2011 edition of the Wind Turbine Recipe Book

Posted on 10/09/2011 by hugh

Three years ago I produced a book of wind turbine designs to supercede my previous book “How to Build a wind Turbine”.  The new “Recipe book” explains in detail how to build six different sizes of wind turbine in any of 3 or 4 different voltages.  I still answer enquiries daily from people who want help with different sizes of turbines and different needs, but the Recipe Book has covered most people’s requirements.  There are some pages about alternator design near the end.

Since then the ‘metric edition’ of the book has sold about 1000 copies each year and the later ‘North American’ edition that uses Inches and AWG wire sizes has sold at the same rate.

The book has been translated into Italian, Dutch, French,Spanish, German, Hungarian and Kiswahili.

I continue to use the book for teaching and I’m in constant contact with home-builders around the world, so new ideas are constantly surfacing.  For example here is a method for optimising coil thickness that I developed lately:

The Wind Turbine Recipe Book latest edition can be ordered using Paypal from my web site and reaches most people within five days.

The 2010 edition in metric units is also available from amazon.com as a Kindle book.  (UK readers amazon.co.uk will find the kindle version here) (amazon.de here)

 

Posted in Books, construction, my own projects | 15 Comments

Wind turbine construction workshops in Athens

Posted on 09/09/2011 by hugh

Nea Guinea (neaguinea.org), is a collective in Athens, Greece

“On the renewable energy workshop we organize two kinds of workshops, one on
the construction of DIY PV panels and the design and installation of small
scale hybrid systems and one on the construction of small wind turbines based
on your Recipe Book. The wind turbine workshops are usually twice a week and
last for 3 months. We have been doing this as Nea Guinea since the spring of
2010 and we have organized three work shops since then, one in spring 2010
were we built a 12V 1200 SWT, in autumn 2010 we built a grid connected 2400
SWT and in sring 2011 we built a 12V 1200 SWT with a secondary school. We will
be starting soon with the autumn 2011 SWT which will be a 24V 3000 SWT. ”

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Gallery: Uganda Veterans Wind Power Initiative

Posted on 09/09/2011 by hugh

My thanks to Mr. AGWOTU SAMUEL for sending me a big pile of photos from Uganda.  See the full gallery here

Posted in construction, developing world, People | Leave a comment

Trends in the small wind industry

Posted on 09/09/2011 by hugh

David Sharman of Ampair has given me his presentation slides intended for the Small is.. conference, and has permitted me to publish them on this blog.  They are worth a look for anyone interested in the past and future of small wind, especially in the UK context.

(Download them in pdf format by clicking on one of the links provided)

Small wind trends DS 02 09 11

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Photo gallery from Romania

Posted on 08/09/2011 by hugh

See Dan Paraipan’s photos here

http://scoraigwind.co.uk/?page_id=702

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Airgap flux experiments at CometME

Posted on 08/09/2011 by hugh

Noam Dotan has been sending me results of some interesting tests that he has done on two alternators:

  • 4200 diameter turbine grid-tie alternator with 20 magnets 46 x 30 x 15 mm and 15 coils 260 turns of 0.9mm diameter wire.
  • 3000 diameter turbine 24-volt alternator with 12 magnets 46 x 30 x 10 mm and 9 coils 55 turns of [email protected] diameter wire.

Noam has been varying the air gap, and then measuring DC output at various speeds to arrive at Vdc/rpm for each air gap.  This (volts/speed) is an indication of the flux density in the gap.  In the case of larger gaps, tests were done with a stator in the middle, and the flux was probably stronger close to the magnet faces.

This curve has an interesting ‘sweet spot’ that is hard to explain where the gap gets wider without affecting the flux very much.

This one is more linear.  The drop in voltage reflects a drop in flux density in the air gap which in turn is due to the increased reluctance of the magnetic circuit with the larger gap.  It’s a trade off: more room for copper wires means lower voltage induced in each wire.

