Windmill ?

Is it possible? Absolutely! Is it practical? Absolutely not!

If it were practical, don't you think someone would be doing it?

Search around, there was a blog on this not too long ago here.

BS. It is both possible and practical. The relatively lower inefficiency of the hydraulic drive has to be addressed, but it has many advantages. One is doing away with the weight and maintenance headache of the gearbox.

As for your second statement it beggars belief. Imagine the conversation; "Don't be daft Orville, if flying were practical don't you think someone would be doing it?"

<...just a thought trying to break that 30% efficiency windmill wall...>

Well, don't go that way, then. A hydraulic drive is much less efficient than a mechanical one, which is kind-of-important whent eh power source is as dilute and variable as the wind.

Consider drives akin to that on the modern safety bicycle instead.

UAA [UNDEFINED ABBREVIATION ALERT!]: "pmg"?

pmg= permanent magnet gizmo.

Remember, this is johnnyb5, who takes license with language just like he does physics.

Once again Mr Lynch sorry to piss on your Wheaties. The only license I carry is bail bonds april and johns bailbonds make a note. You may need me sometime were nation wide. You know when that untamed bad disposition gets out of control. I am certainly humbled by your greatness and as in all my previous post I have come to expect your indelible criticism. Not a physics major by far guess if I was I wouldn't have much use for the discussion board other then to ridicule the infidels.

P.S. You seem like a D V kinda guy. PMG permanent magnet generator or axle flux generator hmmm

Thanks for the enlightenment. I don't eat Wheaties. I'll make a note of your employer's name, for future reference.

Sorry I got your panties in a bunch, check out the reference provided by JohnDG.

That's the one to which I referred.

You really shouldn't take offense at anything that is printed here. It's mostly just in fun. And as soomeone smarter than I once said, opinions are like a$$holes. Everybody has one, and most of them stink!

Glad to brighten your day!

From Globalspec newsletter, 27^th July:

DirectU2 Specs & Techs: The Case for Hydraulic Wind Turbines...

thanks for the lynk it was very interesting maybe mr lynch should give it a view

I can't see where introducing the 20% or so inefficiency of a hydraulic circuit to what you state as a 30% direct coupled drive system would be advantageous. Given certain KW ranges, I'm sure the hydraulic drive would be good for frequency regulation but the system would have to be designed around the minimum mill speed/torque for required output. As the article implies, volumetric efficiencies are out the window over broad operating ranges and become impractical in high KW ranges. The article does give promise for future developments in hydraulic engineering, so go for it.

I don't see a problem with using the hydraulic system approach. I would however recomend using a low speed hydraulic torque motor like whats used on the drives of many skid steer and other industrial equipment drives as the pump. They are low speed so it can be direct driven plus the modern hydraulic components are very effecent. I am not sure where some people get the 20% and grater loss numbers for hydraulic drive systems but the more modern stuff is equal to a gearbox or any other mechanical system with efficencies of around 95% and higher being common.

By the way allthough I am recomending a motor to be used as a pump they do work both ways equaly well and do work in the very low speed ranges ,0 to a few 100's of RPM's, where most pumps dont.

Plus it is wind powered afterall so just put a bigger set of blades on it and dont worry about the efficency losses. Wind is free where I come from.

has anyone looked at http://www.chapdrive.com/ - they are doing hydraulic windmills right (here is a picture of what is a real unit) http://www.chapdrive.com/technology/ they have demonstrated a 225KW and 900KW unit. Presently are demonstrating a 5 MW generator - curious all the talk of Hydraulic being not practical or efficient as various bodies have found their numbers to be real - Red herring is one or many..