Is a Super Micro Grid Right for You?

 

Source: http://www.windpoweringamerica.gov/pdfs/small_wind/small_wind_guide.pdf

Inspecting the figure above, it is shown that heating and cooling is the most dominant load in home energy use.  In other words, if one were to use a wind turbine to power their heating and cooling in its entirety, then that consumer would save 44% on their energy bill! In addition to a wind turbine, if a photo-voltaic system is used to supply the demand used by the water heater, the consumer saves an additional 14% on their energy bill!

  • Wind Turbine (simple) Calculations

Keeping it simple, estimate that a home uses 1000kWh/month on average at $0.10/kWh will result in a $100 bill each month.  Using the figure above, the user spends $44/month on heating and cooling, $33/month on lighting, etc.

If the consumer wants to size a wind turbine to supply all his heating and cooling, this means the consumer’s turbine would need to supply 440kWh/month.  Using 730.5h/month and dividing 440kWh/month by 730.5h/month yields ~600W. That is, the consumer would need a 600W turbine with an average wind speed of 10mph and no losses in the wiring, rectifier, and that 100% of the energy extracted from the wind was either stored or consumed by the user.

Many assumptions would made for these back-of-the-envelope calculations. These are only to be used to give a rough idea of what to expect from the power output of a wind turbine.

  • Payback Calculations

Saving $44/month is nice, but what does it cost to produce these savings? How much is the over-head cost and how long will it take to pay it off?

Basic components for a home-use turbine:

  1. Wind Turbine (including generator) ~ $600 – Walmart
  2. Tower  30′ ~$800 – Menards
  3. Rectifier (for DC power) ~$0.00 (negligible)
  4. Inverter (2kW for AC power) ~$350 -donrowe.com
  5. Charge controller (to keep from over-charging batteries) ~$450 donrowe.com
  6. Batteries* ~$400 – techbatterysolutions.com
*Sizing the batteries depends on how much load is going to be drawn at one time.  For example, a toaster draws ~10amps, and lets say you want to use 10 toasters at the same time at ~100A.  Also, let’s assume you’re using 12V batteries with a 50Ah rating.  Then to supply 100A for an hour, one would need two batteries in parallel to supply the  100A because each battery would supply 50A.  If (for this thought experiment) each toaster required a 24V input, then one would need two batteries in parallel and two batteries in series to supply the demand.
Note: In a reality, the 12V DC from the battery would use an inverter to transform the voltage from 12V DC to 120V AC (wall socket voltage at 60Hz).
Finally, adding the list of components to put up a wind turbine yields $2,600.  Given a savings of $44/month, it would take 59 months or ~5 years to pay for this system.
  • Conclusion

If one is willing to pay for the overhead and is very patient, wind power generation is for you! Before you buy a wind turbine and accessories, one needs to consider [1]:

  1. your property has a good wind resource
  2. your home or business is located on at least one acre of land in a rural area
  3. your local zoning codes or covenants allow wind turbines
  4. your average electricity bills are $150 per month or more
  5. your property is in a remote location without easy access to utility lines
  6. you are comfortable with long-term investments

[1] http://www.windpoweringamerica.gov/pdfs/small_wind/small_wind_guide.pdf [Nov. 12, 2012]

– by Zachary Newell – Posted 11/12/2012 – newell1@illinois.edu

Note: the email provided will not be checked regularly after 12/22/2012