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How to monitor wind speed? (Photo by: Andy @ Flickr)

http://electrical-engineering-portal.com/how- to-monitor-wind-speed February 21, 2013

How to Monitor Wind Speed?

Edvard

Wind

Speed Mistery Or Not?

When considering wind power, most people ask what the average annual wind speedis and howto get that number. The usual response is that you must monitor the wind speed at your sitefor atleast 12 months, preferably longer, to determine whether a wind generator will work for you.

Sounds too long? Well, yes and no

For a home system, this isnt necessary. The costs involved in collecting wind data may not beustif ied when compared to the to tal cost of a small wind machine.

There is no economic formula to determine this, but it doesnt make much sense to spend$1,200on instrumentationif your wind machine costs only $3,000. You can get close to t he actualnumber by making an educated guess using the empirical methods.

Options For Monitoring The Wind Speed

If you decide to monitor wind speeds, you have several options.

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Weather anemometer

1The f irst is to buy a weather anemometerand record observat ions on a regular basis. This is theleast expensive way to collect wind data, but it has disadvantages. For the data to be valid, youmust be methodical in collecting it.

Recording one instantaneous wind speedper daywont do.

If you cant record multiple wind speedsthroughouta day, the quality of your data is questionable.

2A second option is to automate data collection byinstalling a data collection boardin a personalcomputer. This method works, but t he computermust stay on all the time, and there are additionalcosts.

Since these are not plug-and-play components,

some computer hardware and software knowledgeis necessary.

3A third opt ion is to invest in an anemometersystemspecif ically designed for collecting winddata. The least expensive systems simply averagethe wind speed over t ime and cost $200 to $300.These systems usually are sold without towers.

While

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The wind power monito ring system architecture

the

average wind speed is a useful measurement, it also is important to know the wind speed

distribution.

More sophisticated systems usually consist of:

1. A portable tower,

2. Instrumentat ion and

3. Data logger.

These systems are reliable and accurate, but they are expensive.

Af ter collecting data, you have equipment that may or may not be useful to you. The secondarymarket for used towers and data loggers is limited.

If you buy a used system, consider new instrumentation. This will help ensure quality data.

Usually the system has ananemometerand a wind vane. The anemometer measures windvelocity, while the wind vane registers direction. Bot h instruments should be mounted on a windpole or towerthat is as close as possible to the height at which your wind machine will bemounted.

If your anemometer is mounted too low, it will underestimate the actual wind resourceavailable.

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Endurance E-3120 50kW Wind Turbine Specif ication

It is

generally recommended that the hub height for small machines between 60 feet and 120 feet .Your anemometer also should be within this range.

To generate data for all seasons, average wind speeds along with distribut ion and peak gustinformation should be recorded for a minimum of three months, but ideally fo r a full year. Windspeed data can then be used with performance data for various wind machines to determine theexpected output f or each machine at your site.

If you collect data for a short time, it can be correlated with exist ing data to produce a model ofthe wind speeds at the potential site. To do this, you need to develop a correction factor.

For example, assume you have collected average wind speeds of 12.8 mph, 10.8 mph and 10.4mph for the last t hree months, and the published data from a nearby site for the same threemonths is 10.9, 10.2 and 9.5.

Dividing your data by the published data will give you t he following deviation facto rs:1.174,1.059and 1.095. Averaging these results in a correction factor of 1.109. You can multiply the remainingpublished data by this correct ion factor to est imate wind speeds at your site. This method involves

a fair amount o f interpretation, and some sites do not correlate well.

If you are considering a large project, on-site data is a necessity.

These systems require taller towers 40 or 50 meters. They include mult iple levels ofinstrumentation and data loggers that can be accessed remotely. Assessing a sites potential forutilityscale wind development is an expensive undertaking that requires committing significantf inancial resources.

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Wind Turbines How does it actually work? Investment?

Cant see this video? Click hereto watch it on Youtube.

America used 3,200 billion kilowatt-hoursof electricity in 1998.

The Energy Information Agencypredicts that consumption will increase to 4,400 billion kilowatt-hours in 2020. No single energy source can deliver all the electricity we need t o f uel our economy.

What do you think about this?

Resource:Montana Wind Power A Consumers Guide to Harnessing the Wind

http://www.youtube.com/watch?v=sLXZkn2W-lk