August 1, 2006
Q: My husband and I own 120 acres with a small creek and we would like to know if we could find a way to harness the water power to produce energy for our cabin. The creek is about 2-4 feet wide in places, 1-4 feet deep in places, and has a gentle drop through the property. Are there small units that could run off of a propeller system to charge small batteries? Wind power and solar power seem not to be an option for us as we cannot get above our tree line, and we have many trees that we would not want to cut down to open up space for solar panels.
– Bev Szprejda, via e-mail
A: Small hydroelectric batteries that are powered by small streams do exist; you can find them from some of the same dealers who sell solar panels.
Commonly available hydroelectric generators for stream usage are designed to be 12, 24 or 48-volt battery chargers that work with a relatively small volume of water. The generators charge the battery when the water is flowing and then the power is drawn from the battery as needed. Unlike larger hydroelectric systems such as dams, micro-hydroelectric generators don’t need to greatly disturb the path of the stream in order to function.
Calculating whether or not you have enough “head” (the difference in elevation between the water collection point and the turbine) and “flow” (noted as gallons per minute) from your stream to run one of these micro-hydro generators is a little fuzzy for those of us who are not hydroelectric engineers. But we will note that some manufacturers advertise their generators as operating at a head as low as two to four feet.
For flow data on your stream, you might consult such sources as your county’s engineer, local flood control authorities, the U.S. Army Corps of Engineers, U.S. Department of Agriculture or the U.S. Geological Survey.
Micro-hydroelectric generators aren’t especially cheap – with the necessary accoutrements you may spend a couple thousand dollars – and because personal hydropower is a relatively nascent market, you need to maintain a skeptical, “buyer beware” attitude toward any dealers that make wildly optimistic claims or seem less than knowledgeable about this kind of technology. Check with renewable energy groups in your area; some provide workshops on micro-hydroelectricity that can assist you in measuring the flow of your stream as well as setting up and operating your generator.
Although solar panels aren’t a good fit for your particular situation, other readers may like to consider the idea of combining micro-hydro and solar systems on their properties. Think about the complimentary nature of the technologies: When it’s rainy and the solar output is low, the hydro system could be at its peak.