From my earliest days in Cuba I was attracted to the various methods of generating electricity. Since I lived in the open countryside, wind was my medium. I remember dismantling my battery operated toys, much to my parents` horror, and using the motor, attached to self-made blades, to power torch light bulbs. This wind-powered apparatus was used in various ways.
After migrating to Barbados, in 1970, I continued the same trend, this time experimenting with bigger motors. In 2010 I built a device to wind coils, purchased some magnets and built two one kW wind generator, which I used to power my home. While the generators were efficient and produced an adequate supply of electricity, this was not enough to maintain my electrical consumption. I realized that my home needed a 5kw stand-alone system and since I had received specialized training in photovoltaic system I made up the difference with PV modules. This hybrid system has served me well.
However, I have experienced first-hand the challenges which wind turbines create. Firstly, residential wind turbines need a constant supply of wind at about 12 to 25 m/h. In some places in Barbados this is achieved year round. Only between the months of November to May does Barbados get the best supply of wind.
Secondly, gusty winds, which are usually experienced during the months of June to October, are not favourable to wind turbines. Turbines have moving parts and any sudden increase in wind velocity or change in wind direction may destroy them. Specially made turbines may not encounter this problem because they shut down automatically.
Thirdly, trees and buildings are problematic in that they obstruct the free flow of wind and cause turbulence. I have observed some wind generators in Barbados spend more time “hunting” for the wind than in the actual production of energy. For them to be effective and efficient they need wide open spaces very far away from buildings. Turbines function best on flat lands or near the coast line. I lost the blades of one of my turbines because of wind turbulence. It should be noted that this turbine was controlled by a “tail piece” as it was home-made.
Fourthly, height is very essential for maximum production. Putting a turbine low to the ground is like putting a solar module in the shade; non-productive. Height enhances the free flow of wind and negates turbulence.
Periodical checks and general maintenance are also required for the efficient use of the turbines. As I mention before, they have moving parts which are held together by nuts and bolts which may become loose and rusted over a period of time. Cracks may also develop on the blades and need to be attended to immediately. These problems occur in commercial as well as residential turbines.
Most large commercial grid –operated turbines consist of the generator body, the control system, the rectifier and the inverter system. The generator body, which includes the magnets and coils, is the section that actually produces the electricity and is rotated by blades. Other commercial wind turbines carry a transmission or gear-box driven by blades which then drive the generator. The control system usually adjusts the operational status of the wind turbine according to wind speed. The rectifier takes the AC out-put (electricity) from the generator and converts it to DC and feeds the inverter. The inverter takes the DC, regulates it, converts it back to AC, synchronizes it with the grid and sends it to the power grid. To be functional, this entire system must be connected to the power grid. If the grid (electricity provider) fails, the entire turbine shuts down. This is why this system is called “grid-tied” or “grid-operated”.
The residential grid-operated turbines operate basically the same as the commercial grid-operated turbines. They mainly differ in size and may or may not carry gear-boxes.
Alternate to the grid-operated system is the stand-alone system. This system consists of a wind turbine, rectifier, charge-controller, battery bank, dump-load and an inverter. In this system the wind turbine produces the energy; the charge-controller maintains a controlled charge on the batteries where the electricity is stored. Most of the residential stand-alone or off-grid systems are 12volts, 24volts or 48volts.This type of system is recommended for those who want to be independent of the grid.
The advantage of using turbines as an alternate energy source is that they are environmentally friendly. They emit no green house gases nor produce hazardous waste. As the energy they produce is not dependent on fossil fuel, no harmful particles and pollutants are released into the atmosphere. They don`t adversely affect water deposits or surrounding soil. They can co-exist with all types of farms, animal or vegetation.
As the user of a hybrid system (wind turbines and solar modules) I can attest to the fact that I have saved money in electricity. I also get a sense of satisfaction in knowing that I am producing my own energy. I highly recommend the use of renewable energy to all people whether local, regional or international.