MOTHER’s Small Hydroelectric Plant Revisited

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The heart of the speed control: about $30 worth of electronics.
The heart of the speed control: about $30 worth of electronics.
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Here's what you'll need to imitate MOTHER's small hydroelectric plant.
Here's what you'll need to imitate MOTHER's small hydroelectric plant.
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The speed of the alternating current system is now controlled by an electronic load ballast device. A constant load is maintained on the alternator by switching power back and forth between the demand circuit and the water heater shown at right.
The speed of the alternating current system is now controlled by an electronic load ballast device. A constant load is maintained on the alternator by switching power back and forth between the demand circuit and the water heater shown at right.
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MOM'S small hydroelectric plant has been installed for almost five years now, and we've learned a number of lessons about the practical application of very small waterpower systems. In that time, however, the crossflow turbine has been a tireless performer.
MOM'S small hydroelectric plant has been installed for almost five years now, and we've learned a number of lessons about the practical application of very small waterpower systems. In that time, however, the crossflow turbine has been a tireless performer.
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MOM'S small hydroelectric plant has been installed for almost five years now, and we've learned a number of lessons about the practical application of very small waterpower systems. In that time, however, the crossflow turbine has been a tireless performer.
MOM'S small hydroelectric plant has been installed for almost five years now, and we've learned a number of lessons about the practical application of very small waterpower systems. In that time, however, the crossflow turbine has been a tireless performer.
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MOM'S small hydroelectric plant has been installed for almost five years now, and we've learned a number of lessons about the practical application of very small waterpower systems. In that time, however, the crossflow turbine has been a tireless performer.
MOM'S small hydroelectric plant has been installed for almost five years now, and we've learned a number of lessons about the practical application of very small waterpower systems. In that time, however, the crossflow turbine has been a tireless performer.

<p>It’s been more than four years since we reported to you on the construction of a small hydroelectric plant at Eco-Village. In the meantime, we’ve been working steadily on refining the design to improve its performance and make it more practical. And, as our system has matured, we’ve learned some lessons — ones you can “go to school on” to make your own system work (and cost) right the first time.</p>
<h2>The Crossflow Turbine</h2>
<p>You may remember that the heart of our small hydroelectric plant is a homemade crossflow turbine that’s 12 inches in diameter and 18 inches long. The device was made by slicing 72-degree sections from 4-inch Schedule 40 steel pipe and welding 20 of the arcs into end plates made of ¼ -inch mild steel. It still runs essentially unchanged: We removed it at one point and trued its circumference on a lathe, in hopes of gaining power from the tighter fit between turbine and nozzle. Unfortunately, reducing the clearance to 1/32 inch produced no detectable effect on the runner’s output.</p>
<p>In its nearly five years of operation, our crossflow has spun away without a hitch. Even though debris from the lake has slightly bent one of the blades, the tweak hasn’t noticeably affected the turbine’s performance.</p>
<p>Maintenance has consisted solely of an annual greasing of the SCB pillow-block bearings that the 1 7/16-inch shaft rides on.</p>

  • Published on Jan 1, 1985
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