B & Q and wind turbines

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B & Q and wind turbines
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dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Sun Oct 01, 06 10:21 pm Post subject:

People may be interested to see this site
https://www.xcweather.co.uk/
which gives a near real time windspeed map of the UK (and France).

The data comes from airports, so (1) its accurate and (2) its from exposed unsheltered places.

Hover your cursor over an airport wind arrow to get detail (and forecast) for that airport.
Its kinda interesting to see how your local weather compares to Windsave's idea of 5.7 m/sec (12 and 3/4 mph) as a realistic 24/365 average windspeed, and the 28 mph needed for your 1/3 of a kettlepower.

nathanbriggs

Joined: 23 Mar 2005
Posts: 35
Location: Chester

Posted: Mon Oct 02, 06 3:23 pm Post subject:

For those of you that don't remember or haven't seen me before I work with Windsave and helped design the system

dougal wrote:

First, an apology. Windsave *have* now posted a performance curve on their website. The claim is stunningly close to recovering as much energy as is theoretically possible from steady wind. https://windsave.staging.atwwwuk.com/page.asp?partid=99
12.5 metres/second is a Force 6 gale.
Its a strong wind.

This curve is idependantly verified from a wind tunnel test. i.e. constant wind in a constant direction. Its the only fair way to compare any two turbines, but nobody really thinks the real wind is the same as a wind tunnel!

dougal wrote:

Turbines want steady wind, not gusts. Windsave claim that their turbine can respond to "10 m/sec gusts in 20 milliseconds".

Apologies the marketing people got hold of my words and twisted them. The inverter response time is 20milliseconds i.e. it changes its output on a cycle by cycle basis. Clearly the turbine acceleration and pointing into the wind are not part of this time scale!

dougal wrote:

If you have lots of steady wind and no problem with neighbours, do what Dick Strawbridge did with his Windsave and install it on a tall tower well away from obstructions.
Like that, it could potentially pay for itself during its claimed 10 year life. But a proper tower is going to add to the cost...

If I could I would, but Windsave is not quite ready to support this yet. It will come but we have to be very careful with towers. Simply the cost of a tower and in particular a suitable reinforced concrete base pad for a tower is more than everything else combined, in other words it makes more sense with a 5kW turbine than the windsave design. But on my land (if I had any) that's what I would do, but most people don't can't or simply can't afford this option.

dougal wrote:

However, there doesn't appear to any easy way (other than the meter reading and electricity bill) to see just how much, or how little, difference the thing makes. Shame that.

There is a kWh meter on the front which shows the exported energy, a panel in the bottom right with a sexy blue led!

dougal wrote:

I'm frankly confused that Windsave seem to believe that ROCs will be claimable for these units.
Would someone, anyone, *please* explain to me how these can possibly be claimed *without* metering the output using an approved meter?

We are currently campaigning to have the ROCs regulations changed, with the DTI support we have got through the first round of legislation which means a complete change in the Renewables Obligations Legislation is one to two years. In typical governmental fashion Windsave their customers and other campaigners would rather increase the subsidy from 30% than try and change the ROC legislation but the emphasis is on "technologies" that work. The legislative push is towards a lump sum up front to encourage fitting and a reimbursement for succesful generation. This leads to unwieldy, cumbersome funding but it stops previous problems around the world where large subsidies caused people to fit solar panels e.g where payback was in excess of expected lifetime because they could claim back 50% of the original investment but get tax relief on ALL of it!

I will be the first to admit that windspeed is an unmeasured quantity what I hope Windsave will do well is fitting on sites where people definately do have the wind resource and WILL get payback i.e sites taht truly have an average windspeed >5m/s.

However here's the critical point from my perspective.
Today my electricty at home costs 12p per KWh and has gone up nearly 50% in the past 18 months. DTI and other independant predictions (including my own) predict this is a TREND not a blip. In other words electricity prices may reach 30p a unit in 3-4 years, at which point the payback halves to below 3 years. I think Windsave's future is pretty secure

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Mon Oct 02, 06 4:10 pm Post subject:

Nathan, thank you for the detailed post.

