Monday, December 12, 2011

Turbine Design and Economics


  

We know that our estimated total energy required for heating and cooling and to power all appliances in our home is estimated to be 8230 kWh/year.

A realistic goal is to have our wind turbine produce 75% of the required energy, which means we need the wind turbine to produce 6173 kWh/year.

We also need to take into account the efficiency of the turbine and Betz limit.  A good quality small wind turbine is roughly 60% efficient.  This efficiency is multiplied the Betz limit (59.3%) to get an overall efficiency of roughly 35%.

The approximate air density in Iowa City is 1.207 kg/m^3 and the average annual wind velocity we used is 12.2 mph or 5.47 m/s.

Now we have all the necessary values to find our swept area.


A turbine this size has an estimated cost of $20,000.  The total cost can be reduced by 30% from a Federal Tax Credit and an additional $920 from Iowa's Renewable Energy Production Tax Credit.  This results in an estimated net cost of $13,080


Assuming it costs $.10/kWh with an average annual utility inflation rate of 4%, you could break even after 11 years and 2 months.

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