Tuesday, 21 September 2010

Misleading arguments

I understand why some people feel that wind farms are unattractive to look at, and can spoil the view. Beauty, of course, is in the eye of the beholder; but some beholders consider them an ugly intrusion. I'm also aware of the problems which local communities can face during construction - we saw that for ourselves during the recent construction of a wind farm just up the road near Alltwalis. And I know that there are some unresolved issues surrounding noise in some cases which can cause major problems for some residents.

But most of the other reasons used by those campaigning against wind farms - particularly when they attempt to stray into technical areas - seem to be exaggerated, wilfully misinterpreted, or else just plain wrong. It's a pity, because it can mean that genuine and valid concerns about specific sites can end up getting lost in an ill-informed debate about the principle.

Today's letter in the Western Mail (Danish lesson) is a case in point. To read it, one might conclude that both the Danish Government and its power company have decided that building onshore wind farms was a huge mistake which they have now come to regret.

However, as this report shows, that is significantly at variance with the truth. But why let mere facts get in the way of a good piece of rhetoric?

12 comments:

Siônnyn said...

I am not one who objects to wind turbines on aesthetic grounds - In the right place I find them rather majestic pieces of engineering. Rather handsome in fact.

However, some years ago, in order to be better informed of the issues so that I could defend them against the NIMBYS, I began to look into the Economics, and I have been able to find NOTHING that suggests that they make any contribution at all to reducing the carbon emissions in this country. The Carbon debt that is built up in the manufacture, transportation and commissioning of these turbines is very significant, - and the carbon released by the peat displaced in the locations where they are built, and the trees that have to be removed (Brechfa, for instance) is highly significant.

They only have a design lifetime of 20 to 30 years, and the cost of de-commissioning them is never taken account of.

The quoted efficiency is always over stated. In some areas the load factor (ie actual as opposed to theoretical output) is as low as 16%, though all the figures quoted in their support assume a near 100% efficiency. Also , I never see figures included for the infrastructure needed to bring the generated power to the grid. (Transformers, pylons, etc) Nor allowances made for transmission losses which are inevitable given that the sites are almost always a long way from the source of demand.

Add that to the intermittent nature of the wind, and the need for spinning ( carbon or nuclear ) reserve capacity , and I have been unable to draw any conclusion other than they are a futile 'feelgood' gesture towards carbon reduction, and they are compromising one of the last natural resources that we have left in Wales - our natural scenery.

If we could capture and store the energy produced at times of low demand, then the equation might change. But at present, we don't have the capacity.

If anybody can point me to any definitive sources that would lead me to a different conclusion, then I would be very grateful, because I really don't want to be spoilsport, , but in the meantime, I remain a wind sceptic.

John Dixon said...

Siônnyn,

Will do my best to answer the points. You may find this, this, and this useful in general terms as a response to some of the points you raise. I've relied quite heavily on the last of those in responding to the detail of your questions, partly because it's pretty recent work.

Forgive me if I paraphrase your questions just a little before responding to some of the detail.

”Wind farms don’t reduce carbon emissions”

This may help.

”Carbon cost of manufacturing, transportation and de-commissioning not included.”

In energy terms, the payback from a turbine is around 6 months; even including construction costs etc, the payback will be around 2-3 years.

”Quoted efficiency overstated”

I think you mean load factor rather than efficiency, here. There is general agreement that wind farms run at around 30% of quoted capacity on average. But so what? The important question is whether they still pay off, in economic and environmental terms, at that level of performance – and they do. But the infrastructure – power lines etc. – has to be designed around their maximum capacity, because at some times, they will generate at that capacity.

Incidentally, ALL generating equipment produces at less that 100% capacity, since all capacity is subject to maintenance, and some capacity to being turned off when not required. The load factor of conventional power stations is around 50%.

