Small Hydropower Science Projects
Whether water exists in the form of rain, seawater or ice, it is constantly moving as part of our planet's water cycle. When we use water's motion to generate electricity, it is known as hydropower, and is a renewable source of energy. Hydropower plants enable moving water to push a turbine, which produces electricity. In small hydropower science projects, you can probe the ways in which water's kinetic energy can be converted into mechanical work.
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Investigate the Force of Flowing Water
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Slice off the top of a milk carton. Use a nail to pierce a hole that is a half inch from the carton's bottom and in the middle of the carton's side. Make a second hole that is a half inch directly above the first hole. Punch a third hole that is an inch above the second hole. Make a fourth hole that is two inches above the third hole. Use a single strip of tape to cover the holes. Draw a line close to the carton's top. Pour water into the carton until the water level meets that line. Place the carton on the perimeter of a sink. Position the hole-punched side so that it faces the sink. Remove the tape. Measure the furthest distance of each stream as it hits the basin. Allow the water to stream out of the carton. Observe the changes in the streams. Use separate pieces of tape to cover the holes, and refill the carton with water up to the line. Take the tape off the bottom hole. Measure the distance of the stream as it hits the sink. Cover the bottom hole with tape. Take the tape off the second hole, and measure the distance of the second stream. Repeat this procedure for the last two holes. Observe how differences in the water's weight, or water pressure, affect the distance and speed of the streams coursing out of the carton.
Convert Energy from Falling Water
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Gather a 9-inch aluminum pie plate, scissors, ruler, protractor, drill with a 3/8-inch bit, a 3/8-inch-thick nylon spacer with 3/8-inch inner diameter, tape, glue, 2-foot-long and 5/16-inch wide wood dowel, large plastic bucket, 30-inch-long cotton string, hex nut, measuring cup and stopwatch. Cut the sides off the pie plate so that you're left with the flat round bottom. Draw a 1 cm-thick line from the plate's top to the bottom. Draw a second line that is perpendicular to the first. Draw another cross over the first cross but at a 45 degree angle. Use your protractor to draw a 2-cm wide circle where the crosses intersect. Cut only the right side each of 8 lines that lead up to the center. Fold the paddles along the left sides of the 8 lines. Ask an adult to help you drill a 5/16-inch hole through the waterwheel's center. Cement the nylon spacer over the hole. Tape the spacer to the waterwheel to hold it in place. Take the handle off the bucket. Ask an adult to drill a hole on each side of the bucket where the handle was located. Thread the dowel through one hole in the bucket and through the hole in the waterwheel. Then thread the dowel through the other hole in the bucket. Tie one end of the string to the hex nut. Knot the other end around the dowel. When the dowel turns, the string should wind. Put the waterwheel and bucket beneath the faucet of a large sink. Turn on the tap. Use your stopwatch to record how long it takes to fill your measuring cup with two cups of water. Divide the 2 cups by the number of seconds to derive the flow rate. Do not turn off or change the tap. Measure first the height of the water flow, and then place the waterwheel under it. Time how long it takes for the waterwheel to wind up the string. Conduct three trials for each of three different flow rates. Determine if a stronger flow rate affects the time it takes to lift the weight.
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Experiment with Your Waterwheel
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Create a waterwheel in the same way that you did for the second project, but alter the design to probe the effects of a waterwheel's shape on how much time it takes to perform work. Design two other waterwheels, one with only four paddles and another with sixteen paddles. Compare the performance of waterwheels with fewer and more paddles to your original waterwheel. Change also the water source or the flow rate of water. Use a water hose and a very strong flow rate to test its affect on wind-up time. Slow the water from the sink faucet down to a trickle. Measure how long it take to wind up the string. As a third experiment, add a hex nut to the end of the string to increase lift weight. How does the increase in work load affect wind-up time? Record your data in a table.
Build a Dam
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Use a drill with a 1/2-inch bit to make a hole in the bottom of a five-gallon plastic bucket. Replace the bit with a one-inch hole saw and make a second hole a few inches from the first hole. Use a 1 1/2-inch hole saw to make another hole a few inches from the other two holes. Smooth all holes with a file, and then plug each hole with a right-sized rubber stopper. Gather a toy boat propeller with a 1 3/4-inch diameter and a 1/8-inch hole, a brass rod with a 3/32-inch diameter, and brass-plated 3/32-inch dura-collars. Thread the propeller through the rod. Thread a dura-collar on each side of the propeller. Tighten the collars with screws and wrench to complete your turbine, and then place a bright sticker on one propeller fin. Create a stand with bricks. Set a bucket on top of the stand. Place a container beneath the bucket to catch water. Position your turbine over the 1/2-inch hole in the bucket. Ask a classmate to time 10 seconds with a stopwatch after you pull the plug from the 1/2-inch hole. Count the propeller's rotations during those 10 seconds. Repeat this process twice, and record the rotations in a table. Repeat this process with the other two holes, conducting three trials per hole to collect sufficient data. Determine which hole provides the most electricity given that a turbine's rotational speed is proportional to generated power.
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