The sexy blue led metering wasn't on Windsave's original plan, the white box, or seemingly the wall-mount box pictured now on Windsave's website.
ISTR that for ROC purposes the meter has to be specifically approved. Neither the presence of the meter, nor application for approval is mentioned (that I spotted) on Windsave's website.
If it has an appropriate meter, and generates enough, ROCs would indeed become possible.
Do you know anything about ROCs for self-consumed energy?

I note that you too have problems with Marketing Depts !!

My biggest beef is with Windsave's marketing - trying to sell the thing for urban rooftops, which are generally admitted to be the least suitable locations for windpower.
As you say, mounting it in clean air on a tower would be much better. Not only should it generate more, and make less nuisance, but it also ought to last longer too.
As I have said, I worry that Windsave might do for windpower what the Sinclair C5 did for electric cars, and that having a very obvious whirlygig in an unsuitable location could turn out to be the next 'squarial'.

As regards future energy, and specifically electricity, prices - the outlook is very confused.
Much of the recent rises have been due to increases in UK gas prices - because so much of our electricity seems to be generated from gas fired stations. The pinch point on gas supplies would seem to have passed, not least with the opening this very week of the Norwegian pipeline. Everyone (even British Gas

) is forecasting, and contracting on the basis that gas prices will soon be falling - leading, in turn, to cheaper electricity.
However, the nukes are reaching end of life. Which suggests that generating capacity is going to be the next pinch point.
I'd say prices, over the next 5 years could go either way. 5 to 10 years... well it looks like we'll be getting more nukes, which I interpret as ensuring supply and probably stabilising prices. Look more than 10 years and for sure I can see significant inflation of energy prices.
The joker in the pack being the geopolitical situation, and its impact on oil prices, employment and industrial energy demand.
I'm glad I'm not an energy trader, but even though I'm a dour pessimist, (

) I really wouldn't be betting on electricity going up 3x from today's prices in as little as 3 to 4 years.
However, everyone can make their own call.

Last edited by dougal on Mon Oct 02, 06 4:14 pm; edited 1 time in total

Treacodactyl
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 25795
Location: Jumping on the bandwagon of opportunism

Posted: Mon Oct 02, 06 4:13 pm Post subject:

nathanbriggs wrote:

However here's the critical point from my perspective.
Today my electricty at home costs 12p per KWh and has gone up nearly 50% in the past 18 months. DTI and other independant predictions (including my own) predict this is a TREND not a blip. In other words electricity prices may reach 30p a unit in 3-4 years, at which point the payback halves to below 3 years. I think Windsave's future is pretty secure

People are now being advised to not lock into a long term gas/electricity bill IIRC as it's felt the home energy prices have risen too much and shouldn't rise much more in the short term. In the last week there's been quite a bit of trouble due to people betting on high gas prices.

I'm all for renewables but if someone has to make a purely financial decision I thing it's worth doing some research on predicted energy prices.

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Tue Oct 03, 06 1:36 pm Post subject:

nathanbriggs wrote:

... However here's the critical point from my perspective.
Today my electricty at home costs 12p per KWh and has gone up nearly 50% in the past 18 months. DTI and other independant predictions (including my own) predict this is a TREND not a blip. In other words electricity prices may reach 30p a unit in 3-4 years, at which point the payback halves to below 3 years. I think Windsave's future is pretty secure

dougal wrote:

...As regards future energy, and specifically electricity, prices - the outlook is very confused.
Much of the recent rises have been due to increases in UK gas prices - because so much of our electricity seems to be generated from gas fired stations. The pinch point on gas supplies would seem to have passed, not least with the opening this very week of the Norwegian pipeline. Everyone (even British Gas

) is forecasting, and contracting on the basis that gas prices will soon be falling - leading, in turn, to cheaper electricity.

