Build Your Own Wind Generator

Copyright © 2008

www.DIYPowerSystem.com

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Copyright 2008 www.DIYPowerSystem.com

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Table of Contents Table of Contents ................................................................................................................ 3

Wind Power Explained ....................................................................................................... 4

Wind Turbines – Why Buy a Wind Turbine ....................................................................... 5

Wind Turbines – How to Build a Wind Turbine ................................................................ 6

On the Parts Necessary to the Wind Turbine .................................................................. 6

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Wind Power Explained

Even if nowadays wind power evokes for most people a highly advanced

technology to which only a certain financial elite has access, it must be said that

the use of wind power has in fact a fairly old tradition.

Thousands of years ago, ancient people would rely on wind power in order to

make their ships sail across seas and rivers, and this way of employing wind

power persisted a long time within more or less advances civilizations. Another

use of wind power regarded the grinding of grains.

It’s only at the end of the 19th century that people started to understand the true

potency of wind, when they were constrained to find a source of energy in very

specific circumstances (villages of U.S.A. needed a source like this one in order

to cover their electricity needs). Nowadays, wind power is used at a large scale,

due to some features common to all sources of clean energy.

The difference between wind power and hydroelectricity consists of the force that

is used to generate mechanical energy. First, it’s the wind which plays that role,

and in the second case, water is used to create energy.

Obviously, the differences are not that major. But how does wind produce

energy, after all? A wind turbine contains some rotating blades which actually

transform the power of the wind into kinetic energy.

The kinetic energy is then collected by a generator. The part which enables the

transition of kinetic energy to the generator is the shaft. Now, it is within the

generator that the electricity is produced by force of electromagnetic induction.

Energy is released due to the fact that some magnets spin around a coil.

Electrons are set free from their atoms due to the force of the wind which moves

the magnetic fields, generating power, and this power, called kinetic energy, is

then turned into electricity.

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Wind Turbines – Why Buy a Wind Turbine

Homemade wind turbines do exist. However, some people think that building all

by themselves such an item is a little too unusual, so they choose to buy one.

The truth is that wind turbines are not so difficult to build.

On the contrary, all the elements needed for building one and for making it run

properly are the ones mentioned above, a system that allows it to be kept in the

wind, and a control system.

On the other hand, buying a ready-made turbine is much more uncomplicated.

And yes, buying wind turbines general is worthwhile. Wind turbines can generate

electricity in the amount proper for covering all the energy needs of an average

user.

Despite the fact that the prices are somewhat high – some thousands of dollars,

or even tens of thousands of dollars – it must be said that wind turbines are worth

buying. The initial investment will be recovered, since the electricity bills will be

diminished by 50% or more, that is, by 90%.

In addition, it must be mentioned that the wind turbine market undergoes a

somehow expected evolution: more and more efficient technologies are sold for

lower prices, which is convenient for anyone, since more and more people

decide to use such devices in order to cover their electricity needs. This is truly

an opportunity for profit and principles regarding the use or renewable energy to

meet on the benefit of each other.

However, before buying a wind turbine, one must determine if it will really be

convenient for them to buy one. In order to determine, people should establish

the proportion of wind speed in their area to how much energy they monthly

consume. 10 mph should be the minimum average wind speed, and, with respect

to the energy consumption, that is much more easily controllable, in case it

needs to be controlled.

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Wind Turbines – How to Build a Wind Turbine

Not all people find it convenient to buy a wind generator, even if most of them

admit that such a device finally proves to be worthwhile. It’s just that they simply

can not afford to pay some thousands of dollars for such a piece of machinery.

For such people, building a wind generator is the one satisfying solution, since

the costs will not exceed $ 100.

Although from this perspective a wind turbine seems very appealing, before

starting to build one, people should face the reality. If they don’t actually live in a

windy region, there is no reason for them to build one. In such cases, using other

systems – systems that fit the climatic circumstances of the region – is much

more recommendable.

All the parts necessary for building a wind generator can be purchased from the

Internet – eBay is one of the most popular solutions – at extremely convenient

prices. Apart from them, one has to make sure they have the necessary tools:

some screwdrivers, a grinder, a jigsaw, a socket set and some sandpaper.

With respect to the parts, there should be no problem with finding a DC power

motor, a body assembly, a tail assembly, the necessary blades for collecting the

wind power, a hub to connect the propeller to the motor, a battery bank, some

nuts and bolts, and some hardware. On top of all these, one has to make sure a

tower is in the close vicinity of their home.

On the Parts Necessary to the Wind Turbine

The Batteries

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Batteries are essential to the generator because through them one gets to store

the energy produced by the generators. So, since one has to buy some batteries

if they have decided to build a turbine, they should look for some cheep items.

EBay is, again, the best source of inexpensive items, but one should be aware of

the fact that deep cycle batteries can be acquired for free.

All that must be done is to be at the right place at the right time. Some stores

throw away items even if such items haven’t expired yet. One may just get lucky

and find the perfect battery this way.

The DC Motor

Again, eBay is a great place where anyone can purchase an inexpensive DC

motor.

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The Blades

When it comes to turbine blades, it must be said that unlike the ones used in the

past, modern turbines have two or three blades. These blades must be built from

high density materials, such as high density wood, glass fiber and epoxy

composites.

When building and designing a wind turbine, one has to pay special attention to

blades, due to the fact that they represent the most sensitive and likely to break

rapidly element of the entire system. The blades undergo a constant mechanical

stress caused by centrifugal forces and fatigue. This is precisely why the moment

of designing the blades is a very important one for the outcome of the entire

project.

Another important aspect concerning the blades is their shape. They must be as

aerodynamic as possible, since they determine the amount of energy collected

by the wind turbine.

