General Info – Page 2 – Wind Turbine Magazine

If you’re thinking of installing a wind turbine, you obviously need to decide what size of wind turbine you’re going to install. Not only in terms of how much electricity it will generate, but also in terms of how physically high it will be. The best height for a wind turbine is basically as tall as you can get permission for, from your local authorities. The taller the wind turbine, the higher the wind speeds are, and the longer its blades can be, and the more efficient it will be at generating electricity. However, obtaining planning permission is not the only factor that goes into deciding what size of wind turbines to install. The factors that affect your decision will largely be determined by whether you’re installing a wind turbine to power your home, or developing a wind farm on your farm land or industrial estate. Whether you’re considering a wind turbine to power your home, or whether you have a farm or industrial land where you’re thinking of installing a wind farm, I’ll explore all the factors that go into deciding what height of wind turbine to install later on in this article. However before we get into that, let’s first quickly look at how the much physical size of wind turbines have increased over the last few decades. The Average Height of Wind Turbines Since the 1990s Some would argue the height of a wind turbine is measured from the ground to the tip, but for the purpose of this article we’ll refer to the height as is its distance from the ground to the rotor of the turbine. According to, U.S. Energy Information Administration, since 2012 the average height of onshore wind turbines in the USA has been around 80 meters (about 280 feet). In 2020, the average height increased to approximately 90 meters (295 feet), which is as tall as the Statue of liberty. The average height for massive offshore wind farm turbines out in the sea is projected to increase significantly over the coming years. From an average of 100 meters (330 feet) in 2016, to around 150 meters (500 feet) or more. Why is the Height of a Wind Turbine Essential? The altitude of your wind turbine is critical in terms of how powerful and 'cleaner' the airflow will be at various elevations. Taller towers are often more costly, but the added expense of a taller turbine is readily justified by the cost savings and increase in energy efficiency for the aforementioned reasons. Taller towers allow for bigger blades, and the higher the tower the faster the wind at increasing altitudes. However, for onshore wind, it usually follows that the higher the towers, the more problems there are with planning. It’s therefore essential to speak with your local regulatory bodies, to check for any constraints regarding the installation of taller wind turbines. With that said, here are things you need to consider when deciding on what height of wind turbines to install. Five Critical Factors that Affect Wind Turbine Height This is by no means an exhaustive list, but here are some of the constraints that could determine how large your wind turbines are. What size are other wind turbines in the local area? Many local authorities don't like to have lots of different size wind turbines near each other, as they consider them visually unappealing. If your land is surrounded by medium size 225kw or 500kw wind turbines on 30 or 40 metre towers, then you may have trouble applying to install large wind turbines, with 45 metre blades on 90 metre towers. So it's best to check — what are your local, state or county and national planning policies regarding wind turbines, and their height? Are there any local zoning or homeowner association restrictions that would limit your tower height? Are there any large buildings, trees or other structures nearby? If your wind turbine is close to any large buildings or structures, then the tower will need to be tall enough to get the bottom of the rotors above the air turbulence. As shown in the illustration below, the rule of thumb is that wind will be disrupted for a distance of up to 20 times the height of the structure, and to an altitude of two times the height of the structure. Image - https://openei.org Bear in mind that large wind farms may be operational for 30 years or more. That's plenty of time for trees and other vegetation in the surrounding area to grow big enough to start causing problems. They could start to cause turbulence which significantly affects electricity generation. If you're investing in wind turbines for your home or farmland, make sure you have legal agreements in place which prevent anyone from planting anything which could interfere with airflow over the coming years. Are there any plans to erect new buildings or structures in the local vicinity? Existing structures are obviously easy to identify. But has anyone submitted plans to the local authorities to build anything which would potentially cause turbulence and affect your turbine's efficiency? Make sure you check with local authorities to find out if anything is in the pipeline before you proceed. Radar & Telecommunications Links If you have local radar stations or airfields then the height of your turbines could very much be restricted. Companies like PagerPower can help determine if any such constraints exist. They can also identify if there are any invisible UHF telecommunications links passing over your proposed wind turbine site. If there are, the telecommunications operators may object to your planning application - and in most cases that would simply cause your planning application to be rejected.] However, it is possible in some cases to mitigate both radar and telecommunications issues, allowing you to install wind turbines on the largest possible tower. It all depends on who the organisations are, and their policies towards wind turbines. Local Landscape & Topology If the area surrounding your wind turbine site is mostly 'rolling hills', this could impact your turbine's performance by causing turbulence, and disrupting the air flowing through your wind turbine's blades. Again, this can be mitigated by installing wind turbines on the tallest towers possible. Conclusion The altitude of your wind turbine blades, and the local landscape, greatly affects how powerful and 'clean' the airflow is likely to be. As mentioned above, taller towers are often more costly, but the energy returns easily outweigh the additional cost for most installations, whether for on a home, on a farm, or out at sea.