A Windy Future
Posted by Tom Quirk, August 18th, 2009 - under News, Opinion.
Tags: Energy & Nuclear
THE Australian government didn’t get its carbon trading legislation through the Senate last week and has now decided, at least for the moment, to just push ahead with that part of the legislation relating to renewable energy targets.
It seems this legislation is likely to be passed sometime this week and according to many pundits the big winner will be wind farms.
Wind is available now, is relatively cheap, and could snap up all the relevant concessions under the new legislation before emerging technologies like geothermal and solar thermal are ready for rolling out.
Is this good news?
According to the following article… wind farms in South East Australia are unlikely to supply any significant power output that system operators can rely upon, rather they will load the distribution system with sudden variations in power that are not predictable and are of a size that is ten times larger than the random variations of user demand.
Wind Farming in South East Australia
By Andrew Miskelly and Tom Quirk
IT is often claimed by their advocates that wind farms can be a reliable source of electrical power if they are dispersed over a sufficiently wide area. The wind will be blowing somewhere, it is claimed. There is now a sufficient number of wind farms in South Australia, New South Wales, Victoria and Tasmania for an assessment of the value of wind farms as a source of reliable electricity generation..
This analysis is based on the performance of 11 wind farms listed in the table below for June 2009. The data was sourced from the Australian Energy Market Operator (AEMO formerly NEMMCO) website. The power output is recorded in 5 minute intervals and this allows the performance of the wind farms to be examined in detail. An example of the behaviour of two South Australian wind farms and the summed behaviour of all six South Australian wind farms is shown in the above chart.
These curves show that, for example, 80 percent of the time, all SA windfarms provided more than 8 percent of rated output, and that 8 percent of the time they provided just 80 percent or more of their rated output.
These power curves are representative of the general behaviour of wind farms. The performance of all the wind farms is given in the following table. 
The capacity factor, the average output relative to the installed capacity shows an overall average of 30 per cent for a total installed capacity of 833 Mw. The capacity factor varies from month to month throughout the year and varies from year to year. But these values are indicative of the performance to be expected from new wind farms as they are brought on line. A modest decline in the capacity factor for new farms might be expected if the best sites have already been taken.
The 90 per cent reliability figure represents the amount of energy that can be relied on for 90 per cent of the time. It is given as a percentage of the installed capacity so that comparative performance can be assessed. 90 per cent reliability for conventional coal fired power stations or gas turbine generators is greater than 90 per cent of the rated output. It is clear that the one benefit of grouping wind farms is that the 90 per cent reliability point is increased from 6 per cent for SA, 5 per cent for Victoria, to 10 per cent overall. Again this figure should be expected to vary from month to month and from year to year.
One of the most important details of this analysis is the geographical separation of the wind farms. This is shown in the map below. In fact the windfarms extend over 900 km North-South and East-West. This separation can be used to investigate if any significant benefit is gained by such a spread of wind farms. 
The next three figures show the June 2009 performance of the wind farms in NSW, Victoria and Tasmania compared to that of South Australia. South Australian wind power generation has been used as the standard as it is the largest sample and despite having 6 wind farms added together performs as if it were one farm despite a spread of some 500 km. 
It is clear that the responses in each area are correlated. The correlation of South Australia with Victoria is the clearest example. This has been refined in the next three figures that show a measure of this correlation. This is a running correlation with a sliding 24 hour window that shows the extensive variations over time.
These figures show the strong positive correlation of South Australia with Victoria. However it is important to note that the other two states do not provide any significant comfort from their geographical separation: that is they show no significant inverse of the South Australian-Victorian correlation.
Another demonstration of this general wind correlation is to look at the total wind power profile and compare that to a profile assuming equal installed capacity in all four states.
The figure below shows that no great change occurs and the geographical spread does not enhance performance. 
The conclusion is that the only benefit from a large geographical spread is an increase in the 90 per cent reliability point from typically 5 per cent to 10 per cent
The other issue that can be examined is the short term fluctuations in the outputs of wind generators. These fluctuations add to the difficulties of maintaining voltage and frequency in the power system. Sudden changes in the demand for power raise similar problems but long experience with the daily load curve enables system operators to prepare for these changes. Fluctuations in output from the wind generators are, contrariwise, completely unpredictable.
