Intermittency of Wind Power Generation

SirPeter

So much of greenery is, in any case, dogma. For example, I don't know anyone who would rely on , say, wind power for their household electricity, for obvious reasons. So that means we have to have installed capacity to back up the wind generators. Otherwise you'd have a very unreliable supply of electricity.

That doesn't mean, as some fondly imagine, that there is a little man with a switch somewhere in Ireland with his finger poised so that when the wind dies down he presses the switch and, hey presto, no one notices the smooth transition from wind power to other forms of power.

It means we have to run the two side by side, so the real benefit from wind power is , actually, quite negligible. But the dogma has it that wind power is "good" and anyone who questions it "bad".

One often overlooked benefit from this political and economic fiasco is that it looks as if all the green party will be without any seats on the far side of the general election. Their time in office, both propping up the most venal FF government ireland has ever had, and for their "green terror" imposing taxes on anything which moves and on many things which don't, all in the name of "greenery", has been a disgrace, and should not be forgotten.

positron

SirPeter wrote: »

That doesn't mean, as some fondly imagine, that there is a little man with a switch somewhere in Ireland with his finger poised so that when the wind dies down he presses the switch and, hey presto, no one notices the smooth transition from wind power to other forms of power.

It means we have to run the two side by side, so the real benefit from wind power is , actually, quite negligible. But the dogma has it that wind power is "good" and anyone who questions it "bad".

Out of context on this thread, but I completely disagree! While it's true that you would need a backup system, today's technology is developed enough to have the backup system providing to the grid on-need basis, which would mean all of the wind power produced will get used, while the backup system only produces enough and saves on conventional fuel / nuclear fuel or whatever.

Wind, along withe rest of the renewable energy ideas that's now gaining momentum (solar, wave etc) are most definitely good, and if they don't look attractive to you today, that's only because we are drunk on the cheap fossil fuel, which we will run out of sooner or later, and that's probably when wind becomes good to some of us. (Can I also add, every time you move, breath, walk or whatever, you are actively busy filling the coffers of middle eastern countries who still don't have democracy, and who still don't care about basic human rights? We are very conveniently overlooking these factors too! )

Anyway, I suppose that's all for many other threads, so suppse we should go back to the topic at hand for now.

SirPeter

positron wrote: »

Out of context on this thread, but I completely disagree! While it's true that you would need a backup system, today's technology is developed enough to have the backup system providing to the grid on-need basis, which would mean all of the wind power produced will get used, while the backup system only produces enough and saves on conventional fuel / nuclear fuel or whatever.

It seems you think there is a little man with a switch and his finger poised!

Electricity in conventional systems is made by boiling water to produce steam, and the steam is then used to drive turbines which produce electricity.

How long do you think it might take for a power station, for example Poolbeg, or even the most up to date power station in Cork, to turn on the oil fired or gas fired burners, and get them to heat up the vast quantity of water to enough steam needed to turn the turbines and produce a continuous supply of electricity into the grid?

And once you have thought about that, at what point does the man with the switch decide to do that in relation to the wind dropping? Half an hour before it drops? At the same time it drops? 20 minutes after it drops?

positron

I am not professing to be an expert this this area, but I think you are probably slightly exaggerating the issue as if the wind and coal power are the only two things supporting the grid and has to cover each other's back at any given time.

While intermittent nature of wind (and other) source, it's not the end of that. There are various ways to cope with it. More here:
http://en.wikipedia.org/wiki/Intermittent_Power_Sources

Can I just remind everyone (mostly myself) and this is seriously out of topic for the thread, and probably should be discussed in a different thread?

SirPeter

positron wrote: »

...today's technology is developed enough to have the backup system providing to the grid on-need basis, which would mean all of the wind power produced will get used, while the backup system only produces enough and saves on conventional fuel / nuclear fuel or whatever.

positron wrote: »

I am not professing to be an expert this this area, but...

Really, you can’t make a post and then say no one should reply to it as you think it’s off topic!

You make a claim, then when I pose questions about it you say you aren’t an expert in this area. That’s fair enough, but the practical problems which I pose need answers, and you have made a claim which needs exploring.

Especially as a lot of people think you can fire up a conventional powered electricity plant in seconds, or even less (which is obviously a fallacy), and don’t think through the lack of logic in that position.

positron

Fair enough I suppose. May be it's worth taking it to a separate thread then? I have created this one.

positron

SirPeter,

Here's another interesting read about dependability of wind energy. (I haven't read it thru - will do soon)

Link to Google Cache of a Renewable UK page

PS: And the earlier link that didn't get copied: http://en.wikipedia.org/wiki/Intermittent_Power_Sources

djpbarry

This thread is derived from a discussion that began in this thread.

djpbarry

SirPeter wrote: »

It seems you think there is a little man with a switch and his finger poised!

