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This page is open for moderated public comment. Please put your comment at the top of the page, and sign it with name and address, otherwise it will not be noticed, or not accepted. Note that you can also send your comment directly to the wind farm company: http://www.totnescommunitywindfarm.com/Totnes_Community_Wind_Far_1./Contact.html The intermittency of wind powerIan Bright, Managing director of TRESOC writes, 9 February 2012 The national grid has spare generating capacity or backup to deal with fluctuating demand, e.g. when the nation's kettles are switched on at the end of a favourite TV programme, or to deal with the unscheduled shut down of a large power station. Wind turbines feed power in to the grid continuously all over the country. There is never a period when there is no wind at all in the UK so the total output of electricity from our wind turbine fleet is continuous and varies quite smoothly over time. The UK grid operator National Grid Transco reports that "... intermittency of wind does not appear to pose major problems for stability". Other grid operators in Europe are able to manage much higher levels of wind power in their networks than we currently produce in the UK. Those with the patience to develop an understanding of this complex subject are recommended to read the BWEA Briefing Sheet: Wind Power and Intermittency Tim Padfield writes, 8 February 2012 Wind power - is it useless, inefficient, expensive, variable, needing 100% backup, subsidised and ugly?The last of these pejorative adjectives is subjective. I won't try to persuade. The other accusations are merely insults unless the utterer can provide evidence that they are true. It is a shallow response just to repeat the opinion of people whose only speciality is having opinions: the Duke of Edinburgh, The Daily Telegraph, the 100 MPs who recently (5 Feb 2012) sent a letter to the PM, and our local dogmatic lobbyists. In this post I try to bring some rationality into the debate by describing how the electricity supply operates, with and without wind energy.  The conventional power stations linked together in the UK grid provide a constant and adequate capacity. It is about 80 Gigawatt (GW). The Giga means a billion times the watt, which is the scientific unit of power. Power is the instantaneous rate of conversion of energy into action. If you push your bike up a hill slowly you will exert less power than if you push it up quickly, but the total energy used to reach the top of the hill will not be significantly different. The total energy expended, measured in slices of bread and jam, can be transformed, for cross-fuel comparison, into watt-hours: the power multiplied by the time during which it is exerted. In the diagram, the instantaneous power being drawn from the grid, which must always exactly match the power fed into it, is indicated by the fluctuations of the red curve bounding the orange area. The energy, which is equivalent to the fuel consumed, is represented by the orange area beneath the curve. The electric power available to the UK is represented by the horizontal black line towards the top of the graph. The maximum typical daily demand is 65 GW. The first thing to say about wind turbines is that we don't need them to keep the nation's televisions running. The large daily variation in electricity consumption means that at least half the conventional generating capacity must adjust its output to the continually varying demand, because electricity storage is very limited. The agility of the various types of generator to change their output varies. Reservoir-backed hydro is the quickest to react but gas powered generators are also fast to adjust their output, without serious loss of efficiency in energy conversion. The orange area on the graph represents the week's energy consumption in Gigawatthours (GWh). Of this, a constant portion is nuclear, the rest is fossil fuel with carbon dioxide release depending on the ratio of coal to gas and at a price varying with the swings of the market.  In this graph wind generation has been added, as a fictitiously varying contribution averaging about 15 GW. Because the wind can drop below the threshold for generation over a large portion of the UK at the same time, the 80 GW of conventional generation capacity has to be retained. However, no additional capacity need be added, so the often quoted phrase "wind needs 100% backup" is true but not in the sense that every new wind turbine has to be backed by a new gas generator shadowing it. The wind generators cause an additional cost of construction and maintenance. In return, the fossil fuel consumption is reduced to the shrunken orange area of the graph. The wind is not entirely free, since the landowner demands payment for use of the air passing over her land (except that aeroplanes have the legal right to use it). The wind is, however, an inexhaustible and local resource independent of the international market and international politics. Opponents of wind power assert that the frequent variation in power output of conventional generators, to maintain the balance between demand and supply, causes inefficiencies which entirely negate the fuel saving indicated by the graph. However, there are several sober and objective calculations claiming that altering the conventional power output up and down is not a serious waste of energy. It has been done for the last eighty years to cope with the variable demand so there is no particular extra burden in coping also with a variable supply. The magnitude and speed of the fluctuation will diminish as the number of wind turbines increases and as the capacity of the Europe-wide grid increases. At the same time new gas power stations with quick reaction time and good efficiency at part-load will gradually replace the relatively inflexible ancient coal fired ones. The calculations by both supporters and opponents of wind power are so intricate that it is impossible to check the arithmetic without a deep education in electrical engineering, meteorology and statistics. Just repeating assertions by individuals with no special insight is a lazy response that poisons rational discussion over the merits of wind power. Peer review by experts is the only usable guidance. Peer review is not perfect, but it has got science and technology a long way into permeating every aspect of our lives, mostly for the better. Occasionally, particularly in Ireland which has the greatest proportion of wind power installed, the wind power