I was walking through my neighborhood last week and I saw a house with two wind turbines spinning away in the back yard. They were definitely noticeable because of the spinning motion, but they weren’t really an eye sore. The engineer in me got really excited and I decided to do a little research and find out more about this renewable energy option.
After a quick internet search, I found out that these particular personal wind turbines are probably Windspire brand turbines. Based on their website it looks like they produce a few different models of turbines from 1 KW output up to 5 KW output. The nice thing about these wind turbines is that they were pretty quiet. Now, to be fair I was about 50 yards away, but I didn’t hear anything.
The average house in the U.S. requires about 1 KW every hour to meet its energy demand. The problem of relating this to sizing a wind turbine is that the wind does not always blow. In general we can assume about a 25% capacity factor for wind turbines. In other words we have to assume that the wind is only blowing about 25% of the time. In order to power your house using mostly wind power, you would need to install about 4 Kilowatts of installed capacity. After you multiply that 4 KW by the 25% capacity factor you come out close to the desired 1 KW. Of course you will also need some sort of a battery storage system to store the excess energy to be used at times when the wind is not blowing.
On the Windspire website it looks like they will sell a complete 1.8 KW wind turbine package for $13,500. I assume this house in my neighborhood bought two of the 1.8 KW style turbines which would get them pretty close to the 4 KW desired generation. So not including the battery storage they probably spent $27,000 on this wind turbine system. If I do some back of the napkin math, I spend about $100 every month on my electricity bill. So that is $1200 per year that I currently spend. It would take me about 22 years to make that wind turbine system pay off. For a comparison, a similar roof-top solar capacity would cost between $25,000 and $30,000.
This is one of the big problems with these types of home renewable energy solutions. They are not economical yet. I commend this company for putting out a product that helps us to move in a more renewable direction. I also am happy that there are people who will buy these systems for what I assume is a personal commitment to go renewable. The problem is that if we want these systems to have a mass impact we need to figure out a way to make them economical. Average Americans move every 5 years for installing a 22 year payback wind turbine makes no sense. For this type of technology to have a big impact, it would have to have a payback time of a maximum of 5 years.
If you have a home renewable energy system installed at your home please let me know about it in the comments below.
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