Wind generation can be forecast up to one day in advance with over 90% accuracy. Same day forecasts are ∼94-95% accurate.

http://www.eirgrid.com/operations/systemperformancedata/windgeneration/

mgmt

djpbarry wrote: »

Wind generation can be forecast up to one day in advance with over 90% accuracy. Same day forecasts are ∼94-95% accurate.

http://www.eirgrid.com/operations/systemperformancedata/windgeneration/

Tell me you're joking???:eek:

You cannot rely on wind power. Full stop.

Do you want to live in a world full of brownouts and blackouts?

djpbarry

mgmt wrote: »

You cannot rely on wind power. Full stop.

And yet, as shown in the link above, Eirgrid's wind generation forecasts match actual wind generation reasonably well.

SeanW

And yet, as shown in the link above, Eirgrid's wind generation forecasts match actual wind generation reasonably well.

They show that what happened bore only a marginal resemblance to what they thought, at one point their own forecast was 300MW too high! I don't call that reliable.

djpbarry

SeanW wrote: »

They show that what happened bore only a marginal resemblance to what they thought, at one point their own forecast was 300MW too high!

At one point? What about the average performance over time? A cursory glance back over a few days’ data suggests the forecasts are at least 75% accurate on average. Now that's far from perfect, but I would hardly call it a "marginal resemblance". Furthermore, I'm guessing these forecasts are made reasonably far in advance - at this time, there are forecasts available right up to 18:00 on 13/10.

zod

if only we had a way to store the wind energy.

..maybe using pumped storage

.. maybe using our fairly unique coastal valleys..

oh yeah now I remember

PaulGogartyTD

zod wrote: »

if only we had a way to store the wind energy.

..maybe using pumped storage

.. maybe using our fairly unique coastal valleys..

oh yeah now I remember

Storage is the key. It is possible. And not just pumped storage and coastal values, but also conversion to hydrogen, which would fuel cars. It may seem expensive now, but as oil and gas peak it could make Ireland super-efficient in the medium term, but only if we ramp up while we can afford to.

quentingargan

Another hidden, but very low cost alternative to storage is demand side management. By incentivising people and businessess to use electricity at times when the wholesale price is low, you can ensure that a higher percentage of our energy can come from renewables.

There are many processess that use a lot of power which can run at times when electricity is plentiful and cheap. Dairy farmers for example can run their coolers at night only to reduce their costs. The wholesale price of electricity varies from 2.5c to 25c depending on the time of day, so there is a potential incentive there. Already large industries are able to avail of wholesale pricing and time their processess accordingly. Hopefully smart metering will allow consumers and small businesses to do likewise:)

Heroditas

PaulGogartyTD wrote: »

Storage is the key. It is possible. And not just pumped storage and coastal values, but also conversion to hydrogen, which would fuel cars. It may seem expensive now, but as oil and gas peak it could make Ireland super-efficient in the medium term, but only if we ramp up while we can afford to.

Pumped storage has been dismissed due to the ridiculously high costs associated with it.
There's a reason only Turlough Hill exists in Ireland and it's because it was the only suitable cost-efficient site.

Countless studies have been carried out, the latest by Poyry working on behalf of the CER to look at Demand Side Management and storage has been analysed and found to be not cost effective.

I can see us still using natural gas for a sizeable percentage of our energy needs for many more years until there is another quantum leap forward in renewable technology. Time will tell.

positron

Like PaulG mentioned earlier, when the price of oil goes up after peak oil (whenv ever that is, let's not go there, but I am sure we can agree that will happen someday), a lot of the renewable energy methods now considered expensive, will look a lot less expensive.

With respect to wind and other 'unpredictable' renewable sources feeding to the grid, while coal powered reactors may (I don't know, SirPeter says they do) need a prolonged process of bringing up the output, I know new generation nulcear reactors are well capable of producing more to match the load.

http://www.eoearth.org/article/Advanced_nuclear_power_reactors

IMHO, moving away from conventional fuel sources (especially oil and gas from middle east) is of huge significant, not just for economic reasons, but also for ethical reasons. I think a long term renewable solution can be reached in future, but we will need a short to mid term nuclear solution to support us until then.

Again, IMHO, with the right balance of conventional, nuclear and renewable sources feeding the grid, it should be able to (without needing little people, magic hands etc) sustain a very reliable and robust grid, and a grid that also makes us some dosh by selling the excess production to the EU.

SirPeter

djpbarry wrote: »

What about the average performance over time? A cursory glance back over a few days’ data suggests the forecasts are at least 75% accurate on average.

