| Down home & downwind By Rex A. Ewing |
David Brugge hears it all the time from the armchair energy experts: "Why don't you heat your domestic hot water with solar energy?" they needle him. "It would be so much more efficient than using wind." Possibly. But it wouldn't be nearly as much fun. And for Dave, it's the pure fun of his ongoing love affair with wind power that makes the idea of homegrown energy worthwhile.
Of course, it doesn't hurt that the property on which sits his log home and wind turbine is located near the highest point in Chautauqua County, New York (just a few miles outside of Frewsburg), or that he's within 20 aeronautical miles of Lake Erie; a long, slender stretch of water that just happens to be canted in the same direction as the prevailing winds. Without the impediments of hills, houses and trees to slow it down, the wind on the lake has carte blanche to ramp up the RPM and settle into cruise control. Put these geographical facts together and you arrive at an equation for wind power custom made for a man like Dave. The system Dave ultimately developed to utilize all the free energy that blows across his property is, well, a bit different than most. Customarily, wind energy is used to charge batteries, but not without going through some changes, first. That's because the energy created in a turbine's alternator is what's known as three-phase alternating current, or AC. Alternating current is the natural form of energy created when a magnet rotates around a stationary coil of wire (called a stator), and to ensure that there is no choppiness in the rotation of the turbine blades, three sets of magnets are usually evenly spaced around the rotor (the part that moves in relation to the stator). The result is three electrical currents that are separate but "in-phase" with each other.
But alternating current is a waveform (a sinusoidal, or sine wave, to be precise) defined by its motion, and a battery has no way of storing it. To get the energy from the turbine safely into a battery, the three-phase AC has to be changed into direct current (DC) by running it through a rectifier, which is a fairly simple and inexpensive array of solid-state diodes. In order for the battery's energy to be useful to homeowners, however, the DC energy from the battery has to be converted back into AC, in the form of 120-volt AC house current, and for this a power inverter is required. All in all, it runs into a sizeable investment in components, and one Dave decided he would rather avoid. So instead he came up with a very clever idea: he did his stator windings so that his turbine would output not the usual 12, 24 or 48 volts used for battery-based systems, but 120 volts AC. This enabled him to bypass the rectifier, batteries, and inverter altogether, and use the output from his wind turbine to heat water directly in two off-the-shelf residential electric water heaters.
In the pre-heater, both the top and bottom elements are connected to a separate phase, while the third phase drives the lower element in the main heater (the top element in this tank is hooked into the power grid). It's like plugging three different wires into three separate appliances. It works despite the inherently "wild" voltage and amperage output of his custom homemade turbine because—in sharp contrast to motors and electronic devices—resistance heaters are relatively indiscriminating about the current they are fed. For overload protection, Dave has wired into the system thermostatically activated space heaters for those times when the water in either or both tanks is hot and the wind is still blowing. As the system is currently set up, a wind speed of 15 miles per hour is required to start the blades spinning. This is because, by design, the tanks' heating elements draw large amounts of amperage through the low-resistance system, and the turbine simply cannot kick in until there is enough wind to provide the amount of current the heating elements demand. To solve this problem, Dave is busy working on a controller that will start out in a high-resistance mode and automatically switch to a low-resistance mode (that is, from a Star to a Delta configuration, for you techy types) as the wind speed increases. All in all, it's a marvelously inventive system, and one that Dave is understandably proud of. The catch—and probably the main reason Dave considers his system to be so much fun—is this: if you want a turbine that outputs 120 volts AC, you're going to have to build it yourself. This Dave did with plans he acquired from OtherPower.com, a website run by off-grid mountain folks who use homemade wind turbines to power their own homes. Dave finds the OtherPower.com discussion board particularly helpful, though admittedly he knew quite a bit about electronics before becoming interested in wind power. This is because he spent several years as an electronics technician for Bausch & Lomb, and several more years installing and servicing UPC scanning systems, before moving to the country, building a log home and setting up his wind turbine.
The geometry of Dave's axial-flux turbine differs from the revolving-drum configuration of most commercially available turbines in that the stator's windings are imbedded in a flat "plate" around which the two rotors (also plate-like in design) spin, one on either side, creating a strong magnetic field across the copper windings of the stator. In addition to lending itself to the capabilities of a well-equipped home workshop, it's a design that allows for comparatively more power at low wind speeds. The alternator, of course, is only part of a much larger system consisting of the propeller blades, the tail, and the tower. For the latter, Dave was fortunate enough to acquire an 85-foot Rohn guyed-lattice tower, a former communications tower he salvaged after a demolition crew "felled it like a tree." Hinged at the base, the tower can be easily raised and lowered with the aid of a gin pole and an electric winch. The tower, Dave will tell you, was perhaps the easiest part of all. That's because it takes a bit of experimentation to get everything else working together. As a case in point, Dave's first turbine was a 12-foot diameter, single-phase machine that burned up in a storm because the  furling (a passive mechanism that causes the turbine to turn away from the direction of the wind, thus protecting itself from overloading) was set to activate at too high of a wind speed. The problem was largely corrected with Dave's second machine, an 18-foot diameter 3-phase, 3-kilowatt turbine that served faithfully until, in a high wind, the stator burned out and the blades were deflected into the side of the tower. The unfortunate episode convinced him the blades were too long and the furling was still set too high. But Dave is confident the third machine finally has the bugs worked out of it. By shortening the poplar blades (custom carved by his friend Dave Moller, owner of royalfabrication.com) to a 16-foot diameter and re-engineering the furling mechanism to cut in at wind speeds of 25 miles per hour, the new turbine should be tough enough to stand up to high winds and powerful enough to heat Dave's domestic hot water. And if, after months or years of service, Dave should discover that the machine still needs a little tweaking? Well, hey...that's what makes his ongoing labor of love so much fun. Besides his frequent forays into the uncharted wilderness of wind energy, Dave is also a representative for Kuhns Bros. Log Homes. If you'd like to chat with him about wind turbines, or log homes, or just about anything else, he can be reached through his website at: www.madbbs.com/users/bruggelog. He'll be glad to hear from you. Rex Ewing is the author of several renewable energy books, including Power With Nature, Got Sun? Go Solar, and the newly released Crafting Log Homes Solar Style. He lives with his wife, LaVonne, in a handcrafted log home powered solely by the sun and wind in the foothills of Colorado. His books can be purchased at the Countryside Bookstore. |
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