Vertical Wind Power Generators

Sharon asks…

How to create a generator with copper and a magnet.?

I’m trying to create electricity to power a small computer fan by spinning a neodymium magnet surrounded by copper wire. My problem is the fan, like many things, has a positive and negative lead and so if I hook up the power from the copper coil to the positive lead the where would I attach the negative lead so that It completes the circuit?

Windmill Farms answers:

Your wire has two ends, and depending on the orientation of your magnet relative to the loop, the direction you wound the loop, and the direction you spin the magnet, one wire will be positive, and one will be negative. The magnet needs to be oriented and spun so that the loop passes through the poles of the magnet. If the magnet poles and coil are lined up so that the poles don’t move in relation to the loop, you won’t generate any current (for example, the coil is laid on the horizontal plane, the magnetic poles are aligned vertically, and you rotate the magnet so that the poles stay vertical).

Charles asks…

What kind of alternative energy solutions are feasible in Portland?

So, I’m a college student in Portland, Oregon, and an ameture hobbyist that enjoys tinkering with electronics. I was thinking about starting an initiative on my campus to build more eco-friendly energy sources, but the campus is convered with really tall trees and gets small amounts of sunlight (it is Portland, after all). I think those two things rule out a wind turbine system or a solar panel system. Does anyone know of any alternative energy solutions that intelligent and driven students could build in a place like that?
Honestly, I don’t really care about the carbon footprint or how all alternative energy is supposedly just a gimmick that makes people think that they are doing something good when they aren’t. I don’t know enough about global warming to even know if it is a process that humans have a significant control over. The more I read about it, the less I know. That being said, I just want to have some energy that doesn’t spew smoke and won’t be used up. I’m more concerned with aesthetics and renewability than really saving the environment.

Windmill Farms answers:

As a college student in Portland, you should already know about this.

Http://www.metaefficient.com/renewable-power/new-rooftop-wind-turbine-tested-the-helyx.html

Vertical wind generators require less wind to operate, and less area to install.

Http://www.metaefficient.com/renewable-power/new-rooftop-wind-turbine-tested-the-helyx.html

http://www.pacwind.net/news.html

James asks…

How would you calculate horsepower for a windmill without a generator?

I need to find horsepower for mini windmills for a science fair project, and so i need a formula.

Windmill Farms answers:

Horsepower (hp) is the name of several non-metric units of power. In scientific discourse, the term “horsepower” is rarely used because of its various definitions and the existence of an SI unit for power, the watt (W). However, use of the term “horsepower” persists as a legacy in many languages and industries, particularly in the automotive industry because of their continued advertising of maximum power output of internal-combustion engines in “horsepower” units of measurement.

There are two important factors to consider when evaluating the measurement of “horsepower”:

The various definitions of the “horsepower” unit itself
The various standards used in measuring the value of “horsepower”
These factors can be combined in unexpected ways — the power output for an engine rated at “100 horsepower” might not be what a reader expects. For this reason, various groups have attempted to standardize not only the definition of “horsepower” but the measurement of “horsepower.” In the interim, more confusion may surface. In contrast, the watt, defined by the International System of Units (“SI”), is not encumbered by varying definitions.

That said, if your intent is to physically test a mechanical windmill device for its horsepower capacity, you are testing mechanical horsepower. Obviously the wind speed will affect your outcome, I’ll let you do what you want with that. If you can attach a known weight to the windmill so that it will lift the weight a measurable vertical distance, and you have a reasonably accurate stop-watch, you can calculate the horsepower output of your windmill. One horsepower is defined as power equivalent of lifting 550 pounds a vertical distance of one foot in one second. So if you tied one end of a rope to a 550 pound weight, suspended the rope over a pulley, and tied the other end to a horse, and the horse was able to lift that weight one foot in one second, he would be capable of generating one horsepower. Or if a 220 pound man can run up a 5 foot (vertical) staircase in two seconds he is generating one horsepower.
Here’s the formula:
W = weight(pounds), D = distance(feet), T = time(seconds)
Horsepower = WD/(550T)

Ruth asks…

what are some science experiments involving wind tunnels?

Windmill Farms answers:

Wind tunnels have been used in a wide variety of projects including fundamental aerodynamics, aerodynamics of racing cars and road vehicles, rotorcraft aerodynamics, aeroacoustics, aeronautics, wind engineering and industrial aerodynamics.

Field Testing a Portable Wind Tunnel for Fine Dust Emissions

Wind erosion has been studied using both stationary and portable field wind tunnels. A portable field wind tunnel was developed in Lubbock, Texas for measuring sediment transport from a variety of surfaces and locations. A portable wind tunnel provides a unique opportunity to study wind erosion in natural field conditions. As field
measurements of dust emissions can be very expensive as well as unpredictable, generating aerosols using a laboratory dust generator has become accepted as a method for simulating such conditions. This study compares dust emissions measured on an agricultural field using a portable field wind tunnel with dust emissions measured
using a dust generator.