The variations have been assessed by looking at the difference of wind farm output from one 5 minute interval to the next. By sampling over some 8,000 5 minute intervals it is possible to build up a measure of the performance of all wind farms and their aggregate output, rather like calculating a standard deviation(1) . This can be extended to looking at differences 10 minutes apart and so with increasing separation it is possible to see the time development of wind variations. A complete picture, extending over seven days, is shown below. It has been standardised to the installed capacity of the wind farms as it a measure of the wind’s behaviour, not the behaviour of the wind farm.
The conclusion from this is that the wind has some consistency for up to about 48 hours but with increasing fluctuations. Beyond that time the fluctuations are some 25 per cent of the installed capacity. This does not imply that the wind varies smoothly. On the contrary, this is the average performance of a generator with greatly varying output.
The general conclusion from this analysis is that wind farms in South East Australia are not likely to supply any significant power that can be relied upon, and thus system operators will have to schedule generators as if there were no wind power at all. Wind farms will load the distribution system with variations in power that are not predictable and are ten times larger than the random variations of user demand.
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1. 
dribble (August 21st, 2009 at 6:55 pm) wrote:
“Windmills are not a sustainable energy solution. It requires a 500MW coal fired power station to be replaced roughly by 1500MW wind farm plus 500MW backup gas turbine power station.”
I don’t think that that’s accurate. My understanding is that gas turbines can be brought online quickly for the relatively predictable peak power periods of the day, but that they aren’t particularly tunable.
Steam-generated power from coal, nuclear, etc is supposed to be much more dispatchable for dealing with the less predictable fluctuations in output from wind farms, when the latter are a relatively minor ingredient in the whole enchilada.
Hydro is also dispatchable, but it’s probably not a major wind-power back-up option for the Southern half of Australia.
Neil,
I’ve been told by other electrical engineers that the average efficiency of a coal fired station in Australia is closer to 25% when all factors are taken into account e.g. transmission (your example of the snowy mountains power lines has its inverse in summer in Australia when the high ambient temps increase the resistance of power lines dropping efficiency even further). The newer ones are better while the old ones are appalling. Now gas fired peaking plants, wind, geothermal, nuclear etc are all going to be subject to the same distribution limitations as coal. The other thing with coal in Australia is that due to siting etc we throw away all that perfectly good waste heat which if captured could up the efficiency dramatically of even the worst coal fired plants.
I’m suprised that the denialists here ignore the limitations of coal while concentrating their ire on just one form of generation, wind (which has been taken over by the corporates anyway) and offer no sort of systems analysis on wind and associated developments as well as other forms of renewables such as marine, geothermal, bio mass and systems such as distributed etc. They also ignore the vigorous debate on taking nuclear forward amongst the greenies.
But then its my contention that denialists don’t care about high technology or actaullay what makes a good power system or what we actually use power for as for them its all about ideology.
BTW An engineer I know once did a calculation on how long the brown coal in Victoria was likely to last. This was around the time that Mcfarlane was resources minister in Canberra and who declared that there was 800 years of brown coal left.
My colleague reckoned that no one had included growth in useage rates for that 800 year figure so he recalculated it and came up with a figure of between 60 and 80 years using 2.5% growth in extraction per year. He may or may not have been correct but he just didn’t believe the assumptions put out by the power industry.
Jeremy C said “”I’m suprised that the denialists here ignore the limitations of coal while concentrating their ire on just one form of generation, wind (which has been taken over by the corporates anyway) and offer no sort of systems analysis on wind and associated developments as well as other forms of renewables such as marine, geothermal, bio mass and systems such as distributed etc. They also ignore the vigorous debate on taking nuclear forward amongst the greenies.”"
Several of us have posted on taking nuclear forward. What we see of the greenie nuke debate is “inaction in action.” As an engineer in power supply, let me point out that some of the limitations of wind that apply to coal still apply to wind; and that I don’t see either camp addressing certain problems with their technology. This includes both “greenies” and “deniers”. Both are trying to sell something, and are putting the best light as possible on their choice.
The main problem, that we do not yet have a solution for, for most, if not all of, the alternative energies is that they are not “on demand” capable. Our modern civilization, from computers to home light bulbs, and our infrastructure is set up and made with the assumption of “on demand” capability. It is not something that can simply wished away as sod tries to do. The cost of variance is severe, and the cost of changing the infrastructure (motors, computers, etc.) is monumental. Ignoring this, simply allows those who work in the field or are knowledgable to “pile on” with the facts.
