The use of waterwheels to free human beings from heavy labor is almost as ancient as the use of draft animals. The earliest applications of such wheels were to raise water from wells and to turn millstones to grind grain. Later, waterwheels were adapted to provide power for other processes to which a slow, ponderous, unceasing rotary motion was suited. In early America, textile factories and sawmills were generally built on riverbanks to take advantage of waterpower.
Making your own stove
Small wood stove can be made from a 15-gal. closedhead heavy gauge grease drum after cleaning drum of any residue of grease. Tolerances need not be precise. One weld and some furnace cement to hold stovepipe flange to stove top are needed. All other parts bolt on. Cut rectangular openings for fuel loading and ash removal; then cut doors from sheet metal to overlap the openings 1/2 in. all around.A personal hydroelectric power source has the potential to sustain every household energy need and provide an unexcelled level of independence. Having enough water flow is less a problem than one might imagine, particularly in hilly areas where hundreds of thousands of potential hydroelectric sites remain untapped. With a drop of 50 feet from water source to turbine, for example, a brook small enough for a child to jump across can provide enough power for a single-family dwelling. However, bear in mind that the smaller the installation, the higher will be the construction cost for each kilowatt generated. Scaled against the cost of power from a public utility, it may be 10 to 20 years before a small installation pays back its initial expense, though rising fuel costs may substantially shorten the payback period.Old-fashioned gristmills could grind 5 to 10 bushels of grain an hour. The miller poured the grain into a hopper from which it trickled down through the eye of the upper millstone onto a bed stone. As the 1/2-ton upper stone rumbled over the bed stone, it scraped off husks and pulverized the grain. The husks were then separated with a sieve, leaving flour.

Modern Waterpower Systems

Waterpower achieves its greatest usefulness when it is converted into electricity. Lighting fixtures, heating systems, small appliances, cooking ranges, and machinery of all sorts are some of the common applications. The conversion is made possible by electrical generators that transform rotary motion into electric current.
Though not originally designed for the purpose, old-fashioned waterwheels can actually be used to run generators, but not without overcoming a major obstacle: electrical generators do not operate efficiently except at high speeds, on the order of 1,500 revolutions per minute. To reach these speeds, a large step-up in the waterwheel’s rate of rotation is required, somewhere in the vicinity of 100 to 1. Wooden gears simply will not work—friction alone would destroy them. Instead, rugged, well-made gears or pulleys are required that are not only highly efficient but also capable of handling the huge forces present in the shaft of a waterwheel. Heavy-duty tractor transmissions have been adapted for the purpose and can provide several years of service. The design and construction of a system that will last 20 years or more calls for a high level of mechanical ingenuity plus persistence and luck in finding the appropriate used or abandoned equipment.Gearing problems can be circumvented by using a turbine instead of a waterwheel. Turbines are devices that convert water flow directly into high-speed turning motion. Little in the way of supplementary gearing is needed to achieve generator speeds. In addition, turbines are much smaller than waterwheels of the same power output, hardly larger than the generators with which they are coupled. Turbines run with a high-pitched whine—not as soothing as the rumble and splash of the old mill wheel—and some are subject to cavitation (wear caused by air bubbles).
Pelton turbines operate best with heads of 50 ft. or more.
The high-velocity jet of water that results from such heads spins the bladed runner up to generator speed without the need of additional gearing. Pelton runners can be any size from 12-ft. diameters for megawatt installations down to 4- to 18-in. diameters for home installations. Very little flow is required to run a small Pelton turbine, in some cases no more than the water issuing from a modest spring. The need for a high head, however, restricts installations to hilly or mountainous locations. Also, springs tend to dry up during some parts of the year and freeze up during other parts, so care must be taken to select a water source that will provide year-round power. A recent improvement in impulse turbines is to orient the jet at an angle to the blades, as in Turgo turbines. These units are smaller and faster than Peltons.

