Bishop Hill Ouch
Sep 28, 2012 Energy: gas Energy: wind Mark Lynas The defence of windfarms put forward by Mark Lynas and Chris Goodall, which was discussed a couple of days ago, has now had a response from Gordon Hughes. Hughes is less than impressed with the two greens' table manners:
A final note on civility. After my GWPF report on the economics of wind power, Mark Lynas contacted me by email with a substantial number of requests for elucidation and additional data. I replied promptly and at considerable length. He is entitled to take a different view of the evidence and to reach different conclusions about the impact of further investment in wind power on future emissions of CO2. However, it is neither courteous nor constructive in the broader context to create a straw man that is supposed to represent my position when I have provided detailed analysis and arguments that are clearly different. It is an elementary precept of both journalism and academic enquiry to check whether the views presented are accurate. No attempt has been made to carry out such checks in this case.
He seems even less impressed with their analysis of the electricity grid:
[T]he Goodall-Lynas evidence is incomplete. It relies upon data about the plants which are supplying electricity to the grid. It takes no account of the CO2 emissions of plants that are operating as spinning reserve. For simplicity, let us suppose that all spinning reserve is provided by gas combined cycle plants (CCGTs). If changes in wind output are balanced by changes in the level of spinning reserve, then the total amount of gas that is burned – and, thus, CO2 emissions – is completely independent of change in wind output. In terms of the Goodall-Lynas evidence, higher levels of wind generation displace gas generation one-for-one. But, there is absolutely no saving in CO2 emissions because the gas plants carry on running as before but they are just feeding less electricity into the grid. The reason for the error is that their figures take no account of what is happening in the parts of the electricity system that they have ignored.
There's much more in this vein. Read the whole thing - it will cheer you up no end.
Reader Comments (85)
steveta: "While it is very easy to belive that 'spinning reserve' CCGT uses a lot of gas, it's pretty hard to beleive that it uses the same gas as a fully loaded power station."
Think of 2 cars. Car A with cruise control. Car B without.
Car A is chugging along at 75km per hour.
Car B is dring at 12km/hr for 5 minutes, then 90k for 25 and then 50k fro 1 day and then 100k for 2 weeks and then ...
Which one uses less fuel?
Nic Lewis; what's happening is that real data are being examined by real engineers not paid to lie for RenewablesUK etc. There are other reports coming out. they all point to the same basic phenomena:
1. Up to 10-12% penetration there is about ~1/3rd the CO2 saving. However, taking account the CO2 cost of the expensive, maintenance hungry infrastructure, there is little if any CO2 saving. Later on, the stream turbine hunting robs efficiency and you can't get more than a couple of % CO2 saving.
2. The grid is destabilised because windmills are asynchronous parasites. Up until June, Germany had 900 grid failures in a year. Any could destroy key plant and shut supplies down for weeks, maybe months in key areas. The big power industries are being closed down and unemployment is rising fast. Hence they are desperately building 16 coal stations and 13 CCGTs to recreate the power system.
3. We are heading to grid collapse this winter. No shops, no cash points, major crime in blacked out city centres. Next year it'll be very bad because of the closure of all the coal stations. iadvise anybody who can to move out of inner city areas with social housing as a source of mobs.
4. What we need to do is to put some experienced engineers into DECC with a veto on the greenie idiots who populate it.
Has anyone seen the latest DECC consultation on what is needed to bribe communities to host a wind farm? It starts off with all the usual lies about wind power. It could have been written by renewableUK. It even has intermittent wind power acting as backup to baseload nuclear power when it is offline.
http://www.decc.gov.uk/assets/decc/11/consultation/wind/6437-onshore-wind-call-for-evidence-document-part-a-com.pdf
steveta
The point's been answered before: if you unload a CCGT from full power (which is its optimum efficiency point and may be as high as 60 %), then its efficiency reduces. How much? The most modern plant can be unloaded by 50 % when the efficiency will have fallen to 50 %. That''s the first increase in CO2 reductions. Then there's the extra CO2 emissions required to actually shift the CCGT output; efficiency falls further when you ask a plant to change load. Then there's the extra load required to start and stop those plants completely at times when it's forecast will be at full tilt, or almost stopped.
Determining how much CO2 a fleet of CCGTs mixed with a 28 GW fleet of windmills will cut emissions is a complex analysis that can probably only be carried out doing full system studies, and probably only NGT can do this. But these have not been done. So we're blithely embarking on a windmill programme on the hope that that will cut emissions.
