low carbon solution.

12

Stewart,

West Lothian 17/08/2006 15:04:00

The claims and counterclaims about how many "homes" can be served by this or that wind-turbine array is more or less irrelevant, it's a bit like the popular journalistic unit of measurement -The London Bus !.

What seems appropriate to me is that we use all our skills and technology to pursue genuinely SUSTAINABLE technology, otherwise we will be accused by our children, and their children of profligacy, that we spent capital thinking it was revenue.
Nuclear fission is based on fissile capital left over from the last, nearest super-nova, it is limited in resource and thus not sustainable, nor has the disposal of the resultant active waste any real sustainable qualities other than as a long term problem.

Renewables offers genuine and long term sutainability, mostly derived from that fantastic FUSION reactor we have close by. Lets try to use our skills and our dwindling resources to see if we can't get on this bandwagon, otherwise we will have to apply dirty old fission with all it's inherent problems just to drive the machines that will make the products marked "Genuinely Sustainable"


 

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