Propeller turbines are most effective at relatively low heads of from 3 ft. to 30 ft. The propeller is completely submerged and is impelled more by the dead weight of the water than by the water’s velocity. in high-head installations, propeller turbines suffer wear from cavitation. in addition, they work well only over a narrow range of speeds, so care is required to match the size of the turbine to the available stream flow. For example, when flow drops to 50 percent of a propeller turbine’s optimum, the power output will drop by about 75 percent, and when the flow drops to 30 percent, the output becomes nil. To overcome this limitation, some large hydroelectric installations use several turbines in tandem, shutting down one or more whenever the flow lessens. Others employ Kaplan turbines, whichCross-flow turbines work well when the head is greater than 3 ft. Water from a rectangular orifice passes through a barrel-shaped runner in such a way that the water strikes the ring of blades on the runner two times. This turbine is a relative newcomer; it has not yet been built in megawatt sizes but shows a great deal of promise for use in small installations. Moreover, it is simple enough for a person with a home machine shop to make; yet it can match the performance of the other turbines shown, whose fabrication requires a high level of technology. it works well over a wide range of water flow, is relatively free from problems caused by silt and trash, and is not affected by cavitation. To improve efficiency, the rectangular orifice can be partitioned and parts of it closed off during periods of low flow. some step-up gearing may be needed for optimum generator speed.Francis turbines can be used over a wide range of heads 4 ft. and more. As with a propeller turbine, the runner is immersed in the head water, which is guided onto the blades of the runner by a ring of adjustable vanes. The Francis turbine is highly efficient at its optimum flow but easily damaged by grit and cavitation. it is frequently used in large hydroelectric stations and is relatively expensive. As with propeller turbines and other interior-flooded turbines, a draft tube beneath the unit with its bottom rim immersed at all times in the tail water (the water flowing out of the power station) is a valuable adjunct: as water drops from the turbine runner down the draft tube, it sucks more water down with it, adding to the effective head of the system. This added head can be of substantial importance whenever the overall head of the remainder of the installation is small.
Before you buy a turbine, you should measure the characteristics of your stream, particularly its head, so you can match the turbine to them. (“Head” is the vertical drop the water makes from the point where it is diverted from the stream to the point at which it reaches the power–generating equipment.) Peltonwheels, for example, perform best under high head conditions; propeller turbines, the reverse. “Flow”—the volume of water carried by the stream past a stationary point each second—is also a factor in turbine design.

Finding Out How Much Your Stream Can Do

To determine the amount of power available in a stream, it is necessary to measure the water flow and make calculations from these measurements. This is not a hard job, since a rough estimate is usually all that you will require. Generally, wide seasonal variations in flow put a limit on the degree of precision that makes sense when measuring a stream.
Changes on the order of 100 to 1 in the volume of water carried by a stream are not uncommon from one part of the year to another. In the Southwest, large rivers as well as smaller streams often dry up completely for long periods of time.
The key information that your measurements should provide is whether or not a stream will yield enough kilowatts of electricity to make its development worthwhile. You will also want to get an idea of how large the equipment has to be to generate these kilowatts and what type of installation should be used.
A rough estimate, however, may fail to provide sufficient precise data to determine how the installation should be constructed or what specifications the turbine and generator should have. For greater precision professional surveying instruments may be needed; but before involving yourself at this level of complexity, consult the turbine supplier with whom you expect to do business. He should know the degree of accuracy required.
A stream should be measured several times during the year so that its overall potential can be estimated and the power-generating equipment tailored to the variations in flow. The measurements will have value even when the flow is so large that only a small fraction will satisfy your power needs. It is particularly important to measure a stream near its low point during the year. Also, potential flood level should be ascertained if equipment is to be installed near enough to the stream so that it could be destroyed by a flood. When a dam is to be constructed, knowledge of flood potential is crucial.
If you are not familiar with your stream’s annual ups and downs just by living near it, contact the nearest U.S. Geological Survey Water Resources Office (a branch of the Interior Department) for information on water runoff in your area. The information is free and likely to include rainfall and river flow data going back many years. If a stream is too small to have been directly measured by the office, a knowledge of local water runoff will help you form a profile of its behavior.
Measuring head
Head is measured in step-by-step fashion proceeding downstream from the water source to the planned hydropower location. You will need an assistant to help you make the measurement plus the following equipment: a carpenter’s level, a camera tripod or similar support, an 8-foot-long pole, and a tape measure.
Set up the tripod near the water source and place the carpenter’s level on the tripod’s table. Adjust the table to the horizontal, then vary the tripod’s height until the sight line along the level’s upper surface is lined up with the water source. Next, have your helperhold the pole vertically at a location downhill from the tripod so that you can sight from the other end of the level to the pole. Call out instructions as you sight toward the pole, and have your assistant make a chalk mark on the pole at the point where the sight line intersects it.
Now set up the tripod and level downhill from the pole at the location where the sight line, looking back uphill toward the pole, will intersect the pole at a point near its base. The assistant should now mark the new point of intersection, measure the distance between marks, and jot the measurement down. Once this is done, both chalk marks can be erased and the pole set up at a new location downhill, where the entire procedure is repeated. Once the power site is reached, add up the figures you have jotted down and you have the head.