The field wind tunnel vertical slot sampler captured large sediment in a trap at the base of the sampler and pulled finer suspended material up through a tube onto large glass fiber filters. The air in the tube was sampled by a GRIMM analyzer which gave real-time measurements of dust concentration. Data was averaged over field wind tunnel runs and test plots within a site. Dust concentrations from the initial wind as the field wind tunnel was brought to speed were treated separately from the dust measured from the dust produced after introduction of the abrasion material.

Https://dspace.lib.ttu.edu/etd/bitstream/handle/2346/ETD-TTU-2009-12-111/COX-THESIS.pdf?sequence=6

Wind Tunnel Aeroacoustic Tests of Six Airfoils for Use on Small Wind Turbines

Aeroacoustic tests of seven airfoils were performed in an open jet anechoic wind tunnel. Six of the airfoils are candidates for use on small wind turbines operating at low Reynolds number. One airfoil was tested for comparison to benchmark data. Tests were conducted with and without boundary layer tripping. In some cases a turbulence grid was placed upstream in the test section to investigate inflow turbulence noise. An array of 48 microphones was used to locate noise sources and separate airfoil noise from extraneous tunnel noise. Trailing edge noise was dominant for all airfoils in clean tunnel flow. With the boundary layer untripped, several airfoils exhibited pure tones that disappeared after proper tripping was applied. In the presence of inflow turbulence, leading edge noise was dominant for all airfoils.
There are six different sources that independently generate airfoil acoustic emissions: inflow turbulence, turbulent boundary layer trailing edge interaction, separating flow, laminar boundary layer vortex shedding, trailing edge bluntness (von Karman) vortex shedding and tip vortex formation. These sources are superimposed to form the total noise spectrum from a wind turbine blade. The spectra are often summed to calculate an overall sound power level. (etc.)
http://www.nrel.gov/docs/fy04osti/35090.pdf

Carol asks…

How do you connect wind turbine driven asynchronous motors to the grid?

I am looking to connect generic asynchronous motors (from washing machines, vacuum pumps, etc.) to vertical axis wind turbines. I need to know how to wire it so that I can sync these squirrel-cage induction machines to the electric grid by allowing me to plug them into an ordinary electric outlet in my home, 20-50 AMP. Since the generator is an induction device, if the grid goes down, then the generator should stop generating, which is what I want. By syncing to the grid I can avoid the cost of an inverter and not require batteries. This would allow to reduce my energy costs, and my net meter would register those savings.

There are companies that plan to sell such a device, including the turbine, generator and interconnection device for $400: http://www.clariantechnologies.com/main/page_home.html

I would rather use by own home-built vertical axis wind turbines and spare asynchronous motors as generators, so I need to know how to wire them and what, if any, interconnection device is needed.

I have asked the local electric company to provide me information about any required protective device that would be needed for this type of generator setup. I know (thanks to a previous response to a question here at Yahoo) that there is a possibility that if the grid is down and the turbine continues to rotate, an induction generator can sustain an open circuit voltage provided there is no load – this is an unlikely situation, but it is something that my electric grid supplier will tell me about.

I know that induction machines such as these must be connected to a grid that can supply reactive power in order for them to function as generators. Exactly how they are connected I do not know.

I need to know how to wire the wind turbine driven asynchronous motor to the grid so that reactive power is applied to it. And I need to know if I need a special controller that would allow that asynchronous motor to function as a generator such that I can just plug it into an ordinary electric outlet in my home.

Windmill Farms answers:

I can mention a few points at least – it may not be a full set of instructions partly because your spec. Leaves a few questions open.

1. 20 to 50 A is too much for a normal wall outlet especially if it is single phase.

2. Are your generators (motors) single or 3 phase. You will need a corresponding connection.

3. You need to get the electricity supplier’s approval before connecting at least anywhere I ever heard about.

4.You’ll need a switch (1 or 3 phase, as the case may be) for the current and voltage of the generator. Overcurrent protection should be there anyway??

5. Wire the motor up through the switch and plug it in. When you switch on the machine will start as a motor. Wind blowing on the turbine will speed it up and start generating (power flow outward). Note that the motor, when run as a generator, will run slightly above synchronous speed (positive slip). If the wind dies down you will revert to motor operation which will drive the turbine and you could end up paying a lot to generate wind. You may therefore need a reverse power flow detection to disconnect when there’s not enough wind.

6. Next you need to be careful the turbine can’t run away when it gets windy (with the generator off-line for whatever reason) and overspeed your machine (you’ll damage it)

7. I’ll edit here if I think of anything more.

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