And thermal efficiency is another factor. The CCGT power station being built at Pembroke may generate a higher percentage of its stated capacity, but the thermal efficiency will be around 40% - i.e. 60% of the energy in the gas burned will be lost as waste heat. I’d worry far more about that loss – which is directly producing carbon emissions, and which will cause consequent heating of the water in the Haven – than about the fact that a wind farm will only produce at an average of 30%.

”Intermittency needs spinning capacity”

All generating capacity needs backup; the Grid needs to be able to deal with a failure of any component. And if a 2GW nuclear plant fails, then there needs to be a spinning capacity of 2GW in place. Failure of a ‘traditional’ plant is a more serious failure than a reduction in wind speed; the former is sudden and unexpected, the latter more gradual and predictable within limits. This is a good analysis based on National Grid figures

Spirit of BME said...

You quote "National Grid figures" , well, that must be right ??!! or are they singing from the same song book as HMG in order to stay on message.

Sionnyn points are well made - I like the cut of his jib.

Mr Dixon, you must have a garden ,so how many of these big turbines do you want .

John Dixon said...

Spirit,

I suspect that the people at the Grid know a little bit more about balancing electricity supply and demand than you or I do, but if people prefer to believe those without that expertise, I can't stop them.

The garden isn't big enough for a really big turbine, but there are a few just up the road with more to follow.

Siônnyn said...

John - thank you for your reply.

I have seen most of your links before, and recognise the 6 months carbon payback time for a wind turbine from the the Wind energy association - which is a trade body, but when I questioned them, I was unable to get any convincing data to back this up.

The friends of the earth, and other lobby groups desperately want win to work. We'd all like that, but statements like an x Mw wind farm COULD power y households really mean nothing in real terms. There is an awful lot of wishful thinking in these papers.

As far as balancing the grid in concerned - yes there are well developed methods of predicting demand , but in the case of Wind alone, there is no good way of predicting supply.

Down time for maintenance in traditional generators is predictable, and so can be managed. Catastrophic failures are very rare. But in the case of wind-generators , a sudden drop in wind can cause widespread chaos on the grid, as happened in Europe in 2005, when a large part of Europe went dark when the wind stopped in Denmark and Germany suddenly and simultaneously.

The other problem, of course, is that it is the peak demand that has to be covered, and out of the 30% load factor that you quote, it is likely that only a part of it will be available at peak demand times.

There is a paper HERE, that seems to me bit more dispassionate than your sources, which paints a very different picture.

We need more pump storage schemes that will allow us to sore off-peak energy. I agree that a move away from carbon based generation is desirable in the long run, but it seems to me that the rush to wind seems to have been based more on emotion than sound economics.

Of course, the big scandal is that the Tidal Lagoon proposed for Swansea bay, which would have produced electricity for 20 predictable hours a day, was scuppered by Andrew Davies and the DTI, who were smitten both by Wind and the prospect of the Severn barrage. The tidal lagoon, and the dozens which would have followed it around the coast of Wales, would have been a truly visionary step for Wales to have taken, and would have cost the taxpayer NOTHING (it was fully privately funded) yet Andrew Davies refused to even discuss it with the company, Tidal Electric, who have now gone on to do schemes in Canada, China, and I believe, Russia.

John Dixon said...

Siônnyn (Part 1),

I accept that many of the arguments which I use in support of wind energy come from groups and organisations which support its use. That doesn’t necessarily mean that the arguments are wrong, though; just that any arguments from vested interests need to be subject to a degree of scrutiny.

“As far as balancing the grid in concerned - yes there are well developed methods of predicting demand , but in the case of Wind alone, there is no good way of predicting supply.”

Wouldn’t entirely accept that. The weather is forecastable up to a point, and the wind doesn't just stop. Indeed, electricity (and gas) suppliers have been using forecasts for many years to plan the addition of capacity as and when needed. The processes for doing that have grown ever more sophisticated, and the provisions in place (even without the addition of wind energy to the grid) have long included the concept of ‘interruptible’ supplies. Plus, I don’t think anyone is suggesting an energy policy based on ‘wind alone’.