An honest discussion would at least convince people that the problems, and oppurtunities were worht discussing. And of course, for MGW or GHG’s, nuclear has to be put on the table, or most will simply believe this is just another conspiracy by “greenies” to punish the modern world for not wanting to be in the stone age.
John,
WRT to nuclear its the ‘greenies’ who are advocating IFR (and other forms), go look at bravenewclimate.com.
As to ‘on demand’ it comes back to what you want to do with energy and why energy is used in a particular form to complete a particular task, thats a question the energy efficiency experts ask. As to your monumental costs of changing infrastructure (whether the lap top, a motor, power lines) all infrastructure is changed, renewed etc. E.g. computers will be renewed in a shorter time than motors which will be renewd in a shorter time than power lines and so on. The point is, this monumental cost goes on all the time.
Its seems to me as an engineer that ‘on demand’ is tied into a centralised energy system and that as a concept a distributed energy system may offer different ways of energy availability than the brute force of on demand. For example, the CSIRO’s development of smart agents allowing loads and generators to actively interact with each other is a step toward changing the paradigm behind on demand.
Is it also that being actively despatchable is more a case of not being able to turn coal fired generators on and off like a light switch and Australia, up to the noughties, had, according to the IEA, a generation led energy system rather than a user led energy system. This perhaps makes it very difficult for people to grasp that we can do things differentley and as evidence I point to how the arguments always centre on whether one piece of kit (wind or coal) is better than another piece of kit (coal or wind) rather than questioning the way energy is used across society and what are the best ways to accomplish this.
BTW “let me point out that some of the limitations of wind that apply to coal still apply to wind” lovely phrase but very silly logic.
You said “”BTW “let me point out that some of the limitations of wind that apply to coal still apply to wind” lovely phrase but very silly logic.”" Yep. Strike the “of wind”. Comes from posting while engaging wife in conversation. It was for those who mention transmission losses and other losses as though wind does not suffer the same through the grid.
Yes, on demand is tied to a central system. One can decentralize, but note that such reduces the utility percentage, if it is not put on the grid, and has to be wasted. If it is put on the grid, the on demand system has to regulate the power and voltage to keep the grid from failing. So the question is, will it be cost effective? Note that the wind solutions sod and others are pointing to are centralized manifestations. That is probably why they are talked about as another piece of kit.
As an engineer you should know it is one thing to wear a computer or motor out versus blowing many on the grid at once. The other part that is missing, that should be known to you as an engineer, is that whether it is a computer or a motor, its underlying infrastructure of utility (software, driving a fan) and the human/societal interface are based assuming on demand energy. Workers, software, fans etc, may not work with less than an on demand system.
Take your CSIRO’s smart agents. “” The technology is expected to lead to more efficient energy management and reduce the incidence of costly blackouts caused by excessive demand at peak.”" This may help with reducing costly balckouts caused by excessive demand, it may help with offlaoding over production on the grid. However it addresses the problem, I was examining which was excessive generation when not needed, by changing the timing of consumption. The interface where humans use the system is on demand. The infrastructure is on demand. They do not necessarily match this proposed changing. There will definetly be some matching and some increase in efficiency. The question is how much? It will make renewable energy sources, better utilised and more economically attractive. However, it does not solve the problem of industry, commerce, healthcare, etc, that will still be on demand, and cannot tolerate random blackouts, downtime or overvoltage.Trying to apply this smart agent to industry will net little gain. Same is true for commerce. The last time I checked, about 70% of on demand was by industry and commerce. There may be some gain by having some commerce and industry to change hours. However, large commercial and industrial units have acheived economy of scale with 24 hour solutions for over 100 years now.
Further in talking about infrastructure, perhaps I was unclear. It is not that it is a motor but, say, an on demand blower. The whole manufacturing chain will be composed of on demand. Though a motor may die, one does not ever replace the real unit which is the system that manufactures. So,one cannot assume that a motor can somehow wear out and we can change the basic infrastructure problem without replacing the whole or most of the whole manufacturing system. This poses a problem for any solution, no matter how smart it is, that most of our commerce and industry is set up for on demand and changing it will require far greater sums of money than even the worst cost projections for AGW.
You state “”A generation led energy system rather than a user led energy system.”" I would need to read what you are talking about. I saw the IEA site. I am not familar with the point you are making, since generation is typically developed in anticipation of user demand. So I am unfamiliar with “user led energy system.” The IEA appear to be a think tank group concerned with environmentally friendly energy. Could you point to me the article that has this explained so I can read it. Thanks.
bravenewclimate.com I will read. The first article article I read made good points.
