Currently pondering making a vertical axis wind turbine (VAWT). These are the ones that look like revolving doors, or radar systems, rather than a conventional windmill (which would be described as a horizontal axis wind turbine or HAWT).

Why?

It is generally quite windy where we are, although gusty - if there is wind in Eastbourne then it is blowing here. And as a family we recently watched The Boy Who Harnessed the Wind, so ... it is written. Actually, I have been pondering the idea for some time, but the five-year-old's enthusiasm might be the necessary spur to action.

Vertical vs Horizontal

I am not an expert, but it seems to me that the main advantages of VAWTs is that they have fewer moving parts, do not require reorienting if the wind direction changes, and are lower to the ground for ease of maintenance.

They are also less efficient because one blade (or more than one, depending on the number installed) is always being pushed by the others, but I think I can live with that for now. I'm not wanting to eke every joule out of the system, I simply want to have something working.

What info is out there?

https://youtube.com/watch?v=Er-BCHPDGNw

https://blog.arcadiapower.com/vertical-axis-wind-turbines-advantages-disadvantages/

https://www.sciencedirect.com/science/article/pii/S1364032118308153

http://www.wind-works.org/cms/index.php?id=64

http://www.wind-works.org/

https://forum.solar-electric.com/discussion/350615/12v-dc-wind-turbine-and-connecting-straight-to-2-large-12v-batteries

Parts

Hub

This is where it gets interesting. Currently I'm thinking about mounting the blades on an old bike wheel. This would provide a strong axle, able to withstand being knocked around and still run freely. It also makes things easier to replace, and, with the tyre, provides an ideal surface for the dynamo wheels to press against.

Electricity generation

I currently have two bicycle dynamos which are rated for 6V output. My idea is to mount them in opposition either side of the bike wheel and connect them electrically in series to provide a 12V output.

However, you need more than 12V to charge a 12V battery. The question is whether to try to drive 3 dynamos (3 X 6V = 18V), or whether I need to be looking at a different generator. Or whether I can create more RPMs on the dynamo than expected so as to create a higher output voltage. I suspect this last option won't work because the dynamo will have a protective circuit to prevent it blowing 6V bike light bulbs. Maybe I can cut these out?

Electricity storage

Currently pondering some type of lead acid rechargeable battery. This seems like the cheapest way to go, and most well provisioned in terms of cheaply available charge controllers.

Charge controllers are cheap for solar. Not so much for wind. Solar is relatively constant voltage, whereas wind is highly variable voltage and current (both dependent on RPMs).

Power usage

Electrical power will be used to drive a pump for water to be supplied to the vegetable patch. Control would be via a RasPi which will pump water if no rain or too hot. So there would be a connection to, and use for, the weather station data.

Materials

Bike wheel hubs
Guttering
Cable ties
Some kind of stand or frame? Cannibalise something...