”Down time for maintenance in traditional generators is predictable, and so can be managed. Catastrophic failures are very rare. But in the case of wind-generators, a sudden drop in wind can cause widespread chaos on the grid, as happened in Europe in 2005, when a large part of Europe went dark when the wind stopped in Denmark and Germany suddenly and simultaneously.”

What’s your source for this? I’m aware of an urban myth about a failure in November 2006 which some tried to say was caused by a sudden failure of wind, but nothing in 2005. (Although I understand that subsequent investigation put the 2006 incident down to the action of E.ON turning off a power cable, causing a series of consequential problems.) The wind simply does not stop suddenly and simultaneously across such a large area.

John Dixon said...

Part 2

”out of the 30% load factor that you quote, it is likely that only a part of it will be available at peak demand times.”

I think that’s a bit of an oversimplification. There will be times when 100% is available at peak periods, and times when 0% is available at peak times. On average, 30% will be available at peak times from any one turbine. The calculations shown in one of the links in my previous comment show how this is taken into account.

”There is a paper here that seems to me bit more dispassionate than your sources, which paints a very different picture.”

Different picture, certainly – but more dispassionate? That sounds like a subjective rather than objective statement. And the organisation which published this piece seems to have a number of links to the oil, gas, and nuclear industries. That does not invalidate his work, of course, no more than the fact that the sources I used came from supporters of wind. I haven’t had time to go through the detail of what he’s written and the sources he quotes, but will try and do so.

”We need more pump storage schemes that will allow us to sore off-peak energy. I agree that a move away from carbon based generation is desirable in the long run, but it seems to me that the rush to wind seems to have been based more on emotion than sound economics.”

Don’t agree with the second part of that, but accept the underlying point in the first part. The more we depend on renewable energy, the more we need to ensure that we have means of 'storing' electricity, so that off-peak production is available to meet peak demand. The algorithms behind the balancing are complicated, but I think that the principle is clear. At what point it becomes a problem is a matter of debate – the National Grid figures seemed to suggest that at the current proportion of total supply it’s not too big an issue, but the greater the proportion supplied by wind (in particular) the greater the issue is likely to become. (Phil Williams suggested in a paper to the Assembly that we shouldn’t depend on wind for more than about 15% of total demand, by the way.) Pumped storage isn’t the only ‘storage’ option open to us, of course; electrolysis of water is another.

”Tidal Lagoons”

On that, I think we can agree! I think we’re missing a trick, and should have gone for this earlier. It seems to me at times that governments are obsessed with ‘big’ answers (such as the barrage, or nuclear power), without recognising the potential of a range of smaller schemes to provide more dependable power with more resilience.

Siônnyn said...

Diolch eto, John, for taking the time to reply in detail to my post.

Now in no particular order ( because this particular editor makes it hard to copy the original and comment as you have - so you must either have wonderful patience or be using an alternative editor!) , I will go through the points.
2006 - I was doing it from memory, and my source for it being a drop in the wind (which did happen, I believe, at the time) were reports circulating at the time including on the mainstream media. I haven't really been aware of any updated evidence since then, so you may be right. But the fact that the original hypothesis was considered plausible should at lest act as a warning.

I know also that the new integration of the European grid was bound to cause some problems.

Veracity of sources you are right - my source comes from a site concerned with all energy sources, but bear in mind that the big oil companies are investing huge amounts into making sure they have a future after peak oil, and have nothing to fear from what will always be a marginal source, like wind. The sources you quoted were, for me, a but to full of polemic, and light on facts. As I said - we'd all like to see this work, but we really need to base decisions on data, not just theory and high hopes!


30% Peak time generation

So your 30% is 30% of the load factor = 9% Since this is the only really useful electricity that is being pumped to the grid (the rest going to earth) shouldn't that be the figure that the economics are based on?

Siônnyn said...