exceeds the demand (the pale blue patch on the diagram), so wind energy is wasted, which doesn't matter, but there is active development of energy storage techniques such as generating hydrogen from the surplus power. (The UK attained its maximum 13% of wind power in December 2011 - a notably breezy period, so over-production is not yet a reality.) To summarise: the benefit of wind, and of the equally variable solar voltaic power supply, is solely in its fuel saving. The fuel saved is not much less than the exact equivalent of the wind power generated, the loss being put at around 3% by various peer reviewed calculations. There would be little point in adding wind generation if there were a guaranteed perpetual supply of cheap fossil fuel and if the predictions of global warming could be proved to be wildly pessimistic. The case for wind power lies in predictions that fossil fuels will become steadily more expensive as they become more difficult to extract, and as other nations increase their demand for energy, and as other nations use fuel supply as a diplomatic and commercial weapon, as has already happened in Eastern Europe. Fossil fuels also use foreign exchange because the UK has used up its reserves of oil and gas in less than two generations and must now wait many million years for the fuel to regenerate by natural processes. Encouraging investment in wind power is therefore an insurance against probable rising fuel costs. Tackling global warming requires coordination between nations, which sceptics dismiss as a utopian dream, but the case for wind power does not rest entirely on the global warming panic, though the carbon saving initiatives in the UK and Europe do give economic support. The economic case for wind therefore rests on predictions, both scientific and political, rather than on current fuel costs. This renders criticism that wind power is useless from an economic point of view a meaningless position to take, since predicting the future according to what one would like to happen has not proved successful in the past. The case for subsidising renewable energy is that it will prove to be the cheap option in the medium and long term. Extra expense incurred now will be recovered in the future and the postulated present burden on the poor of high electricity prices will be reversed. It is the job of our leaders to think ahead rather than react fearfully to intemperate and dogmatic assertions by populist commentators and agitators. Returning to the top line of this post: Useless? - not unless there is a prolonged slump in gas price, an unexpected breakthrough in fusion power, or an epidemic that reduces the human race by two thirds. Inefficient? - a meaningless insult unless the measure of efficiency is defined. Expensive? - to begin with yes but in the long run probably not. Variable? - yes but less so as more turbines are installed and long distance load equalisation between nations with different weather patterns becomes better. Requires backup? - yes but not more capacity than we now have. Subsidised? - yes, but all energy sources are subsidised or penalised by political decisions rather than controlled entirely by free market forces. Ugly? - I leave the aesthetic judgment to the individual reader. In the case of the Luscombe Cross windfarm, I see the wind turbines as graceful evidence of human ingenuity added to the drear, almost treeless and flat agricultural landscape of the South Hams high plateau. The piles of silage under black plastic and motor tyres are also evidence of human ingenuity in exploiting the abundant energy from the sun. This article is improvable, in particular by citations to peer reviewed technical articles. I rely on the readers' help on this. This is a wiki so don't hesitate to contribute directly to this text. Anonymous contributions are not allowed, and all changes are reviewed by the editor before publication. TURBINES - ITS THE ECONOMY STUPID! It is strange that the approach of Industrial wind propagandists is to argue in small details for their cause when their over-arching ambition is of the vastest scale imaginable - the reduction of the temperature of the PLANET'S atmosphere. We therefore get mired in debates as to whether a pair of 300 foot high moving structures will have a high degree of visibility in open countryside or what noise they will make, how many buzzards or bats will be killed etc. The straightforward fact is that UK wind turbines will not measurably reduce the CO2 content of the atmosphere, any impact they do have and there probably is some will be completely drowned by the carbon effects of increasing industrialisation, urbanisation and de-forestation of India China and other BRICS. The amount of CO2 prevented from emission by UK renewables policy and its ultimate chemical impact is therefore very hard to quantify given the inefficiency of ramping up and down base load generation and a myriad of other factors. What however is completely clear is that wind turbines generate profit for those who opperate, build, distribute and host them and also financially benefit the enire carbon "trading" merry go round. What is equally clear is that all these people have absolutely no responsibility for their claims, if wind fails to lower the temperature of the earth nobody will be asking for or getting their subsidy money back from Vestas. The wind lobby will claim that this financial no money back risk has to be taken and that it is only a strange sort of co-incidence that whilst claiming to be holding back the rise of the oceans and saving the planet they just happen to be making a ton of cash. People always bring their favourite statistic to these debates mine are these produced by the "highly respected" Energy Information Administration and published under the aegis of the Guardian. Per/capita production of CO2 in 2010 : UK 8.35t Denmark 9.01t Germany 9.30t Given the claimed cabon reducing impact of industrial wind it should seem strange to an indeendent observer that Denmark, the most turbine crazy nation in Europe produces more of this "pollutant" than we do. [Tim Padfield interjects: This paradox is easily explained: the European carbon trading scheme allows power companies that reduce their CO2 emission, through wind or solar voltaic, to sell their surplus carbon emission certificates to a cement manufacturer, for example, so the total CO2 produced stays the same. Certificates can be traded all over Europe, so installing wind turbines can be accompanied by, but not cause, an increase in the total emission of a country, even though the wind turbine does reduce the fossil fuel used for electricity generation. For a longer explanation see: http://www.spiegel.de/international/business/0,1518,606763,00.html] Lets get closer to home, why in the interests of the Environment has nobody managed to pedestrianise Totnes High Street? Because there is no money in it. Why in the same interest has nobody been stopped from uselessly burning aviation fuel to go shopping or snow-boarding in Dubai? Because there is no money in it. Why do we not concentrate like lasers on saving more energy - because there is very little money in it. Why are we about to litter our green and gorgeous land with 400ft high useless moving structures.....because there 'is' money in it. Rupert Kempley, 15 Newcommen Road Dartmouth. 