John,
The IEA report I was referring to is: http://iea.org/textbase/nppdf/free/2005/australia2005.pdf. Pages 48 and 49 in particular point out how energy in Australia is weighted towards the supply side rather than the demand side i.e. end user which is the clumsy term I was using. I IEA is the central body for the OECD on energy policy, stats and related areas such as technolody.
I see you looked at smart agents but I still don’t agree with what you said about about on-demand. On-demand is a response to something we want to do. What I am saying is that an on-demand system constructed with coal fired stations in a centralised system is not the only approach and smart agents are one pointer to technology and/or approaches that we are not slaves to coal fired on-demand, that other approaches can be done. I also stick with my statement that infrastructure gets renewed constantly.
I also thought your reference to black outs etc is a side issue as organisations with critical functions e.g. hospitals and operating theatres have had power back up for years seperate from a centralised on-demand coal fired system.
So as Australia moves away from a supply led energy system then I would say that both the concept of on demand will change and how it is met will also change and will be decoupled from base load coal fired stations.
Sod: “every drop counts. any other questions?”
A few drops in the ocean aren’t going to do anything, so does every drop count? Nope they dont. If you look at the green shopping bag of delusional energy solutions, there is not a lot left after you get past the windmills. My question was, and is, ‘What are you going to do about a real solution to the CO2 catastrophe that you allege exists?’ The answer of course, is nothing that is actually going to work on any large scale. Try as I might, I cannot see the industrial power requirements of the world being met by windmills and solar panels. But if these energy requirements are not met, the CO2 will keep pouring out and the catastrophe will allegedly arrive. You had better stock up on boating equipment while it is still relatively cheap.
Thanks for the link. Now your comment makes sense. I would note from the pages you highlighted “”The White Paper’s observation that undue government involvement that overrides market forces will rarely improve security in the long term is consistent with the experiences of many IEA countries. Instead of viewing energy security as being a trade-off with market competition, the Australian government wisely establishes ways in which market efficiency and motivations can be used to enhance energy security…In contrast to its impressive economic efficiency and sound energy security, environmental sustainability is Australia’s single biggest energy policy challenge. The issues related to environmental sustainability have not garnered as much attention in Australia as they have in other IEA countries. This is explained by a number of factors, namely Australia’s large supply of domestic fuels; the economic and employment benefits related to exploitation of high carbon-content fuels; the boost to economic competitiveness from inexpensive energy; and a large land mass and dispersed population which mitigates local pollution.
The supply side is economic criteria not utilization criteria from the grid as we were discussing. The on demand point was simplification of the US version the Energy Information Administration. I believe that we will disagree about smart agents. I see their problem as they are passive in nature, i.e. they are an increase in effeiciency by changing a parameter (say the time you charge your car), and do not address the dynamic (charging your car) which is what drives the on demand grid. You have simply put the demand on at a convienent time. You have not changed the actual specifications of the system.
Certainly infrastructure does. However, as I pointed out these units work in systems, and unless you wholesale change out the system the incremental cost will indicate that it is less expensive to repair a system than replace. In engineering school, I was taught that one had to consider incremental costs when comparing and also take into the time cost of money. Just the time cost of money for wholesale changeout of systems around the world would be far greater than the draconian costs associated with 20/20 plan for CO2 being touted.
As the technology becomes available one can make sure new systems avoid the pitfalls of the sytems that we use today. However, considering that incremental costs often extend the life of a system to about 50 years versus replacing with a new system immediately , and the technology is yet to be had, we are looking at 2060 before large inroads can be made for the systematic problem of energy distribution and its usage. However, depending on what technology we use, the world may well have to support two systems with its resulting increase in costs, which is figure I have yet to see even from those who don’t use the one piece of kit approach. I have not claimed that we are slaves to coal plants. In particular, I think the bioaccumulative heavy metals associated with coal needs more urgent addressing than CO2. The dangers of metal accumulation are wll known and documented.The CO2 potential harm has large CI’s, and even the accuracy is being well argued in science at this time. See Radiative and Dynamical Feedbacks Over the Equatorial Cold-Tongue: Results from Seven Atmospheric GCMs, D.-Z. Sun and T. Zhang, C. Covey and S. Klein, W.Collins, J. Kiehl, and J. Meehl, I. Held, M. Suarez
By comparing the response of clouds and water vapor to ENSO forcing in nature with that in AMIP simulations by some leading climate models, an earlier evaluation of tropical cloud and water vapor feedbacks has revealed two common biases in the models: (1) an underestimate of the strength of the negative cloud albedo feedback and (2) an overestimate of the positive feedback from the greenhouse effect of water vapor. … These biases, however, highlight the continuing difficulty that models have to simulate accurately the feedbacks of water vapor and clouds on a time-scale we have observations.