However, analysis of grid systems elsewhere (USA, Eire, Netherlands, Denmark) indicate that for large windmill fleets mixed with CCGTs, the CO2 savings are minimal - based on real data, not models.
Mr. Drake you say "If it was truly zero-cost to reduce CO2 emissions why would any of us wish to hold back, given that some in our society are convinced that this is the only way to avert disaster?"
There are any number of people believing any number of things. You may think that is a good reason to reduce the consumption, emission of any one of these things. But in fact the British skeptics have lost the argument about CO2 and have changed the subject to the facile argument about where to put the decimal point.
Arguing against the harmful effect of CO2 requires fortitude and know how. Arguing about where to put the decimal point anyone with a half decent vocabulary can do.
I continue to think that long term maintenance will be the straw that breaks the wind-camels back.
Many years ago our local Gas fired plant offered yearly tours (alas not since 9/11). And it was always fun to see the big 250 megawatt turbines. Typically with one or more offline for maintenance.
The point is that maintenance is a constant and continuous cycle for any high end machine. In a plant with six turbines they routinely only have four operational, one ready and usually one offline for maintenance. In a large plant, they have the people, the tools, everything there to do this work. And they just follow a schedule.
Now think of a large wind farm with dozens or hundreds of small turbines on the top of towers. And consider how you are going to efficiently maintain them. Simply put it will be a nightmare.
SteveW - your smart meter story is shocking enough, however this one trumps yours:
12 Sept: StopSmartMetersOrg: Smart Meter or NO Power at All? Nevada Energy Sends Three Armed Men to Disconnect Power- Just for ‘Opting Out’
http://stopsmartmeters.org/2012/09/12/smart-meter-or-no-power-at-all-power-company-sends-three-armed-men-to-disconnect-power-just-for-opting-out/
Sep 28, 2012 at 6:15 PM | Bruce
Re the car analogy what if the route taken involves uphill and downhill stretches and the non-cruise control car is running at a constant throttle position and goes uphill slowly and downhill fast, whereas the cruise control car goes uphill at the same speed it comes down? The calculation becomes far more complex in that situation.
However I do think we're better off, in all respects, without windmills.
SandyS, I've graphed the UK energy data - demand and wind. The hills you mention are predictable in terms of demand.
Less power needed at night and on weekends. More in the winter etc. Very monotonous predictable graph.
Wind power is all over the place, but the amount of winds fluctuations is small compared to the demand so the system can cope. If wind was over 20%, the fluctuations would be bigger than the day/night, weekday/weekend fluctuations.
sl149q
"Now think of a large wind farm with dozens or hundreds of small turbines on the top of towers. And consider how you are going to efficiently maintain them."
Hard enough on land. Far worse offshore...
Bruce
"the amount of winds fluctuations is small compared to the demand"
But changes in demand are more predictable. Power station staff know when Downturn Abbey is on...
jamesp, I should have said:
""the magnitude of winds fluctuations is small compared to the fluctuation of demand because wind rarely generates more than 4GW and demand fluctates by as much as 15GW in a week"
You can compare the weekly demand graph to the weekly wind graph.
http://www.gridwatch.templar.co.uk/
Demand: 25GW on sunday to 42GW on Wed and Thu
Wind: 0 to 4GW.
Imagine if the grid had 20GW max of wind instead of 4GW max. You would need 20GW of spinning reserve.
steveta: you still haven't got the point which is that when you force a steam turbine to change its power output, you use more fuel than if it operates at constant output. So, windmill system save very little CO2. The exact saving as determined experimentally is <2% of the CO2 you would have emitted had all that power come from the optimally-run fossil fuelled plant. Some systems emit more CO2. This figure takes into account the CO2 cost of the windmill infrastructure.
So, it is not worth investing in windmills unless you have hydro which can be instantly throttled to accept wind surges with no efficiency loss. In our case that has to be pump storage with nuclear power stations doing the refilling at 30% efficiency loss. if I were in charge I would insist that every wind farm had some form of energy management to reduce thee peak/mean power ratio. This could be electrolysis for example. But you wouldn't get wind investment!
steveta:
"if you unload a CCGT from full power (which is its optimum efficiency point and may be as high as 60 %), then its efficiency reduces. How much? The most modern plant can be unloaded by 50 % when the efficiency will have fallen to 50 %. That''s the first increase in CO2 reductions."
