If you are interested in making your own vertical axis wind turbine (VAWT) generator, then the first thing to consider is the turbine blades. Back in 2010 when we first published this article, a vendor on ebay was selling a kit of VAWT blades for a Savonius type wind turbine generator. An image of the completed kit is shown below, but unfortunately these are no longer available. The blade set was designed to be fitted onto a suitable permanent magnet generator or stepper motor to make a functional wind turbine generator.
These VAWT blades were made from lightweight aluminium sheet with a 1.000″ diameter hub fitted to the centre. The hub could be connected to the generator/motor by screwing it directly to the generator/motor shaft.
This kit sold well for a period with prices reaching up to £40 plus £6.50 for UK postage.
Sadly, at the time of updating this article (January 2014) no-one is selling DIY VAWT blade sets of this type. Every now and the a commercial blade set is offered for sale such as the Sea Hawk blade set (and additional components) pictured above offered for £250 (compared to the retail price of over US$1000).
Hopefully the image of the DIY blade set can still be used as an inspiration for anyone with metalworking skills who would like to make their own VAWT wind turbine.
How Much Power Can These VAWT Blades Generate
This VAWT blade set has blades with a height of 29cm and an outside diameter of around 40.5cm. This gives a swept area of 0.12 square metres. The amount of power in the wind is given by:
* find out more about this wind power calculation here.
Therefore, in a 5 m/s wind (average wind speed in a pretty good location), there is 0.5 * 1.23 (at sea level) * 0.12 * (5x5x5) = 9 Watts of wind energy hitting the blades. In a (quite strong) 10 m/s wind, 74 Watts of wind energy are hitting the blades.
Not all of that wind power can be converted into electrical power because of the Betz limit and the inefficiencies in the generator and bearings etc – so we will assume that one-third of the power can be turned into electricity. Therefore a wind turbine generator made with these small VAWT blades will generate no more than 3 Watts of electricity in a 5 m/s (11mph) wind, and a quite decent 25 Watts in a 10 m/s (22mph) wind.
The design of these blades can of course be scaled up within the limits of the materials used and the quality of the construction. Making the blades 3 times longer than 29cm for example should cause no problems with 1mm aluminium sheet, and therefore the power output (attached generator permitting) would be three times higher giving a more useful wind turbine battery charger.