April 17, 2014

Wind Energy Considerations

Wind turbine generators and the use of wind energy are in fact the most reliable form of renewable energy providing that proper considerations and planning have been taken in advance. First we need to clarify a number of misconceptions that many people have regarding what makes a good and viable location to erect a wind turbine generator. Not everyone can utilize wind turbine generators for their energy needs and by not considering what is actually required could needlessly waste money in the attempt. Those who have employed their use are experiencing a greater sense of energy independence and tend to smile every time they receive their monthly electric bill due to the net metering and large cost savings they are experiencing.

Quality Wind -vs- Ground Chop

There are numerous wind turbine owners who thought that because they happen to have quite a bit of wind blowing by their building, or live on a hill and assumed that surely this must be a great location for a wind turbine who ultimately found out afterwards that there were other considerations which they neglected. First you need to know the difference between what is known as “Quality Wind” and “Ground Chop” because not knowing the difference can be a very costly mistake. Quality wind(s) are air streams that actually can power wind turbine generators because they blow at or near a constant wind speed rate sufficient for meeting a wind turbines minimum speed requirements. On average, most wind turbine generators have a minimum wind speed requirement of 9 – 12 mph before they will begin generating electricity. The elevation of these quality winds varies greatly from state to state unless you happen to reside in a wind corridor where they are typically closer to the ground.

There are micro sized wind turbine systems available which have far lower wind speed requirements and can be roof mounted but for the purposes of this article and the practical application we are focusing on 3.2kw wind turbine generators or larger which can power a home. To be certain that your wind turbine generator is placed properly in these wind streams it is critical to have a wind site assessment performed by a North American Board of Certified Energy Practitioners(NABCEP) wind site assessor because the wind stream’s elevation is going to dictate the height of your mast or tower the wind turbine generator is mounted on. Low lying hills, forested areas, man made structures all play a role in the wind you can feel at the ground level and they can be very deceiving. A good rule of thumb is that your tower should be tall enough so the wind turbines blades are a minimum of 30 feet above any ground clutter at their lowest point in their rotation. Throughout the state of Wisconsin for instance, tower heights on average are a minimum of 80 – 120 feet tall as this places the head of the wind turbine and its blades well above any trees, buildings or other ground clutter and into the quality wind stream and is not affected by these types of obstructions to wind movement.

A good location for a wind turbine generator large enough to provide you with large enough energy generation volumes to provide you with all the power you need for your home is going to require a significant amount of acreage, and the taller the tower or mast the more area you will need. Because of this homes located in residential areas are not a good choice for these systems and solar options would make a far better alternative as most height restrictions can be overcome while allowing for adequate energy generation. Agricultural or rural locations with plenty of wide open space are great locations for wind turbine generator systems and offer great cost savings when it comes to most cooperative electric utilities.

Ground chop can be described as winds that are affected or channeled by buildings, tall trees or forests, hills or anything which will affect how air is channeled and causes its path to be altered. For instance, many of us have probably experienced strong winds that blow between buildings, or seem to be coming from one direction but in reality are coming from the opposite direction and we are simply experiencing a curling effect as an obstruction causes a vortex. These vortex’s can be formed in any direction around a 360 degree axis so low level winds blowing across the roof of a building can appear to be blowing directly at the down wind side of a building when in fact we are simply feeling the horizontal vortex that resulted. While winds such as this might cause some to think that this particular location would make for a great wind turbine generator installation project they are in fact not and should not be given a second thought.

To be sure, there are of course several locations where quality winds can be relatively closer to the ground and typically they are located in well known wind corridors around the world. However, if you do not know for sure and you proceed with your project and find out after it is completed that your wind turbine system only has a 60 foot tower or mast when it needed a 120 foot tower or mast the costs associated with correcting this error in judgment will be excessive and in most cases cost prohibitive. A project of this nature and magnitude is expensive enough without having to overhaul it because of poor planning so making sure you get it right the first time is absolutely critical.

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