What is the national CO2 reduction from renewables?

[wookey]

I have been doing some reading recently and there is some quite well-argued work on the net suggesting that the actual emissions reductions from installing big wind and PV are much smaller than the simplistic value you get from assuming that each kWh generated replaces a fossil one. What I have not yet been able to find are similarly detailed and engineering-based documents showing that in fact big wind and PV _do_ generate the expected significant emissions reduction on which we are replying. I find it hard to believe that such documents don't exist, so can anyone give me any pointers?

The debate is well-summarized in this long thread on Brave New climate, an Australian site which is good because posts have to have references otherwise they tend to get deleted, so there is a lot of meat in the discussion: http://bravenewclimate.com/2011/05/21/co2-avoidance-cost-wind/

That thread was started by a recent paper looking at current wind generation data and suggesting that you only get a 4% emissions reduction (i.e 4% of the 100% you'd expect) at 20% wind generation penetration into the grid. That paper is not pubically available online which is unfortunate, but the priciples are well-argued. I do now have a copy blagged which I will read and critique when I get the chance.

There is also this paper from 2004 which essentially makes the same case for the UK: http://www.ref.org.uk/attachments/article/171/david.white.wind.co2.saving.12.04.pdf . We have 7 years of data since then which would no doubt help confirm/deny the arguments laid out there.

The australian threaqd also references this article several times: http://theenergycollective.com/willem-post/57905/wind-power-and-co2-emissions which is in the Eastern US context, but again reaches the same conclusions.

The arguments are actually quite involved, because it is complex, but it boils down to the fact that all plant has ramp up and down times, some only ramps very slowly, and the quicker reacting plant (gas) has an efficiency cost to ramping. You can't ramp gas plant up and down from 0 to 100% at constant efficiency. Below 50% a CCGT plant is operating as an OCGT plant (i.e only the turbine, not the steam part), and in practice in order to have fast-reacting 'peaking capacity' ready you are actaully running such plant at 'idle' at low (30%) efficiency. There is also some cost in having generating capacity available which gets used less often because normally cheaper (negligible marginal cost) wind-(and PV) power is used if available.

The sums and arguments are made more confusing/complex by the large (predicatable) daily changes in power consumption, which are of similar magnitude and period to the wind variation, but sometimes in the opposite direction, which requires a higher ramp-rate (but nothing like the rate required when a major conventional station goes off-line).  

The argument is made that lots of ramping up and down is like braking and accelerating your car all the time - it uses a lot more juice, thereby negating much of the savings you were hoping to make. I'd expect this to be a second-order effect but I need some evidence. These people make much of the 'unpredictability' of wind output variation, but as it changes no faster, and usually more slowly, than the diurnal variation, I'm not convinced that it really changes things from the existing situation, so we already pay those ramping costs, and putting that cost onto wind is not a fair allocation (but they are costs, and do need to be accounted for).

Another point is that even over an area as large as Eastern Australia, the wind generation tends to all go up and down together and there are times of very low generation when you really do need either a lot of storage (where, what, how much does it cost?) or nearly as much conventional capacity as now.

Overall, the complaint is that the renewables generation capacity costs moreto install in the first place, and has further costs in terms of grid strengthening (because you have more power that needs shifting about the place to compensate for renewables spatial and temporal variation), rarely-used convential capacity or storage, and ramping efficiency costs, that overall you'd be better off simply not bothering with it and putting in a load of realatively-cheap French nuclear which can also load-follow (I hadn't realised this was possible) instead.

So, I'd very much like to believe that all the engineery-sounding waffle in those threads and papers is actually just pro-nuclear anti-wind people cherry-picking data and distorting the numbers, but I have to say that in reading the whole thread (admittedly not all the papers yet - there is an awful lot of stuff to read) there are a lot of good point made (with data) on the anti-wind side, and whilst some good arguments are also made on the pro-wind side, they tend to be very short on data and lacking in the necessary details.

So, where are all the papers showing that putting in 10GW of wind really does reduce emissions by say 60% of the average grid intensity? We really ought to have enough data by now to be able to prove this one way or the other - it's not something to simply speculate about. Installation and operating costs are well-known, and the effect on the grid should be too.

If the 'renewables don't actually work' crowd are right, then that's actually quite important, and we should take notice. I don't think they are right, but I don't have the data to argue the point effectively. Someone must...

