Well that's taken the wind out of my sails! - wind power's future

I'm a bit of a windmill fan, if you'll excuse the pun. I have a personal project (albeit a bit on-and-off) to power the pump for our goldfish pond from a windmill. Ok, I could just go and buy a solar cell array and hook it up to the existing pump , but hey, that would be too easy.

So when I did a recent evaluation of domestic wind turbines as an alternative to solar photvoltaic (PV) power, it was a bit of an eye-opener. The small turbines being offered for domestic power production end up as little more than toys. The devil, as always, is in the details.



Take for example this chinese-built unit, seemingly very attractive from a price vs output perspective  - $8000 for a 3kw turbine seems very cost justifiable.

The trouble is, that when you read the specs, that output is at a wind speed of 10 m/s. The start wind speed is 3 m/s.

Now the really important fact here is that wind power varies as the CUBE of wind speed, so at 3 m/s, that turbine will actually be producing only just above 100w, or enough power to run 4 compact fluorescent lightbulbs, or a desktop computer.

Now if you look at the NIWA map of mean wind speeds for NZ, my area (Bay of Plenty) shows mean speeds of 2-3m/s.

That means that my wind turbine is on average going to be producing a fraction of its rated power, blowing the economics away.

The lesson here is that it is easy to get over-excited about new technologies, but you have to do your homework thoroughly before taking the plunge and investing in it.

As an aside, if I was unfortunate enough to live in say Wellington, or around Foxton, it might be that my wind turbine provides nearly all my power,  with my PV solar array just filling our the troughs in the supply!