POWER FROM TERRACE

[toluganti]

URL: http://www.thehindu.com/todays-paper/tp ... 226802.ece

If we think energy from wind mills is new technology, we are totally wrong. They existed in Babylonia 2,500 years ago, Persians tried them out 1,200 years ago and Europe in general has had windmills for over 700 years. Generally, the rotating blades were used to move simple mechanical parts for lifting water, pounding grains or extracting oil in mills. Wind power to move sail boats and later to explore the world by larger ships has been in vogue for thousands of years. During the 20{+t}{+h}century, it caught up in the U.S. and rest of the world for more diverse applications.

Wind turbine on the terrace of Raya's house in Chandra Layout, Bangalore

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While there are wind turbine clusters with hundreds of them dotting the landscape, we are discussing here mainly the small-scale unit practical for typical urban public buildings. They supply power for lights, TV, battery charging and such needs. With blade diameter ranging from 0.5 to 7.0 metres, and average wind speeds upwards of 2.5 metre per second, we can generate power in the range of 0.5 kW to 10 kW per hour.

For routine household needs, even smaller units with blade diameter less than 3 metres, generating up to 2 kW, can be considered. DC generators in the 12 to 24 volts range are adequate for household needs.

For such small scale, magnetic alternator-type generator serves the function. Also, horizontal axis devices deliver maximum coefficient of efficiency. These can be easily mounted atop any well-designed building. The legs of the tower cannot be directly placed on a slab, but preferably need RCC pillars or an inverted beam arrangement to transfer the load down.

Technically speaking, periodic records of wind speed across one year taken through anemometer is required to accurately assess the power generation. Altitude, air density, topography, speed, wind direction, trees, buildings and such others increase the air turbulence, reducing the power generation. Using scientific formulae based on density, velocity and wind sweep area, technical experts can advice on the installation of the turbine.

The choice of rotor depends upon the purpose of generation – slow running multiple blades are good enough for water pumps while the fast running ones with fewer blades, with wind blowing perpendicular to the blades, are required for electricity.

If the wind can create a drag and lift effect, it further boosts power generation. Of course, there will be the tail vane to rotate the blades in wind directions. Generally, the blades need to have aerodynamic design, good strength and light weight material. Accordingly, aluminium and fibre are preferred over steel.

India, on an average, has around 3 metres per second speed, making it a viable nation for tapping wind energy. Of course, this average has no meaning, for the spot speeds are important. Wind energy unit is a one-time investment, so across years of operation the cost per unit goes on reducing, making it a sustainable source of energy.

[toluganti]

But how about the effects of wind turbines like loss of mobile signal and all? Also, both solar and wind turbine uses batteries to store the generated electricity. Wont the battery maintenance add up to the total cost later?

[msn1270]

if we consider the rotation of the Wind Blades, its frequency falls under low frequency spectrum, whereas the Mobiles works at several GHz Spectrum, even if we consider the 3rd or 6th or 9th harmonics also, there wont' be any interference on mobile signal operations.

Regarding the Battery, if you take care of them periodically, you can run up-to 5 years without any hassles. Compared to the Savings on Electricity Bills, the maintenance cost will be lesser.
One of my colleague residing at Basaveshwara nagar using solar panel based Back up power system with Lead acid batteries (that too a non-branded one) from past 12 years without any issues
even though the vendor had given him 3 years warranty.

[toluganti]

That is real good news. As I was born in times where we used to pay Rs30/- for 100 units of power consumed in our house, I'm getting uneasy to pay Rs.400+ for 110 units now a days. I was wonder why Govt treats us like milking cow and extract from us. Should a small family consuming 200 units a month should shell-out Rs1000/- every month?

So, my thoughts went into, how can I bring down the BESCOM unit consumption to less than 100 units and pay less that Rs.500/- per month. Thanks for the info and clarifications msn.

[pvr59ksl]

Hi all

I am looking for a reasonably priced solar water heater for my new house. From the internet it is learnt that Evacuated Tube Collector (ETC) is better than Flat Plate Collector (FPC) systems. I have short listed Supreme Solar 200L which is costing about 19,500-. Has anyone used this ? What other brands are good as well as reasonably priced. I also heard that ETC tubes are manufactured in China. Can we trust ETC ?

[msn1270]

Most of the Solar water heaters in our market(Both FPC & ETC) are manufactured in china. Only the final assembly & labeling will be done here.

Even though the ETC model is cheaper, is also fragile and tubes can break easily due to human mistakes and also by stone throwing or similar incidents.
Over a period of time, there are water leakage issues are reported at the end points.

Most important thing is that you need to test the water for hardness and presence of any type of chemicals to narrow down the right kind of Solar water heater(materials used in making it) for trouble free usage.