A letter Sam wrote that appears in the Oct/Nov 2008 issue of Home Power magazine.
I developed a 5-gallon bucket generator as a low-cost hydro-electric system for the developing world. The picohydro systems that I saw for sale in the United States were very expensive, so I sought to create a system that would be affordable to lowincome people. With this economy in mind, my system uses only the generator, one standard lead-acid car battery, an inexpensive solar dump-load regulator, and a 100-watt inverter. For first-world applications, the system could use a large battery bank and provide considerably more usable electricity, but in the interest of creating an affordable solution, a single, standard car battery was used in our tests. As in an automobile, the battery experiences minor fluctuations in charge, but is never drained very much.
During trials in Guatemala, we used another 5-gallon bucket that was fitted with hardware cloth to serve as a trash rack. A 2-inch-diameter penstock was then run from the trash rack, and down the mountain for a total drop (or head) of 98 feet. When the turbine was hooked up, it was generating about 60 watts. Ten cell phones could be charged at a time without discharging the battery.
The generator uses a permanent-magnet alternator (PMA) and off-the-shelf PVC pipe and hardware. Everything except the PMA is readily available at almost any hardware store. The turbine itself is made of eight 45-degree PVC elbows, cut in half and mounted with rivets to part of a bucket lid. The PMA is mounted to the lid of the bucket using threaded rod. A manifold is mounted to the lid of the bucket and plumbed through, culminating in four nozzles also made from PVC. While a considerably more efficient generator could be made using a Pelton or Turgo runner, the idea behind the design was to make something that could be easily constructed and serviced with readily available materials. The PMA with cooling fan was about $360, and the other hardware and PVC was about $40, totaling $400.
Our long-term goal is to incubate microbusinesses that charge cell phones in areas where there is no electricity. We are also exploring the idea of microlighting using high-output LEDs.
Sam Redfield – West Shokan, New York