Yes, health care and others already have back-ups. Though as you state they are separate from coal powered systems, yet they are not separate from the system of controlling CO2 or emitting CO2. I was using their dependency to highlight that such constant and deliverable energy is expected of our systems by the public. I may not have done this well.That is why I named other use categories and stated they “cannot tolerate random blackouts, downtime or overvoltage.”
John,
Ahhh, I see what you mean in using back up power supplies as emphasising a dependence on on-demand, i didn’t understand that before. and i also see your point about incremental costs extend the life of systems far longer than components.
I highlighted pages 48 and 49 because thats where the report notes the nature of australia’s energy system being supply-led up to the early 2000′s;
“Australia’s vast, reliable and inexpensive fuel resources have been a
substantial factor in the country’s economic growth. They have also led to a
supply-side approach to energy rather than a demand-side approach and
partly as a result, Australia has one of the highest energy intensities in the
IEA. Australian TPES grew by 2.4% annually since 1970 while the IEA
countries on average saw a 1.5% annual growth in TPES. Projections by
ABARE forecast continued high energy demand growth well above IEA
averages. Because of its abundant domestic energy resources, the country has
had no apparent motive to pursue efficiency ambitiously and has had less
experience in these areas than other IEA countries. Nevertheless, the
advantages of greater demand-side attention are relevant to all aspects of the Australian energy sector and should therefore be seen as a major opportunity
across the board. The use of demand-side options to address energy questions
could, in many cases, provide more attractive solutions than on the supply side.
Benefits of greater efficiency would include, but are not limited to, reduced GHG
and other emissions; increased energy security; improved productivity and hence
competitiveness; greater economic efficiency in meeting peak needs that the
market does not price well; reduced need for network and infrastructure
expansion through suppressed demand and hence the ability to take advantage
of more advanced technology”
One thing I take from this passage is that we waste a heck of a lot of energy compared with our competitors and one day that may come back to bite us.
If you get the numbers, one of the strange things is that US overall efficiency is so ahead of others that even though we are second in emissions, we are 7th in per capita energy consumption. This is not the best measure. SOmewhere on the net they list efficiencies and depending on assumption and weighting usually Japan, US, and France “lead” in certain respects.
One of the better offers I have seen is solar/NGas high temperature or pressure systems for extending solar into the night with molten salt or other similar systems. In this case, the two energy sources share the basic electric generation reducing capital outlay as seen in wind with a 4:1 or even 5:1 at best potential:realizable generation. In order to be close to economical will reguire infrastructure improvements to handle the variability. Running dual inputs to a single energy transmission is tricky if both are well behaved. If one is not well behaved, problems can lead to inefficiencies quickly. However, the solar can be well predicted in a short term and a high temperature salt system has a lot of thermal inertia to compensate for small fluctuations.
In this case, the advantages of solar, quick response of NG, and large thermal inertia reduce the problems of the source at the source by being well matched. This is not true of the Denmark wind scheme. But, having dual controls, safeties, heat sources, etc, do add to the cost. And of course, when the sun don’t shine you emitt CO2. But it can beintegrated in a far reaching diverse system to reduce overall CO2 longterm.
I have been looking up the numbers for NSW electricity production, which are given below. The numbers for current production are from Wikipedia, the numbers for proposed alternative are taken from the Greenpeace document “Policy Report: A Just Transition to a Renewable Energy Economy in the Hunter Region, Australia” June 2008 pg 42
Current 2009 NSW electricity production in MW
Coal 12000
Hydro 4245
Gas 1000
Bioenergy 100
Gas co-generation 100
Wind 16
———
Total 17460 MW
Proposed Greenpeace NSW alternative 2020 in MW
Wind 4900
Hydro 4245
PV 3575
Gas co-generation 3500
Bioenergy 1550
Solar thermal 2000
Geothermal 200
———-
Total 19970 MW
Total investment cost is estimated by Greenpeace to be $12b for NSW. There you go chaps, complete replacement of NSW electricity production with alternative energy (sorry, I hate the word ‘renewables’) in ten years for a mere $12b. Sounds cheap, looks like it can be done for a quarter of the price of the new $43b optical fibre broadband network. Go for it.
