wind+resistance=heat

[electrondady1]

 i am pleased that information is begining to come out in regards to heating with wind power. my understanding at this point is that a geni constructed specifically for runing heaters should be of high voltage 120 -240 volts. that is should be very efficient , so the heat is not in the stator. which to me reads as low internal resistance. so in order to achieve those two things it would be nesecery to make a very large geni. or perhapse use an overdriven geni on a slow moving high torque mill. i understand it is next to impossible to get the unit to startup under load and capacitors could be used as part of a control device to aid in this problem. if anyone would care to clarify or give more specific information please post away. all information welcome.

[Dave B]

I want to keep things as simple as possible and I will be heating with wind also. No batteries, inverters, rectifiers etc. just the wild AC to variable loads depending on rpm. If it's turning it's heating, no matter how little. Many comments here are based on assuming most everyone is talking about charging batteries IE: useless power available in low winds. Well, possibly if you're talking 10' diameter blades, 5mph wind and charging batteries. Resistance heating is a different deal and anyone doing it out there knows what I mean. Great to hear of others interested so we can learn from each other on this subject also. Dave B.

[oztules]

hi daveb

Depends on what you are talking about. If you are talking about capacitors and induction motors which are overdriven, then the capacitors are integral with the stator fields anyway. They will allow the rotor to speed up without load, until the remnant magnetism in the rotor generates enough power to charge the capacitors up enough to drive the stator windings. (not strictly accurate but close enough for this discussion). This by definition, means that the prop is well and truly going before the induction generator begins to develop power. so by choosing the cap size, we can gain some control of startup speed.

To use caps to control other types of gennies is up to your own imagination. Capacitors in series with the load i guess could control the power out, without generating heat in the stator. When at low rpm, low frequency would no get enough capacitive reactance to pass much voltage through. As Frequency increased, so power transfer through the cap will increase. The higher the rpm, the better the capacitor transferres the power to the heating element. Never tried this in this application, but have used it instead of small power transformers in some applications to give stablised power for small circuits that people cannot come into contact with. (Caps in this instance would be oilfilled high volatge run caps) Have also used this method to run 110v transformers on 240v, and also to lower current in battery chargers. (just an animal I guess)

At high voltage 50 hz, 300uf caps can transfer massive amounts of power. The startup capacitors on single phase cap start cap run motors can transfer many HP to the start windings in 5hp motors, but would give the prop some chance to develop decent torque before power transfer got serious.

Just what this may do to efficiency is beyond me, maybe flux could help here. It could certainly control, but wheather it would cruel the efficiency too much I don't know. (just another odd-ball idea I guess)

the only other ways caps could be used to control startup, would be in circuits to pull in relays, but really the right choice of relay would do that anyhow. (unless you have a low voltage relay, and you use a capacitor as a resistor to lower the voltage the relay sees.

It is interesting to notice that unlike using a resistor to lower voltage, lowering voltage with a cap does not waste power heating up the resistor, so there are no real losses to deal with.

.....oztules

[electrondady1]

i have wired a house and rewired a truck. and for the last two years have studied this site in order to understand how to generate electricity.that is the extent of my know how. like dave has said, the main thrust of this site is towards battery charging and thats great. its possible to extrapolate alot of the knowlege for my own purposes. but i's looking as though to create enough power to heat with i will need to increase the size of my geni's by an order of magnitude(as per hugh's nervana geni).i was hopeing to build alot of small windmills ( 20-30  x 100 watts each) and pool there output to get a good power source.  i want to avoid a battery if possible . i was thinking i might be able to rectify each seperatly,  tie them  together  then use a capaciter to pulse power to a baseboard heater.

[oztules]

electrondady1

sorry to have confused the monica's of yourself and daveb. Got it right this time.

I see no reason why you shouldn,t go on with your original premise of multiple wind gennies. The capacitor you speak of will not transfer dc. If you pulse the capacitor you may as well pulse the load directly, and cut out the middleman.

However, once rectified you could tie them all together anyway, and use a simple relay to pull the load on line when it gets up to your nominated cut-in voltage (directly determined by the relay.) The relay shouldn't chatter around the startup region. When it pulls in, it may take 18v or so for a 24v relay, but once pulled in,it may only require 8v to hold it in. (if not soften the spring a little that returns the points back to original position). Take the relay  voltage off before the rectifiers, and this will give you some isolation from the load variations. (use seperate rectifiers and a big cap for driving the relay this will also help antichatter))

This is a useful property, as when the load pulls in, the voltage on the output will drop, and the relay would have fallen out, but by fiddling with the spring and gap, you can put on a fair amount of voltage variation on and the relay stays on.

Anyway, if you build your first one, you can play with all kinds of setups. For 100w you could electronically pulse, switch or whathave you cheaply, and experiment with what works for what you are capable of. That capability will increase markedly once you start playing for real. If you fiddle around and cook up your own brew, you are in a much better position to fix it up later.

This last point is useful if you plan 30 of them.

You are probably correct in thinking bigger could be better, but building a little one first seems to be the tried and true method for getting started into this kind of thing.

I do things upside down .I would get the mill up and running first, and then figure out the best way to utilise it... ie build your first mill, and then play.