Weather Forecasting

Now in terms of demand, the weather forecasts, are of course very good, as the periods of time are longer. But in terms of supply, we are still al long way from being able to say 'the wind will blow at between 15 and 35 knots (the operating speeds of the present generation of turbines) over Brechfa between 4:30 and 7:00 tomorrow'. Let alone the next day.

emotional decison making OK - perhaps I was over stating it a bit - but I am sure that a lot of this was motivated by a consensus that 'something must be done'! And I am also still concerned by the lack of good evidence being published as to the ACTUAL performance of wind farms in reducing CO2. No it's true that it is a couple of years since I looked into this in great detail, so if you know of anything recent and independent that analyses this, please let me know. please let me know.

BTW, there is another source of energy storage which I saw in Scientific American recently - Literaly spinning flywheels floating on super conducting magnets in a vacuum. Probably not hugely efficient once you take into account the energy needed to cool the magnets, and maintain the vacuum, but if we are using energy which otherwise is just going to be earthed, then why not? And each wind farm - or even each turbine, could have its own! Now that I can see working! I'll post a link when I've gone through my back copies of Sciam.

On tidal lagoons - the whole thing is a scandal, and needs a tenacious investigative journalist to unearth the whole story, and put it together for publication. I have sources, including a direct line to the MD of tidal Electric, who was very very keen to see this started in Wales. so if you know of anybody - please, let me know!

Now championing tidal lagoons, I would suggest, would be a brilliant addition to Plaid's green portfolio!

John Dixon said...

Siônnyn,

”But the fact that the original hypothesis was considered plausible should at least act as a warning.”

I think it says more about the dangers of the internet. As I recall, a blogger in Texas started the story about it being down to a failure of the wind, and that got picked up and spread. Whilst I'd like people to totally trust everything I put on my blog (of course), the truth is that not all internet sources are reliable -and repetition is no recommendation.

”So your 30% is 30% of the load factor = 9%”

No. It’s 30% of the nominal capacity. At peak times, the turbines will generate at a load factor of anywhere from 0% to 100%, depending on wind conditions. On average, they will achieve 30% load factor; the fact that it's in peak hours doesn't change that. Sorry if that was less than clear.

”we are still a long way from being able to say 'the wind will blow at between 15 and 35 knots (the operating speeds of the present generation of turbines) over Brechfa between 4:30 and 7:00 tomorrow'.”

True. But we don’t need to be that accurate either. Balancing supply and demand is a complex process which works at different levels over different timescales. It’s an example of how campaigners can take a perfectly true statement and make more of it than is justifiable.

”And I am also still concerned by the lack of good evidence being published as to the ACTUAL performance of wind farms in reducing CO2.”

That’s a point which I understand. And it isn’t an easy one to answer, Not least because it's not something which is being measured accurately enough. And it doesn't help that demand for electricity isn't constant either. We can be certain that electricity from wind turbines is entering the grid, and having entered the gird it is being used. It is therefore either meeting an increased demand or else displacing electricity produced from other sources; in either event, it is a lower carbon alternative.

The part which is very hard to pin down conclusively is the extent to which the high-carbon plant whose electricity is thus being displaced is shut down (thereby directly reducing carbon emissions) or remains on standby (therefore still contributing to carbon emissions). Gas plants, for instance, are easier to shut down and start up than coal or oil plants. The argument that wind contributes nothing to reducing emissions depends on the second scenario being true (and/or some assumptions about the additional carbon costs involved in starting and stopping plant). And, from my initial reading of the link in your previous comment, that second scenario is the basis of the argument advanced therein.

This link discusses part of the issue. It’s a technically complex issue; it would be nice to have a clear, undisputed answer to the question on which all sides could agree rather than each side picking its own ‘experts’, of course. I’m clear that moving to a renewables-only energy policy is the right thing to do, and I think that the evidence is there to show that it works.