I assume that the 4900MW of windfarms would need to be multiplied by a factor of 3 for practical purposes, requiring approx. 15000MW actual wind turbine installation in NSW, or approx 85% of the current total installed electricity generation capacity.
However be warned that the coal saved in shutting down the NSW power stations will of course be shipped straight out for burning in Asia. The overall CO2 emissions savings are therefore likely to be minimal.
With respect to sod’ posts, they are now getting laughable
he replied:
“this is complete nonsense. Denmark for example is backing up its wind with norwegian water power. you don t need the full back up, if you spread out the wind fields. ”
The whole point of the original article, which people like sod seem to have forgotten in their parallel universe is that spreading the windfarms out across SE Australia, compounds not mitigates the problem.
I don’t know where Greenpeace get their numbers from that dribble quotes but they are garbage. $12b will only get you 4000MW of wind – I think their numbers are out by a factor of 10. Oh and 2000MW of solar. What is going to happen when the sun goes down and electricity demand peaks? The geothermal is a non-starter, they haven’t even got their 1MW plant working yet. Don’t quote MW, quote GWh out of each source and on proven technology, not someone’s dream.
What used to happen was a lot of coal fired plants were in cities and their water was used for district heating. Battersea Power Station in London was the most famous example. However, the size of modern plants, NIMBYs and the drive to get cheaper power by reducing transportation costs meant that they had to move. Most of the heat out of a thermal power station is very low grade, less than 100°C. There isn’t much demand for it, especially in summer.
s
Wind turbines have other shortcomings as well.
http://www.theaustralian.news.com.au/story/0,25197,25964195-5006785,00.html
The accompanying decibel chart in the printed version of the paper, has a lawnmower at 90db, a power drill at 80db, a wind turbine at 75db, a vacuum cleaner at 70db etc.
From the article,
“Three months ago the first of 128 turbines started turning and almost instantly Mr Dean became sick. He started waking with headaches……..His wife also began experiencing an inexplicable malaise………It was only after the 57-year-old couple travelled to their other property…….and instantly fell well again……’
What gives? Is this common?
The Greenpeace report states:
“Approximately $12b would need to be invested in renewable energy, co-generation and energy efficiency measures for Scenario 1 between now and 2020. This may be an over estimate, as it makes no allowance for technology cost decline over the period.” (p. 11)
Scenario 1 is the assumption that the Hunter region generates 100% of electricity for local use (23% of NSW electricity) (p. 9)
Therefore my quickie email cost figure was in fact incorrect. The $12b represents a changeover of production in the Hunter region only. Using these figures an estimate for the whole of NSW would be about $50b. My apologies to all concerned.
Jeremy mentioned demand-side approaches to energy policy. If I’ve understood what he was trying to say, here’s one small example.
My local utility in Sacramento County (California) has a program called Peak Corps, with an interesting quid pro quo. You agree to allow the utility to remotely turn off your air conditioner/heat pump for specified periods of time during the peak usage hours during the Summer. In return, you get lower rates for the electricity that you do use.
As a side-note, this PUBLICLY OWNED utility has lower rates than in most of the surrounding area, whose residents are serviced by a private utility that’s supposedly guided by Adam Smith’s ‘invisible hand’. Or should I say middle finger?
If you look up the Greenpeace Australia alternative energy universe offerings on wind farms you are referred to an article by Mark Diesendorf, ‘The Base-Load Fallacy’
http://www.cana.net.au/documents/Diesendorf_TheBaseLoadFallacy_FS16.pdf
Quoting from the article:
“To replace the electricity generated by a 1000 megawatt (MW) coal-fired power station, with annual average power output of about 850 MW, a group of wind farms with capacity (rated power) of about 2600 MW, located in windy sites, is required.
