Windmills have come to stay as a major source of renewable energy. Given the potential of wind, ample scope is there to remain so. . One major hindrance to the growth of its population is maintainability and its associated cost. As a machine , a wind turbine needs periodical maintenance. It is really a herculean task to do preventive and breakdown maintenance on a windmill . Its construction offers greater challenges in terms of accessibility, serviceability and safety. Maintenance will comedown if machine reliability goes up; but to make it reliable, a combination of best design, superior materials, auto/ self lubricating systems etc have to be in place which is not practicable at a low price. Is it possible to make a windmill which is maintenance friendly? Yes, if the turbine is at ground level . How to redirect wind to the turbine at floor level? This article is meant to present a novel concept of “ Wind turbine at ground level”.
Changing the Direction of Wind
Air is basically a fluid; it can be made to follow a path determined by a system. A pipe / duct with its open end facing the air stream can transport wind to another point away from stream. A rotatable open pipe with a provision to orient itself to the direction of wind flow will do the purpose. A simple pin- bush arrangement is sufficient to have the swivel arrangement.
Maximising the Wind Capturing
Now we have known the way of redirecting the wind to a desired location. Level of capturing is restricted by the open end diameter of the duct at the collection side. Obviously, wind collected over a bigger diameter is voluminous , thus a reservoir of more kinetic energy. To make it happen, size of the entire duct needs to be increased, which will complicate the system. We can very well invoke the principle of convergence nozzle in this application. Wind capturing can be maximized by modifying collection mouth to the plain nozzle ( funnel) shape. Nozzle at capturing point helps to minimize the structure size & weight besides improving wind velocity. Collection duct can have more nozzles in intermediate stages which will reduce duct size further. These convergent nozzles can transport wind without much loss of internal energy. Lesser the convergence angle, higher the transfer efficiency. Needless to say, duct is to be free from sharp bends.
Wind Turbine Construction
Wind is captured over a wider area and let out through a smaller opening at the other end. So, size of the turbine can be considerably reduced. If a turbine with a size of 4 mtr is planned in a conventional way- instead capturing tower to the size of around 4 mtr is to be installed as per this principle and whose output can made available at say 1.5mtrs of diameter, after tapering down the duct size gradually and thus it leads the requirement of a turbine of reduced size. This drastically reduces cost on turbine. Also, there is a possibility of installing many turbines along the duct with a single tower.
This concept can be developed to make a Wind Power Plant. Many capturing towers in a cluster can be connected to a single generating location under one roof. Further there is a flexibility to operate the wind turbines selectively by regulating the volume / pressure, using appropriate instrumentation systems, according to the wind flow pattern.
Discharge of Utilized Wind
After extracting the kinetic energy from the wind, it can be let out at the ground level itself.. Better way would be take to the collection zone and let it in the direction opposite to the collection. We use a coaxial ducts for this purpose.
Advantages
• Easier to erect; easier to maintain. Only moving part at height is revolving funnel, whose maintenance can be minimized by the use of appropriate material after heat treatment.
• Smaller turbines ; easier to produce in bulk.
• Quicker implementation.
• Less costlier.
• Above benefits attract more investments in this segment of renewable energy.; more energy generation.
• This concept can be used to ventilate buildings, complexes – helps to minimize the use of exhaust/ refresher fans.
• This principle can be horizontally deployed to improve volumetric efficiency of compressor and generators engines ( A separate article is planned by the author on this subject )
Disadvantages
• This system is confined by the capability to erect capturing towers of larger sizes.
Conclusion
This system is at concept stage and it is a viable one . Researchers and manufacturers can put some more efforts to find out the optimal convergence angle and air letting out system. With this evolution, a paradigm shift in the wind energy technology is certain.
Concept and authored by
K Senapathy B Sc, B Tech, M.S.,
Manager – Production
Lakshmi Precision Tools Ltd.,
Arasur, Coimbatore,
Tamilnadu, India
senapathyk@yahoo.co.in
About the Author
Author is a Production Engineering graduate from Madras Institute of Technology, Chennai, India , with a post graduation in Technological Operations from BITS, Pilani ( India ) and taken up various assignments in Maintenance, Manufacturing and Engineering functions in auto-components industries in India. Currently, working for Lakshmi Precision Tools, Coimbatore , India as Manager-Production.
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