Read about a home built 2kW wind turbine constructed from scrap

http://www.reuk.co.uk/DIY-2kW-Wind-Turbine.htm

A large number of our site visitors have found our article How I Built a Wind Turbine to be interesting reading and a useful resource. That relatively simple wind turbine was constructed using an Ametek PM motor as its electricity generating alternator.

In this article we will look at a DIY wind turbine generator constructed from scavenged parts with 3.4 metre diameter wooden wind turbine blades and a homemade alternator.

Building a Wind Turbine
This wind turbine was not built following exact plans, instead the information from a selection of books and online resources was pooled and the turbine built accordingly. Of particular use was Hugh Piggot's book Windpower Workshop which is essential reading.

Wind Turbine Blades

Three wind turbine blades each with length of 1.7 metres for a swept diameter of 3.4 metres.

First the wooden wind turbine blades were carved with an efficient aerofoil section and twist much like a propeller. Three 1.7 metre long blades were hand-carved (following calculations from Windpower Workshop) aiming for a tip speed ratio of 8, and a rotation speed of 450 rpm in a 22mph wind.

The Alternator (Generator)
The generator was designed with a 24 Volt three phase stator (3 coils each phase) and two rotors with twelve 46x36x12mm rectangular shaped NdFeB (Neodymium) magnets each. The hub and rotor assembly was built out of scrap 1995 BMW front strut with a pair of brake discs.

Rotor made from brake disc with 12 Neo magnets

The magnets were first superglued in place on the brake discs, and then cast permanently in resin.

Casting the magnet rotors in resin


The nine stator coils were wound using a homemade coil winder and reclaimed enamelled magnet wire. To keep the coils tight they were taped and superglued while everything was put together waiting to be cast in resin as per the rotors.

Wind turbine stator coils waiting to be set in resin.

Metalwork
A turbine this size must have a mechanism to prevent it from spinning too quickly in very strong winds. A simple self-furling system was chosen and constructed from scrap parts. This limits the wind turbine output to around 70 Amps (2.2KW) stopping the turbine from going out of control.

Base of wind turbine tower


The wind turbine tower was constructed from 4" pipe with a piece of 3" pipe welded to its base to act as a bearing when the tower is to be raised or lowered. This is in turn fitted to an 'H' shape welded from RSJ offcuts to be buried as the base anchor in concrete in the ground.

With everything put together, the completed wind turbine was raised for the first time (using a gin pole and a car to tow everything to vertical). The finished tower is held vertical by three (wire) guy ropes.

Wind turbine


The total financial outlay so far was a miserly £350!

Wiring and Controls
On a wind turbine of this size a great deal of care and attention needs to be paid to the wiring, controls, and battery bank. Firstly it is essential to have a suitable dump load to prevent the (expensive) batteries from being overcharged. Keeping on with the recycling and reusing ethic, an old 240 Volt fan heater was converted to operate as a three stage 1kW dump load (pictured below with 42 Amps passing through it):

Old 240V fan heater used as a wind turbine dump load

A water heater dump load was also put together to turn excess energy into useful hot water, and a 1.5kW (3kW peak) power inverter purchased to convert the 24VDC from the battery bank into 240 VAC for use in the home.

Relays were wired into the domestic electrical system to automatically switch between (wind charged) battery power and mains electricity. (See our article Switch from Inverter to Mains Automatically for more information).