Computer simulations and modelling show that the integration of wind power into an electricity grid changes the optimal mix of conventional base-load and peak-load power stations. Wind power replaces base-load with the same annual average power output. However, to maintain the reliability of the generating system at the same level as before the substitution, some additional peak-load plant may be needed. This back-up does not have to have the same capacity as the group of wind farms. For widely dispersed wind farms, the back-up capacity only has to be one-fifth to one-third of the wind capacity. In the special case when all the wind power is concentrated at a single site, the required back-up is about half the wind capacity. (Martin & Diesendorf 1982; Grubb 1988a & b; ILEX 2002; Carbon Trust & DTI 2004; Dale et al. 2004; UKERC 2006).”
In other words, the green intellectuals recognize that the average power output of a wind farm situated on a windy site is approximately 1/3 of its nameplate capacity. They also state that the backup is required is 1/5 to 1/3 of the wind capacity for sites averaged over a wide area. They don’t state whether wind capacity is the same as average power output, but go on to state that backup of up to 1/2 is required for a single site. Thus what they appear to be saying is that backup capacity of only 1/5 to 1/3 of the average power output is required for combined sites situated over a wide area.
The graphs provided by Andrew Miskelly and Tom Quirk for combined wind farm performance in SA and VIC for June 2009 show that this assumption is invalid. The combined output is highly correlated, and there are days when total combined output drops to the 0-10% level. Thus the backup capacity needs to be 100% of the combined wind farm average power output, ie 1/3 of the nameplate capacity, at least in this geographical area.
To clarify the above issue concerning the meaning of ‘wind capacity’ and ‘average power output’, I also include this quotation from ‘A Clean Energy Future for Australia’ found on the Energy Science website.
http://www.energyscience.org.au/reports.html
“For example, in an electricity grid with total generating capacity of 10,000
MW, 2,000 MW of wind power would have an annual average power output of about
660 MW, so this amount of base-load capacity (coal in eastern Australia) could be
retired or deferred. At the same time, to maintain the reliability (e.g. as measured by
LOLP) of the grid at the pre-wind level, up to about 300 MW of peak-load gas
turbines may have to be installed in grids without sufficient hydro plant. Because
these gas turbines have low capital cost and rarely have to be operated, they are like
reliability insurance with a low premium (Martin & Diesendorf, 1982, 1983).” (p. 87)
Here the green intellectuals are saying that 300MW of backup is required for 660MW of average power output, which I assume relates their non-combined wind farm scenario in which they state that backup of approximately 1/2 wind capacity is required.
In the Greenpeace power plan highlighted by dribble, they imply 2000MW solar can replace the equivalent thermal generation. If one looks at the load curves and do the numbers, it is about 8000MW solar and 60GWh of pumped storage needed. There are no large installations anywhere but the budgets indicate solar will be about $8,000 per kW. When challenged on the price, the greens wave their arms and talk of efficiencies of large scale and cost reductions for technology. Their plan for NSW to get 100GWh of generation will cost over $100B, running costs not much lower than current, involve large civil works across all the parks and scenic areas (where do you put wind farms or pumped storage) and still not give reliable power. Is that really the Utopia they want?
“Is that really the Utopia they want?”
Apparently so. The green idea of pastoral heaven appears to be wall-to-wall windmills. Perhaps after a while they get to be like telephone poles, you don’t really notice them.
The greens also claim that diversified power generation systems will empower local communities. I can’t really see how a wind farm in your back yard owned by a multi-national corporation is going to accomplish this though.
The link to the greenpeace report from which I quoted the power generation figures is:
http://www.greenpeace.org/australia/resources/reports/climate-change/just-transition-report
It describes how by 2020, newly unemployed coal miners and power station workers in the Hunter Valley will all have funky new sustainable jobs installing solar panels and manufacturing wind turbines.
This whole discussion misses the point. The only “green” in wind power is money; what is “green” about a feckless, unreliable source of electricity that requires the total devastation of a countryside or shoreline for dozens of km in order to generate a piddling amount of power (say, 50 MW)?
These wretched monstrosities are disfiguring the landscape and destroying habitats — both human and wildlife — on an incredible scale all over the world. Germany and Denmark, the most turbine-ridden countries in the world, have halted all new installations; E.On, which operates Germany’s grid, fears that much more from turbines will destabilize the grid; Denmark has to export nearly all its wind power to the much larger grids of Norway and Sweden because its own grid can’t take the rapid variation in output from all its turbines.
Wind turbines are simply a method of vacuuming taxpayers’ — and ratepayers’ — money into the pockets of international financiers; that is all they do. As actual commercial power sources, they manage to actually be WORSE than useless.
CO2 is not a pollutant. “Wind power” is a fraud based on a lie.