One thing I don't think they take into account adequately is the rising cost of fuels, and the finite nature of existing reserves (which of course is a killer argument in favour of renewables, eventually), but of course those arguments aren't simple either. We can't predict future prices well, and there is an enormous thorium reserve which it might make sense to use for the next 50-100 years if in fact it'll produce much more significant emissions reductions (which ultimately is the thing that really matters).

So, please read that lot and show me the data for why they're wrong and we can produce 80% emissions reductions in 40 years.

Oh, and please, for this thread, can we stick to the BNC policy of no posts without references. I don't want your unsubstantiated opinions, I was facts, data, engineering and science, and that means references. It dramatically increases the signal:noise ratio. 

[desperate]

This lot

 http://www.windbyte.co.uk/windpower.html

it has to be said are pretty anti wind, but as you have found it isn't easy to find substantiated arguements against, and believe me I have tried.
I was horrified at how little fossil generation capacity is replaced by the wind generators and how the ratio goes downwards as capacity increases.
Security of supply trumps quite a lot of renewables I guess.

Desp

[billi]

And ?

Why so much text ?  When the petrol pumps are empty , we have to walk !



You can paralyse / frighten society towards that fact  .... , if there is time enough   keep on  wasting

I have that tone in my ear since  more than 20 years  

There is only one  democratic vote and this  is called Renewable

Billi

oh   a link as well    

http://www.grist.org/solar-power/2011-06-09-solar-getting-cheaper-fast




..... and what is  a Nation when we talk about Climate !

[GavinA]

I guess I'm going to have to properly get into this at some point as this is the second site that's linked to that article, but I don't have time to fully dig out references etc at this minute in time.

a few points though that immediately spring to mind...

1 - You can't extrapolate from Australian experience to the UK, as Australia is a huuuge continent limiting the potential for power balancing of supply / load between one main population area (and therefore, generation area) to another using the existing grid, and with no near neighbours with which to balance supply/demand via HVDC interconnectors. As far as I can tell, they also only have about half the pump storage we have, so 1/4 of the load balancing, and only in one site, but I could be wrong on that.

We have around 3GW of pump storage, equating to more like 6GW of actual carbon free load balancing capacity capability, plus a 2GW (so 4GW load balancing capacity) HVDC interconnector to France with it's mostly nuclear power, a smaller interconnector with Ireland, and new interconnectors planned / likely between us and Germany, Norway, Iceland, and possibly further afield which would give us far more options than just increasing the spinning fossil fuel reserve to balance out our wind power.

2 - In this country we're currently not using out pump storage properly to replace spinning fossil fuel reserve for wind, as for some odd reason that I can't quite fathom to do with the nuts structure the neoliberal idiots in charge have put in place, it seems to be cheaper to use gas on part load instead, and mostly use out pump storage to soak up france's excess nuclear generation at night, and flog it back in the morning peak. I don't have time to dig out more details on this, but it's referred to in this parliamentary document from 2008

Pumped hydro has found it difficult to compete for contracts in the current liberalised energy market against smaller, less expensive OCGTs due to their high capital and maintenance costs. 

It's therefore largely a matter of the internal economics of the grid if gas is being used ahead of pumped storage, and should be solvable via a small tweak of the regulatory regime if a government were so inclined. 3GW pump storage should easily be able to remove the need for any additional actual spinning reserve for far higher levels of wind than we currently have as wind well distributed across the country, and actually being relatively predictable with relatively slow drop off and pick up rates compared to changes in demand, or the impact of a single large nuclear / fossil fuel gen set going off. There could be problems with the wind being distant from the pump storage (I think this is a major reason for the HVDC undersea interconnector between north wales/merseyside and west coast of scotland that's either being planned or built.

This is also another reason why we need the severn barrage, which could be built to also act as a short term pump storage facility on top of it's tidal generation role (link to mackay paper on this, but there's a better earlier paper around that I can't find now).

3 - If this were to be the case, then there should have been a demonstrable increase in the level of spinning reserve required to be operated by the grid over the last few years. The figures to demonstrate this either way should be findable via the reports linked to from this national grid page. I started digging through it, but unfortunately the data for pre 2007 is presented slightly differently, and only one aspect of the 'fast reserve' data is fully presented (the cost, not the electricity used). My initial impression however is that if anything the amount of 'fast reserve' used seems if anything to have gone down since 2005, however there's lots of rough extrapolation going on in that, and someone would need to put all the data in a spreadsheet, and probably illiminate other factors such as weather, and the shut down for repair of various nuclear power stations in that period and other such things to get anything like an accurate picture. Might be worth doing a trawl of google scholar to see if someone's already done the legwork on this, if not I might see if I can flag it up as a potential dissertation topic at our friendly local uni department, but that'd take 12-18 months or so to get results.

