Vertical-Axis Wind Turbines for Powering Cellular Communication Towers B. Plourde * , J. Abraham * , G. Mowry * , W. Minkowycz ** * University of St. Thomas School of Engineering St. Paul, MN 55105-1079 jpabraham@stthomas.edu ** University of Illinois at Chicago Department of Mechanical Engineering Chicago, IL 60607 ABSTRACT Cellular communications are rapidly penetrating markets across the entire globe. Very rapid adoption is occurring in developing countries such as China, India, and Brazil. In many cases, wired communication is being bypassed. The electronic equipment which is housed on communication towers requires large amounts of reliable electricity for their operation. On the other hand, in some regions of the world, continuous supply of electricity is not available. In these cases, auxiliary power is supplied by diesel generation which is polluting and expensive. In other cases where grid-connected electricity is not available, the entirety of power is provided by diesel generation. To alleviate the issues related to power availability, a novel, vertical-axis wind turbine has been designed, constructed, and implemented to power communication towers. The turbine is specifically designed to attach to communication towers without interfering with the existing electronics. Results show that the proposed design is capable of providing for the electrical requirements of a typical communication tower. Keywords: vertical-axis turbine, wind power, cellular communications, off-grid power, Savonius turbine 1 INTRODUCTION This project deals with the design, development, and evaluation of a novel vertical-axis wind turbine which is particularly suited to be affixed to cellular communication towers. The turbine is a drag-type turbine (Savonius turbine) and does not rely upon lift forces for its rotation. The goal is to provide electricity to supply the needs of the electronic equipment connected to the tower. Typical power requirements are in the 1-1.5kW range. While vertical-axis turbines produce less energy than their more common horizontal cousins, there are a number of advantages which make the vertical-axis design more appropriate for this application. First, drag-based vertical turbines begin rotation in lower wind velocities than do horizontal variants. Second, they are less sensitive to wind direction and they do not require a control mechanism to ensure that they face the wind. Additionally, since the style of turbine blade selected for this application is driven by wind drag forces rather than lift forces, it rotates at a slower rate and thereby imparts a reduced vibration load to the tower structure. A prototype wind turbine was designed and constructed in a modular manner to meet the power production needs of a typical communication tower. Rotor modules can be added or removed from the design to allow the device to be tailored to meet the specific needs of individual towers. The turbine was designed, in part, through the use of computational fluid dynamic software which allowed an optimization of the turbine shape to maximize power production and limit the thrust loading which was imparted to the tower. A number of novel features were implemented to aid in the optimization. First, specially designed one-direction venting structures were utilized to reduce deleterious drag on the blade. Second, a special cap was incorporated to increase the amount of wind which was captured by the blade. Details of these features will be discussed later. An early variant of the turbine was built and tested in a large-scale wind tunnel operated by the University of Minnesota. Results from the tests show that the venting marginally improves performance while the capping structures gave rise to a large improvement. The final design has been shown to be a viable solution to the issue of off-grid or unreliably powered communication towers. NSTI-Nanotech 2011, www.nsti.org, ISBN 978-1-4398-7138-6 Vol. 3, 2011 750