If we are looking to optimise the gap so as to get mimimum stator resistance for the chosen operating voltage, then flux density has higher value than gap width.  A higher flux density means fewer turns of thicker wire, so the effect of flux on resistance is squared.  Wider gap simply allows thicker wire (although the calculation is more complex since you need to allow mechanical clearance and thickness of resin and/or glass on coils/magnets).

The chart below (using 3 metre turbine data) multiplies the usable gap (gap minus 7mm) by the square of the voltage to get an index of the value of that option and they are all pretty much the same.

From this I conclude that we are around the top of the optimisation curve, which will be a pretty broad peak.  We can choose our air gap based on available wire sizes and suffer no big penalty for using a larger or smaller gap so long as we do a good job of filling the space with copper and choosing the right number of turns.

Thanks for the data, Noam!

CometME have installed 7 home brewed wind turbines of 1 KW per the Hugh Piggott ‘Recipe book’, and in the next two month they will install another 5 home brewed turbines of 2 kW each. They build hybrid solar and wind systems, and by now they provide more than 150kWh daily for more than 1000 people.

Facebook page for CometME

Posted in CometME, construction, developing world, People, wind systems tutorial | Leave a comment

A simple counter, based on low cost calculator

Posted on 07/09/2011 by hugh

Noam Dotan has published this from CometME in Palestine:

Counting the turns may be confusing especially if you need to wind some 260 turns per coil. A simple counter is based on low cost calculator where the ‘=’ key is wired through a magnetic switch (like the one on a bicycle speedometer) and all you have to do is key in :1 + =. each time the switch is activated by the magnet in each revolution, the ‘=’ key is ‘pressed’ and the number increased by

Posted in CometME, construction, developing world | 1 Comment

Is small scale wind a truly appropriate technology in developing countries?

Posted on 06/09/2011 by hugh

Thanks to Robin Lovelace for these videos of a debate at the Small Is… Festival 2011 between Teo Sanchez (Practical Action), David Sharman (Ampair), Aran Eales (V3 Power), and David Howey (Oxford University).  The debate was ably chaired by Steven Hunt.  Here is a link to the whole set of videos on youtube.

I still don’t know myself whether it makes economic sense to build small wind turbines locally to help the poor but it’s certainly a lot of fun trying to.  And it has been proved that building wind turbines does tend to make people happier. Our work is as much about empowering people as it is about powering their homes.

David overplays the threat of people stealing his intellectual property and putting him out of business, but he brings a refreshing reality to the discussion.  And it is true that volunteer and aid programs can just as easily undermine local business development as they can foster it.  David has sent me his Small wind trends DS 02 09 11 slides for the presentation.  They contain some bewilderingly crucial facts about small wind development in the UK.

Solar energy may very well prove cheaper than wind energy, but a mix of wind and solar on a good wind site is hard to beat.

Posted in construction, developing world, People, UK small wind scene, Video links | Leave a comment

The old diffuser scam resurfaces in Japan

Posted on 06/09/2011 by hugh

Yawn Here we go again with claims of getting 3 times as much power by putting a fancy hoop around the wind turbine and mounting it at ground level.  And people will get fooled again and lose their money again.

Here’s a link to the story last time they tried it, in New Zealand

Posted in products/technical, Rooftop madness, Video links | 3 Comments

A vacancy at I Love Windpower – Tanzania

Posted on 06/09/2011 by hugh

There is a vacancy at I Love Windpower – Tanzania for a student (M.Sc. internship) on the subject of developing a wind map of Tanzania. As long as no suitable candidate has been found, the vacancy will be open.

Establishing key figures for a Wind map of Tanzania
Who: Academic student Physics or Business Management
or related in field of Renewable Energies
Period: 1st September 2011 – 1st December 2011
Location: Dar Es Salaam, Tanzania
website: www.i-love-windpower.com/tanzania

Contact: Roland Valckenborg for more.

Posted in construction, developing world, Notices, People | Leave a comment