4 - The impact of wind power on carbon emmission in the first few years of high levels of generation shouldn't really be seen as giving much information about the potential long term impact wind can have, as their are a lot of grid changes (new HVDC interconnectors), storage changes, and dynamic demand type changes that ought to be made once the notion of high levels of wind being in the system actually starts to look more like a reality than some wild hippy fantasy. If the French had taken the approach in the 60's about nuclear that this article takes now about wind, then they'd never have ended up with the high levels of nuclear they've now got. This has only been possible because of 4 decades of policies and measures to massively level off their demand levels, resulting in nighttime base loads that are far higher per capita than virtually any other country, and much lower morning and evening peaks. It's kinda funny that the pro-nuclear lobby in this country don't recognise this, and understand that a similar level of changes over a similar time span will be needed to facilite either high levels of wind and other renewables, or nuclear in this country, and that while these changes are implemented, the existing infrastructure will have to take up the slack.

some thoughts for you, sorry it's not all referenced fully, I'm a wee bit busy doing this solar thing these days.

[GavinA]

After a little more googling...

Australia has around 20 GWh total of PSH capacity and can add around ~2 GW of power into the grid. Up to 5 GWh can be stored per day.

[source]So around 5GWh vs the UK's 23-25GWh, albeit at around 2/3 of the instantaneous generation capacity.

[brackwell]

To use data from 2004 and/or Aus. must be flawed !  Give someone a new Mc.and they first have to accept/learn it,then use it and then add on/adapt to maximise its use. We are probably only half way along that route as Gavin explains above.

 The National Grid is run for money not for save the planet and if it is cheaper/convenient they would not doubt let the wind stand idle. This is always the problem with new technology where its asset price is todays price which competes with a written down price of something approaching zero.  The old coal fired plants can be the most inefficent polluting things on the planet but can always show a return on the investment.

Is wind the wild card? Perhaps not if you follow http://www.eirgrid.com/operations/systemperformancedata/windgeneration/    where the days prediction seems to be relatively correct and we must assume the UK national grid is doing the same.

Spare production capacity is obviously required and available and i suspect that the nat. grid has to hand out some sweets to this capacity otherwise they might sulk and close the plants down. If electricity supply is totally privatised then which co. is going to stand up and build spare capacity knowing it will rarely be used and maybe even not at all !!   They will only do this if they are guarenteed a certain  income regardless of used or not.  Now the grid as paid they might as well use it as the buffer.  It is totally irrelevant to the economics of the Grid whether it is used efficiently or not at all.    Follow the money and then you will understand.  Nothing to do with wind generation.

Of course the nuclear lobby or the greenies or someone else wanting to make life more difficult can use these facts to spin whatever they want.  I always remember Wedgie Benn- you could never fault his arguments as he led you up the garden path to a result which i personally didnt agree with and thats because he started from a wrong statement!  QED

Ken

[renewablejohn]

Wookey

Sorry I dont have the time to dig out the actual articles but the best country to quote to counter these sort of irrational claims is Austria. There in a fortunate position of having an existing high level of hydro electric capacity and an ever increasing wind power industry that just needs the joined up thinking of pumped storage to put the final piece in the jigsaw. Austria also has no nuclear industry due to there government listening to the views of the population.

[desperate]

Wookey,

I've had a poke around in the DECC website        http://www.decc.gov.uk/en/content/cms/statistics/publications/dukes/dukes.aspx

I think there is some good information here that may be used to guesstimate the CO2 reductions, there is loads of stuff here which frankly is beyond me to digest and make sense of, apologies if you have already been here.


GavinA

Our total pumped storage capacity is only capable of supplying the grid for half an hour assuming no other generation is available, so I guess several hours worth in the real world, which would certainly provide balancing capacity for short term slews, but it isn't capable of smoothing any kind of lull. As I understand it though its real value is the speed at which it can be brought up to full power, 12 seconds I believe which is a huge slew rate sufficient to bumpstart the grid after a blackout. I've no idea how quickly the store could be refilled after such an event, which is critical if we plan to use pumped storage to smooth lulls and slews. My feeling is that at the moment the capacity is far too small to back up large scale renewable generation.

