using ventilators for turbine

[UTTER DESTRUCTION]

Hello guys,Im new here, i have been doing research about wind turbines for a long time but unfortunately the location i live in doesnt meet necessary required wind speed. At nights, its 2-8 km per hour but in the day time it s between 14 km-30 km per hour. I saw a japanese dude on youtube who uses double ventilators to speed up the wind turbine. Lets say each ventilator spends 50 watt so it will be 100 watt at total. And if we use 1500 or 2000 watt turbine, we can produce more energy than we consume with ventilators. Even if turbine produce 500 watt at least it will be 400 watt energy in each hour. so it will 400*720=288 kw in a month. What do you guys think? Am i thinking wrong ? Here is the video

New Wind Energy Technology - YouTube

[Rob Beckers]

Hi Utter,

Alas, there is no such thing as a free lunch (or TANSTAAFL as Heinlein put it)...

You can NEVER make more energy with that wind turbine than those ventilators are using. In fact, the turbine will make much, much less than the power consumed by those ventilators.

The second law of thermodynamics had something to do with that as well.

What you are describing is known as an "over unitity" machine, where more energy comes out than was put it. Nature unfortunately does not work that way. You always get out less than was put in, usually much less, and the rest is lost as an increase in entropy (ie. more heat, more random motion etc.).

Any time someone tries to sell you an over unity type of machine don't walk, run (and/or point out to them that those things do not work).

Cheers,

-RoB-

[UTTER DESTRUCTION]

Hi Utter,

Alas, there is no such thing as a free lunch (or TANSTAAFL as Heinlein put it)...

You can NEVER make more energy with that wind turbine than those ventilators are using. In fact, the turbine will make much, much less than the power consumed by those ventilators.

The second law of thermodynamics had something to do with that as well.

What you are describing is known as an "over unitity" machine, where more energy comes out than was put it. Nature unfortunately does not work that way. You always get out less than was put in, usually much less, and the rest is lost as an increase in entropy (ie. more heat, more random motion etc.).

Any time someone tries to sell you an over unity type of machine don't walk, run (and/or point out to them that those things do not work).

Cheers,

-RoB-

Hi Rob
Thank you for the answer.
Whay you say is true. You cant produce power without a source. A power wont just how up magically. You need another kind of power source to produce energy. But We just dont produce energy out of nowhere, We consume 100 watt or 150 to produce electricity. In the video 2 ventilator seems to be creating enough wind to get the job done. We see wind turbine spins so fast that it actually looks like its turning backwards. Im pretty sure the turbine in the video reaches its optimum rpm and producing optimum energy as advertised.
Im planning to try this with hy 1000 wind turbine as this turbine is very efficient and produces more power than its advertised.

[UTTER DESTRUCTION]

I would like to hear other friend's ideas as well :)

[Dave Schwartz]

In the video you see, there is no load at all on the turbines (there is nothing attached except the support - and a tether to the tail of the HAWT to keep it from yawing wildly). That's why they are spinning. So in this 'demo' there is no energy being produced and probably several hundred watts consumed. If they were loaded to anything near what those fans are consuming they would quickly come to a halt.

The fans (ventilators) cannot be 100% efficient in converting electricity to air movement... they lose energy to heat (resistance in the motor coil windings, bearings) and noise. After that loss, you cannot be 100% efficient in coupling the fan's air output to the turbine (not even using a duct - which will lose energy in friction of the air with the walls)... not only are the turbine blades less than 100% efficient but the turbine loses energy just like the fan did (blade noise, generator winding resistance, bearing heat). Then you're going to lose more energy in the inverter transforming the energy back into a form that can be used to run the fan.

This is why, as Rob says, you cannot get more energy out of the system than you put into it (and in the real world you are guaranteed to lose some). Its captured in the laws of thermodynamics and no one has ever found a way around them. Those who claim they have (i.e. invented a perpetual motion machine) are either only fooling themselves, or most likely, trying to fool other people out of their money.

[UTTER DESTRUCTION]

In the video you see, there is no load at all on the turbines (there is nothing attached except the support - and a tether to the tail of the HAWT to keep it from yawing wildly). That's why they are spinning. So in this 'demo' there is no energy being produced and probably several hundred watts consumed. If they were loaded to anything near what those fans are consuming they would quickly come to a halt.

