On wind turbine ratings.... the average power out of a wind turbine will generally be much less than the rated power. Unless, of course, you have a nice constant 28mph wind with no turbulence or variation.... most turbines tend to be rated around 25 to 30mph. I have had a little 200 watt rated (at 28mph) turbine up at my house all winter. It is a quite windy location where 2x6's move around the yard in gusts and woodpiles blow over. I've measured an 85mph gust on my anemometer at the top of my chimney, and 50mph gusts are common all winter. This turbine, over the 6 months of winter, peaked out at 250 watts, and only produced 15kWh all winter.... not so good (meaning that the average power it produced over the winter was about 3 watts). On especially miserably windy days, it could produce up to 0.7kWh though -- which still means it was only averaging 30 watts even on the really windy days. Even though I have lots of gusty winds, my average windspeed is not great (especially only 15 feet off the ground where this little turbine is). I had a bigger one, rated at 1kW, up for a few days. It peaked out at about 2.1kW, and was capable of doing about 2 to 3kWh over a windy day. Tower failure in 90mph winds (estimated) brought it down, and I haven't gotten it back up again yet. You can see from these numbers that in a gusty wind regime like mine, even a turbine that peaks at a quite high number, does not consistently produce anywhere near that amount. The places where wind farms are installed are usually selected for consistent even winds... not really high gusty winds, like most people psychologically think of as windy areas.
To figure out how much a turbine could be expected to produce in your area, the best way is to get a year's worth of 10 second (or 1 second) windspeed data, then use that, along with the power curve of the turbine (if a turbine that is professionally made and for sale doesn't have a published power curve.... be very very suspicious), to figure out what it would have produced for that year. A little cruder method... but one that we usually have to use since we don't have the actual monitored wind data, is the published energy curve (harder to find than power curves, but many manufacturers are starting to include them), and the average annual windspeed (or better, average monthly windspeed). citydata.com has average monthly windspeed (usually taken at an airport, at 10 meter height). Z -------------- next part -------------- An HTML attachment was scrubbed... URL: /pipermail/attachments/20090620/79c2a093/attachment.html _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/sustainablelorgbiofuel Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (70,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