Desperate

[billi]

Perhaps one finds some  info in here ....

http://www.skepticalscience.com/renewable-energy-baseload-power.htm

The current energy production structure consists primarily of coal and nuclear energy providing baseload power, while natural gas and hydroelectric power generally provide the variable reserves to meet peak demand. Coal is cheap, dirty, and the plant output cannot be varied easily.  It also has high initial investment cost and a long return on investment time.  Hydroelectric power is also cheap, clean, and good for both baseload and meeting peak demand, but limited by available natural sources.  Natural gas is less dirty than coal, more expensive and used for peak demand.  Nuclear power is a low-carbon power source, but with an extremely high investment cost and long return on investment time.

Renewable energy can be used to replace some higher-carbon sources of energy in the power grid and achieve a reduction in total greenhouse gas emissions from power generation, even if not used to provide baseload power.  Intermittent renewables can provide 10-20% of our electricity, with hydroelectric and other baseload renewable sources (see below) on top of that. Even if the rapid growth in wind and other intermittent renewable sources continues, it will be over a decade before storage of the intermittent sources becomes a necessity.

I guess that is not true for some countries to date , cause their rapid  install of renewables  forces ideas of storage soon

http://www.americanwindenergyassociation.net/documents/factsheets/Backup_Power.pdf

The “no reduction in emissions” myth
Wind opponents sometimes argue that wind energy doesn’t actually reduce the fuel use or
harmful emissions of other power plants. On its face, this claim does not make sense: utility
system operators must precisely balance the total supply of electricity with the total demand
for electricity at all times, so the electricity produced by a wind plant must be matched by
an equivalent decrease in electricity production at another plant.
When it is available, system operators use wind energy to reduce the output of the power
plants that are the most expensive to operate, which are almost always natural gas or coal
power plants because of their high fuel costs. Wind energy is also occasionally used to
reduce the output of hydroelectric dams, which can store water to be used later to replace
more expensive fossil fuel generation.
By directly reducing the use of fossil fuels, wind energy significantly reduces emissions of
the greenhouse gas carbon dioxide (CO2) and other harmful pollutants. A number of
detailed power system studies, as well as real-world experience with wind plants, have
demonstrated that wind energy significantly reduces fossil fuel use and emissions:
• In 2007, wind energy in the U.S. reduced CO2 emissions by over 28 million tons,
equivalent to taking almost 5 million cars off the road. On average, each Megawatthour
(MWh) of wind energy – the amount produced by two typical modern wind
turbines in an average hour – reduces CO2 emissions by 1,200 pounds.
• The U.S. Department of Energy’s (DOE) 20% Wind Energy by 2030 Technical
Report calculated that obtaining 20% of our electricity from wind energy by 2030
would cut cumulative CO2 emissions by over 7.6 billion tons.1
• The DOE report found CO2 emissions would be reduced by over 825 million tons in
the year 2030 alone, an amount equal to 25% of all electric sector carbon dioxide
emissions in that year--the equivalent of taking 140 million cars off the road.
• The DOE study also found that wind energy would cut the amount of natural gas
used for electricity generation by 50% in 2030.
• A study by the grid operator in Texas found similar results, concluding that adding
3,000 megawatts (MW) of wind energy to the state’s grid would reduce CO2
emissions by about 5.5 million tons per year, sulfur dioxide emissions by about
4,000 tons per year, and nitrogen oxide emissions by about 2,000 tons per year.2
• In regions where a large share of electricity comes from coal power, the emissions
savings of wind energy can be even larger. A DOE analysis found that Indiana could
reduce CO2 emissions by 3.1 million tons per year by adding 1,000 MW of wind
power.3
• The 30 MW Kaheawa wind plant in Hawaii directly offsets power from oil-burning
power plants, reducing oil imports by almost 10 million gallons per year.4
20% Wind Energy and Climate Change
As America and the world grapple with the immense problem of
climate change, one energy source stands out as an abundant,
affordable and readily available supply option: wind power. The U.S.
Department of Energy’s 20% Wind Energy by 2030 Technical Report
(www.20percentwind.org) finds that wind power can supply 20
percent of America’s electricity by 2030 and reduce projected
emissions of carbon dioxide (CO2), the leading greenhouse gas, by
25 percent.
This fact sheet is one in a series aimed at informing decision-makers
and the public about this critically important option for America’s
energy future and countering persistent myths about wind energy.

