Sunday Times : "Urban greens struggle with windy dream"

David Hansen wrote:

No, but thats what wind turbines produce.
So they won't help me reduce my massive fuel bill much will they?

Yawn. Son, I am way ahead of you.
Done just about every sort of calculation possible on energy use for this house..it was my own design.
Anything a wind turbine could do is utterly and completely trivial compared with half a dozen other things I could do at far less expense.
Like a new chainsaw blade. That will save me a few hundred this winter..I have a couple of blown over trees to be cut up ...

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On Mon, 13 Nov 2006 10:40:09 +0000 someone who may be The Natural

So, your calculation didn't tell us anything particularly useful then.

Indeed.
Not your bill for heating. As you admitted above, you don't heat the house by electricity. However, it will reduce your bill for electricity and it will make a contribution to reducing greenhouse gases.

In note that you were unwilling or unable to counter the point I made.

That doesn't surprise me in the least, which is why groups like Friends of the Earth recommend doing other things first and only going for a wind turbine after doing those other things. This isn't a change in direction on their part either, they have always spoken about reducing consumption first.
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David Hansen, Edinburgh
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On Sun, 12 Nov 2006 22:06:43 +0000, David Hansen

Unfortunately that check is being carried out by the sellers using a calculator which is wildly inaccurate for over 80% of the population in the UK.
--
Peter Parry.
http://www.wpp.ltd.uk/
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On Mon, 13 Nov 2006 10:37:59 +0000 someone who may be Peter Parry

The limitations of the model are well known, not the least because they are stated by the modellers. I would be delighted if a better model was available, perhaps just of the larger built up areas, though I can hear the whining from some if this was funded.
In the meantime when people ask me about such a turbine I put it in the context of other things and advise a small weather station, which I have mentioned here before, as a means of determining the likely output.
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David Hansen, Edinburgh
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On Tue, 14 Nov 2006 09:07:13 +0000, David Hansen

They are not known to the poor sods being conned into buying this rubbish.

They are available, it just that few in the UK seem to want to use them. The Wind Atlas Analysis and Application Program (WAsP) shares the same design characteristic of NOAB in that it copes best with low, smooth hills of small to moderate dimensions. However, unlike NOAB it includes compensation for surface roughness. It is by no means perfect but it is more accurate than NOABL in urban environments.
The Danes have used it to map urban areas in Denmark in some detail taking local terrain and roughness into account. As I have said before the results can be downloaded from their web site in standard map overlay form for anyone to use. The overview map is at http://www.windpower.org/en/tour/wres/dkmap.htm

What is to fund? If you are really that interested in objective analysis as opposed to greenwash pop down to Edinburgh University Institute of Energy Systems, they have had a copy of WaSP there for over 5 years. Wind Prospect in Castle Street are also users.
However, you can easily add surface roughness calculations to NOABL data and the Danes have provided a (free) calculator to do this at
http://www.windpower.org/en/tour/wres/calculat.htm
using this it is easy to correct the NOABL figure to take into account surface roughness, although this still leaves the basic accuracy of the wind measurement as an uncorrectable factor. As I am sure you know only 22 measuring points in the UK and 200 over all of Europe are used as the basis for all these models.
Published work on urban wind generation include :-
(The Ealing Urban Wind Study from the Centre for Sustainable Energy) At a mast height of 35m they found a predicted average wind speed of 4.4m/s and calculated a wind generator at this height would be motionless for 21% of the time [no real measurements were taken in this study]. The major revenue was calculated to come from subsidies in the form of ROC's and LEC's. The payback period exceeded 50 years. "As is typical of urban areas, average wind speed at the proposed site is significantly lower than that normally encountered in rural, less built-up areas, where turbines are usually sited. Energy production and turbine load factor will therefore also be low."
(ESRC Working Paper Number 2006/1 Economic Analysis of Micro-generation Deployment Models) "The corrected average wind speed for the urban environment varies between 2.66 m/s and 4.09 m/s. Annual electricity generation is therefore quite different. In our modeling a 1 kW device (under optimistic assumptions) will hardly achieve an annual electricity output of more than 1,000 kWh (site: Aberdeen) and can be as low as 100 kWh (site: Coombe 2)"
[if a wind generator cannot reach the subsidy level (ROC) of 500kWh/yr] it would take more than 60 years to payback. Our data sample suggests that most of the micro wind output is consumed on-site. This is contrast to previous studies that assumed that 60% of micro wind output will be exported to the grid (Energy Saving Trust, Econnect et al., 2005)23."...
"The modelling results used in this paper suggest that payback times for micro wind turbine installations are greater than manufacturers’ estimates."
John Shore of Resource Research “The public have a right to know that most of the media hype surrounding this subject is based on wishful thinking and not on realism. The situation has been made worse by two or three companies who hope to exploit the issue of climate change by making unrealistic performance claims for their products. Wind turbines are very useful green electrical generators, when placed on windy sites at least 10 metres above any obstruction within 150 metres. A 1 kW turbine with a blade diameter of at least 2.5 metres can produce over 3000 kWh/year in a windy field, but will struggle to reach 700 kWh/year on a roof-top. My personal experience of roof-top wind turbines are that they very rarely make a serious contribution to the energy needs of a dwelling, especially in urban areas. Very few of my customers who have mounted turbines onto buildings have been pleased with the power output.”
--
Peter Parry.
http://www.wpp.ltd.uk/
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Can I thank you Peter for your excellent evidence & fact based contributions to these threads ;-)
Incidentally, the figure mentioned above for the "Combe 2" site mirrors the calculation I did from my own weather station data. 100kWh gross, 50kWh net over a year (1kW turbine). Still better than the poor chap in the Sunday Times article that made 10p in two months!
--
steve