What the Power Can Do

After measuring the head, velocity, and area, multiply together the numbers you have obtained and divide the result by 23. You will then have the usable stream power in kilowatts. Expressed as a formula, the calculation is:The divisor, 23, is in the formula to make the answer come out in kilowatts and to reflect an overall system efficiency of 50 percent.
For example, for a head of 10 feet, a stream velocity of 1.4 feet per second, and a cross-sectional area of 4.8 square feet, the usable power output is:

Measuring velocity
Estimate of velocity can be obtained clocking how rapidly floating objects move down the center of the strem. select a portion of the stream that is reasonably straight and without obstructions, turbulence, or eddies. Tie strings across the stream at two locations spaced 20 ft. apart, with each at right angles to the direction of flow. Toss a cork, or other object that floats, into the center of the water upstream of the first string and time how many seconds it takes for the stream to carry the cork from one string to the other. The divisor, 23, is in the formula to make the answer come out in kilowatts and to reflect an overall system efficiency of 50 percent.
For example, for a head of 10 feet, a stream velocity of 1.4 feet per second, and a cross-sectional area of 4.8 square feet, the usable power output is:Divide this amount into 20 ft., multiply the result by 0.7, and you will have the stream velocity in feet per second. (The factor of 0.7 is necessary to reflect the fact that portions of the stream flowing along the banks and near the bottom move more slowly than the surface of the stream where the measurement is made.) As an example, suppose the cork took 10 seconds to traverse the 20-ft. distance from string to string. Dividing 20 by 10 and multiplying by 0.7 gives a velocity of 1.4 ft. per second. For greater accuracy, repeat the measurement several times, then average the results.

Measuring area
Cross-sectional area of a stream must be measured at the same location at which you measured the stream velocity. Mark off one of the strings in equal intervals. six to 12 intervals should be enough, depending on the size of the stream. Measure the depth of the stream at each of the marked points on the string, record each measurement, and calculate their average after all the measurements have been made by adding the figures together and dividing by the number of measurements. Multiply this result by the width of the stream, measured from bank to bank, and you will have the area.As an example, suppose your stream measures 6 ft. across and you have marked your string at five points, each 1 ft. apart with depth measurements at each marker 1/2, 1, 11/4, 3/4, and 1/2 ft. respectively. The measurements add up to 4 ft.; 4 ft. divided by five gives an average of 4/5 ft.; and 4/5 ft. multiplied by six results in an area of 4.8 sq. ft.
To find out how much electricity is available to you over a period of a month, multiply the figure you have obtained for power by 720—the number of hours in an average month. In the example above the 2.92 kilowatts (if this output is constant) would provide 2.92 × 720 = 2,104 kilowatt-hours per month.
The computation is similar if a container is used to measure flow. Just take out velocity and area from the formula and substitute the flow measurement in their place.

