A reader says:
I have got land with a wind density of 140 watts/sq. meter at 50 m up. I’m thinking of installing a 100-kW generator, but using 14-m blades (These were used on 250-kW turbines where wind density is 354 watts/sq. meter) I can get a good capacity factor. However, the strength of the blades can be just 40% of blades used for 250-kW turbines.
But I do not know the weight of 14-m long fiberglass blades for either the 250 kW and for 100 kW turbines. I know the weight of each 100-m long blade (Ed note: Mahesh may mean a 50-m blade) for a 1-MW turbine is about 50 tons (Ed. Note: maybe for the entire rotor), and that the weight of the blade is not linearly proportional, but rises with some exponential function. A 9-m blade weighs about 547 kg and a 14-m version, about 760 kg.
If I want to use a different material for the blade, I do not know the relation between strength, length, and weight of a blade for particular power capacity.
Can your readers provide a generalized formula for calculating blade weight for particular length to produce a required power? I know strength to weight ratios of different materials but I do not know how to calculate required strength. Or, can you suggest a good article or book to study this?
Readers can add comments below. –PD
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