The Ekodyne Turbine
“Local” or “distributed” energy is the name of the game in terms of future wind-energy development. Wind farms suffer huge transmission losses since they are often located hundreds of miles from major metropolitan areas. A major study/report shows how much energy is lost attempting to transport electric power through the grid over long distances. The simple solution is to develop wind generators suitable for on-site generation of electricity within residential, urban, and commercial locales. But that requires the design of wind turbines capable of overcoming a lot of problems and deficiencies of the currently popular Horizontal-Axis Wind Turbines, or HAWTs (so named because they rotate around a horizontally-oriented axis). The Ekodyne is in fact exactly such a design.
The Ekodyne turbine is a vertical-axis wind turbine or VAWT. See these videos of the prototypes:
You can see how they are spinning around a vertical axis of rotation. It is also clear that the vanes are large, box-like structures moving relatively slowly, unlike the sharp, fast-moving blades of HAWTs. This one difference already means that concerns about bird and bat kill and safety to persons and property that one associates with HAWTs is unlikely to be a problem with the Ekodyne turbine. That further means that it would be safer to place installations of Ekodyne turbines on rooftops of residential and commercial buildings in close proximity to people and their property. Maintenance personnel, likewise, would find rooftop locations to be more safely accessible. There have been instances of “catastrophic failure” with large HAWTs, and smaller HAWTs that are sometimes located in suburban and commercial neighborhoods move at much faster RPMs, resulting in what is called “motion blur,” and posing local hazards to persons, property and wildlife.
Besides being safer, another major advantage of the Ekodyne turbine is the basic nature of its design, rotating on a vertical-axis. That means the turbine does not need to be turned to face into the wind. Whatever direction the wind is coming from, it will be captured by the vanes of a vertical-axis turbine. This allows the Ekodyne turbine to operate effectively in turbulent conditions where wind direction is erratic and shifting rapidly. And since the turbine is much less sensitive to turbulence than HAWTs, multiple turbines can be placed side-by-side on a rooftop. HAWTs themselves create turbulence, and thus require being spread apart at some distance to avoid interfering with each other. Ekodyne turbines could be placed in a dense formation, each unit close to others, thus maximizing the capture of any wind energy flowing across a rooftop--any wind power flowing through and missed by one unit can be caught further along by the next unit.
The future of renewable energy production seems to lie in the use of both solar and wind energy generation. Solar and wind are not incompatible and work well together, since the wind will often be blowing when the sun is not shining. Unfortunately for HAWTs, there is no easy way to accommodate both solar and wind installations in the same place, using the same land or roof top areas. This is not the case for the Ekodyne turbine—there is no incompatibility of combining solar panels with Ekodyne units. Another feature of the vertical-axis design is that it allows a flat, horizontal area on top of the turbines. While the turbines may be rotating on a vertical axis, they are effectively rotating within a horizontal plane. Thus, one could easily erect a flat, horizontal field of solar panels on top of an installation of Ekodyne turbines, and have the advantages of both main sources of renewable energy.
The operating principle of the Ekodyne turbine is very simple. Lightweight flaps hinged at the top cover the back of box-shaped vanes. When the wind is blowing into the front of the vane, the flaps stay down by gravity and capture the wind energy. When the vane has rotated around so that the wind is now blowing on the back of the vane, the flaps are blown up out of the way and the wind spills on through unimpeded. The flaps are not made to open and close by complex mechanisms, nor synchronized in any complicated way with wind direction—they just hang down naturally to catch the wind or blow up out of the way when wind is hitting their backs. Each vane is essentially a big box with loosely hanging flaps over holes in the back. With such a simple, straightforward design, manufacturing and maintenance costs should be relatively low. HAWTs operate at high speeds with resulting major stresses, creating materials and structural design challenges. But with the Ekodyne design, simple and inexpensive weatherproof materials can be used to construct the sides and flaps of the vanes. Possibilities include aluminum, steel, or plastic frameworks, with sides and flaps fabricated from aluminum sheeting, fabric, fiberglass, fiberglass reinforced foamboard, plastics, or any lightweight weatherproof durable material. Installation costs should be lowered, since the Ekodyne turbine can be manufactured in parts—made in parts easily assembled on site—decreasing shipping and transportation costs. And unlike HAWTs that must be mounted on towers, rooftop locations of Ekodyne turbines will have much lower installation and maintenance costs through increased accessibility.