and ongoing 


Billi

[desperate]

Good links there billi,

more specificly to my earlier post

this

http://www.decc.gov.uk/assets/decc/Statistics/publications/dukes/313-dukes-2010-ch7.pdf

may have the info needed to work out the reductions in co2 possible, haven't had time to read through all of it though.

anyway bedtime for me.......

seeya

Desperate

[Philip R]

More (electrical) energy storage needs to be built. It will require damming up some Glens in Scotland, thus fulfilling one of Mr Salmonds wishes to make Scotland green!!. and building some more pumped storage plants.
The Regenysis (polysulphide) flow battery scheme developed by National power pre RWE needs to be redeveloped and bought to market. Otherwise we will have to burn less gas as base load, pump it into Cheshire salt caverns and release ( decompress it and peak lop using combustion turbines (waste of prime hydrocarbon feedstock!!).

Dinorwig and Ffestiniog discharge over a few hours and take a little longer to recharge. Believe Loch sloy was changed to a pumpstorage from a straight hydro, may have muddled the Scottish plants.

Without energy storage, further penetration of renewables( especially wind)  will prove futile as fossil based spinning reserve will be running at very low load and grossly innefficient.

Philip R

[GavinA]

desp - you're correct, but the argument being made in the article is that we actually need to have spinning reserve actually spinning at low efficiency levels just to meet any potential immediate drop off in production from wind. My point is that we don't, as we have 3GW of pump storage that can be generating in less than a minute, and is fully capable of supplying that immediate buffering requirement if the economic framework were adjusted to make it more profitable for it to be used to do this rather than being used mostly to soak up the french nuclear generation over night, and then sell it again in the morning peak.

This would then provide enough time for eg CCGT to fire up to pick up the slack from the point that the pump storage starts being exhuasted, and the pump storage can then revert to pumping mode if the wind picks up again / wait for the next drop in demand to fill up again to restore it's buffering capability.

We could also pretty easily put in place dynamic demand systems capable of reducing the load by several GW for short periods (outside of / in addition to the existing interuptable supply contracts) which could cut the power to fridges / freezers / heat pumps / storage heaters for specified periods of time either when the voltage or frequency dropped past a certain level, or on command from a central control room. Germany have no introduced a system for their bigger solar systems to reduce their output in response to a signal sent down the grid from the grid operator, so the technology exists and could easily be adapted.

Looking at the immediate impact of wind / other renewables on the actual carbon intensity of the grid is a useful exercise, but immediately jumping to the conclusion that renewables are a waste of time as the article seems to is nuts, and IMO exposes the authors likely pre-existing bias (the pro nuclear sticker on the site is a bit of a giveaway on this score). Instead it should really be a stimulus for focussing more effort on implementing all the other things that have been known about for decades as being needed for a low carbon electricity supply based on high levels of renewables. Had the previous government not virtually excluded engineers from it's renewables advisory group, or weasel peed around with it's energy policy reviews for most of it's time in office (and arguably had the tories not flogged the power companies off in the first place) maybe this would already be in process and we'd not be in a position where the pro-nuke lobby could write articles such as this.

On the plus side, the Scots aren't hanging around waiting for westminster to pull it's finger out. Not only are they upgrading one hydro station to pump storage, but are also planning the first new pump storage units to be built since the 1970's with a 600MW and 300MW scheme planned by SSE for the Great Glen area specifically to buffer the large quantities of wind they've already got, and are planning to build up there. 1.8GW HVDC subsea interconnectors are also planned linking the east and west coasts of Scotland with the east and West Coast of northern England, with the West coast link scheduled to be up and running before 2015, and the East Coast by 2018. Presumably the West coast link will also facilitate greater use of the welsh pump storage to buffer scottish wind and vice versa.

I've just come across a document published by the Scottish Government last year that looks worth a proper read, judging from the executive summary... "Energy Storage and Management Study"

[brackwell]

Gavin - spot on.

This whole discussion starts from the false premise that renewables is the cause of all the idling coal plant. What tosh. These plants would be idling/on standby regardless of renewables as this is what is required to accommodate medium size fluctuations in demand on a daily basis - there must be data around to prove this idling plant was around long before there was a single wind turbine.

