Bryan Lawrence : Windpower: Local Solutions to avoiding burning carbon

Bryan Lawrence

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Windpower: Local Solutions to avoiding burning carbon

I've mentioned in the past that I'm interested in small scale wind power generation. It strikes me as crazy that many of those advocating the importance of windpower seem to think that it can only be done with massive wind farms. There are many of us who live in windy locations who could generate a significant amount of local power with small wind turbines. Done right (i.e. as part of the house structure) it ought to be relatively inoffensive to look at (we're used to chimneys already) and harmless to birds (or not any worse than our large glass panels which take out the odd bird from time to time ... certainly there are no large raptors flying around our house).

So I'm glad to see advent of just such a house-scale wind turbine. There are some obvious questions first:

  • What will it cost?

  • How noisy will it be?

  • Will I be able to feed back energy into the national grid?

  • How windy is my property?

  • (Update) Do I need, and if so, will I get planning permission?

The windsave site is rather coy about the first question, but it's not quite an issue yet as I wouldn't be planning to do anything about it til next year (there are only so many house based projects one bloke can do with a new child and a full time job). They do point out that there are some quite good subsidies available though ...

The answer to the second question is quite comforting:

  • Free spinning (loudest noise potential)

    • 5 metres behind blades gusting to 5m/s /12miles per hour, 33.0 dB

    • 5 metres behind blades gusting to 7m/s / 16 miles per hour, LAeq 52.0 dB

  • 3 metres behind blades, height 1.5m background noise LAeq 36.0 dB

Compare these with typical fridge/freezer when running of between 40 and 50 dB. But I guess it would be interesting to know what it would sound like with winds at 30 mph (maximum generation) and 50 mph+.

Apparently the energy can feedback into the national grid, although it's likely the average house "on idle" will use as much as it can get from these systems (given it's rated at about 1kW/h at not far short of full speed). It's also not obvious there will be any easy way of metering that ...

The second to last question is something I can maybe do something about ... it might be interesting to see a map of mean and standard deviation wind speed for the UK. The obvious problem is that one needs the wind info at the microscale, and we only have the data at a much larger scale, but it'll still be interesting. Now to find the time ...

(Update continued) The planning permission issue will be interesting too ... given one needs permission for a second satellite dish, it would seem likely that councils will try and get involved ... but I hope they wont be obstructive. If house scale wind turbines become common, they'll be just as much part of our normal housescape as chimneys.

The bottom line though, from their web site is this:

There are approximately 23 million households in the UK today. If just 2 million of them - roughly 10% - were to have a micro-wind generator installed on their roof, that would take a potential 1,000,000 tonnes of CO2 out of the environment each year!

Categories: environment

Comments (2)

Oli on Wednesday 31 August, 2005:

The figures you give for dB rating and comparing them together are very misleading. You are aware that dB is used to define the level of noise, however, this can only be used to compare different noises if the measurements are taken from the same distance. A dB is a log number, so a 1dB increase means its twice as loud, a 2db increase means its 4 times as loud. Measuring at set distances is done within everything from Dept of Transport (motorcycle road noise limit 94dB) race limit for motorsport (105dB max) to nightclubs (85dB max)
The turbine is measured at 5 meters behind the blade, where the figues for the electrical items are not measured from the same distance. I would assume it would have been at a distance of around 10 cm or so.
I hope this information can be used to help your readers have a better understanding of sound.

bryan on Friday 02 September, 2005:

Fair comment (although to be strictly true, dB measures sound intensity which isn't the same as loudness, one can argue that to the ear a 10dB difference is twice as "loud"). I used to teach sound physics :-) ...

... but if you can find any information that I can use that is more accurate, I'll be glad to use it.
Meanwhile, what I take from this is that it might be true that the sound of the turbine five meters from the blade might be significantly less than the sound of a freezer standing up close to it. But as you say, it might not.

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This page last modified Wednesday 24 August, 2005
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