Given all of these supposed advantages of the Ekodyne turbine, what’s the catch? If it is so much better than HAWTs, why hasn’t it already been adopted by the wind energy industry to replace HAWTs? And the Ekodyne turbine isn’t the only VAWT. VAWTs of many different designs have been around for at least a century. If VAWTs are so much better than HAWTs in the ways described so far, why haven’t other VAWT designs replaced HAWTs long ago? These questions focus on what turns out to be the central, essential, and most important advantage of the Ekodyne turbine over all other VAWTs ever designed, and why it poses a strong challenge to HAWT designs as well.
The whole point of wind turbines, obviously, is to generate electricity efficiently. And this is where traditionally VAWTs fail miserably by comparison. Inventors historically have tried to design VAWTs, recognizing their many advantages over HAWTs. They have been well aware that wind forces acting on the backs of vanes create great resistance to the turbine’s rotation and severely decrease efficiency. Think about a basic anemometer for measuring wind velocity—a series of cups mounted on arms catch the wind and turn as a unit. While the front of a cup or vane may be open and collecting wind blowing into it, which makes the turbine rotate, at the same time the back of that vane and the backs of other vanes tied to it are running against the wind and the wind is pushing against those vane backs resisting the turbine’s rotation . Let’s refer to this as the “backwind resistance problem.” A brief search of patent history reveals numerous designs attempting to address this problem, from “clam-shell” vanes that open and close during the rotation, sail vanes that furl and unfurl, rotating housings that only allow wind from the upwind direction, etc. None of these designs have been successful, because they require such things as complex synchronization mechanisms that use up energy to operate, or they fail to address the problem of static air resistance against the back of a vane even if enclosed in a housing. The Ekodyne design is the only vertical-axis wind turbine based on a non-lift machine concept that simply and easily solves the backwind resistance problem. The flap mechanisms drastically improve effectiveness of wind energy capture by reducing the resistance of wind or even static air forces against the backs of the vanes. The flaps simply blow up out of the way and let the air flow through when wind or static air blows against them. Thus, the rotation of the turbine is not impeded, and note well that this is accomplished without employing any synchronization mechanisms or wind redirection designs. The backwind resistance problem has been the bane of VAWT designs, and only the Ekodyne turbine appears to offer an elegant and effective solution.
As an aside, it must be noted that there have been some designs that are technically “vertical-axis” in nature but use the same principles of aeronautical forces as many HAWTs. The shape of the blades of, for example, Darrieus rotors or designs employing lift or “thrust” blade shapes similar to airplane wings, do not suffer from backwind resistance issues. However, they fail in one other significant way—they are often not “self-starting”. That is, wind blowing on the blades will not by itself cause the turbine to begin rotating. One needs to employ a separate motor to set the turbine moving before it can begin to work. This is not a problem with the Ekodyne turbine. In fact, another potentially great advantage of the Ekodyne turbine is that it is not only self-starting, but wind tunnel tests indicate it will be self-starting at very low wind speeds, as low as less than 5 mph.
An important question still remains unanswered, however. Even if the Ekodyne turbine works better and more efficiently than other VAWT designs, does it work as efficiently as HAWTs? That is the primary research question that must be answered by further investigation. The wind tunnel test results using small models suggests that the Ekodyne design may well equal or rival the efficiency of similar-sized HAWTs. Only further testing with larger prototypes can ultimately answer the question. The National Wind Technology Center at the National Renewable Energy Laboratory (NREL) in Golden, CO has agreed to do the testing, analysis, and certification of a prototype. Ekodyne, Inc. is currently trying to locate funding to support this testing. However, one final consideration should be kept in mind. Discussions with NREL engineers reveal that the important factor in judging the merits of any wind turbine design is not its efficiency in terms of energy productivity, but what they call the “cost of energy.” Analysis of that factor is based on an examination of all associated costs involved with a design’s implementation in the field, including design, manufacturing, installation, maintenance, and production/transmission costs, siting and licensing expenses, and expenses resulting from other social or political factors. Thus, the ultimate potential value of the Ekodyne turbine may well outstrip that of HAWTs even if it only modestly rivals their efficiency.