Yet another Scottish rooftop turbine

Anent the WindSave turbine, yet another similar product has appeared: the Renewable Devices Swift. It’s Scottish too, and again there are few details. The Scotsman has the story.

Someone commented here that one could build such a device cheaply from parts from any DIY store. This isn’t quite the case. Properly formed blade sets are not trivial to make, and while you could build your own generator, weatherproofing it and making it CE-compliant would be hard.

WindSave: All Betz Are Off!

Update, May 2005: While it’s true that WindSave appear to have made their device obey the laws of physics (at least according to their published spec), I’m keeping this posting intact.

If the data on their website are to be believed, WindSave cannot generate the figures they claim. There’s much geeky theory involved, but basically, they’re claiming efficiencies that cannot be attained.

In short, they are claiming coefficients of performance of 0.724 and 0.887 for their turbines. Unfortunately, the theoretical maximum efficiency for a wind turbine — the Betz limit — is 0.593. So something, somewhere, is screwy. I’m pretty sure it’s not my sums, as they’ve been verified by an external source.

I worry that the UK energy minister, Brian Wilson, has been taken in by this. Five minutes with a calculator and a wind energy primer shows that these things are too good to be true.

Continue reading “WindSave: All Betz Are Off!”

Wind Energy Links

On Nov 11, I gave a talk on wind energy and WindShare to the University of Toronto Natural Philosophers’ Club. As there was so much interest, I’ve decided to put up some useful links. Please feel free to comment/add more, and I’ll incorporate them into the body of the entry.

Links

  • OSEA — the Ontario Sustainable Energy Association. Dedicated to community-based renewable energy.
  • The Kortright Centre — teaches short courses in renewable energy. They’re run by the Toronto and Region Conservation Authority.
  • Home Power Magazine — the source for home-scale renewable energy. The previous issue is always online.
  • Grassroots — a local store who can help with any renewable energy/low energy installation.
  • IPPSO — Independent Power Producers’ Society of Ontario.
  • CFRE — Citizens For Renewable Energy. Based near the Sky Generation wind turbine on the Bruce peninsula.
  • CanWEA — Canadian Wind Energy Association
  • Heiner H. Dörner — catalogues wind energy designs that didn’t quite work. Has some pictures of the huge 4MW turbine built on Cap Chat.
  • Centre for Alternative Technology — based in mid-Wales, this charity has impressive resources on all aspects of renewable energy
  • Scoraig Wind Electric — Hugh Piggott has been home building small wind turbines for his remote community for years.
  • Fair Isle — Britain’s most remote inhabited island. They’ve been using wind power for years. Coincidentally, this is where Catherine & I met … ☺

Books

Paul Gipe has written some of the best books on the subject. My favourite book of his is Wind Energy Comes Of Age (John Wiley & Sons, Inc, New York, 1995. ISBN: 0-471-10924-X). It gives a good overview of the technology, and a rare look into the impact on society of wind energy.

If you just want the heavy theory, the Wind Energy Handbook (Burton, Sharpe, Jenkins & Bossanyi. pub John Wiley & Sons, 2001. ISBN: 0-471-48997-2) has everything you need. Based on the famous Loughborough Wind Energy Course (formerly at Imperial College, London, where I took it), it’s absurdly complete.