Let's do the sums on this. Let's say the rated output is 1MW and work out the inputs:
Case 1: 1MW rated output x 100% load factor x 1/60% efficiency = 1.67MW input
Case 2: 1MW rated output x 50% load factor x 1/50% efficiency = 1MW input
Saving in case 2 is 0.67MW input (i.e. gas burned per hour in "Therms" or whatever, i.e. CO2 emission per hour)
Conclusion: That's a *decrease* not an *increase* so if we've reduced the output to balance an increase of wind generation we have reduced total CO2 emission. Therefore the suggestion that wind power does not reduce CO2 emission is false in this case - unless of course we are using Mannian logic ;-)
My understanding of the 380MW CCGTs (at least the 15 year old ones we have), is that at full load, they generate about 250MW on the GT and 130MW on the steam turbine. As they back off load, most of this load is shed from the steam turbine so there is little difference in the gas burn. Once they get down to about 200MW, it is all GT. Much below about 180MW they are too unstable to run.
So there is little difference in the gas burn over their useful range. If they are taken off line and go cold, it can take a lot of gas to get them up to even generating. This is totally wasted energy. Stops and starts, even load changes, also significantly shorten the machines life as well and the blades are very expensive.
CCGTs are built to base load or at most two shift between 2/3rd and full load. Any other operating regime means going to less efficient open cycle machines.
First off, there are two Gareths here. Hello other gareth!
Bruce said:
I think aim is to have existing power acting as that reserve. The government hasn't been talking about expanding coal, gas, nuclear, etc to match increases in wind generation but is looking at renewing existing capacity.
It's all a bit of a con too. If you look at the BM Reports page they list the total available output at the bottom as around 70GW which includes 4GW of wind. They can't guarantee 70GW, only 66GW. If they build more turbines the total available output will be said to have increased but no one can rely on it and the level that can be guaranteed will still be only what is from conventional sources of power.
In the face of all these efforts to impose expensive and unreliable wind power on unwilling taxpayers, perhaps we need a coalition called Break Wind?
Sep 29, 2012 at 9:45 AM | Gareth
They can't guarantee 70GW, only 66GW.
Sorry, but they can't even guarantee 66 GW.
At the moment, there are 62 proper power stations with a capacity of 65 GW (coal 27 GW, CCGT 28 GW and nuclear 10 GW).
Of that, the only output which can be guaranteed is 27 GW coal plus 10 GW nuclear, a total of 37 GW. It can be guaranteed because these 33 proper power stations hold sufficient supplies of coal, fuel elements and consumables on-site to cover long periods of supply disruption. So, NG can only guarantee 37 GW.
The 28 GW of CCGT does not have any natural gas fuel stored on site, instead it all hangs on the end of a network of pipes shared by the rest of the UK, therefore the output cannot be guaranteed.
It can only get worse.
Ancient coal and nuclear proper power stations will gradually fade away, retired or murdered, over the next few years.
LCPD alone will see the 37 GW reduced to 29 GW by midnight, 31 December 2015, if not before.
By the end of the decade, that 29 GW will be reduced to 23 GW as 6 GW of nuclear is gradually retired between now and 2019.
New coal is effectively banned as a result of Ed Miliband shrieking "no new coal without CCS" as he wallowed in the general euphoria in House of Clowns at the passing of CCA 2008.
New nuclear is now too expensive for the guys who might have built them as a result of the endless hand wringing for years on end in the House of Clowns, so, if you want new nuclear, the government now will have to agree to a guaranteed price of £140 to 160/MWh delivered. The phrase "we have got you by the short and curlies" springs to mind.
New CCGT is getting more and more unattractive for the guys who might build them as a result of the headlong rush into more and more wind which means that the reduced running hours of the CCGTs means that they cannot make ends meet. Maybe the CCGT guys will follow the lead of the nuclear guys and demand a guaranteed price for their output.
So, no new coal, no new nuclear and new CCGT looking shakey.
Trebles all round.
The premise is false, so you can put down your pencil sharpeners and erasers. More CO2 is a benefit, it is currently making our planet more green and lush, with corresponding increases in crops and wildlife, by about 10% over the past half century, without significant warming problems. In fact, the optimum earth temperature is somewhat higher than it currently is. Cheers.