However, the performance of the blades can be optimized by different control

devices able to manage the rotor speed, thus preventing or delaying fatigue or

even the failure of the blades, as well as it prevents the overheating or the

overloading of the electrical generator. However, for homemade turbine blades,

following the steps and the indications presented below should be a sufficient

guarantee for the successful outcome of the project.

In order to manufacture the blades for the turbine, some ABS or some PVC pipe

is excellent as raw material. In case it is PVC pipe that happens to be at hand, it

must be mentioned that it should be covered with some UV protector in order to

expand the life span of the blades made from it.

Since the material is found, all one has to do is cut 3 blades from this material,

trying to maintain at the same time a proper diameter for all of these blades.

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Keeping to a single diameter and to some pre-established sizes should not be

too difficult.

Cutting the first blade by the book is a guarantee that the other two will be cut

properly, because the first will be used as a pattern for the other two. An eight

feet diameter is perfect for most turbines, but if circumstances don’t allow the

builder to cut such dimensions, than all they can do is adjust the size of the

blades to their possibilities.

In order to cut the blades, the pipe should be cut, at its turn, in quarters. Some

proportions and measures must be continuously kept in mind. For instance, the

length of the blades should be around four or five feet in order to attain a total

span of 8 feet.

But sizes can be different if the diameter of the pipe is different. For instance, for

a ten inch diameter of the pipe, the blades should mount up to seven inches at

the bottom and to five inches at the top.

After cutting the right sizes, some extra cuts and some holes must be made in

order to enable the future steps in the building process.

The indications given above regard the construction of a wind turbine provided

with three blades. It must be said that in early times, rudimentary turbines could

count up to 40 blades or even more.

Today, instead, two or three blades seem to represent the optimal number of

blades for the system. The number of blades is not an arbitrarily chosen one. On

the contrary, depending on how many blades we decide to provide our turbine

with, we also decide a series of factors, such as, the structural dynamics, the

weight of the nacelle, the design tip-speed ratio, the power coefficient, and many

others.

A three-blade wind turbine was chosen for presentation for the simple reason

that, if compared to wind turbines with two blades, this one had a much more

constant power production and also a much more steady gyroscopic force.

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It’s true that two-blade rotors are much simpler to be assembled and to be lifted.

However, efficiency is much more important than the ease of building the system,

not to mention the fact that complications entailed by the third blade are not so

consistent after all.

The Hub

A hub is not so difficult to find. Junk yards or local stores specialized in selling

similar products, or, again, eBay, are the best places for acquiring a hub. One

does not actually build a hub.

All they have to do is to attach the blades previously cut to the hub. For that, they

need some bolts and some flat steel bars. Before attaching the blades to the hub,

one has to make sure the diameter of the hub is compatible to the one of the

shaft on the DC motor.

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1- Leading edge polished even to diminish friction

2- Trailing edge diminishing pull

3- Bolts

4- Hub

5- Steel bar

The Axis

The proper axis is necessary in order to assure an efficient rotation of the blades.

That is, the blades must rotate even when the wind is not that strong. The axis

can provide a guarantee that they will.

However, the blades also must rotate efficiently in the opposite situation, that is,

they must not move irregularly on stormy weather, otherwise the wiring and some

other parts of the generator risk to be compromised in their future activity.

An issue intensely debated today with respect to axis is whether to choose a

vertical or a horizontal one. Vertical axes, on the one hand, present the

advantage of easing enormously the installation of the entire mechanism, since

they simplify it by force of a vertical drive shaft. In addition, being omnidirectional,

a vertical axis eliminates from the beginning the necessity of a yaw mechanism

the role of which is to adjust the turbine to the direction from which the wind

blows.

The limitations of vertical axes concern the attachment of some guy wires at the

top of the axis. Another difficulty regards the fact that they are much more difficult

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to control with respect to power output during periods or moments with extreme

winds.

The Tail Piece

Some scrap metal from some old appliance or from a junk yard is perfect for

manufacturing a tail piece. A tail shape must be cut and attached to the back of

the system. Its purpose is to provide some extra stability and balance to the

generator, which, eventually, leads to an increased efficiency of the rotation of

the blades.

The Charge Controller

One can build a charge controller if absolutely necessary, but it’s not worth all the

trouble since they can find the item extremely rapidly at low prices in a variety of

places, eBay included.

The charge controller on a wind turbine has the same purpose as a charge

controller on the solar power system, that is, it monitors the amount of energy

stored in the battery, which offers to the user the possibility to prevent

overcharging. Overloading is damaging for the battery, reducing its efficiency and

life span.

The Dump Load

Since overcharging the battery is not recommendable, the extra energy must be

taken care of. A dump load is where such energy is sent. A number of items,

such as a water heater or a backup battery pack are fit for a dump load.

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The AC Inverter

The inverter is meant to turn the direct current into alternating current. This

process is essential because most of the appliances commonly found in a house

run on AC only. EBay is the most recommendable source for purchasing AC

inverters.

The Wiring

There is no standard way to do the wiring on a wind turbine since it depends on

the material and on the particularities of each turbine. However, there is a

recommendable order in which the wiring should be made.

Beginning with the DC motor, going through the charge controller and the battery

pack and ending with the AC inverter is the most advisable pattern. However,

asking an electrician or an authorized person for help can also be a solution.

The Tower

Anything that stands eight to twelve feet above the ground can be defined as a

tower for the purposes discussed here. Of course, the device needs to be quite

solidly fixed in the ground and it must be able to sustain both the turbine and the

entire process developed by the turbine. Should no tower be available, one can

always build it if they have the necessary skills and tools.