4. Add A Fin You need a fin on your turbine to steer it into the wind and keep it there. We made our fin from 9mm (3½in) plywood. It’s hard to give a specific size for the fin, but as a rule of thumb, make it ½ of the area encompassed by the wheel. The longer the arm it is attached to, the smaller the fin can be.
If you find your turbine does not turn into wind, increase the size of the fin or lengthen the arm it is on. You can design your fin to be any shape you want, as long as there is enough area in it to steer the turbine into the wind. We used a steel tube as the arm to mount our fin and bolted it to the steel tube in two places. The other end of the tube was drilled and bolted through the brake-mounting hole on the forks with a single bolt. The rear end of the fin was tied to a suspending brake cable attached to the mudguard lugs on the forks.
5. Paint Your Turbine Ideally the paintwork should take into account the fact that the turbine is going to be out in all weathers day and night for a long period.
6. Find A Windy Location The turbine needs to be in clear air as much as possible so apply permaculture principles and spend some time observing where the best wind is. The prevailing wind is generally south westerly over the British Isles so if in doubt put it somewhere with clear air to the south west. We used 50mm2 (2in2) pine as a mast to mount our turbine but you will need to size your mast to suit the weight and size of turbine and the conditions it will experience. If in doubt, go for additional strength as an over-strong mast will not affect performance.
Mounting methods vary and are a matter of improvisation. We used jubilee clips around the headset and the mounting mast, tightened up to quite a high level.
7. Connect Your Turbine To A Battery You’ll need a battery to store all that free electricity! The most commonly used battery for small-scale generation appears to be 12V. Most cars run on 12V so there are many devices out there, which are compatible with that voltage. When you connect the dynohub to the battery, you need to bear in mind that dynohubs generally generate AC but the battery will require DC. Some older hubs have a rectifier built in but if yours doesn’t you’ll need to use a bridge rectifier to convert the AC to DC. Subsequent to this, the voltage will need to be stepped up to 12V from the 6V dynohub output.
There are instructions on the web on how to do this (see Resources). They are a bit more tricky to put together than the rectifier. The trickle charging dynamics of the
10 Permaculture Magazine No. 63
www.permaculture.co.uk Above: Allotment turbine on tall mast to ensure clear air.
Opposite: top: Fin mounting arm bolted through brake point. bottom left: Fin attached. centre: Turbine secured to mast with jubilee clips. below right: Rectifier.
turbine are unlikely to be optimal for most batteries so battery life/performance will vary. There are a variety of resources on the web concerning batteries (see Resources). Be careful to ventilate the battery storage area well, as charging lead/ acid batteries release hydrogen, which can form an explosive mixture with air if confined.
8. Put Your Feet Up & Let the WindDo The Work… Resources www.reuk.co.uk/Sturmey-Archer-Dynohub.htm www.reuk.co.uk/12-Volt-Deep-Cycle-Batteries-forSolar.htm www.reuk.co.uk/Bridge-Rectifier.htm www.electronics-lab.com/projects/power/030/ www.dimensionengineering.com www.cranks.org.uk www.golight.org.uk
Beth Tilston is a positive change activist from Brighton. She is the founder of the social enterprise Go Light (see website above) who work with organisations and communities to provide positive action for energy descent. She is also writing a book based on her experiences of eating within 100 miles of where she was for a year.
Will Harley is a Brighton based engineer/project manager with a special interest in small scale, DIY, sustainable technology. Will volunteers for a local free bike workshop and has recently helped to install a small scale wind energy system on a friend’s allotment. He would be interested to hear about any other projects making useful stuff out of scrap. Contact Will at: firstname.lastname@example.org www.permaculture.co.uk
No. 631Permaculture Magazine