Treacodactyl wrote:

..People are now being advised to not lock into a long term gas/electricity bill IIRC as it's felt the home energy prices have risen too much and shouldn't rise much more in the short term. In the last week there's been quite a bit of trouble due to people betting on high gas prices.

Well, as of today Gas prices have collapsed.
We have a (temporary) glut.
So much so that they can't *give* it away.
Today, they are actually *paying* people to take it away...
https://news.bbc.co.uk/1/hi/business/5402370.stm
I wonder why our strategic storage is *only* 96% full. This would seem to be the time to "fill 'er up"!

I'm very glad indeed that I'm not an energy trader...

James

Joined: 11 Jan 2006
Posts: 2866
Location: York

Posted: Wed Oct 04, 06 9:27 am Post subject:

dougal wrote:

Putting a wind turbine on an urban roof is about as sensible as mounting a solar panel in the shade. Quite simply, its about as poor a site for such a device as you could find.
There will be shelter from some directions, turbulence from the roof its mounted near and from other nearby buildings. The turbulence increases turbine noise and reduces the power that can be extracted from the wind.

Increased turbulance has another nasty side effect. It will exponentially increase the vibration passed downward into the building, thereby greatly increasing the risk of structural damage over a laminar flow environment

I looked seriously into the possibility of a wind turbine last year. I�m no expert, so allowed Hugh Piggot (https://www.scoraigwind.com/) to guide me. His site is well worth a read. He�s extremely concerned about what is happening.

I have read a few times that as a rule of thumb the turbine needs to be located a distance of ten times the height of the nearest obstacle away from that obstacle. And furthermore, the wind turbine needs to then be sited above the level of that obstacle.
So imagine if you�ve got a tree 20m tall. You�d need at least a 25 m tower 200m away from the tree, with a similar space the other side before a turbine would be worth considering.
This just isn�t possible in an urban environment.

judith

Joined: 16 Dec 2004
Posts: 22789
Location: Montgomeryshire

Posted: Wed Oct 04, 06 9:36 am Post subject:

James wrote:

You�d need at least a 25 m tower 200m away from the tree, with a similar space the other side before a turbine would be worth considering.

[Daft girlie question]
So how come, in wind farms, there are lots of turbines all sited relatively closely to one another? Don't they create interfering turbulence too?
[/Daft girlie question]

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Wed Oct 04, 06 11:06 am Post subject:

judith wrote:

So how come, in wind farms, there are lots of turbines all sited relatively closely to one another? Don't they create interfering turbulence too?

They do.
Which is why there is such a lot of computer modelling as to exactly what the best arrangement of the things might be, and why aesthetics ("can't you just move it that way a bit?") actually has a commercial cost.
There's a juggling act between the size of the site and the number, size and precise location of the turbines, given the wind regime and site topography (3D shape), so as to maximise the power generated, and minimise costs while striking a sensible balance between the initial capital and ongoing maintainence costs ... The arrangement may sometimes look haphazard, but believe me, its calculated.

And generally, they aren't sited close to one another in an up/downwind direction. To get decent photos of such big things, generally you'd go well back from them and use a long lens - which maks them look closer together, and pleases the photographer by getting more of the things into his frame.

nathanbriggs

Joined: 23 Mar 2005
Posts: 35
Location: Chester

Posted: Thu Oct 19, 06 1:25 pm Post subject:

judith wrote:

So how come, in wind farms, there are lots of turbines all sited relatively closely to one another? Don't they create interfering turbulence too?

Never excuse this sort of question as daft judith and it coincidentally makes my point exactly. Of course wind is BETTER above the height of obstructions and 10 x their height back from them, but it is hardly nonexistent even 1 x their height back??

However wind is a little counter intuitive for example Wind turbines are on high towers and you would think situating them on cliff top would improve their "height" but actually the optimum is about 1 x the cliff height back from the cliff edge ....oops did I just prove my point again???

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Thu Oct 19, 06 2:32 pm Post subject:

nathanbriggs wrote:

... you would think situating them on cliff top would improve their "height" but actually the optimum is about 1 x the cliff height back from the cliff edge ....oops did I just prove my point again???

