# How do I determine how many wind turbines I will need???

Feb 20, 2009 03:43 pm
How do I determine how many wind turbines I will need???

My home and shop use about 1800kwh per month and I noticed the wind turbines are rated by watts only.

How do I convert from one to the other in order to determine how big or how many wind turbines I will need to significantly or completely eliminate my electric bill???

33 Posts
Feb 20, 2009 04:37 pm
Re: How do I determine how many wind turbines I will need???

That depends on your wind supply and how reliable it is. Some places like coastal places have very very steady wind supplies. Some places don't. So it just depends on if you want to storage your excess or sell it back.

Feb 21, 2009 06:55 am
Re: How do I determine how many wind turbines I will need???

Take a look around Mr.Moschilli, anybody looking? Good, cause this can be a real head scratcher. Wouldn't want anybody to think you dandruf or anything.
http://rredc.nrel.gov/wind/pubs/atlas/maps.html
This web site has maps of the United States and its average wind speeds. The first map is a yearly average. Take a look at the legend in the lower right hand corner. Its very small. Even if you blow it up its hard to read but it looks like it gives an estimate of watts per square meter at a given elevation of a supposed turbine. I can only assume that the watts per square meter would be the total area of the propeller which can be indicative to its maximum output at a given wind speed in miles per hour. (The bigger the swept area of the propeller, the bigger the generator, the more power it can make.)
With an electric bill of \$165.00 a month, if you live in the southeast (any where white) and you want to eliminate that bill, your better off going PV. If you live in the Northwest (any where blue or black) you have a fighting chance.
1800 / 30 = 60 kWh's per day
Areas of white: 0 to 100 watts per meter squared at 30 meters high - 60,000 / 100 = 600 square meters of swept area.
Areas of black: 400 to 1000 watts per square meter at 30 meters high - 60,000 / 1000 = 60 square meters of swept area.
Get it?
Obviously the total swept area can be one or more wind genny's.
Keep in mind though that these are only averages. As they say, "your mileage may vary."

http://www.bergey.com/
Go to this site and click on Bergey Excel and look over the specifications. You'll see that in a sustained 31 mile per hour wind its rated output is achieved. Now look at the map again and it looks like in the white areas, average winds speeds at 30 meters elevation, are up to 8 mph average. This is right at the cut in wind speed of the Excel. Obviously not the best choice for those areas but a better choice for those areas in black and at a higher elevation.

Lets say it was in a black area and at 164(?)feet. According to that map we can expect average sustained wind speeds of up to 26 mph. Much closer to rated output of the Excel. I would think that under those circumstances, one Excel would be sufficient. Where as in white areas at 30 meters, multiple Excels would be required and at, roughly \$30k a pop that could get expensive real quick. While your at the Bergey site read a round and familiarize yourself with the technology and terminology. Knowledge is power!
Does anybody know where a map is that we can actually read the legends?
« Last Edit: Feb 21, 2009 07:02 am by Thomas Allen Schmidt »

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