Vertical Axis Wind Generators

[sluissa]

I know wind generators are a long debated and heated topic, but I've been doing some thinking along with a minor amount of research along with some inspiration from the movie, Waterworld.

I realize a setup like in the movie would be expensive if it would even be possible, but what about something on a slightly smaller scale. something portable which you would be able to haul up the mast when the sail isn't up and take down when you want to sail. It just seems to be a perfect situation for a device such as this, you have a large vertical pole that is already secured and normally has relatively heavy windloads put on it.

This type of generator is called a Darrieus Wind Turbine (http://en.wikipedia.org/wiki/Darrieus_wind_turbine)

It has a few downsides, such as it is not self starting, but that could easily be remedied with a bit of electrical work and a wind sensor(or just the occasional push when you want to start it).

It also has a resonant mode which is when it turns at a certain speed, it will start to shake apart if left at that speed long enough. A simple enough fix would be to wire in a brake to a speed sensor, so that if it reached that dangerous speed it would slow the thing down, or at least give you an alarm so that you could do something about it(manual brakes, or use the generator as a brake.

The good part is that once the turbine is stopped, it shouldn't start again unless started by an automatic mechanism or by your own hand.

Obviously there are down sides. You would be unable to use it while sailing. It would be fairly large and bulky to stow. I'm not even sure what it would sound like, but from what I hear, unlike windmill type blades where the edges spin much faster than the center(causing alot of wind noise) pretty much all of this spins at pretty much the same speed.

Also, if built large enough, say a majority the height of the mast(1/2 to 3/4 maybe?) it would produce alot of power, although i'm uncertain how much, and if it might be too much for the batteries to accept it all.

The whole thing could be sized so not to interfere with any rigging while spinning.

I just want to know why there hasn't been much research into this type of generation since while you're not sailing, you've got a giant pole which tons of wind flows by but nothing is gained from it. Tiny windmill gens just seem to take up more space than they should.

Sorry if any of this sounds unfeasable, as some of you may know, I'm simply a newbie here and I don't even have a boat yet. This just seems to me to be a design that should be explored.

[sluissa]

this probably isn't as simple as I think it is, I think it's still possible, but probably not with as big of a generator as I was considiering.

Like I said, it would have to be sized so not to interfere with the rigging.

[CaptainK]

That would be a "cool" approach to this kind of technology.

But like you said. There's alot of "unknowns" about this particular piece of technology?

And also is this. You'd have to put that wind vane about 25% up above the deck. And below the rigging cables. SO as not to get fouled up in them.

And during the time when not in use. You'd have to put the blades in a position where it won't be a hinderance to the sails. (That right there is a challenge, in it's own right!!)

[sluissa]

well, as far as them being a hindrance to sail, I was thinking it might be possible to just remove it from the mast when not in use, but if that's too complicated, just a system to lock them into a position(if only using two blades) perpendicular to the boom if the boom was secured going straight back, I know there's a better way to explain this, but I don't have all the terminology down yet... basically they'd be in line with those cross bar things about 2/3s up the mast... not sure what those are...

anyway, yeah, I think it could work, but you're right, there are too many unknowns that I couldn't figure out without knowing alot more science or spending alot of money building something that may or may not work

[CaptainK]

sluissa once whispered in the wind

basically they'd be in line with those cross bar things about 2/3s up the mast... not sure what those are...

Those "things" are called spreaders!!

Here's a wonderful link that could help out, in learning all those parts?

http://www.boattalk.com/sailboatparts.htm

Now those blades could be remove. Sort of like what they do with helicopters. But you'd have to dissconnect them. And reconnect them up before use. That's one option?

The other like what you're trying to say is. Is to run it up the mast?

Sounds like you're wanting to mount one on the mast. I don't think that would work vey well?

[CaptainK]

Thank you for your thoughtful response to the knottybuoyz crew!!

These posts were actually not for me. But, for our forum member sluissa!!

Yeah. I myself would love to read up, about anything from your archives from work?

Looking forward to some more good reading!!

[CaptainK]

Hear Hear!!

[coot]

I just want to know why there hasn't been much research into this type of generation since while you're not sailing, you've got a giant pole which tons of wind flows by but nothing is gained from it. Tiny windmill gens just seem to take up more space than they should.