Nathan, where does that info about 1x the cliff height come from?
My understanding was that there was considerable turbulence extending behind the clifftop - for example landing a hang glider on a clifftop is a very dangerous thing to attempt, specifically because of the turbulence.
I understood that the conventional advice was 10x the obstruction height as horizontal separation - the same as for trees or buildings.

By the way, the Centre for Alternative Technology has its reservations about urban roof turbines...
*Link to CAT on Roof Turbines*
I am by no means the only advocate of more use of windpower to be extremely sceptical about the effectiveness of these things in an urban rooftop setting.

nathanbriggs

Joined: 23 Mar 2005
Posts: 35
Location: Chester

Posted: Thu Oct 19, 06 3:20 pm Post subject:

Hi Dougal
just fyi I'm getting thoroughly mauled on self-sufficientish at the moment

The data came from https://www.windpower.org/en/tour/wres/hill.htm but I can't find the specific page, they had an example windfarm on a cliff edge and showed the best actual "first site" was a cliff height back from the edge. i learnt a lot from this site, sometimes the internet is worth it, however I am always surprised how people take the data from this site and try and apply it wholesale to 2m blades.

Turbulence at 2m is a little different to turbulence on blades circa 50m!

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Thu Oct 19, 06 3:56 pm Post subject:

dougal wrote:

nathanbriggs wrote:

Nathan, where does that info about 1x the cliff height come from?
My understanding was that there was considerable turbulence extending behind the clifftop ...
I understood that the conventional advice was 10x the obstruction height as horizontal separation - the same as for trees or buildings.

nathanbriggs wrote:

There is a picture on that site illustrating just how *far* back from a mere 30 foot cliff it is necessary to site turbines...
How wide is the darkish grass strip between the turbines and the white cliff? Does it look like 10x the height of the cliff or 1x?
https://www.windpower.org/en/tour/wres/escarp.htm

And it is interesting to see the "wind shade" computed behind an obstacle.
The figures are side-on views of a tower block and a 50m tall (yellow) windmill. The dark areas show the reduced energy zone above and downwind of the obstruction.
The lower figure has numbers for the energy % available...
As can be clearly seen, the "wind shade" is very extensive...
https://www.windpower.org/en/tour/wres/shade.htm

Quote:

Turbulence at 2m is a little different to turbulence on blades circa 50m!

Yes, everything is speeded up, the weathercocking of the turbine, the resonant frequencies of the blades and supports...
Turbulence is of *more* concern to hang gliders than 747 pilots, and on a 2m rotor its similarly going to be of more concern than on a commercial turbine - because the little guy doesn't have the inertia to smooth out the effects of the turbulence... And while this must impact on the smoothness of the power delivery, (and the requirements of your box of tricks), it mustn't be forgotten that its a very serious mechanical concern - albeit with different vibration and oscillation frequencies and force loadings for big and little rotors.

Oh, and judith - about wind farms and turbine separation in flat (less complicated) sites... have a look at this page on the site Nathan has flagged up
https://www.windpower.org/en/tour/wres/park.htm
The turbines are staggered (to reduce the shading) and each row has a 7x separation in the direction of the prevailing wind...

tahir

Joined: 28 Oct 2004
Posts: 45669
Location: Essex

Posted: Thu Oct 19, 06 4:58 pm Post subject:
https://solarwind.org.uk/news.php Has some nice looking units, including a very reasonable 660w unit

nathanbriggs

Joined: 23 Mar 2005
Posts: 35
Location: Chester

Posted: Fri Oct 20, 06 3:25 pm Post subject:
found this on a competitors website what do you guys think? Its part of my search to find a quick concise way of describing turbulence without bringing in to much mathematics [/img]

MarkS

Joined: 01 Aug 2006
Posts: 2626

Posted: Fri Oct 20, 06 3:29 pm Post subject:

nathanbriggs wrote:

found this on a competitors website what do you guys think?

Probably blatant breach of copyright ?

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