I'm sure "average performance over time" will be a great comfort to all of us, and the corporate "all of us", who find that for 25% of the time they get it wrong, and we find we have no electricity. Hospitals, for example, would be delighted, no doubt, to find their theater lighting not working mid way through an operation because the wind stops blowing. Without installed capacity ready to cut in at a moments notice, wind power is of little value.

While we are all keen to see alternative forms of power generation found and used, wind power for most uses is simply too unreliable to be of much use until we find a means of storing it.

djpbarry

SirPeter wrote: »

I'm sure "average performance over time" will be a great comfort to all of us, and the corporate "all of us", who find that for 25% of the time they get it wrong, and we find we have no electricity. Hospitals, for example, would be delighted, no doubt, to find their theater lighting not working mid way through an operation because the wind stops blowing.

Have a look at this data on the Eirgrid site and show me a point at which wind generation suddenly drops to zero.

Heroditas

Around 30MW being generated this afternoon from an installed capacity of about 1800MW.

Dear oh dear.

SirPeter

djpbarry wrote: »

Have a look at this data on the Eirgrid site and show me a point at which wind generation suddenly drops to zero.

Excuse me? You may not realise it, but your instruction to "show me a point" comes over as a little bossy and confrontational. That may not, in fact, have been your intention, but that’s how it comes over to me.

Are you not able to look for yourself rather than barking instructions at me to do it for you?

Heroditas wrote: »

Around 30MW being generated this afternoon from an installed capacity of about 1800MW.

Dear oh dear.

The great thing about our current system is that, even though the power is reduced to less than 2% of the capacity in the example you give, not one customer of any of the power companies will have their supply reduced or cut off, as the conventional power stations have been running alongside the alternative supply and the power is not interrupted for even a microsecond.

Wind power is wonderful, but not as a reliable means of supply. There are still those who don’t understand how power generation works, and who believe that while the wind blows one or two or even more of our conventional power stations close down, and all or some of the workers all go home.

When they are told that the conventional power stations continue producing electricity as normal, and that it simply isn’t possible to shut them off without having interruptions to supply when the wind drops, as it takes time to fire the conventional station up, they simply put their fingers in their ears and go “na na na na na na” and don’t want to hear how the world works in reality.

Wind power is wonderful, but not as a reliable means of supply to the national grid.

Heroditas

Or else, instead of putting their fingers in their ears, they say "well what would you do then?"

djpbarry

SirPeter wrote: »

Excuse me?

I said, have a look at this data on the Eirgrid site and show me a point at which wind generation suddenly drops to zero. It might, y’know, add some weight to your argument.

SirPeter wrote: »

Are you not able to look for yourself rather than barking instructions at me to do it for you?

You support your own points – that’s how this forum works.

SirPeter wrote: »

Wind power is wonderful, but not as a reliable means of supply. There are still those who don’t understand how power generation works, and who believe that while the wind blows one or two or even more of our conventional power stations close down, and all or some of the workers all go home.

Has anyone on this thread espoused that belief? Or is this just more of your own opinion?

SirPeter wrote: »

When they are told that the conventional power stations continue producing electricity as normal...

Define “as normal”.

SirPeter wrote: »

Wind power is wonderful, but not as a reliable means of supply to the national grid.

And yet, there it is, reliably supplying power to the national grid. Of course, I suppose that depends on one's definition of "reliable".

positron

djpbarry wrote: »

Of course, I suppose that depends on one's definition of "reliable".

Absolutely, and how 'reliable' are traditional power stations themselves? Hydro depend on rainfall, coal/oil ones depend on reserves, imports, world politics, currency fluctuations and what not.. I know this is far fetched, but there are issues with traditional power plants too - which is only going to get worse in future.

The Nipp

SirPeter wrote: »

Hospitals, for example, would be delighted, no doubt, to find their theater lighting not working mid way through an operation because the wind stops blowing.

hospitals or anyone who needs 100% reliable power will have some form of expensive UPS installed.

gas turbines, chp plants, hydro stations can be switched on at a moments notice. there is more to the national grid than wind turbines and always-on fossil fuel behemoths

lostinsuperfunk

not one customer of any of the power companies will have their supply reduced or cut off, as the conventional power stations have been running alongside the alternative supply

This isn't correct. The output of wind generators, like all other generators, can be subject to fluctuations. The system needs reserve generators to allow for this. There are different categories of reserve which are able to react at different rates. The fastest of these is "spinning reserve" -- these are the constantly-running generators you refer to, which have spare capacity to rapidly balance supply and demand. The system doesn't need to maintain spinning reserve to cover all the wind generators. There are other categories of reserve which act more slowly. This is standing reserve, it is not running all the time, but can start up within minutes if the wind falls off or if a large generator goes down.
The variability of wind can also be dealt with to some extent with wind forecasting which allows other generators to be scheduled for when there is low wind. So yes, some other generators do not operate when there are high winds, but this happens as part of a schedule, not in an ad hoc fashion. The forecast is updated every few hours, you only see the day-ahead forecast on Eirgrid's site as far as I know.