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Another thing that is misleading is the use of the Rayleigh Curve or Weibull distribution for average windspeed.
<http://www.windsave.com/page.asp?partid ™>
Intuitively its wrong, _no_ periods of zero wind? Come on! While it doubtless applies at typical, wind rich, commercial sites, for domestic situations its way off the mark, as shown from my own data.
Wind Av Equivalent DAYS mph per year 0 55.2 1 41.4 2 39.7 3 39.4 4 38.6 5 37.5 6 30.1 7 23.1 8 17.7 9 12.7 10 9.9 11 6.9 12 4.1 13 3.0 14 2.1 15 1.3 16 0.9 17 0.5 18 0.3 19 0.1 20 0.1
This is an analysis of the whole of 2005, recorded average wind speed in 10 minute intervals. Collected by a Davis Vantage Pro anemometer, mounted 8 feet above the end of the roof ridge of my bungalow in the middle of Yorkshire.
Intrigued by the energy that may be available in gusts, on a moderately windy day I observed the weather station readings for 10 minutes, noting every 2.5 second sample of wind speed.
Instant. Wind No. of mph samples 0 1 1 1 2 5 3 19 4 8 5 19 6 34 7 23 8 14 9 10 10 23 11 16 12 23 13 12 14 9 15 1 16 4 17 3 18 9 19 3 20 4 21 2 22 1 23 0 24 0 25 1 26 1 27 0
Average for that period recorded as 9mph, peak 26mph Now that is more or less Wiebull shaped, although there are sampling/conversion anomalies in the data.
Now before I get labelled as an "anti" again, let me say in a (much) more exposed site I would be watching the technology very closely. But not for this semi-rural site!
Someone I know, about 8 miles away, until recently used a wind turbine for a fair portion of his electricity. He has a good site, on sloping ground exposed to the west, house built on somewhat of a mound, 30-40' lattice tower in the back yard. Wind and an occasional diesel genny provided all his electric, but he had to be very frugal, gas fridge, solid fuel cooking/HW/heating, 12V portable telly etc. Old age has now forced him to finally have a grid connection for a few of life's comforts.
--
steve

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On Tue, 14 Nov 2006 21:13:57 +0000, Steven Briggs

The quoted numbers above is interesting and I'd hoped someone with a grasp of statistics would comment. For myself I can only see a method to indicate the likely utility of power generated under your conditions if I can work out the instantaneous energy available in the wind, so your ten minute samples would be good for this, about 52000 entries?
I'm more interested in seeing how closely I can match wind generated electricity with my own use and minimal reliance on batteries or grid supply rather than an exercise in exploiting subsidies.
AJH
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.. and you're willing to invest £1500 in doing so??
Let me send you my Paypal account details. I have a great opportunity for you.
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AJH wrote:

I would say the short answer is you would be far better off with photovoltaic cells.
I fly model planes, and just about any hour of the day, I am fairly aware of the wind speed. Its usually around 7-12mph, and anywhere near the ground, extremely variable. Especially at dawn and dusk, where there is a boundary layer up to about 50 feet then a smooth transition to proper wind at 1-200ft.
winds in excess of 10 mph at anything near the ground are extremely rare..thats the sort of day when you notice it is 'quite windy'..and the days when its over 30mph are probably less than 10 a year.
That's is out in the country. In town its even calmer.
I don't say that someone up on a high moor with no trees around can't make a go of it, but not the rest of us.
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wrote:

I don't expect people to remember an occasional poster's comments but this is essentially my view, previously expressed, also. I also am optimistic about the contribution solar thermal and PV might make as fuel prices rise. In the meanwhile I do make cost effective use of renewable energy for heating.
I can see from Steven B's posted figures that 55 days equivalent without wind annually is difficult to reconcile with power on demand but I am not clever enough to make a judgement on the data as presented and I would like to see the full dataset to give an idea of the time constant involved.
I've seen how "incentives" to produce electricity have skewed the renewable energy market so I want to look at things fundamentally, I don't accept the biased views of a certain globetrotting, perennially unhelpful, poster should influence such an enquiry.
AJH
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AJH wrote:

