Domestic windmills put to bed.

[Peter Parry]

Probably not, see

Piggots site is also good but disorganised. is no standardised way of measuring power curves and an obvious advantage to a manufacturer to use anything that looks better and is vaguely justifiable in court if the customer wails afterwards.

In this particular case I'd be very wary as they are quoting "Will generate approx 14,000 kW per annum". This can only be achieved if you assume 8 hours a day, every day, at 5kW rated power.

5kw requires 13m/s wind speed or Force 6 on the Beaufort Scale, a "strong breeze" defined as large waves with foam crests and some spray. Large tree branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult."

The chances of achieving this for an average of 8 hours a day over 12 months are zero.

What they appear to be doing is using the 30% capacity factor used (and rarely achieved) by commercial wind farms. This is wildly optimistic for small windmills where a capacity factor of between 0 and 4% is appropriate for urban areas and about 7-9% for rural.

To put it in perspective the 50m tower and windmill at Renewable Energy Systems in some fields near here manages 7% capacity factor.

Average wind speed isn't bad - as long as you chose the right average. The Warwick Trial has come up with a series of fudge factors which, applied to NOABLE data, are plus or minus 20% of what they are measuring at their sites. For urban sites the correction factor is

0.5 so you will get just over 1 tenth of the amount of electricity the salesman will tell you or you calculate from NOABL. In view or their gross overstatement of the capacity factor I'd assume the power curve is equally inventive. About 1mWh/year rather than the 14mWh/year they quote might be achievable.

I notice they are also using a rather puny 12m tower. This has the advantage of being cheap, quick to erect and keeps the planners happy (so increasing sales) but you are also keeping the generator in turbulent air (even in the country) For a 6.4m diameter rotor this is way too low.

The effect of wind shear is greatest at low level so Increasing the height of the windmill rotor from 9m to 18m will increases the expected wind speeds by 10% and the expected power generated by about

30%. 25-60m should be the height you are aiming for if you want any real output.

[Andy Dingley]

Actually about 9m/s, a quite reasonable Beaufort 5, if I read their tiny graph carefully enough. The peak of the curve is 6kW, their rated output is quite reasonably rather less than that.

[Andy Champ]

I race sailing dinghies.

Believe me, inland in southern England it isn't often F5 or above.

Andy

[Roger]

The message

from Andy Dingley contains these words:

That is about 20 mph. Daily average here hasn't been over 7.1 mph yet this month. A few gusts in the low 30s but even then the sustained wind speed was only in the order of 12 mph. Given that about 7 mph is needed for any output that looks extremely unpromising.

[Roger]

The message from Peter Parry contains these words:

Thanks Peter.

I am in a fairly exposed location with possibly more than my fair share of wind but the chances of me risking some of my savings on a wind turbine look vanishingly small at the moment, even if the planners do have a brainstorm and allow a small tower in Bradfords Green Belt.

[Andy Dingley]

Shouldn't keep 'em so close to the water then. If you stuck your dinghy up a tower, it would experience much more useful wind. I fly kites - never any shortage if you go high enough 8-)

That's a good thing, or it would blow all you soft southern jessies over. Northerners not only require less external heating (being warmed internally by beer, pies, stotties and bravado) but we've got the weather to generate all the power we might need to top it up. Knew we should have kept the capital at Jorvik.

[Andy Champ]

Suprisingly for you I know Jorvik fairly well. In fact, I've been sailing on the river a few times, between Bishopsthorpe and Skeldergate bridge (and lost a burgee on it once, trying to get underneath).

(I understand there's a new bridge in the way now to stop anyone else trying that trick.)

There's even less wind in York than around here.

The top of the moors is another matter.

Andy

[Dave Liquorice]

Quite. A quick guesstimate from my monthly graph we might just have made a

10mph average for this month so far and the same for July. 10 mph is 4.4m/s. In fact looking back over the last 12 months I doubt the 12 month average is much different.

We are at 1400' on the North Pennines and pretty exposed. When it gets windy it gets really windy, F8 several times a year, F9 for F10 about once a year.

[The Medway Handyman]

Do you ever beat them? You must swim really fast...

:-)

[The Medway Handyman]

Chatham dockyard, which goes back to the Victory & stuff has now been redeveloped as St Marys Island, up market dockside apartments etc.

Its the windiest place in Kent I swear it, slight breeze in other areas, wind nearly pushes you over on St Marys Island.

I reckon it originally became a dockyard becasue they knew it was a very windy place & the sailing ships neded that.

[Roger]

The message from "Dave Liquorice" contains these words:

That's a lot higher than me. I am at only 535 feet above the junction between The Worth and The Aire. Stick Marley, England into Google Earth and you will probably find me under a red dot (although the elevation given is a bit off).

[Bob Eager]

Yup, nearly as bad just across the road at Pembroke, where I sometimes work!

[Andy Champ]

No, no, I stay *in* the dinghies.

The trick is in keeping your balance while trying to keep one foot in each boat... :P

Andy

[Simon Stroud]

Andy showing his wicked sense of humour right to the end!

He'll be greatly missed around here.

Cheers! Simon.