Capt'n Midnight

mgmt wrote: »

Tell me you're joking???:eek:

You cannot rely on wind power. Full stop.

Do you want to live in a world full of brownouts and blackouts?

Two of the main causes of brownouts are when there isn't enough capacity, the other is when you have the likes of Enron messing with the supply.

You are 100% correct in saying you cannot rely on wind power but only if you completely ignore the rest of the grid. Gas power stations can start up fairly quickly. If we invested in more pumped storage a la Turlough Hill we'd have full power in about a minute, if we pre-spin the turbines like they do in Wales you are talking about 10-15 seconds to achieve full load.

In markets with large industrial users you can offer discounts if they reduce their demand at peak time, this can be cheaper than building extra capacity or powering stations for short periods of time, also interconnectors are good for catching wind in other places.

I'm still trying to find a utility company that shows unsmoothened demand curves to show that it's worse than people imagine
http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Demand/Demand60.htm - 5 minutes
http://www.eirgrid.com/operations/systemperformancedata/systemdemand/ - 15 minutes


windpower by itself isn't the solution, the ideal solution is hydro but we've already got most of that, we've fossil fuel stations with differing characteristics , coal / peat / oil / gas - even with them one size doesn't fit all. we should be looking at tidal turbines and biomass too.

But to recap, it's possible to build pumped storage systems with very fast responses, in theory we could use a big flywheel to keep the system running for even that little time too. The electricity supply voltage does fluctuate , it's built into the standard, and most ectronic devices use regulators so they should not be as badly affected as in the old days. ( Surge protection is a differenty story , be thankful that our electricity is fairly clean and spike free )

bartizan

Capt'n Midnight wrote: »

Gas power stations can start up fairly quickly. )

How quickly does it take for a gas power station to (i) realise that the wind has died down and (ii) boil water from scratch to steam point before the turbine begins to turn?

Capt'n Midnight wrote: »

if we pre-spin the turbines like they do in Wales you are talking about 10-15 seconds to achieve full load.

What happens for the 10-15 seconds you claim it might take?

Capt'n Midnight wrote: »

In markets with large industrial users you can offer discounts if they reduce their demand at peak time, this can be cheaper than building extra capacity or powering stations for short periods of time, also interconnectors are good for catching wind in other places.

I )

Surely the other places want to hang on to their own wind power rather than export the little bit of it they have? No where I know of has 100% of their power supplied with wind, so how do they meet their power needs if they are exporting their wind power to someone else?

Capt'n Midnight wrote: »

windpower by itself isn't the solution, the ideal solution is hydro but we've already got most of that, we've fossil fuel stations with differing characteristics , coal / peat / oil / gas - even with them one size doesn't fit all. we should be looking at tidal turbines and biomass too.

But to recap, it's possible to build pumped storage systems with very fast responses, in theory we could use a big flywheel to keep the system running for even that little time too. )

You are right that wind power is not the solution, and its unreliability is its achillees heel. The only effective way we have to store it is via pumped storage, but its worth remembering that pumped storage only works if the wind has been blowing when it is needed to pump the water. If the wind is not blowing when power is needed to pump the water back up the hill, then obviously we still need back up from other more reliable sources.

Capt'n Midnight

bartizan wrote: »

How quickly does it take for a gas power station to (i) realise that the wind has died down and (ii) boil water from scratch to steam point before the turbine begins to turn?

the gas station does not wait for the wind to die down
www.met.ie - we actually have weather forecasters, actually more important are the demand forecasters. Wind gradualy dying down in different parts of the country over a period of hours is less of a problem than the spike in demand when everyone plugs in the kettle after corrie (in the UK there was something like a 2,800 MW spike after England lost thier last penalty shoot out )

What happens for the 10-15 seconds you claim it might take?

I like they you cast aspersions on my 'claim' ,
The voltage drops and the frequency drops too. BUT because of steam pressure in some plants and flywheel action in multiple generators in most plants it's unlikely to drop out of band.

http://www.esb.ie/esbnetworks/en/business-customers/voltage_problems.jsp
ESB Networks delivers electricity in a voltage range of 207 Volts to 253 Volts. This is in accordance with European Standard EN50160.

