The solution to today's power shortage problem is literally blowing in the wind. Wind power is the answer to today's electric power supply problems. If conventional sources of electric power are supported by local wind generator farms, then the problem can be solved effectively. Harnessing renewable sources like wind energy is the only way of solving our energy needs, while not disturbing the balance of nature.
If you are a proactive person, who believes in radical and effective solutions to problems, then going for designing your own generator, to solve the energy needs of your house, is the way to go. In this article, I provide you with basic design tips.
A wind generator, aeroconverter, wind power unit, or a wind turbine converts wind energy into electrical energy. The earliest recorded use of windmills, of vertical axis type, is from 200 BC in Persia. These early windmills were used to power water distribution, grind food grains, and draw water.
The first electricity generating windmill, was reportedly built in 1887 in Scotland by James Blyth. Since then, wind farms have developed by leaps and bounds in Europe and today wind power capacity of Europe has reached a staggering 74,767 MW. If a windmill could be installed in every conducive place on Earth, an estimated 72 Terawatts of electric power might be generated.
A generator consists of many components that make the generation of electricity possible. Three main parts are the blades, the wind turbine which converts wind energy into mechanical energy, and the generator inside, which converts this mechanical energy into electricity. Other important parts are the electrical storage mechanisms and control mechanism of the generator. Let us see the prime design considerations.
Wind Resource Assessment
An installed generator is useless, without adequate wind blowing in the area, to turn its blades. Therefore, the first and foremost step in creating plans is to decide on a location and altitude at which, you will get adequate power generation.
To determine that, you need to make a wind resource assessment report of your area. Information about wind speeds in a particular area can be had from your local meteorological department, which will have decade old data sets for your particular locale.
You can measure wind speeds yourself, by taking help of anemometers and recording data for some months. Another important factor is altitude and orientation of the wind as well as local range of temperature variation. The data about wind speeds will help you decide on a location for your home wind generator and give you an idea about what kind of wind turbine capacity should you install.
Theoretically, according to Betz's law, for horizontal axis wind turbine, you cannot convert more than 59.3% of the wind's kinetic energy into usable electric power. This law was devised from the study of the aerodynamics of a horizontal axis wind turbine.
The most important consideration is the blade design of the turbine. The two primary types, according to structure, are horizontal axis and vertical axis based blades. The horizontal axis, three blade design offers maximum efficiency. One important factor that affects the design is the tip speed ratio. It is the ratio of wind speeds to speed of the blade tip.
You should aim for a design that gives you a tip speed ratio of 6 to 7. The blade structure has to be designed after taking aerodynamics into consideration. Things that you need to consider while designing your generator blades are the expected wind speeds at the site, the speed and torque limits, and the strength of the entire structure.
The generators need to be mounted behind the blades, at the top of the tower. The torque generated by the wind is transmitted to the generator, through a gear box, which drives a dynamo inside, to generate AC power. Through the use of gears, more rotations of the dynamo rotor are achieved in a single blade rotation. Design a generator after taking the expected wind speeds and power generation limits into consideration.
You need to consider the designing of a control mechanism to control the speed of rotation and power generated through gearing mechanism. Also needed is a braking mechanism to stop the blades from rotating during maintenance.
The height of a tower can drastically affect the amount of power supplied by the generator. Wind speeds increase almost exponentially, as the altitude rises. So, higher the tower, better it is for your plans. The tower needs to be sturdy, to hold the weight of the blades and generator mechanism. You will need batteries and electrical lines that can transfer the power generated for use in your house.
Use of Materials
The use of materials for building your blades, towers, and other equipment matters as it will affect cost, stability, and the output of generators. Fiberglass composites are normally used to create the blades as they are lighter than other materials (creating lesser rotational inertia) and they offer the necessary sturdiness. They are all essentially glass fiber reinforced polymer composite materials. You may need to get the blades fabricated. Inquire about the cost of every option available and decide which one will suit your plan.
Creating a Tailor-made Design
Taking all the above factors into consideration, you must create your own plans, taking your requirements and the on-site conditions into consideration. You can find many basic design models of wind generators online. After taking into consideration, your installed power generation goals, established constraints imposed by on-site conditions and your budget, you can make your design.
Creating generator designs is not only a great exercise for budding engineers, but also a proactive way of contributing to the global endeavor to reduce pollution caused by conventional energy resources like coal and fossil fuels.