Domestic wind turbines

[The Family Cyclist]

Missing on the idea of a domestic wind turbine. Realised that with the feed in support being reduced/cut not gonna make my millions but do any of the learned folk on here, or even those who just like to share their opinions have any experience.

[Asterix, the former Gaul.]

Missing?  Musing?

My neighbour's son (in France) made his own out of recycled electric motors. 

It seems they are simple enough.  What's the legal aspect?

I am told that solar panels tend to be leased by the houseowner and this causes extra difficulties when buying/selling.  My brother has just had that experience.   

[Polar Bear]

Most solar is owned by the property owner, not necessarily the occupier, but the value is actually in the feed in contract in the UK.  I worked on a divorce recently where we established that a feed in contract is in fact an investment asset.  Taking the panels and hardware away and reinstalling them elsewhere requires a new contract and the value may be lost.

As turbines generate electricity all year round and all day round they are a much better prospect for off grid in UK than solar is.  Storage batteries will still be required as indeed the wind does not blow 24 x 7 x 365 although in turning a turbine terms, it is pretty damned close to this in the UK.

Smaller domestic turbines are very poor at providing enough juice.  There is some sort of almost exponential increase in generation capacity every time you double the blade length.  The other main issue for domestic turbines is that in urban areas wind is disrupted to the extent that your average chimney pot or mast mounted turbine becomes even less efficient.  There are also rules to be followed.

I have been looking at options for us to generate our own juice but our house has a north/south ridge making solar inefficient.  We might be able to erect a domestic turbine towards the far end of the garden but I would expect all sorts of objections from the neighbours from it interferes with their satellite television and broadband, it's so noisy that they cannot hear their diesel engined car, to it invades their privacy spying on them in their bedrooms, devalues their home or is simply an eyesore.

I think that my best bet is to invest in commercial renewables living as we do in victorian terracing albeit with longer than average gardens.   

Worth viewing

[Polar Bear]

More information

As a guide, apparently a turbine needs to be operating in an area or at a height where wind speeds are at least averaging 5m/s.   Below this and the inverter is eating electricity and your installation may in fact eat more juice than it produces.

[Quisling]

Don't bother is my learned opinion - and I'm a keen supporter of renewable energy.  I used to sell small turbines (5kW and upward, so bigger than typical domestic scale.)  A wind turbine is subject to the fan power law (i.e. output is proportional to the cube of the windspeed).  A small increase in swept blade area therefore massively increases output of the turbine.  The swept area of a domestic scale turbine is so small as to be fairly useless, although they have their place for charging batteries on boats etc.  If you own several acres of land then the biggest turbine you can get through planning permission is sensible, however - expect significant resistance from the planners.

A wind turbine should ideally have clean laminar wind flow approaching it for at least 10x the height of any obstruction which precedes the turbine.  Clean laminar windflow does not sensibly exist within the built environment so any wind arriving at the turbine will be turbulent and have less power to drive the generator.  The efficiency and output of micro turbines, sited within the built environment, is so poor that they do not represent any sort of decent return on investment.  They also create a degree of noise and vibration, which is okay if it's not mounted directly to the fabric of your house.

For a typical UK home (south of Hadrian's wall), with any sort of available roof space, I'd go for solar PV or solar hot water to provide renewable energy into the home.  PV panels now offer reasonable efficiency compared to those on the market when the FITs were introduced in 2010, i.e. you get much more generation for the same area of panels.  They are also pretty much maintenance free (although the inverter tends to pack up after 10 years or so) and silent, and there are still lots of installers with plenty of experience.  PV is also covered more adequately by permitted development so you shouldn't need planning permission unless you are in a listed property or within a conservation area (or several other caveats).  I can't remember whether small windpower is covered by permitted development, but if it is it's probably only up to a very small output limit.

[Quisling]

I have been looking at options for us to generate our own juice but our house has a north/south ridge making solar inefficient. 

North-south ridge is not necessarily a problem, depending on how much roofspace you have.  Installing PV on both faces (i.e. East and West) of the roof would require two inverters, but you'll actually generate better throughout the day and therefore be more likely to use more of the energy generated (although with battery storage these days you can get round that problem!)  I installed PV on a WSW facing roof at my last house and was pleased enough with the results.

https://www.solar.sheffield.ac.uk/panel-data/comparison-of-east-west-arrays/

[Polar Bear]

Well, the ridge is actually nne / ssw and the east side, actually facing ese is interfered with by a south side jack roof limiting panel numbers and shading the roof, an overlapping neighbouring roof on the north side shading a good section of the roof, and neighbours trees.  The other side is clear but given that it is oriented north of west rather than south it remains sub optimal.

I am watching developments as I am sure that one day it will become affordable.  In the meantime I am considering thermodynamic water heating and a storage battery to charge at night on cheap tariff and power the house during the day.

Sorry to go OT JF.   

[mrcharly-YHT]

What Quisling said.

I looked into them extensively when I lived aboard a boat. Unless you are in a high wind area and have no neighbours, they aren't worth it below *bigsize*.

Output is proportional to swept area and since area of circle is pi r squared, doubling blade length increased swept area by factor of four.

Small turbines are very noisy in high winds. Big, expensive ones keep the noise down by having software constantly adjust the pitch of the blades.