I think if I went away from oil/electric here, I'd probably lay out solar panels, and maybe a small mill on a tower, and try and set up a heat pump to freeze the garden and heat the house.
I wouldn't expect to replace it, but bill reduction is always good. The houseis large and te requirements for airchanges make an upper limit to what insulation is worth applying..a heat exchanger would help..
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wrote:

I have no chance of a turbine at home, too built up and very small semi detached house, I will be doing solar dhw. Not being an economist I tend to a simple rule, I need a rate of return on investment of >10% and a minimal maintenance life exceeding 10 years before I'll jump. This means capital spend must be kept low.
The reason for my interest in the wind figures is because niches do exist where they appear to have a decent payback. Now the heatpump powered by such a device with some intelligent, but simple, switching appears to be a means of getting better utility out of the unscheduled supply from the wind, for both heating and cooling. On a first stab at it it seems likely that 33% of the power supplied will be at a time when there is minimal electrical demand, what price do we put on that. It looks likely to me that a system that puts a value on, and uses, all the wind generated electricity will trump the higher cost of a UK 83 compliant grid inter tie and "spilling" the electricity to the grid.
Again the scenario I am working to is that grid connection is existing, there is no credit from the grid electricity provider for "spillage" and ROCs cannot be claimed (though this point may be debatable). The building is an isolated house sitting in a hectare high up near Exmoor, its owner has no truck with renewables but will accept an economic argument. Given the above how valuable is the wind generated electricity assuming a site with a resource able to generate 30% of the installed capacity over a year ( whether this is the case will only be demonstrated by a trial)? Then how much will it cost in installation and maintenance.

Yes, I have a simple wood stove which I need to ash out weekly and light daily, I still make use of the convenience of a gas central heating system that switches itself on.

I think it is perceived wisdom that making best use of what ever energy source you have is the first step.
AJH
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On Wed, 15 Nov 2006 23:01:17 +0000 someone who may be AJH

I think one needs to differentiate between the two. Solar thermal is now on the verge of becoming mainstream. OTOH PV is still something for those who wish to encourage the market. Given some years PV will also move to the mainstream, but it isn't there yet.
A 1kW panel, made from 50 x 20W panels would cost £3750 and cover an area of about 6m x 2.5m with fixings. http://www.navitron.org.uk/photovoltaic_solar_cell.htm
That's just the panels, a figure of £6000 per kW is given for the array at http://www.atob.org.uk/Climate.html installed.
By contrast a 1kW wind turbine is £725 http://www.navitron.org.uk/wind_turbine.htm
Obviously to the £3750 and £725 figures one would need to add an inverter and mounting.
The amount of electricity one would get out of each depends on where it is installed. PV works better in southern England, wind varies around the UK.
In the UK PV is not well matched to maximum demand, which tends to occur in winter after dark. Wind output is generally higher at times of maximum demand.

The large scale incentives are engineering neutral. Obviously this means that operators have chosen the most mature engineering, onshore wind (together with some work on hydro). However, one can also argue that wind demonstrates that renewables work and this encourages investment in other forms of renewables.
The small scale incentives are largely engineering neutral. The big exception is that there is a much higher grant for PV, in order to encourage the market.
--
David Hansen, Edinburgh
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I've posted all the data in a spreadsheet at <http://www.knaresboroughweather.co.uk/Windanalysis2005.xls for anyone who wants to have a play. (About 4.5meg)
--
steve

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On Thu, 16 Nov 2006 21:05:39 +0000, Steven Briggs
Cheers Steve
AJH
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On Tue, 14 Nov 2006 17:12:01 +0000 someone who may be Peter Parry

"Poor sods" are "conned" into buying all sorts of "rubbish". Why single out wind turbines and moan about the fact that not everyone thoroughly researches every purchase?
Those that do research before purchasing something find out that leaflets can only show a subset of the available information on that something.

"Available" was a bad choice of word, "in use" would have been better.
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David Hansen, Edinburgh
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David Hansen wrote:

We don't. Here we also herald the deficiencies of Saniflos, inappropiate Combi boilers, Toyota Pious' and electrical underfloor heating, not to mention flexible baths, and chipboard walls.

Indeed. Perhaps you should listen carefully to what you just said...
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On Wed, 15 Nov 2006 09:06:46 +0000 someone who may be The Natural

If you could indicate what you are referring to then that would be useful. If you are referring to what you quoted then you are making a large assumption if you claim that I only read leaflets.
--
David Hansen, Edinburgh
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David Hansen wrote:

leaflet covers a broad definition..including learned papers produced by people who have missed some fundamental points.
Nature doesn't get a decimal point moved for example, Scientists can.
If you want to save energy on towns, roof them over. Preferably with something opaque so that they don't spray light into the night sky.
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