Surely the other places want to hang on to their own wind power rather than export the little bit of it they have? No where I know of has 100% of their power supplied with wind, so how do they meet their power needs if they are exporting their wind power to someone else?

yeah other countries store thier wind power in a big bucket until they need it, 'cos other wise they'd generate revenue by exporting it :rolleyes:

In case you haven't grasped the concept, wind power is a use it while you can resource, sell the surplus to pay for the when you need to import over an interconnector

Interconnectors and National Grids mean wind power can be used in a different area to where it was produced.

If the wind is not blowing when power is needed to pump the water back up the hill, then obviously we still need back up from other more reliable sources.

In case you haven't grasped the concept, wind power is a use it while you can resource,

Also wind power is probably more reliable than other resources other than hydro. It's rare for a whole wind farm to fail, true you can't depend on a wind farm to produce X MW next week but given the weather patterns you can be resonably sure it will deliver Y MW in a few hours time. Here we have a few large power stations that would cause major problems if they suddenly went offline, in the North they were even more susceptible to stuff like a strike at one power station crippling them.

derealbadger

the key is connectivity if you were to have a world wide grid with all the different renewables wind solar wave etc and have substantial storage they could make up the majority of power needs the wind is always blowing somewhere and the sun is always shining somewhere lol on the sun bit somewhere just not here

Jim Martin

I get the impression that the more electricity that is transmitted by bigger grids, the more energy loss is encountered so is not the whole thing a total waste of time?

djpbarry

Jim Martin wrote: »

I get the impression that the more electricity that is transmitted by bigger grids, the more energy loss is encountered so is not the whole thing a total waste of time?

Transmission losses are certainly an issue, but it's not an insurmountable problem. For example, high-voltage direct current (HVDC) transmission systems incur far lower losses than AC transmission over long distances, although the up-front capital cost is higher.

Capt'n Midnight

Jim Martin wrote: »

I get the impression that the more electricity that is transmitted by bigger grids, the more energy loss is encountered so is not the whole thing a total waste of time?

On longer lines they use higher voltages to counteract this

losses are a few % rather than a few ten's of % , but even then it's usually cheaper to transmit surplus power than to generate it locally

power lost due to heating is I squared R, so at light loads the losses are lower and it's at peak demand that you have peak losses and at that point power is most valuable

Chloe Pink

Rather than address individual posts, I am providing a link that looks at the "back up" needed for wind turbines.

The link is from Eon UK who are related to Eon Netz, the German grid operators and the largest wind developers in Europe.
Eon UK’s submission to the House of Lords Select Committee of Economic Affairs on the Economics of Renewable Energy, comments on the backup needed for wind in the UK, all 92% of it:

http://www.publications.parliament.uk/pa/ld200708/ldselect/ldeconaf/195/8061708.htm

It is a short submission and well worth a read but points 8, 9 and 10 look at the backup specifically and describe the reliability of wind versus that of conventional power stations, we're talking about 8% versus 95% respectively.

Chloe Pink

The “Tyndall Centre Technical Report 30, July 2005 Conclusion 5, Security of decarbonised electricity systems” refers to the back up plants needed for wind turbines:
"We observed that wind generation has a relatively small capacity credit. At lower levels of wind penetrations the capacity credit of wind generation is found to be about the same as the average load factor of wind. However, as the level of wind penetration rises, the capacity credit begins to tail off. That is why in order to maintain the same level of system security a significant capacity of conventional plant will still be required.
However, these conventional plants will be required to run either occasionally and/or at part load when shortages of supply are likely to occur due to a low total wind power output. Considering that conventional plants at full load are the most efficient and generate the lowest amount of CO2 emission (per electricity produced) such occasionally and/or part-loaded plants will be less utilised and/or produce more CO2 per electricity produced."

Chloe Pink

Hugh Sharman is principal of international energy consulting and broking company Incoteco (Denmark).
The title of his Telford Gold Award winning paper on “Why the UK should build no more than 10GW of wind”. explains why there is a limit to the amount of wind capacity we should have in the UK:

http://www.ref.org.uk/images/PDFs/sharman.ice.pt2.pdf

Chloe Pink

The wind forecasts and out-turns can be seen three days at a time at this link under the graph 'Wind Forecast Out-turn':

http://www.bmreports.com/bsp/bsp.php#wind_fc_outturn

Chloe Pink

How is wind looking now as a sensible form of power generation?

Macha

Chloe Pink, please try to formulate your arguments into fewer posts, rather than multiple postings.