I understand that coal fired stations are on a min one hour notice of their requirement and as the wind can be predicted on the big scale (none/medium/gale) at least 24 hr in advance and on the medium scale of +/- 5 kn 6 hr in advance -whats the problem?   The hydro back up is required for the immediate variation eg adverts in coronation street and half time in the cup final etc.

At our present usage of wind if it fluctuated from zero to a gale it would not fall out of the overall tolerance on the grid of  230 +10/-6 % 

Ken

[brackwell]

Not quite on topic but interesting background read  www.claverton-energy.com/?dl_id=325
Ken

[brackwell]

From Wicki,

Use of the Reserve Service and Frequency Service in practice

An example illustrating how the Reserve Service and Frequency Service are used in order to cope with intermittency and variability is given below:

    Consider, if a 660 MW turbine generator set (the standard size of large steam turbine) trips (large power stations usually consist of 2 or 4 sets each of 660 MW). This can happen for all sorts of reasons: a coal crusher might break down, boiler tubes might fail, an alternator might start to overheat, insulation might fail on the alternator. In the event of certain failures, the generating set automatically trips out and the grid suddenly loses 660 MW. On a typical day, this might be 1.3% of the total national grid output. Due to the immediate increased load on the remaining generating sets, grid frequency immediately starts to drop from the standard 50 Hz. (An alternative scenario, leading to the same frequency drop, could be a sudden and unexpectedly large surge in power demand as happens at the end of certain TV programmes, when people all rush to switch on electric kettles etc.)
    As soon as this happens, the under-frequency relays on Frequency Response customers begin to trip off their load as the frequency falls, ultimately to shed total load equal to 660 MW. These relays are set at a range of frequencies between 48.5 and 49.5, so the 660 MW of generation that has been lost is not instantly matched by these relays shedding 660 MW of load simultaneously but progressively as the frequency drops, until enough is shed to exactly match the remaining power station capacity. This will then stabilise the frequency at its now lower level—perhaps 49.3 Hz. This all happens in less than a second. These Frequency Response participants are only contracted to have their loads shed for up to 20 minutes.
    At the same time, the NG Control Room issues start-up signals to sufficient of its Standing Reserve Service participants for the shortfall (in this case, 660 MW) which by contract have to become available within 20 minutes. The NG control room is monitoring the situation and if sufficient Standing Reserve capacity does not come on, then it can order more until it has exactly matched what the Frequency Response relays have shed. (These relays are monitored in real time by NGT's telemetry systems.)
    Due to differing circumstances on the ground, different Standing Reserve participants will have different start-up times and reliabilities which again NG monitors using telemetry. However, when sufficient Standing Reserve has become available, which would be in less than 20 minutes, the Frequency Response loads (steel furnaces, cold stores etc.) are gradually and automatically re-connected by the relays. The original NG Frequency Response relays are then re-armed by NG.
    Up to an hour or so later, the output of the Standing Reserve diesels and gas turbines (which are nearly all in the hands of those not involved in commercial power generation) will have been augmented, and then replaced with new levels of large gas or coal-fired power stations which together will have driven the frequency back to its correct level close to 50 Hz. The diesels can then be stood down, ready for the next emergency.
    The replacement generation sources would have come from increased outputs from other power stations on spinning reserve, resulting in increased output. At the same time new levels of spinning reserve will have been created, which might have been stations on hot standby/warming now switched to running. Increased levels of stations on hot standby will also be called for.

The foregoing is a brief description of how the National Grid organises itself and the dispatch of power stations to cope with sudden, unforeseen and dramatic changes in load or generation.

The point to note is that complicated as this may sound, this has been going on for many years as the loads imposed on the grid, and supply of power from power stations is by itself extremely intermittent already, simply due to the sudden and unpredictable failure of these large 660 MW generating sets, or sometimes entire power stations; and the sudden changes in load which can happen at the end of a major TV programme, or events such as the last eclipse of the sun. These latter can cause surges of several GW which whilst larger in magnitude than the sudden loss of 2 × 660 MW sets, are not instantaneous and so are not as severe a shock to the national grid system.

However reliable a power station is, grid operators have to assume that it will fail, so its replacement must always be running and available.

This process is there whether wind power is there or not and wind represents a drop in the ocean with the scenario painted above - ALL the wind turbines would have to stop instantaneously to get close to the above

Ken