”Now championing tidal lagoons, I would suggest, would be a brilliant addition to Plaid's green portfolio!”

And it already is in our energy policy. What attracts me to lagoons rather than a single massive tidal scheme in the Severn Estuary is the huge tidal range around the Welsh coast. Since tidal flow approximates to zero twice in every cycle (high tide and low tide), or four times a day, using the tidal range means that there will be some production at every time of day, and that tidal can therefore contribute more reliably to baseload.

John Dixon said...

Siônnyn,

I’ve now had an opportunity to look in more detail at the link to which you referred me. The argument put forward by the author seems to depend heavily on two studies by others, and on a mathematical model built by the author himself, and referred to as the 'Calculator'.

I cannot really comment on the output from the ‘Calculator’. Like any mathematical modelling tool, it will inevitably have, embedded within it, a series of assumptions. Since those assumptions are not stated in the article, they are not directly open to challenge, even if I had the time to go through them in the necessary level of detail. Note that I'm not saying that they're wrong; merely that they're not open to scrutiny on the basis of the information that I have.

The two studies, on the other hand, are available for review, and I'll come to them in the following comment (I seem to be hitting some limit on comment length...).

John Dixon said...

Part 2

The first paper concludes that there is no fuel saving or CO2 reduction as a result of the addition of wind power to the grid "in the case when these conventional power stations are required to compensate wind electricity variability", and it is quite clear that they assume that variability to be both significant and sudden. The paper seems to be also assuming that any variation to the output of conventional power stations as a result of wind variability is shared across all such power stations (i.e. that all of them reduce their output by a similar percentage). And it makes the assumption that “A wind farm with a 25% duty factor requires a back up station with four times the power of that belonging to the actual electricity produced by the wind farm”.

I'll admit that I haven't checked all their mathematical formulae in detail to see whether the conclusions which they’ve drawn from those assumptions are correct. But I would challenge all three of those assumptions. And unless the assumptions are correct, then any conclusions drawn from them will be open to challenge. I tend to have an instinctive distrust of governments, so their statements that ”The Dutch government uses an incorrect formula for calculating the fuel and emission saving from wind energy. On this subject parliament has been incorrectly advised by government.” are not ones that I would instantly reject. But they should cause us to at least pause for thought.

The second study states clearly that it was “Prepared for Independent Petroleum Association of Mountain States”, and seems to have been written to help that organisation in a campaign against the introduction of RPS (Renewable Portfolio Standards). Doesn't invalidate it, of course, but it does mean that it could hardly claim to be an impartial report.

Again, the report is based heavily on an assumption of fuel and carbon costs associated with cycling plant, where cycling is defined as ”sudden increases or decreases in power generation output”. That, as noted above, is open to challenge, since sudden changes are more of a demand-led issue than a supply-led one.

More specifically, as this passage indicates:

”The underlying problem is the same for both PSCO and ERCOT: the generation capacity of wind resources has become too large relative to the capacity that is available from coal and natural gas facilities. Natural gas-fired combustion turbines and combined-cycle facilities are designed to accommodate cycling. Because gas resources are insufficient to offset all of the wind energy produced in PSCO and ERCOT, coal units must be cycled to counterbalance the amount of wind that cannot be offset by natural gas. As a result, when the wind energy is generated at a high enough rate, PSCO is forced to scale-back generation from its coal-fired resources. But, coal equipment is not built for cycling. Coal boilers are designed to be operated as a base load resource – in other words, to operate at a consistent output level all the time. Cycling causes coal units to operate less efficiently and reduces the effectiveness of the environmental control equipment, substantially increasing emissions.”

the issue revolves around the high dependence on coal powered stations in the areas concerned. In short, the problem isn’t one related to wind energy per se, but the nature of the balance between the currently installed alternatives. Now, that doesn’t mean that it isn’t an issue, of course. It does mean though that we should recognise what the real issue is, and be careful about extrapolation of the finding to other scenarios.