Wind and Weather

5-in-1 Weather InstrumentIt was around mid-February of this year (2015) when the Acurite Weather station and associated things arrived.

I had waffled on whether to purchased one – it was not inexpensive, but, it is also not the cost of an entry level professional unit.  I also really only one initial use for it, too.  I wanted to answer a question that had been ruminating in the back of head for a bit over a month.  The question had come up after the solar panels went up on the chicken coop.  The solar panels only generate electricity when there is enough sun light – often poorly during the day in winter, and never during the night any time of year.  The only other obvious alternative energy generation method was wind. But, it is not as simple as buying a turbine system.  A turbine is useless without wind.  A turbine is also useless even with a small of amount of wind.

Was there enough wind at the house to generate electricity?

We mounted the outdoor part of the weather system on a fence post near the chicken yard; the indoor receiver (with its fancy colorized screen) sits in the kitchen and the Internet bridge lives in the basement.  The Internet bridge is a device that connects via a network cable into a network switch; the indoor receiver wirelessly sends weather readings to this device, and, subsequently, forwards those readings to Acurite’s My Backyard Weather service.

Acurite’s service has limited analytical capabilities.  You can produce simple line graphs of individual readings – wind speed, temperature, barometric pressure, and so on.  But, you cannot produce fancier things like a wind rose, or pull apart temperature readings into night time lows plotted against daytime highs.

Through a bit of a virtual Rube Goldberg setup, I started collecting the readings in a database of my own.  I now have readings, on average, every 20.36 minutes, from February 21, 2015 to the present1.

Using some statistical and graphing tools2,3,4,5,6, I came up with some answers to the original question.

The short answer is it’s unlikely that from six to twelve feet above the ground, there is enough wind to generate electricity.

Let me explain a bit more.

I narrowed the focus of the question to the end of winter.  I only started the collection of data at the end of February, that left March as being the closest month to a true winter-month.

marchwinds-hist2The wind turbines that I had been looking at have a wind cut-in speed of 4.2 to 6.7 MPH.  Below that speed but above 0.0 MPH, the turbine blades and head may slowly rotate, but it is not enough rotation to generate electricity.  The wind rose, above, was quite helpful in coming to an answer.  It shows that we get our dominate wind from the west — seems obvious in retrospect, as there is an enormous bluff/hill to the east.  But having direction of the wind is likely not necessary.  Plotting the March data has a histogram, you can get a very simple yet informative picture; the majority of the wind is under four miles per hour.  That’s well under what is necessary to make a turbine useful.

VariableValue
Wind > 4 MPH22.32%
Wind <= 4 MPH77.68%
Average Wind (MPH)2.49
Max Wind (MPH)10.90
Average Temperature (F)36.07
High Temperature (F)71.59
Low Temperature (F)-7.20

A wind turbine is out of the question.  There are other locations in the yard that could have more wind, but it is unlikely this would be convenient to move the generated power from that location to the battery bank at the chicken coop.  A more plausible scenario is to add both more batteries and more solar panels.  We would be able to capture more energy when it is light out, and have more storage capacity to drawn from when it is needed.

  1. data sample
  2. Jupyter Notebook is a web application for interactive data science and scientific computing.
  3. matplotlib is a python 2D plotting library.
  4. windrose (license)
  5. anaconda implementation of python3
  6. jupyter notebook with sample graphs and calculations