Comparison of the Vortex Bladeless Turbine to the Traditional Wind Turbine Design
Traditional horizontal axis windmills have generally become the face of wind powered energy. Fleets of these windmills can commonly be seen along ridgelines in places known as wind farms. However, are these windmills the best design for collecting power from wind? The company Vortex says no. They recently developed a new style of windmill to compete with the traditional turbine design.
First and foremost, wind is a complex entity to capture. Many things can cause and change wind. It can be caused by uneven heating of the atmosphere. This creates heat pockets and cold zones. Wind can be natures attempt to balance the temperatures in the atmosphere (Society 2012). It can also be caused by features of the Earth’s surface. Rivers, valleys, and mountains can all create and influence current wind patterns. But wind is not just limited to these features. The general variation of the Earth can also create wind. Winds can even be created by the Earth’s rotation. The creation of these types of wind, commonly known as trade winds, is due to a phenomenon known as the Coriolis Effect (“How” n.d.). Ultimately winds vary across the planet by location, weather, and time of day.
The traditional horizontal axis windmill is very good at capturing energy from wind. The wind flows over the blades in a way similar to that of airplane wings. The flow of air over the blade creates a pressure difference between air on top and air below the blade. To “even out” the air pressure. The high-pressure air under the blade pushes up on the blade creating lift (Figure 1). This is what spins the blades of the turbine. The blades of the windmill are attached to a mechanism called the rotor. When the blades spin, they turn the rotor. This rotor is connected to a generator which creates electricity as is spins. What makes these turbines so effective is that they are often high above the ground. Because of this they have access to much stronger winds than if they were on ground level. Also due to the direct connection between the blades and the generator, these windmills are very efficient (“How” n.d.). However, there are some disadvantages to this style of windmill. The base and blades have to be very long to capture the higher intensity high elevation winds. This means it is very difficult and expensive to transport and assemble the pieces. The towers are also made out of heavy-duty materials to support the top-heavy windmill. Also, these windmills are not naturally omnidirectional. Special controls need to be installed in order to continuously reorient the windmill so that it faces the wind. Other controls can be installed to change the angle of the blades in order to be most effective at creating energy. Furthermore, cracks and overuse issues are common in these windmills due to the amount of strain and constant friction that these machines undergo. Also, due to how large these machines are, they have to be spaced quite far apart. Because they take up quite a bit of space they can negatively impact views as well as harm wildlife (“HAWT” 2009).
Figure 1. A diagram of how airflow over a windmill blade creates lift. Lift is depicted by the green arrows pushing up on the blade (“Wind turbine” n.d.)
The Vortex Bladeless Turbine aims to solve some of the common problems that traditional windmills face. This turbine is quite different from the horizontal axis windmill. It is essentially a vertical cylinder fixed to a tall vertical rod. This cylinder oscillates when wind passes around it. The bottom of the cylinder is fixed to the rod and the ground allowing the top to move more freely (“How it works” n.d.). Instead of turning a rotor like the typical turbine, the bladeless turbine captures energy from a phenomenon known as Vortex Shedding. Wind creates circular vortices as is flows. When these vortices flow around a structural body, or the Vortex Windmill in this case, the body oscillates with the wind until it enters resonance with the wind. This means the body and the wind are oscillating at the same rate. This is known as vortex induced vibration. Vortex induced vibration is generally avoided in construction. However, the bladeless turbine is designed to achieve maximum vortex induced vibration (“How it works” n.d.). Instead of using friction to help control this, the bladeless turbine uses magnets to adjust the stiffness of the oscillating cylinder. This would allow the cylinder to reach maximum vortex induced vibration at almost any wind speed. The turbine then uses an alternator to create energy from the cylinder oscillation. The cylinder is also made from a light weight, carbon fiber reinforced polymer, which limits energy loss from the oscillations. The use of this material means that less natural materials are being used in comparison to a typical windmill (“How it works” n.d.). This also means that transportation and installation costs are less because the turbine is lighter. It also does not require the deep foundation that a horizontal axis turbine needs which again, reduces costs. Furthermore, because it is a cylinder with no blades, the turbine is automatically omnidirectional. It also does not have any parts that can wear down under friction. This reduces required maintenance and prevents parts from wearing out fast. The lack of blades also reduces the impact on flying wildlife. The turbines can also be placed significantly closer together. They can even feed off of the displaced wind from other turbines. Unfortunately, these turbines produce less power that a typical wind turbine, however Vortex claims that because they can be placed much closer together, many more bladeless turbines can replace a few traditional turbines and produce the same amount of energy (“How it works” n.d.).
The Vortex Bladeless Turbine seems to solve many problems associated with horizontal axis wind turbines. They require less maintenance, less space, and less money to produce and install. However, they also produce less energy. Despite this, they have the capacity to be installed in places where typical wind turbines cannot. The bladeless turbines are also quite new. The technology has a significant way to go especially in terms of energy production, however it is exciting to see the potential that this new technology has.
Resources
“HAWT, Horizontal Axis Wind Turbines from Gaia Wind, Their Advantages and Disadvantages Plus the Effects of Cyclic Stress and Vibration.” 2009. AZoCleantech.Com. September 29, 2009. https://www.azocleantech.com/article.aspx?ArticleID=191.
“How Do Wind Turbines Work?” n.d. Energy.Gov. Accessed March 30, 2021. https://www.energy.gov/eere/wind/how-do-wind-turbines-work.
“How It Works? - Vortex Wind Turbine in a Nutshell.” n.d. Vortex Bladeless Wind Power (blog). Accessed February 24, 2021. https://vortexbladeless.com/technology-design/.
Society, National Geographic. 2012. “Wind.” National Geographic Society. November 15, 2012. http://www.nationalgeographic.org/encyclopedia/wind/.
“Wind Turbine Blade Design | Alternative Energy Tutorials.” n.d. Accessed March 30, 2021. https://www.alternative-energy-tutorials.com/energy-articles/wind-turbine-blade-design.html.