.............oztules

[electrondady1]

http://www.otherpower.com/images/scimages/2793/little_erma_004.avi

not shure if this will work ,it's supposed to be a little video of a windmill prototype i made about two years ago , before i discovered this site.  ive been studying how to improve the output at low rpm. and have made some progress now . i'm getting ready to jig up to make alot of them . of course it will be nesecery to combine there power.so i think i need to rectify in order to do that. if a relay or a series of them can be used to power up a heater themn thats the way i will go

[Birdmanjack]

I am heating hot water in a little different way but should apply to you as well. Directly from my generator to a 55 gallon hot water tank to supplement my boiler. I am running two elements a six hundred watt and a three hundred watt elements. For now I have just the three hundred doing its job. I have to upsize the blade because I started small to make sure I could carve one. Picked up new prop material today and will let you know how I make out if you are interested. I am running an ametek tape drive motor at 4 to 1 on a jackshaft. It is the bigger motor rated at 90 volts 29 amps. We will see what happens with a better match on the blades.

[JF]

Dear Friends

I am very pleased that the discussion is now taking-off

concerning small wind turbines for heating.

Especially in Europe where there are many restrictions

concerning small "house-size" units. These smaller

heat-dedicated units are very suitable in our weather

conditions with both cold temperatures and high winds.

In our tiny local village by the windy Kattegat coast

- with heating oil prices over $ 1 USD per liter -

there is now great interest for smaller models with

rotors of about 1½ - 2-2.5 meters in diameter.

These would provide a considerable added energy input

to oil-fired hot-water storage tanks during our long

cold wet and windy winters.

We will be following these discussions very carefully

as I know will others - for inspiration and assistance

- as we will be experimenting along the lines suggested

during the present and future discussions

I would however mention - that although in no way can

I profess to the level of electrical-knowledge that many

other contributers to the board posess - that possibly  

interesting information may be found in the book

"Windmills & Wind Motors" F.E.Powell New York 1910

[and sold from this site by WonderMagnets or from

Lindsay Publications - http://www.lindsaybks.com ]

- the final section of this book is concerned with

interesting simple power-load switching systems.

This section is a translation from Prof. La Cour's

famous book from 1908 on the design and practical

construction of rural wind turbine power plants

[such power plants were in operation from 1905-1960's].

Secondly I will include a note from the essential book

"Handbuch Windenergie Technik" - by Prof. Crome from

The Technical University in Bremen - and available from

- http://www.oekobuch.de  

With best wishes to all - JF

[JF]

Dear Friends

Once again difficulties with illustrations

A retry

With best wishes - JF

[electrondady1]

jf, i am afraid the german is lost on me as i recognize only about one of every ten words. but i found Kattegat, so you could be Swedish( such good hockey players) or perhaps a Dain(lots of big windmills around ?)
birdmanjack, yes i am interested, every bit of information helps.
oztules, thanks, you are a wealth of knowlege and an asset to the forum.
daveb, i only started this thread as it looked like yours had ended and i needed more information .it looks as though it is possible to run heaters directly from the generator. i'm thinking the load would need to be just right,small enough for the mill to overcome at startup.you can see i like vawt's, they produce good torque at start up but don't spin so fast.so the solution  for me is in using large diameter rotors and lots of poles.

[Nando]

The idea of capacitor to allow the wind mill to start under load is not a practical one if one needs high watts.

Wind Mill for heating it is best to have a high voltage generator, around 240 volts at peak power ( furling trip point).

To define the peak power capability of the wind mill :

1. ) Measure the phase winding resistance. ( One leg)
   
2. ) Measure the Peak output unloaded voltage at peak RPM ( if you can not calculate the wind mill output voltage verus RPM.
   
3. ) Measure the peak output loaded voltage with 10 % of the maximum estimated load at peak RPM.
   
4. ) Calculate 2) - 3) =
   
5. ) Take 1) * 1.73 = dynamic wind mill internal resistance
   
6. ) Take 4) and divide by 1) = maximum current the generator can produce with 10 % generator internal losses.
   
7. Maximum power out ( approximated) = 3) * 6) = output power.
   
   

~~~~~~~~~~~~~~~~~~~~~~~~~

To be able to harvest the maximum power that the mill at any moment generates, the load needs to be VARIABLE to load the mill at its MPPT point. ( Maximum Power Point Tracking).

This implies that the heating element requires a controller to present such variable load.

Basically, a low frequency PWM controller inserting the load form 99 times its value to its 100 % basic value to extract the maximum MPPT power available.

I am, at the present, assisting a fellow in UK with such project, to harvest its wind mill 6 meter diameter, generated energy using a small PLC = Programmable Logic controller.

The wind mill is set for low wind regime areas and presently he is getting better than 900 KHW-hr/month in the southern west part of England, about 2 miles from the coast line.

The generator, Chinese product, produces around 380 Volts @ 200 RPM, MPPT loaded.

Sometimes the wind mill needs to be stopped because the wind mill is generating too much energy and the generator is producing above its top capacity.

We have not optimized the MPPT algorithm but getting close to it.

Nando

[windstuffnow]

  I could see heating domestic how water with a turbine but heating a whole house would be quite the trick !   I mostly burn wood but I also have an oil burner as a back up.   When I only use the oil burner I burn about 4 gallons of fuel oil a day.   Assuming its 75% efficient that means my requirement is around 17,500 BTU's per hour.   In watts that would end up being a system running constantly 24 hours a day making 5.1Kw .   That would be one heck of a turbine unless you have some continuous winter gales blowing accross the blades...

  You could, however, get a nice 8 or 10 hp diesel driving an alternator to supply electric to your house as well as use the waste to heat your house.   I'm surprised there aren't any "multi purpose" heating systems out there yet.  Actually could combine all the main things you need into one tight package ( electric, cooling, heating, hot water, frig, freezer etc. )  That same 4 gallons could do alot more than it does...

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