I am a first-time poster to this discussion group. I founded an organization called blueEnergy that is working to build a small-scale wind turbine manufacturing industry in Central America. blueEnergy is a nonprofit organization incorporated in Washington DC and is currently running a pilot project in Nicaragua. You can find more information about us by going to http://www.blueenergy.org
We met the WonderMagnet crew at a homebuilt turbine workshop on Guemes Island in April of this year. They have been great supporters of our organization and donated the magnets and copper wire for the unit you are about to see.
The unit shown here was built in Veneta, Oregon about three weeks ago. It was built as a showcase unit and was displayed at the Oregon Country Fair, a three-day festival that attracts over 40,000 people each year. The craftsmanship of this turbine is of higher quality than what we are producing in Nicaragua because we knew it would be inspected up-close by top-notch woodworkers, electricians, and welders. The design is essentially a Hugh Piggott design with a few small modifications.
Here are two shots of the completed unit:
Rough specs:
* 8 feet diameter
* wired for 24 volts AC
* 10 coils, 12 magnets per rotor (24 total) :: 5-phase machine
* conservative estimated power rating ~ 500 watts @ 10 m/s (22 mph)
* estimated cut-in speed ~ 2 m/s (5 mph)
* can get up to 1 kW for short periods of time
We have not had a chance to test this unit thoroughly, so these figures are subject to change.
The turbine was built in 7 days and took about 175 man-hours. This includes time to clean and prep the shop, sharpen tools, and purchase materials. This does not include time for blade balancing which we have yet to do.
The blades are made from CVG (close vertical grain) Douglas Fir. Very nice wood to work with, although we did have some trouble locating the direction of the grain in a few spots. Nothing a disc sander couldn't handle.
Darin Bird (blueEnergy's Director of Technology) welds the stator mountings to the hub case. There was some internal debate about what to call the hub case. Darin wanted "hub carriage" but I am writing this post and I prefer "hub case".
The magnets provided by WonderMagnet (2" x 1" x 1/2" NdFeB, Grade 35) are placed onto a steel rotor disc with the help of a magnet spacer jig. The polarities of the magnets are checked by sticking a magnet in the hand and moving around the disc. If all is as it should be, the hand is alternately attracted then repulsed by the plate.
The stator is cast in resin. A lot of man-hours are hidden in the soldering job to connect all the coils.
A resin-cast magnet rotor.
Darin holds up a completed blade. The blade has 7 coats of clear as well as a partial layer of Blue paint. The grain of the wood can clearly be seen.
The majority of the hub assembly is put together. The aluminum casing serves as a heat sink for the 5 bridge rectifiers that convert the 5-phase AC power to DC power for battery charging.
The blade rotor is assembled. The tip-to-tip distances after assembly were within 1/8" of each other. If we had more time we might have tried for 1/16" or even 1/32".
This close-up of the hub assembly shows how the layers of clear help integrate the wedges at the roots of the blades into the blades.
Darin gives the turbine a whirl. When the turbine was left to spin in the wind (on the stub tower, amongst the trees), we recorded voltages (open circuit) as high as 50 volts.
Once the turbine was completed we moved it to the Oregon Country Fair. blueEnergy had a prominent booth in Energy Park, a section of the Fair where organizations showcase renewable energy technologies. The turbine drew a lot of interest and we were busy talking about the turbine and our project for 3 straight days!
Members of the blueEnergy team. From left to right - Lâl Marandin (head of Nicaraguan operations), Mathias Craig (me, Executive Director), Jules Beck (Nicaragua volunteer), Darin Bird (Director of Technology), Guillaume Craig (Nicaragua volunteer).
Me being interviewed by some independent TV outfit. Unfortunately I don't remember whom they were with.
If you are interested in seeing more pictures of the manufacturing process, we will be posting a more complete set on our website (http://www.blueenergy.org) in the near future. If you would like to receive updates of our work in Nicaragua, please sign up for our E-Bulletin at http://www.blueenergy.org/NewFiles/GetInvolved.html