30 January 2012 Is the variability of the wind a serious handicap to merging wind energy into the national grid?A comment by Tim Padfield, May Cottage TQ9 7TA. 29 January 2012 Ian Phillips has enlivened the letters column of the Totnes Times again (25 January 2012). He doesn't conceal his antipathy to wind farms, and his chosen citations from the technical literature don't give a fair evaluation of the usefulness of wind energy. Over the last eighty years the electricity grid has learnt to cope with the variability, over a factor 2, of the energy consumption of the nation from night to day and from summer to winter, and has also learnt to survive the sudden spikes in demand caused by simultaneous electric kettles heating up after the unpredictable moment marking the end of a Wimbledon final. Now the grid is learning how to incorporate variable sources of power, currently wind and solar voltaic, but surely soon also wave power and tidal power; just about every non-fossil resource except geothermal is inconstant. The UK grid experienced its greatest proportion of wind energy - around 13% - in windy December 2011. This is well within the range of power adjustment that the grid had to manage before wind power was a serious contributor. In the case of Ireland, which has a much greater proportion of wind power to fossil fuel power, there are occasions when the wind power exceeds the demand, so energy is thrown away. The study of the Irish experience cited by Phillips, (which is probably the article put on the internet at http://www.clepair.net/IerlandUdo.html), is not by the Irish generating authority as implied, but by a Dutch researcher. It is densely argued, with many data sources and calculations. It claims to be based on measurement and therefore more accurate than modelling. However, the CO2 production is not taken, as a naive reader might expect, from the fuel consumption but from a circuitous calculation based on the kWh generated divided by the energy efficiency of the generator at its current kW output. This is not a direct measurement. There are many technically complex articles published on the CO2 saving, or waste, from wind farms. Phillips has chosen to cite one article at the extreme range of the many studies of this matter. The article seems not to have been peer reviewed and published in a technical journal - a customary check by specialists on the quality of the research. However, the work of Le Pair and his associates has been reviewed unsympathetically by Michael Goggin http://windfair.net/press/10536.html. Phillips does not make a fair appraisal of the current state of knowledge and does not mention the continuing efforts to incorporate variable energy sources into the grid and efforts actively to control demand from devices which do not need energy all the time, such as freezers and heated floors in houses. He selects only those articles, and those speakers, which support his ambition to stop the erection of a local wind farm. This makes his utterances and his campaign worthless as a guide to informed decision by the local population. Biased and even directly wrong assertions have come also from the proponents of the wind farm so the tone of debate has become strident. The argument that there is a consensus in favour of wind energy, therefore it must be good, clashes with the principle of scientific discourse, where a single person can, and has in the past, overturned a belief held by the majority of scientists. However, the political decision to favour wind energy, and solar voltaic, is necessarily based on a consensus of the views of scientists and electrical engineers, otherwise nothing would ever happen at a national level, or even worse, a single scientist's opinion against the consensus could have a devastating impact on civil society, as with the panic that multiple vaccination causes autism. It requires a long education in power generation and then considerable time and diligence to follow the arguments in the articles cited by Phillips, with sufficient care to judge their accuracy. We are entering a second age of general scientific ignorance, delayed by Wikipedia and the Open Access movement but inevitable because of the huge expansion of science and technology into intricate specialities. An informed judgment on the merits of the many technical initiatives that are affecting our lives is impossible for ordinary people, even those with a technical university education. We have to accept many decisions based on consensus among those who have studied the matter more deeply than we could possibly match. Ian Phillips argues for democratic decisions based on people's opinions, but that counts for nothing if the opinion has been manipulated by unfair presentation of conflicting but deeply technical discussions, to people with no relevant education to enable an informed judgment. In the case of the Luscombe Cross wind farm we can take comfort from the fact that the official attitude to wind power - that it is to be encouraged and subsidised - will benefit our community with a modest amount of money. The local landowner will get a more generous contribution and the local shareholders in TRESOC will get a reasonable return on their investment. This wind farm will surely be the largest generator of revenue in the parish as well as the largest generator of electricity. Ian, if you think expansion of wind power is crazy, take the matter up with your MP, to change policy at a national level. Meanwhile let us accept the current official position - that wind power is not without problems, but will tap an everlasting source of power and reduce our reliance on fossil fuels which we are using up a million times faster than they are being regenerated by biological and geological processes. |