Category The Homeowner’s Guide to. Renewable Energy

A Brief Afterword


n this book; weve explored many ways to conserve energy and trim demand by using energy more efficiently in your home or business to get the most for your energy dollar and also to help create a cleaner; healthier; and more sustainable future. We’ve also explored a wide range of options for tapping into renewable energy. By now; you should have a pretty good idea what ideas you want to pursue. If you are going to pursue some of these projects on your own; you may want to sign up for a few hands-on workshops first. It will make your life much easier in the long run.

Bear in mind that home energy effi­ciency and residential renewable energy are just a few of the ways to achieve greater self-reliance...

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Microhydro is a great source of reliable electrical energy, but before you go out to buy a system, you should have a full understanding of its pros and cons. On the plus side, microhydro is probably the most cost-effective renewable energy system on the market. According to Scott Davis, it delivers "the best bang per buck.’’ Davis goes on to say, "Significant power can be generated with flows of two gallons per minute or from drops as small as two feet.’’ And, says Davis, "power can be delivered

in a cost-effective fashion a mile or more from where it is generated to where it is being used"

Microhydro, unlike almost all other renewable forms of energy (certainly wind and solar) often provides continuous power. That is to say, it provides electricity

day and night, night and day, 7...

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Microhydro systems are pretty easy to install. In fact, people with modest plumb­ing and electrical skills can install most of a system without much trouble. However, battery banks, inverters, and other controls typically used in offi-grid systems require a higher degree of expertise than many do-it-yourselfers possess. Grid-connected systems require a high level of electrical expertise too. My advice is that it’s always a good idea to hire a professional to help you out or to do the job for you. Experienced professionals know the tricks of the trade and can save you a lot of time, trouble, expense, and frustration. I’ve always been amazed when working with experts on wind and solar systems, for instance, how little tricks of the trade make the job go so much easier!

A professional in...

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Power Lines

Most microhydro systems produce low – voltage DC electricity that travels in a wire to the battery bank. Because low-voltage current doesn’t travel well — it loses energy quickly over distance — it is best to keep power lines from the turbine/generator short, under 100 feet. If this is not possible, you will need to use large-gauge wire, which costs much more than standard wire.


Jeffe Aronson installed a low-head micro­hydro system on a stream running through his property in Australia. He did so by building a small concrete dam across part of the river. Although friends recommended that he complete the project without per­mits and "let the bureaucrats find it if they could," Jeffe decided to secure the necessary permits and work with local authorities...

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After designing an intake structure and selecting a turbine, you’ll need to design a pipeline* Pipelines are typically made from either 4-inch PVC or smaller polyethyl­ene pipe* PVC is used almost exclusively when the pipe needs to be over 2 inches in diameter, although 1*5- to 2-inch PVC can be and is used* Four-inch PVC pipe comes in 10- and 20-foot sections that are glued together* Assembly is quick and painless and can be mastered by anyone* PVC pipe not only goes together easily, it is relatively inexpensive* In addition, PVC pipe is very light, so it is easy to install, which is especially helpful in steep terrain* Two-inch polyethylene pipe is used for smaller flows* It comes in very long rolls that are laid out from intake to turbine* Because there’s no gluing (unless two rolls mus...

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Drive Systems

In most systems, a steel shaft connects the turbine to the generator. This shaft com pies the turbine with the generator so that rotation of the turbines runner translates into rotation within the generator, “The most efficient and reliable drive system involves a direct 1:1 coupling between the turbine and generator," notes New. But this is not possible for all sites. In some cases, especially when AC generators are used, it may be necessary to “adjust the transfer ratio so that both the turbine and genera­tor run at their optimum (but different)
speeds," he adds. This is achieved through gears, chains, or belts, Belt systems are the most popular because they are the least expensive...

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AC Generators

Although most microhydro systems pro­duce DC electricity, there are some times when AC generators are advisable, notably for larger commercial applications or for grid-connected systems. These systems can produce more than 3,000 watts of continuous power or 72 kWh per day — far more than most homes ever consume* As Dan New pointed out in an e-mail to me, these systems Tan often supply all of the energy needs of a home.” DC sys­tems typically only provide electricity for

lighting, appliances, and electronic heaters, but not space heat, hot water, or dryers* Those demands are typically satisfied by propane or natural gas* An AC microhydro system, however, could supply heavy-duty machines, compressors, and welding and woodworking equipment* "Most DC systems cannot cover most of this li...

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Choosing a Turbine/Generator

Several different types of microhydro tur­bine/ generators are available. Your choice

minimize maintenance, Harris also offers a brushless permanent magnet generator* These units cost about $700 more, but use larger, more sturdy bearings that last two to three times longer* This greatly reduces maintenance and replacement costs* It is well worth the extra cost*

Harris turbines are for applications with 50 feet or more of head* They pro­duce from 1 kWh to 35 kWh per day,
depending on the model and site* The unit (generator) has an instantaneous output of about 2,500 watts — enough to start most appliances and power tools* Harris microhydro turbines come in 24- and 48-volt models and are manufactured in the United States*

For low-head systems that channel a lot of water through a turbine...

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