There’s been a lot of talk online about vertical axis wind turbines (VAWT) and how much more beneficial they are than a regular Horizontal-Axis wind turbines (HAWT). VAWTs are commonly referred to as an “egg-beater” design, and are commonly found in small wind applications. HAWTs are the most common wind turbines, the “prop type” turbine. They typically have three blades and are most commonly used for wind farms, community wind projects and small wind applications.
The main purpose of a wind turbine is to generate energy and ultimately maximize energy generation from the local wind resource available. There are tons of websites flaunting claims that are shining a negative light on HAWTs and are providing inaccurate information to the general public. We want our customers to make the best possible decision using the most accurate and current information possible which is why we’ve dedicated this blog post to analyzing and addressing the claims made by vertical axis turbine distributors and manufacturers.
Claim: VAWT can take wind from any direction
Truth: Any conventional wind turbine can take wind from any direction, including a HAWT. The only difference from a conventional turbine could be the addition of a tail on an upwind horizontal axis turbine.
Claim: VAWTs don’t require towers or are designed to operate much closer to the ground than conventional turbines
Truth: Unfortunately no person or object is exempt from the laws of physics and VAWTs are no exception. A turbine will never generate usable amounts of energy without a tower so claiming that VAWTs can operate much closer to the ground and without a tower only tells us that it generates a severely smaller amount of energy and is much less efficient. See our previous blog post entitled Investing In Small Wind Power
Claim: VAWTs allow for ease of maintenance on the generator
Truth: Generators and alternators are the most reliable part of any wind system. The parts that typically need attention are the blades, rotor bearings, and governing device. Coincidentally, these parts all become more difficult to access with many VAWT designs.
Claim: VAWTs have a small rotor profile
Truth: The rotor is the “collector” in any wind turbine design. If you want to double the amount of energy collected, you double the size of the collector, which in this case is the rotor. It’s a fact that the amount of energy extracted from the wind is more dependant on the size of the rotor than any other part of the turbine so why would you want to invest in a turbine with a significantly smaller rotor? See our previous blog post on swept area.
Claim: VAWTs can be mounted on your roof
Truth: We can’t verify that any engineering analysis has proven this safe, but homeowners should check with their insurance companies before pursuing this as an option. Keep in mind that a wind turbine mounted to a roof is going to have turbulence and a lesser quality of wind available for producing energy. See our previous post on aiming for quality wind.
Claim: VAWTs are a more “urban” turbine
Truth: If you live in an urban area and want to invest in alternative energy solutions, consider all your options before committing to a VAWT. There is a severe lack of wind resource in urban and suburban areas. Regardless of how “urban” these turbines claim to be, the fact remands that the wind in these areas can be very unpredictable because of the turbulence caused by the extensive amount of ground clutter.
Claim: VAWTs have improved aerodynamic performance
Truth: There are many of these claims floating around on the internet that are touting unachievable performance by any wind technology (regardless of blade orientation or any technical specifications). Most importantly, there is no information to back up these claims and no information on who provided these tests. Sometimes things really are too good to be true!
Claim: VAWTs are bat and bird friendly
Truth: VAWTs are insinuating that HAWTs are dangerous to birds and bats yet there is no data sustaining these claims.
Claim: VAWTs don’t interfere with telecommunications or aircraft navigation
Truth: Once again, vertical axis turbines are insinuating that small horizontal axis turbines are a hindrance to telecommunications. This is completely untrue as one of the largest niche markets for small wind turbines is powering telecommunications, particularly at remote sites. As for the aircraft interference, there is no evidence to suggest that any small turbine, regardless of blade orientation, interferes with aircraft navigation.
Claim: VAWTs have excellent cost saving features
Truth: Although most people don’t realize it, what they should be interested in is not up-front cost, but life-cycle cost of energy generated over the lifespan of the system. Cutting out the tower, for example, may cut your upfront cost by a significant amount but no tower means that the amount of electricity generated, along with the economics, plummets so in the long run you’re looking at a significant loss.
It’s important to remember that there are multiple options when it comes to small wind turbines. Reviewing the manufacturer’s history, whether or not the turbines meet certification standards, the energy production of the turbine, the number of turbines currently in operation, references of existing customers, and some of the feedback from industry veterans will all help with your analysis. Taking the time to choose the right turbine for your location and your needs can make a big difference in the benefits you reap in the long run.