Turbotricity

We’re very proud of the standard of generator we use in our 2.5kw turbine. This is a high efficiency precision built axial flux generator, weighing over 45kg and capable of producing well above its 2.5kw rating. All components are made from stainless steel, aluminium, plastic or copper so the generator is completely corrosion resistant.

It is also unlike any other generator we have ever seen. Generators work because electricity is produced when a magnet passes across a coil of copper. In our case, the coils are on embedded in a drum, with magnets revolving on either side of it. This creates a more efficient, smooth running and longer lasting generator.

We have two sets of neodymium magnets either side of a fixed cage which contains the coils this cage is fixed to the central shaft. The magnets are mounted on the body of the generator and on a second cage. Both sets of magnets revolve on either side of the coils in the stator.

Unusually, the shaft is fixed and the main body of the generator rotates around the fixed shaft. This gives the generator greater momentum and ensures that the shaft and bearings can be protected from the elements, ensuring longer life.

The cables from these windings are brought through the centre of the shaft and carry power from the copper windings out of the generator (and ultimately down the field to your house)

Axial flux generators like ours have movement which his absolutely smooth, with no cogging effect which would be normal with an iron core generator. This means that they begin to generate at lower wind speeds than traditional generators.

Here you can see the shaft of the generator attached to the nacelle, which in turn will be mounted onto the tower of the turbine.

The entire generator assembly is manufactured to very fine tolerances, and SKF bearings are used throughout. This is a generator which should provide many years of trouble-free use, regardless of the working conditions to which it is subjected.

Wind turbines generally don’t work well in built up areas, where they may be placed downwind from houses, tall hedgerows or trees.

An area might still be very windy, but this wind is made up of eddies and gusts with a lot of turbulence. Eddies come from various directions and the turbine cannot respond quickly enough to differing wind directions.

However, turbulence has an even more marked effect. A wind turbine doesn’t really work by wind pushing the blade around – most of the energy happens close to the blade tip which works on the basis of lift coming from areas of high and low pressure, similar to the wing of an aircraft. We all know what happens to the wing of an airplane when it hits turbulence. The same thing happens to the blade of a wind turbine, and the output of the turbine is decimated by this effect.

For this reason, a wind turbine must be as high as you can get it, and as far away from obstacles in the direction of prevailing winds. There are very few instances where a turbine can work effectively in a built up area, so unless you happen to be on the western edge of a housing estate, or have a site which is wide open to wind from anywhere between SW and NW, a turbine won’t work for you.

To assess the effects of obstacles, you should obtain a wind rose from the met office for your area, and estimate the percentage of wind you will lose due to obstacles located at different compass points from the turbine base.

David Cameron notoriously put a turbine on the roof of his house, and many people believed that this is a simple solution to our energy needs. It isn’t – rooftop turbines are the snake-oil of the domestic wind energy market. There are interesting efforts to make vertical axis machines that will work, but none of them are convincing as yet…