I don't think anyone here is advocating a national grid run off 100% wind. Rather, wind will have to be paired with more dispatchable renewables like hydro, biogas, tidal and solar. Increasing the size of the grid and a dispersed pattern of renewable generating stations will also assist in increasing the penetration of renewables.

SEAI held a conference on this subject last Friday in Dublin:

http://www.seai.ie/News_Events/Press_Releases/Pathways_to_2050_release.pdf

Chloe Pink

My apologies for the multiple postings, I was simply trying to provide some hopefully helpful information in manageable chunks.

What is the point of backing up / pairing one renewable with another dispatchable renewable, why not just have the despatchable renewable?

For example, why have tidal backing up wind, why not just have the tidal; if the tidal is generating, we still need to store its output if the wind decides to blow in which case we're back to the problem of storage.

And if the wind isn't blowing at night, the sun won't help us unless we've stored it from the day before.

And which valleys should we flood to increase our hydro storage capacity?

Capt'n Midnight

Chloe Pink wrote: »

It is a short submission and well worth a read but points 8, 9 and 10 look at the backup specifically and describe the reliability of wind versus that of conventional power stations, we're talking about 8% versus 95% respectively.

it's nothing to do with reliability - 48% of US nuclear power stations have either been shut down before planned or had unplanned outages of longer than a year.
you are talking about needing 15% extra capacity to cover for supposedly baseline nuclear

wind power is very reliable, even if a few turbines fail you still have most of the available power

what isn't as reliable is the wind but even still you are claiming that wind can be relied upon to provide 8% of nameplate capacity, and when you consider that the average power from a wind farm is 32% of its maximum capacity what this really translates to is that we can rely on wind farms to provide a quarter of their capacity as baseline.

add in pumped storage and giving major industrial users discounts for reducing demand when asked means you don't need quite as much stand by power

Chloe Pink

Capt'n Midnight wrote: »

what isn't as reliable is the wind but even still you are claiming that wind can be relied upon to provide 8% of nameplate capacity, and when you consider that the average power from a wind farm is 32% of its maximum capacity what this really translates to is that we can rely on wind farms to provide a quarter of their capacity as baseline.

Firstly, I'm not claiming anything, I am pointing to information provided by experts in their field, in this case EON UK and they are quite explicit in what they say:

"On this basis, if the UK required, say, 40,000MW of wind capacity to meet its renewable target by 2020, only 8% of this renewable capacity (3,600MW) could be relied on to meet winter peak demand. This would avoid the need to build 3,600MW of new thermal plant but the remaining 36,400MW of renewable capacity would need to be "backed-up" by thermal plant to meet winter peak electricity demand in 2020."

http://www.publications.parliament.uk/pa/ld200708/ldselect/ldeconaf/195/8061708.htm

I do not see where they say that "we can rely on wind farms to provide a quarter of their capacity as baseline" as you suggest. Assuming you mean 'base load' when you say 'baseline', this would indicate that wind turbines are providing a quarter of their installed capacity, all the time.
This is not the case, the load factor of wind turbines is their output provided over a year as a percentage of their total installed capacity; in the UK, this is approximately 25% (not 32%) i.e. over a year, 100MW of installed wind capacity would yield 25MW. This means that sometimes this 100MW of installed capacity would yield only a few percent of its installed capacity and at others nearer to 100 percent of its installed capacity but not that it yields 25MW all the time.

Lenny Lovett

djpbarry wrote: »

Wind generation can be forecast up to one day in advance with over 90% accuracy. Same day forecasts are ∼94-95% accurate.

http://www.eirgrid.com/operations/systemperformancedata/windgeneration/

To be fair most wind farms are situated in areas where there is nearly always sufficent wind speed to rotate and, let's face it, the number of days that most areas in Ireland do not have sufficent breeze is very low.
.

mgmt wrote: »

Tell me you're joking???:eek:

You cannot rely on wind power. Full stop.

Do you want to live in a world full of brownouts and blackouts?

I doubt anyone relies on it totally but tbf it's not impossible. We use 50kwh wind turbine for one of our factories and it has very pleasantly surprised us in that it has never failed us yet. Granted we are near the coast but nonetheless on calm days there is still sufficent generation. We also supplement it with pv cells and use solar water heating. The entire system is well on target to have paid for itself over three years. So it's has been an excellent investment... And I was very skeptical prior.

The Nipp wrote: »

hospitals or anyone who needs 100% reliable power will have some form of expensive UPS installed.

Yes. we have a UPS system but rarely require it.

While "saving" generated electricity in a battery system is workable a more useful way is to tie in wind generation with hydro electric and use spare generated electricity to power pumps to fill reservoirs that will in turn power the hydro turbines. I'm not explaining myself very well - it's been a long day... !