The fans (ventilators) cannot be 100% efficient in converting electricity to air movement... they lose energy to heat (resistance in the motor coil windings, bearings) and noise. After that loss, you cannot be 100% efficient in coupling the fan's air output to the turbine (not even using a duct - which will lose energy in friction of the air with the walls)... not only are the turbine blades less than 100% efficient but the turbine loses energy just like the fan did (blade noise, generator winding resistance, bearing heat). Then you're going to lose more energy in the inverter transforming the energy back into a form that can be used to run the fan.

This is why, as Rob says, you cannot get more energy out of the system than you put into it (and in the real world you are guaranteed to lose some). Its captured in the laws of thermodynamics and no one has ever found a way around them. Those who claim they have (i.e. invented a perpetual motion machine) are either only fooling themselves, or most likely, trying to fool other people out of their money.

Thx for the explanation. What do you think about the wind speed that turbine gets from the ventilators. Do you think its around 20 mph ?. Btw you guys make sense a bit but those explanations are too pessimistic IMO.You are saying losses. I agree losses will always exist. If that turbine halts when we connect it to a load, why doesnt it halt out there when spinning in the natural wind. Whats the difference between the wind produced by ventilators and natural wind out there?. And may i use the wind turbine off the grid. I will use rectifier, charge controller, battery bank, dump load,and off the grid pure sine inverter 220v. Can i use wind turbine with this configuration? I am asking because in every website, the turbines are always used with grid tie inverters.

[Dave Schwartz]

Wind speed from a fan could be whatever you want it to be... wind tunnels can get up to hurricane speeds but household fans probably don't get over 15 mph because anything higher would probably be uncomfortable (although fans made for the purpose, i.e. fire department smoke-ejector fans would be much higher - and much more expensive).

With system losses, unless energy is continuously supplied, the moving parts will stop. If you're putting 100 watts per second into the system and your system is 75% efficient, then you have only 75 watt-seconds coming out and 25 has been lost (but if it was via a mains-powered fan, you paid for it and that 75 watt-seconds you got had better be more valuable than the 25 you wasted or you're going to be continually losing money). You could put that 75 watt-seconds back into the fan but you still have to pay for the 25 to bring the input back up to 100 to get that 75. If that 25 comes from natural wind, the system will keep running but, in the end you've only created a piece of kinetic lawn art because you're getting no economic value out of it. And when the wind stops blowing, at the end of the first second you only have 75 watt-seconds going into the fan, 56 at the end of second 2, 42 and the end of second 3, 32 and the end of second 4, etc so probably within 20 seconds there won't be enough energy to turn the fan and the whole thing will stop.

Why doesn't loading a wind turbine stop it? That's the magic of the controller's power curve. Rob, Cor and others know way more than I about this (I just have a grid-tied solar array) but its calibrated to know how much load it can apply under each wind speed (which is related to generator voltage) in order to let it keep running at the speed that results in the maximum power.

The grid can be though of as a dead-short load. Individually, every light bulb, refrigerator, water heater, etc has some non-zero resistance so it does not act as a local short but put together all of the ones in all the buildings connected to the grid and the resistance is so low as to be effectively zero and thus a dead short. If you have multiple voltage sources attached to that short, current will be drawn preferentially from the source with the higher voltage until that source's voltage drops to be equal to all the rest because it runs out of current capacity. This is the principle a grid-tied inverter works on... it can force your tiny bit of energy back into the grid by raising its voltage just slightly above that of the grid, thus producing current and loading down your source. Now loading the source will cause the source's voltage to drop and if the controller kept boosting the output voltage to maintain the current into the grid, pretty soon the source voltage would drop to zero, which in a wind turbine means 'stopped'. The magic of the grid-tied inverter is that it knows how to hunt for that sweet-spot where the source is loaded to the point where the output current is the maximum available for the input voltage - this is called Maximum Point Point Tracking (also known as MPPT).

Sure you can use the configuration you list but the efficiency is going to be shockingly bad. I think wind charging batteries and powering loads through an inverter is usually somewhere around 40%. If what you pay for the system (plus maintenance) averaged over the life of the system is less than what you would pay a utility to buy the same amount of electricity from the grid then it might make economic sense. I don't think there are any situations where grid-tying such a system would have a positive economic outcome.