Making the Calculations

Once you determine a stream’s power, you can estimate its usefulness. One way to do this is to compare the kilowatt-hours stated on your electric bill with the stream power you have calculated; you will then have a quick estimate of the proportion of your needs the stream will be able to satisfy. For the comparison use a bill with a monthly charge that is high for the year.
Another way to estimate what the stream can do is to use a capability chart like the one above. In an approximate way the chart indicates the number and type of appliances various power outputs can handle. It assumes that the use of these appliances will be fairly evenly distributed over each month and also assumes that a storage system, such as a bank of batteries, is used in the power system to take care of peak power demands (see A Power System for Hilly Areas, p.75).
One measurement of the stream is not likely to be enough to make a reliable estimate. Because stream flow varies, measure the stream’s velocity and area at several times during the year (over the course of a number of years if possible) and use the lowest measured power to estimate usefulness.

Leading the Water To the Powerhouse

A small dam—one up to 4 feet high and 12 feet across—can often be built of locally available materials such as earth, stones, or logs. Such a dam can provide a dependable supply of water at an intake to a race (a canal for diverting water from a stream to a power station) or at a penstock (a pipe that serves as a race).
To moderate the effects of monthly and seasonal variations in stream flow, larger dams can be built. These will store excess water and release it during

Power Storage, Regulators, and Inverters

All but the simplest waterpower systems have some means of storing power to compensate for irregular stream flow and to hold power for periods of high user demand. It is also important to have some means of regulating the power output so that it matches the demand placed on the system. Power when it is generted has to be sent somewhere, whether to appliances, batteries, or the power company. If no loads of this type are present, or if most or all of them happen to be switched off, the generating equipment may freewheel up to a point where it eventually burns out its bearings and self-destructs. The diagrams below show several methods to store and regulate power.
Where it is necessary to convert from DC to AC, an inverter is used. Inverters come in two forms. One is the rotary type, which consists of a combined motor and generator plus built-in controls for maintaining a constant 60-cycle 115-volt AC output. The inverter motor is run electrically by the 32-volt turbine generator. The other type of inverter is electronic. It is less bulky than the rotary type and roughly 30 percent more efficient (the rotary type is only 60 percent efficient). In addition, electronic inverters consume much less power than rotary inverters when all the appliances are turned off.
System without storage is the least costly to install but very limited in application. The output from the generator has a voltage that varies widely according to how much water is flowing in the stream and how many appliances happen to be switched on. Usually the only appliances that work well with such a system are ones with simple resistance elements for heating, such as hot water heaters and hot plates. The temperature of the heater’s water may not be constant, but the arrangement is satisfactory if sudden demands on hot water are avoided.
Pond formed by damming a stream is the traditional means for storing energy and smoothing the effects of erratic stream flow. A speed regulator, such as the hydraulic model in the installation shown below, is needed to take care of varying electrical demands as appliances are switched on and off. Hydraulic regulators are expensive, however, sometimes costing more than everything else in the powerhouse. Regulators currently being developed to accomplish the same task electronically may become a cheaper alternative.
Battery storage works well for small systems such as the one shown on the facing page. since batteries store and deliver DC electricity, an inverter is required to convert to AC. An attractive feature of battery storage is that it acts in part like a regulator, automatically diverting power into the batteries when house power demand is low and releasing it when demand is high. But to accommodate periods when the batteries have become fully charged, the turbine must be sufficiently rugged to withstand the resulting no-load condition.
Local power utilities usually permit private citizens to sell their excess power to them. in this way the power company becomes a substitute for batteries or a storage pond. A device called a synchronous inverter automatically sends out the excess when the home system overproduces and draws power from the company when the home system underproduces. Power companies tend to pay less for your power than what they charge for their power. Even if they pay nothing, the arrangement still saves the cost of a regulator or batteries.