Chloe Pink

Lenny Lovett wrote: »

To be fair most wind farms are situated in areas where there is nearly always sufficent wind speed to rotate and, let's face it, the number of days that most areas in Ireland do not have sufficent breeze is very low.

To be fair, we are discussing industrial wind turbines as part of a country's energy strategy i.e. 2MW plus and 100 metres high plus.
But yes, wind turbines do turn for roughly 80% of the time but that doesn't mean that they're generating at their installed capacity.
And indeed there are only a few days when wind is so low across all of a country that barely any electricity is generated from wind turbines but these days, none the less, occur.
And it is for these reasons that wind turbines need backup generators.

Interestingly, the wind forecasts do not appear to be 90% or 94% or 95% accurate on 'Wind Forecast Out-turn' graphs at this link:
http://www.bmreports.com/bsp/bsp.php#wind_fc_outturn

I doubt anyone relies on it totally but tbf it's not impossible. We use 50kwh wind turbine for one of our factories and it has very pleasantly surprised us in that it has never failed us yet. Granted we are near the coast but nonetheless on calm days there is still sufficent generation. We also supplement it with pv cells and use solar water heating. The entire system is well on target to have paid for itself over three years. So it's has been an excellent investment... And I was very skeptical prior.

I am interested to know how someone could rely on wind power alone and have an on demand electricity supply; are you willing to expand on this concept?

I am also interested in your investment versus payback costs if you are willing to share them as three years seems pretty swift by all accounts.
Are you on or off grid?
If you are on grid, do you feed any of your electricity from your renewables back onto the grid and if so do you get a good rate for this electricity?
If you are on grid, do you use any electricity from the grid and what percentage of your electricity usage is from the grid and what percentage is from your renewable generators?

Also you state, "nonetheless on calm days there is still sufficent generation". Sufficient generation to do what?

Yes. we have a UPS system but rarely require it.

While "saving" generated electricity in a battery system is workable a more useful way is to tie in wind generation with hydro electric and use spare generated electricity to power pumps to fill reservoirs that will in turn power the hydro turbines. I'm not explaining myself very well - it's been a long day... !

Indeed, if we had bountiful storage capacity, wind turbines begin to look a little better but where are all these reservoirs going to be? And transfer losses still need to be taken into account?

djpbarry

Chloe Pink wrote: »

Firstly, I'm not claiming anything...

You’re claiming plenty – pointing at the sources you’re posting and stating “hey, I’m just telling you what these guys are saying” isn’t going to wash.

Chloe Pink wrote: »

Interestingly, the wind forecasts do not appear to be 90% or 94% or 95% accurate on 'Wind Forecast Out-turn' graphs at this link:

Over what time period? 3 days? Is that statistically significant?

Chloe Pink

djpbarry wrote: »

You’re claiming plenty – pointing at the sources you’re posting and stating “hey, I’m just telling you what these guys are saying” isn’t going to wash.

What would you rather I did, make stuff up?

I would rather not to be misquoted please; where have I written the following words:
“hey, I’m just telling you what these guys are saying”?

I have written:
“I am pointing to information provided by experts in their field, in this case EON UK and they are quite explicit in what they say:

"On this basis, if the UK required, say, 40,000MW of wind capacity to meet its renewable target by 2020, only 8% of this renewable capacity (3,600MW) could be relied on to meet winter peak demand. This would avoid the need to build 3,600MW of new thermal plant but the remaining 36,400MW of renewable capacity would need to be "backed-up" by thermal plant to meet winter peak electricity demand in 2020."

http://www.publications.parliament.u...95/8061708.htm”

Do you have evidence contradicting EON UK on this matter?

djpbarry wrote: »

Over what time period? 3 days? Is that statistically significant?

The same point could have been made regarding your link which also only shows information for 3 days at a time (unless I have missed something): http://www.eirgrid.com/operations/systemperformancedata/windgeneration/
The sensible approach seems to be to keep an eye on the graphs every now and again. Certainly right now, Eirgrid’s forecasting is not looking 90% or 94% or 95% accurate; the "Show/Hide Tabular Data" button at the bottom left of these graphs is quite useful for looking at this.

Anyway, I do regard 3 days as statistically relevant as it shows that wind forecasting is not 90% or 94% or 95% accurate.
Further more, under the “Information” button at the bottom right of the National Grid's Wind Forecast Out-turns graph: http://www.bmreports.com/bsp/bsp.php#wind_fc_outturnit it states:
“Wind Generation forecasts are produced by National Grid's own first generation windpower forecasting tool. The predictability of the wind varies with atmospheric conditions and so there may be periods where National Grid's forecast and outturn values differ significantly.”

djpbarry

Chloe Pink wrote: »

What would you rather I did, make stuff up?

