Wind turbine experiences - please post here

sbkenn

The ESB buy back scheme is crap IMO. There is little incentive, especially in comparison to the UK and continental Europe. The UK buy back at about 3x the price that they sell at, with little or no limit on how much they will buy. The ESB, when I looked anyway, buy at less than what they sell at, and even that is limited to a fairly small kWh figure.

sbkenn

1) Is there a proper name for the rotating part of a windmill ?
It isn't a propeller, and modern ones don't have sails.
2) Can anyone give any insight into the pro's & con's of horizontal and vertical axis devices ?
Darrieus ones obviously eliminate the need for slip-rings, but I believe are a bit more delicate and tend to disintegrate in high winds.

I am looking to build/buy a 1 - 1.5kW machine for my houseboat, and am considering using a pancake motor as the chassis for the generator.

S.

quentingargan

sbkenn wrote: »

1) Is there a proper name for the rotating part of a windmill ?
It isn't a propeller, and modern ones don't have sails.
2) Can anyone give any insight into the pro's & con's of horizontal and vertical axis devices ?
Darrieus ones obviously eliminate the need for slip-rings, but I believe are a bit more delicate and tend to disintegrate in high winds.

I am looking to build/buy a 1 - 1.5kW machine for my houseboat, and am considering using a pancake motor as the chassis for the generator.
S.

1) Usually called a rotor, the sticky out bits of the rotor are normally called blades.
2) is really a matter of opinion. Vertical axis machines have their fan base. The theory is that in an area with very variable winds, particularly built up areas, the turbine catches the wind, regardless of its direction. In such a situation, a horizontal axis machine would be yawing to and fro, trying to get the right wind direction for its blades.

BUT

In built up areas, the main issue is not just wind direction, but also turbulence. The blade of a wind turbine doesn't get simply pushed by the wind, but works like the sail of a boat or the wing of an airplane, getting lift from low pressure. In turbulent conditions, this dynamic is somewhat impaired.

The other downside to vertical axis machines is that although one blade is working in the right direction, its energy is somewhat offset by another blade that is working against the wind. Thus to achieve the same output, they need to have a larger overall area.

This leads to a third problem, which is that because they tend to be bulkier for the same output, it is more difficult to put them on a tall mast.

But there is no "one-size-fits-all" in wind turbines, and in some situations, a vertical axis machine may perform well - particularly in areas where there is good wind at a lower height. They are also less visually obtrusive, and there is a lot of development work going on.

Lack of slip rings is another benefit alright, though I don't have slip rings on one of my (horizontal axis) turbines, and I'm thinking of taking them off the other one. It is so seldom that the wind direction goes more than one or two full 360s in the one direction, at least in our climate, that I don't consider them necessary. Just one more thing to go wrong.

sbkenn

Has anyone used a truck radiator fan as a rotor ? How about with it's duct ? Would putting a 2nd fan on the other end of the shaft produce anything like double the output ?

Thanks

quentingargan

sbkenn wrote: »

Has anyone used a truck radiator fan as a rotor ? How about with it's duct ? Would putting a 2nd fan on the other end of the shaft produce anything like double the output ?

Thanks

The fan on the other end of the shaft would get very turbulent wind from the first set of blades. But you aren't the first person to think along these lines, and incredibly enough, there was one such turbine on display at the Ploughing Match this year. Blades are hugely affected by turbulence - the second set would just be a drag.

Fan blades have the wrong dynamics in many ways for wind turbines. If you want to do a DIY job, you would be better off looking at Hugh Piggotts site on how to carve your own blades. If you don't want to do that, if you PM me, there are some companies who sell blade sets with hubs that you can mount onto a suitable generator.

sbkenn

I have looked at blade sections and required AOA at speed. I guess though, that bought blades would be far more efficient that home made ones, so I'll stick to experimenting with the alternator bit.

Thanks
Shane

kevthegaff

Toplink wrote: »

Hi bladespin,

I am thinking of investing in one it not two of these. I have 2 sites in mind, one for a smaller turbine and one for maybe something larger in time. The site I have in mind for the smaller turbine should be ok, I can brace a pole from the edge of my shed and get the required height upto 12m - 15m.


Regarding the other site, I would be looking to get to the 40m - 60m height, is there anybody who can supply a reliable mast for the purpose of collecting wind data over a period of 18 months. I spoke a company in Scotland who could do it but they would be looking for 10K-15K.

SEI wind maps tell me that average ws is 7 m/s which makes feasibility on the poorer side but I'd prefer to collect my own data.

50m is a pretty high mast so I doubt I am going to get any cheap option here but said I'd ask anyway!

Hi i have a wind monitor about 30-40 metres in height if your interested in it- check out buy and sell- the renewable section

keepitreal

keepitreal wrote: »

<SNIP>.

Mod edit: You can PM those details if you wish but please dont post them here. Read the forum charter.

quentingargan

Toplink wrote: »

Regarding the other site, I would be looking to get to the 40m - 60m height, is there anybody who can supply a reliable mast for the purpose of collecting wind data over a period of 18 months. I spoke a company in Scotland who could do it but they would be looking for 10K-15K.

SEI wind maps tell me that average ws is 7 m/s which makes feasibility on the poorer side but I'd prefer to collect my own data.

50m is a pretty high mast so I doubt I am going to get any cheap option here but said I'd ask anyway!

You will have quite a few issues with the planners putting a turbine at that sort of height. I agree with getting turbines as high as you can, but there aren't many domestic turbines at that sort of height, and the planning exemptions of 13M to blade tip for domestic or 20M for farms is probably all you will be allowed. Its worth a try if you can make your own planning application etc., but my instinct would be to test at lower heights - maybe hub height of 18m or so.

As regards doing tests, there are companies doing this work. I would caution though that turbulence, which affects turbine blades quite dramatically, doesn't affect the cups of an anemometer. So an anemometer might record a mean wind speed of 6m/sec, but the turbine's output might not reflect that wind speed.

You have to accept that there is always a degree of risk in putting up a wind turbine. There is no guarantee of a return on investment. That's why I would prefer to see people taking a punt with smaller turbines than the big 6kw to 15kw ones that are being sold at prices of up to €40K.