Whenever uncontrollable power inputs are allowed into a grid, there are side effect costs due to
the obvious fact that uncontrollable source generators can never lead to the replacement of a single
controllable generator, typically powered by fossil fuels. An uncontrollable power source must be backed up at least 100% by controllable power capacity. While the wind will allow fossil fuel plants to use less energy, the cost of maintaining a power plant is large, regardless of whether it produces any power at all. In effect, you are maintaining and paying two power generators (the wind producer and the backup operator) but only producing and selling a single output stream of power. Production costs will sometimes be almost double what they would have been without the uncontrollable power source.
And aside from situations where it gets even worse due to the fuel costs of spinning reserve, this
extra cost is always there, even if wind operators were able (thru storage) to allow enough notice
that the grid would not need to run any spinning reserve. Uncontrollable sources thus will always
entail much higher production costs, regardless of how often the backup power generators are actually required. Fuel is often not the dominant cost of running a power station - nuclear plants spend only
5 to 10 percent of their operating costs on fuel.
Lets be clear about generators of any type, that run on fossil fuel.
You can increase or decrease the amount of power they contribute to the grid (or main generator bus in my case) simply by increasing or decreasing the amount of fuel input to the prime mover.
When you have two or more generators sharing the load, you can elect to 'balance the load' by increasing/decreasing the fuel into each generator as necessary.
You may have old generating capacity that does not like being turned down a lot, perhaps these generating sets need an updated control system!
It is beyond any doubt that if you reduce the load on a generator, you reduce the amount of fuel they burn. It is a one for one relationship. It can not work any other way.
There will be system losses (bearing friction, generator windage, auxiliary equipment power ((oil pumps, fans, motors, valves, cooling systems etc)) ) which will exist even when the generator is not supplying power but idling.
The generator set will be designed to operate at maximum efficiency at maximum power, run it at a lower power output and the efficiency will reduce slightly.
Running a CCGT system at other power outputs than maximum will cause the steam side to 'protect' itself when and as necessary by shutting down as necessary.
But if you want to run a CCGT system at 50% power then that is up to the owner.
Can CCTG gas turbines be run at low power outputs? Of course they can, less power - less stress.
What all large power systems do not like is cycling - changing the load/power output frequently.
Do wind generators reduce the amount of CO2 from CCTG, of course they do.
How much of a reduction is a tricky calculation but probably not enough to make it a unique selling point for wind generators!
Trying to equate generator load sharing with cars going up and down hills is not helpfull, syncronised generators are all running at the same speed all the time, squirt in more fuel and they take more load/generate more electricity.
It would seem ideal for an engineering department and a stats department at a University undertake a study of all generating capacity within the UK, but it would require a full understanding of the characteristics of each type of generating set in use and 'how they are used by the grid controllers'.
I am not sure that sufficient and accurate information could be made available.
An interim measure would be to compare the raw fuel supply to each station for 12 months and compare with each stations electrical output.
In the world of SMART meters, any smart energy retailer would set a basic pay-as-you-go-tariff and then invite people who want to ensure against freezer shut-downs, dvd recorders not getting the latest Big Brother, etc by paying some kind of premium. Rent-seeking heaven. What is not to like!
Steve ,
What you nsuggest is wonderful but it involves science and analysis, which are beyond the grasp of the climate scientists.. And scientific behaviours cannot possibly be helpful when looking at the demise of our planet from CO2. /snark
Put your pencil sharpeners and erasers away, the premise is wrong. CO2 is beneficial, we should be giving awards to those who produce it. Cheers
Some stuff I gathered together on CCGT and start times:
http://climateandstuff.blogspot.co.uk/2011/05/efficiency-of-power-plant-operating.html
Then go here to see what the national grid is already handling in the way of power variations
http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Demand/Demand8.htm
It doesn't matter that these are predictable you still have the problem of throttling up and down generation by 16Gw in a few hours. Wind generation does not suddenly die all over the country and to some extent can be predicted some hours/days in advance.
Wind and solar inputs of 16Gw should not be a problem.
Note that SPINNING reserve (generators spinning and synchronised to the grid) is not required for all wind power it IS required for at least the output of 1 generator (1Gw in case of sudden loss of a nuclear or coal plant. Warm start will cope with most wind requirements - see here
http://climateandstuff.blogspot.co.uk/2012/08/the-reliabilty-of-nucles-compared-to.html
Note that spinning reserve is NOT required for wind power (it slowly changes and in general can be accommodated by warm stat generators (20 minutes to an hour). Spinning reserve is required for large coal or nuclear station that can be suddenly taken off line (these are running synchronised to the grid and can supply power within seconds).