No, but when you provide a source to support your argument, you cannot then detach your argument from said source in subsequent posts (“...I'm not claiming anything, I am pointing to information...”).

Chloe Pink wrote: »

Anyway, I do regard 3 days as statistically relevant as it shows that wind forecasting is not 90% or 94% or 95% accurate.

Does it? Based on what measure of statistical significance?

Capt'n Midnight

Chloe Pink wrote: »

I have written:
“I am pointing to information provided by experts in their field, in this case EON UK and they are quite explicit in what they say:

"On this basis, if the UK required, say, 40,000MW of wind capacity to meet its renewable target by 2020, only 8% of this renewable capacity (3,600MW) could be relied on to meet winter peak demand. This would avoid the need to build 3,600MW of new thermal plant but the remaining 36,400MW of renewable capacity would need to be "backed-up" by thermal plant to meet winter peak electricity demand in 2020."

why does it need to be backed up by NEW thermal ???
there are quite a number of oil power stations mothballed in the UK these could be prepared to go live at a few days notice , Inverkip power station - 1900 MW , there are others

Why does it need to the be THERMAL
Dinorwig has 1,800 MW of pumped storage , others could be retro fitted to Scottish dams
A Severn Barrier could produce up to 8,640 MW, with others on the English coast.
Existing link to France is 2,000MW

Biomass is still small in the UK - yes it's thermal but it's renewable and you can retrofit some existing stations to take it

The UK could also link to Norway for hydro

In the UK the big threat to supply is if someone cuts off the gas that provides a huge chunk of generation

Chloe Pink

djpbarry wrote: »

No, but when you provide a source to support your argument, you cannot then detach your argument from said source in subsequent posts (“...I'm not claiming anything, I am pointing to information...”).

http://oxforddictionaries.com/definition/claim

Claim
“1 [reporting verb] state or assert that something is the case, typically without providing evidence or proof”

djpbarry wrote: »

Does it? Based on what measure of statistical significance?

None. Basically any one occurrence of the daily forecast not being ‘∼94-95% accurate’ contradicts the statement that: “Same day forecasts are ∼94-95% accurate.”

My comment originates from Post 9 which states:
“Wind generation can be forecast up to one day in advance with over 90% accuracy. Same day forecasts are ∼94-95% accurate.”

The first sentence of the post, does not say that the forecasts “are” 'over 90% accurate up to one day in advance'; it says they “can” be and as such this first sentence means very little as it does not say for example, how often they “are” 'over 90% accurate up to one day in advance'.

However, the second sentence is presented as a statement of fact; “Same day forecasts are ∼94-95% accurate.”
There is no qualifying statement with this post (e.g. x percentage of the time / on average over a year / using statistical measure x) so I took it on face value as it was presented.
Yet when I looked at the link provided and at the link I provided to the National Grid, I observe that they are not ∼94-95% accurate.

In response to other posters questioning Post 9,
you say in post 11, “Eirgrid's wind generation forecasts match actual wind generation reasonably well.”;
and in post 13, “A cursory glance back over a few days’ data suggests the forecasts are at least 75% accurate on average.”

Despite other posters questioning of post 9 and despite the author’s variation from Post 9 (in Posts 11 and 13), Lenny Lovett (in post 44) quotes: “Wind generation can be forecast up to one day in advance with over 90% accuracy. Same day forecasts are ∼94-95% accurate.”
Regardless of what Lenny Lovett was trying to convey in relation to this quote, I felt it worth while to point out that the forecasts do not appear to run in accordance with this quote rather than let the quote be revived again as fact.
This approach seemed preferable to trawling back through what other people had said and also preferable as it would allow the reader to observe it for themselves.

As I said previously, any one occurrence of the daily forecast not being ‘∼94-95% accurate’ contradicts the statement that: “Same day forecasts are ∼94-95% accurate.”

More to the point though, even if we had accurate same day forecasts; we'd still need back up generators for our wind generators for the days when the wind simply isn't blowing much.

djpbarry

Chloe Pink wrote: »

Basically any one occurrence of the daily forecast not being ‘∼94-95% accurate’ contradicts the statement that: “Same day forecasts are ∼94-95% accurate.”

No, it doesn’t. I used ‘∼’ as short-hand for ‘approximately’. I was certainly not stating that every single same day forecast is 94-95% accurate (and I’m sure you knew that). The figures are from this presentation (slide 10), given by representatives of Eirgrid and SONI, which shows normalised errors for forecasts in 2007. ‘Same-day’ errors are approximately 5% on average, ‘next day’ errors are ≤ 10%.