Small Scale Wind Energy Conversion Systems
Posted on Oct 11, 2008 - 04:36 AM
By: Jayanth Krishnappa
Wind is an intermittent source of energy. It is howling one day and is calm the other. Wind is just moving air, but it is moving mass even though it is very light. When wind strikes an object, it exerts force on it and tries to move it out of the way. The amount of energy in the wind is influenced by such factors as its speed and mass. More speed means more energy, as in a speeding car has more energy than a slower car it passes by. Likewise heavier cars contain more energy than lighter cars traveling at the same speed.
Wind energy has been harnessed to generate electricity or pump water from a long time now. The scale of the wind energy conversion systems or the wind mills has a range from very small units of about 500W to huge turbines generating 5MW of electricity. In the recent years due to the increasing awareness of environmental benefits of this technology, small wind energy systems are gaining popularity in households and commercial establishments both in the urban and rural communities. The cost of these systems are far reasonable than what was at the time of introduction of the technology to the market.
Small scale wind power could be utilized as the sole energy source or as part of a hybrid energy system in conjunction with the grid supply or any other renewable generation on the site. Sizing the system according to ones own energy requirement is the key to make sure the investment is worth and consequently ensures a good payback.
When you decide on installing a small wind turbine to cut down your energy feed from the grid supply and thus green house gas emissions in the broad sense, you have to start with analyzing the wind data for your region. In order to size your system and predict the availability of required wind speeds over a given period of time, historical wind data measured by federal or state authorities can be analyzed.
The data for US wind patterns are available from the following links on the internet:
National Climate Data Center – http://lwf.ncdc.noaa.gov/oa/ncdc.html
National Renewable Energy Laboratory – http://www.nrel.gov/wind
On-site measurements can also be made to obtain accurate information. The device used to measure wind speeds is called an anemometer. It is usually used in conjunction with a data logger to store wind speed data over a period of time. It is the average wind speed which is used for estimating the power output of the turbine due to frequent variations in wind speeds. Small turbine performance measurements can also be recorded with these instruments with suitable sensors.
The useful energy output in the form of electricity is a small percentage of the total energy captured by the wind turbine. Factors like the efficiency of the turbine, the generator (alternator) etc come into play. The estimated number is a maximum of 30% of overall efficiency for a wind power system which is designed to strict standards. Despite the hype about the new airfoils and breakthrough generator technology, small wind systems are less efficient than the medium and high power rated systems.
Wind energy systems could be of different configuration in terms of their operation. They might be direct connected systems where the system is supplying the load directly. Storage arrangement like battery banks to store excess energy during surplus supply (high wind speeds) can be used with the system. And the grid connected systems which feed the excess power to the grid and earn the turbine owner some revenue.
Economics of small wind generators can be calculated by predicting the payback of the system. The simplest way to do it is to divide the system cost by its projected revenue. If the time to payback is found to be less than the life of the wind turbine, it means that the turbine has paid for itself. But such calculations usually do not consider the returns that the wind turbine brings after the payback period. So, one can always argue that the profitability of the system is not entirely dependent on its payback period. In addition to this, we are to consider the environmental benefits and the constant rise in energy cost. Integrating such benefits into the payback calculation can result in a realistic estimation of the economics of this renewable technology.
Professional advice in terms of technology, finance and incentive schemes is advisable for prospective owners, because wrong decisions at the time of investment could reflect in poor returns or even a dead investment. Insurance for the wind turbine system is a vital factor. Malfunctions and damages are common on small systems as experienced by many owners globally. Insurance for damages created by the turbines is also necessary for accidents like falling of the tower, damage to people or property due to accidents etc. In an urban scenario, these issues become more important.
As time advances, economies of scale would reduce the cost of installation and maintenance of wind energy conversion systems. The technology is also being upgraded constantly in order to create an efficient and modular system which makes it more feasible. Higher degree of sophistication as in large turbines in terms of safety are being introduced to small and medium scale systems to reduce malfunctions or accidents and also improve operational efficiency. It is sure that we are going to see more of these systems around in the coming years due to its advantages.
Here are a few small wind turbines that we offer:
Skystream 3.7 Compact Wind Turbine
Air-X Land Wind Turbine
Whisper 500 Wind Turbine
Whisper 200 Wind Turbine
Air-X Marine Wind Turbine
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