There are new CCGT machines developed for load following have a look here:
http://climateandstuff.blogspot.co.uk/2011/05/efficiency-of-power-plant-operating.html
Currently the grid is following daily variations of 16+GW without problem in a maximum of 45GW. Wind will be no more of a problem at this level( 35%) see here for a daily plot of NG output
http://climateandstuff.blogspot.co.uk/2012/08/the-reliabilty-of-nucles-compared-to.html
The German problem is not their renewable input but their sudden decision to remove nuclear without updating the required infrastructure. Wind generation is in the North and the nuclear stations in the south. This therefore now requires massive transfer of energy from north to south and hence overloaded grids.
Check out this European energy exchange site:
https://www.epexspot.com/en/market-data/auction/chart/auction-chart/2005-09-14/DE/1d/30d
you will note that in general in 2005 there is one major peak in price but in 2012 there are 2 peaks with a central dip equivalent to peak solar output modified by peak demand. Also note the prices (for Sept 2005 65k/MWh 30day average and Sept 2012 30day average it is 55k/MWh
I see no price jump!
The fuel consumption is determined by the electric load on the generator. You control the speed and the exciter. The speed is controlled by the turbine speed. If the load goes down, the generator would speed up. Instead the natural gas is cut back to the turbine. So gas is reduced at lower generating (just common sense). However, there is a minimum turndown, such as minimum burner pressure, which gives you flame out, a dangerous condition. And you need to keep pressure on the boiler.
'For wind penetrations of below around 5%, wind forecasting is generally believed as not necessary, since "deviations in wind output fail to show up in the ebb and flow of daily operation with [such] small grid penetrations" (Milborrow 2003:37).5 As wind penetration rises, wind forecasting increasingly adds value to wind power.'
http://www.uwig.org/IEA_Report_on_variability.pdf
thefordprefect
"Currently the grid is following daily variations of 16+GW without problem in a maximum of 45GW. Wind will be no more of a problem at this level( 35%)."
Yes, it can be managed, it's not technically impossible. No one here is saying it is. What most of us are saying is that managing it will cost money (a lot of money) and it will also reduce the CO2 savings that you'd see from the windmills (perhaps completely negate them).
gareth (small g gareth)
"Case 1: 1MW rated output x 100% load factor x 1/60% efficiency = 1.67MW input
Case 2: 1MW rated output x 50% load factor x 1/50% efficiency = 1MW input
Saving in case 2 is 0.67MW input (i.e. gas burned per hour in "Therms" or whatever, i.e. CO2 emission per hour)
Conclusion: That's a *decrease* not an *increase* so if we've reduced the output to balance an increase of wind generation we have reduced total CO2 emission."
Yes, case 2 has cut its own emissions. It has also cut its total total power delivery. So if you want to recover that power, you bring on two case 2s. They need an energy input of 2 MW against the one fully loaded CCGT which required an 1.67 MW input
I hope you have seen this, if not, enjoy:
http://www.wnd.com/2012/09/al-gore-bails-from-green-energy-investment/
Capell
" So if you want to recover that power, you bring on two case 2s."
No you wouldn't - we are talking about reducing gas plant output to balance wind and wind. One of your "Case 2s" is wind generated and for all it's other issues does not produce CO2.
I'm starting to feel like xkcd.com/386/
Typo - "balance wind and wind." should be "balance wind output"
doh!
gareth
Well if in your mind you're just running the CCGTs for the sole purpose of balancing wind output then you'd have to attribute the entire emissions of the balancing CCGT to windmill operations; i.e. 1 MW of energy input.
"thefordprefect: Wind generation does not suddenly die all over the country"
Yes it does. Over 3000 10 minute periods in the last year down to under 100MW. Fluctuations from 0 to 4000MW and back.
If wind was 20GW, you would need 20GW of spinning reserve + whatever spinning reserve you need for coal and nuclear.
In fact you would be building two power systems. One to move power from all the wind turbines and one to run when the wind dies down which it does all the time.
Why not build one good grid? Not two.
http://www.windpowermonthly.com/news/
Bishop usefull link. Keep our our Enemy's closer