The basic question that you have to ask about any new technology: What is so much better about this?

Your description and the wikipedia article make this design look pretty unattractive. I don't see any obvious up side that compensates for all the problems. I would guess that most people who look at this design have the same reaction, and that is probably why there isn't much research into it for use on small boats.

Of course, it could be just waiting for somebody with the engineering skills and money to take an interest.

[sluissa]

CaptK: Thanks for your input and the site that labels all the boat parts, really helps when explaining things

knottybouyz: I'd like any info you have on the subject if it's not a problem.

Coot: the main advantage I can see is that it would produce more energy than a tiny little windmill just mounted on the back of a boat.

Like I said, it may not be worth the trade off in size, weight, or cost, like it was stated earlier, too many unknowns.

There are many other designs other than the Derrieus Turbine obviously, it was just the first that sprung to mind as a result of the movie.

It just seems to me there should be some way to make use of the mast while not sailing.

at the very least maybe something small mounted on the top of the mast.

Again, it's just an idea.

[CaptainK]

Top of the mast!!!

I wouldn't go that far?

Maybe mount it mear the top of the mast. But not on top. The top of the mast is where the VHF antenna and anchor light is!!

Also if you happen to live in a lightning prone area. That would not be a very good idea!!

If someone where to mount a windvane device or something like that on the upper region of the mast. I'd put it up around between 3/4 and almost the very top of the mast. But not the very top?

Most people mount their windvanes on a pole of the stern area of their boats. If I was to mount any windvane on my boat. That's where I'd mount mine!!

[GordMay]

Vertical Axis Wind Turbines (Darius & Savonius Rotors) would be a structural* & aerodynamic nightmare on a sailboat, and are inherently less efficient** than Horizontal Axis Wind Turbines

* Require strong support & berarings at both upper & lower ends.

** A VAWT puts out about about 30% of a comparable HAWT.

[CaptainK]

Yeah Gord.

I figured that is what the comparisons are?

The Horizontal Axis Wind Turbines are cheaper and have a better proven history for their worth.

And not as big and clunky like the Vertical Axis Wind Turbines (Darius & Savonius Rotors) are!!

[sluissa]

Gord: are you sure about those facts? Admittedly, I havn't done too much research on the topic but from what I have read, if you compare a vertical and a horizonal turbine that both have roughly the same blade surface area, the efficiency is going to be nearly the same at the mid range wind speed, granted, vertical turbines are much less efficient at low or high wind speeds, but in high wind speeds you normally would secure a wind generator anyway. as far as structure is concerned, the mast of a sailboat is usually(or supposed to be anyway) inherantly strong, built to be able to push the whole weight of the boat through the water I don't see how it would put any more strain on it than would be during normal sailing. as far as aerodynamics, again, I don't see a problem as the sails seem to do a fine job of picking up wind.

Now if you mean there would be a problem finding a place to put it so it wouldn't get caught up in the rigging, then yes, I agree with you.

after thinking about it some more, it doesn't seem like an idea that could be adapted to most masts, you'd have to design pretty much the whole boat around the system which would be out of most people's price ranges.

but, if this were done, I still believe that the VAWT would produce more than enough power for the average boat

info from www.turby.nl (a netherlands site, but you can work your way through it if you try) shows a 3 meter tall, vertical turbine with a rotor diamater of less than 2 meters(designed to be mounted on the roof of a building) can produce 2.5 kW at the optimal 14m/s wind speed(about 27 knots) (I'm not very knowledgeable about electricity and how it's measured, but this sounds like it's comparable to many small gasoline generators)

again, like I said, it's probably not feasable for most cruisers, it was just an idea.

[GordMay]

For more information, Goto: “Wind Energy Systems” ~ By Dr. Gary Johnson
http://www.eece.ksu.edu/~gjohnson/wind1.pdf
Specifically Chapter 4 - “Wind Turbine Power, Energy, & Torque” at: http://www.eece.ksu.edu/~gjohnson/wind4.pdf

and see the turbine comparison chart at:
http://cruisersforum.com/photopost//...php?photo=1917

[CaptainK]

That's alot of reading material Gord?

But, I'm sure it'll make interesting reading. I'll download those files and read once the oportuniyt arrives!!

Thanks Gord!!