www.greenpowerscience.com A simple wind turbine all around you. Alternative energy green job training. Wind power.
Who am I ?
Hi, I’m Erik Astrand and the man behind this site.
My story? I am about to be 50 and all my life I have been interested in technical things. Not sure if the special interest for the wind, and how to use the wind, started when I as a 5 year old boy and got my first sail dinghy.
Anyway, wind power and to build my own wind generator was a dream for several years. I studied many websites and also bought many courses before I finally built my own windmill. This site is about that journey and you will also find some more general articles about wind power.
Enjoy! and check out the about me page to read more.
@krrrr….
Sure, it could turn a very small generator.
Pw = 0.5 * Da * Ab * Vwind^3
Pw = power of wind in Watts
Da = air density (1.23 Kg/m^3 at sea level)
Ab = area of blades in sq meters
Vwind = wind velocity in m/sec
Assumptions:
At sea level.
Wind is 20mph average (this is super windy, 10-12 is a better estimate but I’m humoring you) or 8.9m/sec on average.
Blade area – this is a little rougher to get. Assume your turbine is savonious – air is pushing the blades…
…continued for krrrr….
Savonious, height is 1ft and diameter is 1ft. Blade area is circ * height * 0.25 = pi*d*h*0.25
0.25 because air acts on only one quarter of the blades at a time (others are either blocked by blades being acted on or are returning and therefore spinning towards the wind in a Savonious).
Neglect air friction from returning blades.
1 meter = 39 in & 1ft = 0.31m.
Ab = pi * 0.31 * 0.31 * 0.25 = 0.075 sq meters
Pw = 0.5 * 1.23 * 0.075 * 8.9^3 = 32 watts of wind power.
A really smart guy named Albert Betz (a wind energy expert from Germany) figured the best possible wind turbine efficiency is 59%. The best possible electrical generator efficiency is about 80% (if you use 3 phase AC – good luck finding one of these at this power level!).
32w * .80 * .59 = 15.3 watts. This is about as much of a best case analysis you could imagine. If you had a 100% efficient converter you could light a standard CFL.
Realistic assumptions:
Wind is 11 mph.
Turbine efficiency is 35% (the huge MW wind turbines are about here).
DC generator efficiency 60%.
Converter? Not really sure – lets just say it’s still less than the number I’m about to give you…
32w * (11/20)^3 * .35 * .60 = 1.1 watt
So 10 strung together might just barely light a standard CFL. I would be surprised if you could even get that much out – as it’s loaded the generator will slow decreasing its efficiency more.
“you math people are so smart” maybe. There’s not much math up there. A couple of unit conversions, maybe a trivial amount of algebra. I’ve only looked at this because I want to build a VAWT. I think wind power could be useful to me in a grid-tied setting. There are VAWT units out there producing renewable power right now, this blower rig-job just isn’t a very good way to do it.
I do the math to see if an approach is worth trying. With a serious breeze in the background I can see this…
…see this turbine spinning at a paltry 170 rpm. There’s branches waving all over the place yet this thing can barely overcome the friction in it’s one bearing (see 2:10). It’s not driving a load, the only load is friction! There are so many hints in this vid that this approach is a waste of time.
Why is it that when talking about “green power” as soon as you throw out some math – the same stuff that is used on the big MW turbines – you get a minus score?
In other words, why would you vote down a logical, mathematical analysis? Whether you do the analysis or not, you are engineering something when you build one…and the great majority of successful engineering projects are analyzed first using mathematical models. You can’t say if something will work for sure but you can usually rule things out. Optimization is huge also. It’s one thing to get a tiny 12v bulb to light, something else to make useful power. The difference is analysis.
Ok, last piece of rant.
You want to make something without understanding the underlying principles…try crafts, because you will not be successful at science, engineering or inventing, and certainly not at “green power”.
Why is Everyone kicking on Ike and giving him thumbs down for stating the mathematics behind why this really isn’t that great of a model of wind power generation? I mean aren’t these things designed to suck air into the center from all sides? I personally don’t know much about then, but from the fact they are referred to as “blowers” and looking at their design that is a far different usage than being spun by a single directional wind. It pretty much throws away the mechanical usage that it had.
Hey ike, why are you taking the time to tell people what they Can’t do….you are using a very small % of you power, for the wrong reason…Don’t show off with your Hands off math ! Do something good, we both know you are more than a grumpy old man ? The world is NOT flat, & they can Now grow new body parts in a lab. That math will lock you down, and removes chance. Don’t close any doors ! CRAFTS !? Thanks ike. Keep trying EVERYONE ! :>)
easy now mr invisible particle, one day you will love and seek for the normaility again, but i know you gotta go down there from event hahahahaha. thoose who don´t have that need live i am dead at least inside. there is now escape from hardcore gravity.
Your rant is mostly correct, but the suggestion of a circular wind turbine like that is completely missed. The theory behind it comes from an inviscid assumption at high Reynolds numbers from Navier-Stokes. In a free stream on a cylinder there are two low pressure points perpendicular to the flow where the fluid is moving at double the velocity. Although this is proved by neglecting viscosity, leaving it in the calculation only adds a boundary layer, which doesn’t change the calculation much.
I was wondering if anyone on this channel knew enough to call me on that. I wasn’t 100% sure about that assumption. Alas, not a mech eng and Reynolds numbers and much of fluid mechanics are not my strong suite. Thanks for the info!
Shes hot
This could work better if the vanes were to create either a downward slight pressure or upwards which could put a tower of these to work together. Where wind was blowing through them they could lock together creating more power when the wind was gusty. It could also have a system that directs the wind current into a more efficient direction. Along with balancing and alignment remedies and turbulance redirection Could actually power more than a science guys original mathmatical presumptions.
Why do all the treehuggers wear hats that look like exploded sheep?
Nice job there ikedasquid.
@greenpowerscience
Hey Dan, I emailed you a few days ago, did you get it? I was just wondering
@bigshugdorman yes she is
You said that these windmills did not have a load. But a power generating one will have a load will it not? It still needs to drive what ever will give over the power. As the kenetic energy still needs to be transferred. So that would still be a problem would it not?
@GREENPOWERSCIENCE …no to correct you …but windmills in the early 1900′s was used to pump water not electric…..SORRY
Looks like these would be a bit more bird safe, in that birds will be less likely to fly into them as they do other designs.
Have to keep my eye out next time I am at the scrap yards.
@Anvilshock HEMP……….
Holy Crap, Windmills on farms were for pumping water! Not making electricity!
Nice video, for who is interested .. I have created a new animation on how I build my first solar panel and wind turbine at home.. see it here.. : eco-energy-systems . com