Tuesday, April 12, 2011
Is it time for private wind turbines?
We read so much in the news about alternative energy sources, and how communities are constructing geothermal, solar or wind devices, but what about private use? How can we further advance the front of some form of alternative energy device in each person's home? This is an important question as more and more choose to "live outside the grid" - not only because the grid will become ever undependable in the future (with many more brown outs and black outs as climate change ramps up as millions try to stay cool at once).
Solar actually is already well represented in the alternative array, because ....well, in those places that are subject to higher solar insolations, it is just about the most economical form of heating! The solar water heater then, has come into its own, and I've seen the simplest designs (such as at science fairs) do yeoman service in this regard. The basic design is simple: an insulated box to hold water, with an exit pipe, and the insides covered by black plastic to absorb the solar heat. The outlet pipe then delivers the warmed water to a make shift shower. This type of design has been used over and over by kids in the Caribbean doing their CXC Physics and Integrated Science projects. Of course, a real solar heater requires actual solar cells to collect the energy, but even there - a recurring problem is how to indefinitely preserve it once the Sun goes down.
Here, wind energy can prove to be a very useful adjunct, especially in areas which benefit from lots of wind. But this doesn't mean every manjack ought to go out and start constructing his own wind turbine device! (See image)
First, one has to consider the fact that several acres of land are needed to support even one turbine. The reason is that turbines have to be situated away from buildings, property lines and power poles, say if the thing is ever struck by a tornado and comes crashing down. This automatically limits wind turbines or towers or even simple windmills for widespread urban, personal use.
Even if you have the property advantage, you don't want to have lots of trees around since these will create a large amount of turbulence that slows the wind speed and lowers the power output and hence efficiency. Thus, if you're going to construct a wind system you don't want it runing at 30% or less output!
Code laws for you area may also enter, especially as the best way to escape ambient turbulence is to construct a tower at least 80' - 120' on which the turbine can be mounted. Thus, you're already looking at a device more than 12 stories tall, and porbably closer to thirteen. The advantage is obvious: it places the turbine in the strongest winds dramatically increasing the output. True, one does see residential turbines on short towers, but in all probability their output is too low to have been worth the investment.
What about determining if your area even qualifies as a wind device locale? The key question is: What is the threshold for minimum wind speed in my area that I'm looking at? Most wind aficionados agree here that at least a 12 mph (19 km/h) wind speed is essential - at al altitude of 100 ft. Thus, before starting any such project you need to undertake a thorough site assessment. An initial read can be obtained by going to NASA's Surface Meterology and Solar Energy site at:
If you'r seriously thinking of wind as an optimum off the grid strategy you may even consider a professional wind site assessor, but be aware they may run you from $300 to $500. A list of certified wind assessors can be found at: