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# How do you measure windmill efficiency?

How do you measure windmill efficiency?

In order to answer this question it is necessary to first define what efficiency is. Efficiency, in regards to energy production, is the ratio or energy output compared to energy input, or in layman’s terms the ratio between how much of one type of energy is produced by another type of energy. This means that windmill energy efficiency will be based upon the amount of wind energy is needed to produce electrical energy.

The first part of this problem will be to measure the amount of wind energy that a windmill exposed to which turns out to be wind density X the blade diameter squared X wind velocity cubed X constant or d*D^2*V^3*C.

To figure out wind velocity a number of devices can be used including a recent technological developed produced by a Netherland’s company makes measuring wind speeds and velocities easier to do as it uses lasers to take the measurements. This device can be used to measure wind speeds at heights as high as 200 feet while standing on the ground.

While this technology may not be available for students to use yet, other data collection devices do exist. If the student is not able to find a wind velocity measuring device to use for their windmill science fair project then they can collect data from local weather services.

The second part of the problem is the amount of energy output that is produced by the windmill. This can be calculated using the following formula:

KWH/year = (.01328(D^2)(V^3)), where D = the diameter of the blade round and V = wind velocity.

Now that the two sides of the equation are ready you can calculate your windmill’s efficiency:

(KWH/year)/(d*D^2*V^3*C)

Why Is Efficiency Important?

Efficiency ratings help you to realize how much energy is being lost in the conversion process. This loss is caused by friction and the laws of thermodynamics. When you are working on a windmill science fair project the efficiency rating can be used to support the appeal of modifications that you have made to the overall design of a windmill, or to support the use of one form of energy over another.

Calculations and Science

Science is full of math. Math is used to determine relationships between physical elements. If you are interested in pursuing a career in the sciences you will need to learn a number of math formulas. You will use these formulas to better understand your science.