Making the Simplest DIY Wind Energy Generator - How Hard Could it Be? -- Episode 608

thanks for explaining the different kinds of wind generators designs and how they work, I'm sure alot of people find this interesting.

my main focus was to get the project done in time, as the previous designs broke to easily I opted for the simplest design I could find on the internet, the sheets ar not straight but slightly bent mounted in it+ the 90 degree offset is meant to give it some kind of scoop shape, surely not the best design.
I'm an electronics guy, not a mechanical design wizz so it wasn´t my focus to implement a specific better design. more eyballing off pictures.

Very often another iteration etc. would do the trick to come to a better conclusion, but as I said, I have only a very limited amount of time for each project and quite often the improvements are not visible on camera or are so minor that it is not worth spending more time on it once the principle is proven.

Hang on, those blades don't seem right. It is important to decide whether you are aiming for a rotor that uses lift, or one that uses drag.

The latter, known as the Savonius, has an assymetric appearance - typically using "scoops" whereby the wind sees the backs of the scoops on one side of the rotor and the open fronts on the other side.  The drag force on the open fronts is greater than the force on the backs, so a nett rotational force is produced. The spiral rotor that the presenter first tried (and which fell apart) was an example of a Savonius rotor. Because Savonius rotors rely on drag, the blades cannot move faster than the air that is pushing them, so they tend to be high-torque, low speed rotors. 

The second attempt, using two polyethylene sheets with a 90 degree twist, presents a symmetrical profile to the wind, so it doesn't seem like it can operate as a Savonius (drag) rotor.

The other type of rotor used in vertical axis turbines is the Darrieus. The blades have an aerofoil cross-section and experience lift as the air passes over them. They appear symmetrical at first glance, but of course the back of the aerofoil is presented to the wind on one side, and the front on the other. Importantly, the rotational force relies on the blades experiencing their own "headwind" as they rotate.  The resultant lift force from the headwind combines with the lift generated by the wind to produce a rotational force.  This means that vertical axis Darrieus rotors *are not self-starting*.  They do, however, spin considerably faster than the Savonius, albeit with less force. 

Those strips of polyethylene don't seem to have any aerofoil shape to them, so I don't see how they can generate lift.  But even if they do somehow take on an aerofoil shape when the wind blows on them, the rotor still wouldn't be self-starting.  And bearing in mind that they present a symmetrical cross-section to the wind, I don't see how they can act as a Savonius rotor either.

I presume that design - with the polyethylene strips twisted through 90 degrees - was found on the Internet somewhere, so perhaps they do somehow work to a limited extent, but they certainly aren't going to be "good" in any sense apart from simplicity of manufacture.

The Savonius is self-starting, quite easy to make, and generates higher torque than the Darrieus, albeit at considerably lower rotor speeds (because it uses drag rather than lift). I think the presenter gave up too easily on his first attempt at a rotor. That "air scoop" design - twisted so the torque is constant as it rotates - has a lot going for it. It just needs to be made more robust. I think he should get his generator working with the Savonius rotor and see how effective it is. Upgrading to a Darrieus - after having done a bit more research - can be the subject of another project and video. 

it seems i did not properly explain the purpose of the diodes in  the generator so I made a little video addressing that:
https://youtu.be/bnhHCh-6wXc

Perhaps has some potential for a novelty garden windmill/spinner kinetic sculpture of some sort ?

Traditionally they tend to be wood choppers, or winding a well winch handle but I guess with a electric generator then there are some new hi-tech options.

An eInk display could be updated to show messages and it wouldn't matter if there were days with no wind as it could just stay displaying the last update. 

Some low power LED lighting could be used to brighten up garden spinner on a dull but windy day, or in the darker winter evenings.

POV type display on the rotating blades displaying speed / direction etc. or message received over LoRa.

yeah, i just took what i had on hand to get it working.

a combination will probably always make the most sense

Nice project, also another good lead in to the supercapacitor challenge.

I had spotted this Winturer project which looked quite interesting:
https://www.instructables.com/WINTURER-a-Portable-NP-F-Battery-Charger-Wind-Turb/

as an alternative to solar out in the field. Although wind + solar would likely be a better option as you never know how the weather is going to turn out.

mayermakes Nice project.  At those power levels, you could make your bridge rectifier out of signal diodes - specifically the germanium 1N34As - and get a bit higher voltage to the capacitors.  If you could get away with even a small solar panel, that would be a super combination.  Solar in the middle of the day when the wind is low and wind when the sun rises and sets and the wind is up.

What to power?  Something LoRa.  Maybe temperature - to remind you that you would rather be out in the country.