Thanks for input. I've got to go higher and have a plan which won't give me 70m but should give me 30m at which I would expect to see some improvement. My turbine was planned as part of a bigger project which is to install a ground loop heat pump (I can manage about 40m length in trenches ). That won't heat the house totally but should make a very useful contribution. The turbine output I envisaged as driving the pumps so I'm hoping to get enough output for this.
In the UK because we don't have the average plot size and acres of space that the US, oz, and New Zealand have our planning laws are tighter , altho I must admit that I have n't really investigated this yet. This means a 70 metre tower might be difficult (I live in a residential area , altho on the very edge of town. I intend to spend the minimum possible as I'm 68 and payback time is a consideration.
A vawt is more aesthetically appealing and I have some ideas that may help with output. I always have a lot of projects on the go and am quite happy to proceed at a slowish pace but things are moving. I bought a couple of diggers this summer (one goer to do the digging and a beefier one for restoration and then digging if my ground proves as rocky as I expect ). I certainly think boreholes would be difficult (we're pretty regulated on these too ).
To get enough o/p to drive the heat pump system , I'm going to have to use every trick I can with a vawt at 30m and am considering wind lensing (aesthetically ok again) , one or two ideas for efficient self starting, and a few other ideas which I will need to test with models first. I had hoped to do this last winter but other projects keep intruding. I'm pretty relaxed about this however as they are all interesting and I'm not in a race.
On my side I have an extensive metal working facility (some of which generates projects which keep intruding ) , and I think a cheap and easy way to achieve 30 metres altho this will not put the turbine in a clean airstream ,BUT it will be higher than most things around it.
I'm also watching the progress of Aerogenerator X , which you can find if you google it, as this seems a good vawt approach to higher power at a lower altitude, but this is largely unproven . Some of the companies backing it are no slouches so there may be something in it.
Rgds. and thanks for interest
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