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                     VITA TECHNICAL BULLETIN
                      1-kW RIVER GENERATOR
                     by MATHEW G. BOISSEVAIN
The plan presented here is a detailed description of a
1-kilowatt (1-kW) generator unit, which was prepared in 1971.
The plan is scheduled to be revised and updated in the near
future in order to incorporate additional data.   At the time,
this plan was prepared, the generator had not been built on the
scale shown here.  Therefore, until such time as testing results
can be integrated into the plan, VITA offers this material as
an idea paper.
By way of background, the designer of the 1-kW river generator
made the following assumption in his calculations:
     80% efficiency for each of the three "V"-belt speed-up
     stages so that enough power is available to operate the
     unit at 4.7 ft/sec water velocity.  It will certainly operate
     at 6.0 ft/sec.
Mathew G. Boissevain is a design engineer at a major U.S.
corporation.  During his many years as a VITA Volunteer, he has
developed several types of water wheels for powering water
pumps and has worked for almost 20 years designing machines
used in automated processes--for example, artificial kidney
equipment, circular weaving loom, various mail-sorting devices,
food-processing machines.
Please send testing results, comments, suggestions, and
requests for further information to:
                    1600 Wilson Boulevard, Suite 500
                      Arlington, Virginia 22209 USA
                 Tel:  703/276-1800 * Fax:   703/243-1865
               VITA Technical Bulletins offer do-it-yourself
              technology information on a
              wide variety of subjects.
              The Bulletins are idea generators
              intended not so much to provide a definitive
              answer as to guide the user's
              thinking and planning.  Premises are
              sound and testing results are provided,
              if available.
              Evaluations and comments based on each
              user's experience are requested.  Results
              are incorporated into subsequent editions,
              thus providing additional guidelines
              for adaptation and use in a
              greater variety of conditions.
                     1-kW RIVER GENERATOR
The river generator uses the flow of river water to produce
1-kW of electrical power.  It has four 5-ft diameter propellers
attached to a log float.  The float is anchored to the river
From actual trials with 40" propellers, it is calculated that
water flowing at 4.7 to 6.0 ft/sec will turn the 5-ft propellers
with enough power to generate 1000 watts of electricity.
The propellers are connected to the generator by a series of
"V"-belt pulley drives that speed up the slow 66-revolutions
per minute (rpm) of the propellers to the fast 3600-rpm of the
A variable speed pulley at the generator and a built-in volt
meter will enable the user to adjust the generator rpm and
voltage for varying river flow and generator load conditions.
Most of the pulleys, shafts, and "V"-belts are identical.  This
simplifies building and reduces spare parts needed.
Due to slow speeds (except at the last stage) the unit should
last a long time, if built as instructed.   It does not need
elaborate dams, river falls, or pipes, as do Most hydroelectric
plants.  You can build as many of these generators as
needed, spaced about 100 feet apart downstream.   By comparison,
a paddle wheel, under identical conditions, would need paddles
at least as large as the entire back frame of the river generator
(see drawing, rear view) to provide the same amount of
power.  Also, it would only turn at about 5-7 rpm and would need
more speed-up stages of "V"-belts.
The 1-kW river generator will produce about 720-kW hours per
month, which should be enough energy to run a simple household.
Some effort must be made to conserve energy, and to spread
energy use as evenly through the day as possible.
This design requires access to a river that runs with a speed
of from 4.7 to 6.0-ft/sec year round with a depth of at least
6-ft over a 21-ft width.  This principle will also work on a
smaller scale with a corresponding reduction in power output.
If you have access to a waterfall or higher water speeds, you
could make a 1-kW or bigger unit with smaller (but stronger)
propellers, turning at higher speeds, and with fewer pulleys
and belts.  These higher speeds can also be obtained by building
dams, etc.
Purchased parts (see parts list) total US$612.81, based on 1971
list prices in the United States.   To this, you must add tax and
shipping and the cost of all lumber and logs used.   To reduce
cost, you may be able to find your own parts (airplane propellers,
large fans, washing machine pulleys, etc.).   Because
prices may have changed drastically since 1971, be sure it is
economically feasible before you begin construction.
*  Wood saw
*  Hammer and/or hatchet
*  1" wood drill
*  1/2" wood drill
*  3/16" metal drill (for nail holes in item 21)
*  Allen wrenches (for 1/4" set screws in pulleys)
*  Metal file
*  Pliers to cut and twist 1/8" wire
*  Wrench for 1/4" bolts in propellers
*  .669" diameter drill for increasing hole in cast iron pulley
     (item 13) from .625" diameter to .669/.673" diameter.
*  14 straight logs, 5"-8" diameter X 21' (Bamboo may also be
   used instead of logs.  Use wire around joints to make strong,
   durable structure.)
*  Planks, 2" X 4"; as shown on page 9.
Find a place in your river, close to home, that has a water
speed of 4.7 to 6.0-ft/sec.  This must be measured exactly.  (At
3-ft/sec water speed, you will get only about one-fourth of the
power, or 250 watts.) To measure the speed, measure off 50-feet
along the river bank and mark with sticks.   Then, count the
exact time required for the water to carry a log or branch
between the sticks.  The time must be 8.3 to 10.6 seconds.  The
place to build your river generator is upstream from the location
chosen, so it can be launched like a large boat and
floated into place.  After the frame has been built, attach the
rope (item 20) to the pointed end and anchor the float in
place, using a boat anchor, a large rock, or a 2-inch steel
pipe driven into the river bottom.
Float.  Before spending money on parts, it may be wise to build
the log frame and test it out to make sure it holds together
under all river-flood conditions.   The author has successfully
built smaller frames than the one shown.   Unforeseen problems
may arise with a larger one.
Build the frame as shown in the following drawings.   Be sure to
reinforce all the joints with metal plates (item 21).   (Tin cans
could possibly be used here.   Remove ends, flatten, then dip in
paint to prevent rusting.) The wire (item 22) is used to keep
branches, etc., out of the propellers.   Also, use wire braces at
the back section (see rear view), and on all joints when building
the frame with bamboo instead of logs.
Drive System.  Next, make all the wooden parts shown on the
"side view" drawing.   Items 18 and 19 should be made of hardwood.
Soak it in water after drilling the hole.   Then open up
the hole as needed until the 1-inch shaft turns smoothly.  Do
the same for item 3 (pivoting frames--to provide V-belt
tension), but soak it in oil around the hole where the shaft
goes by filling oil holes after shaft is assembled.   Enlarge if
necessary to provide smooth running shaft.
Attach item 9 to the vertical members on the float, with the
shaft in place.  Make sure the shaft is square with the frame as
shown in the drawing.  It is important to end up with the
dimensions as shown in the "rear view" drawing, because the
"V"-belts are not adjustable in length.
Shafts.  Attach the pulleys to all the shafts, as shown.  File
or drill 1/8-inch into the shaft under all the set screws.  This
prevents the pulleys from turning on the shaft.   The propellers
attach with a split bushing and will grip the shaft tightly
when the bushing is bolted tightly against the propeller hub.
Belts.  Install all propeller belts and weight down each item 3
on both sides of center with rocks, as shown.   This will provide
a constant, even tension on the belts and reduce belt wear.
Allow the belts to set in the exact position of item 12 before
bracing it as shown on the "rear view" drawing.
Repeat above with the tall item 12 at the center of the float.
After the unit is back in the water and operating under load,
add rocks as needed to prevent belt slippage.   Don't make the
belts too tight as this increases wear.
Adjust the variable speed pulley on the generator to get the
120-volts needed.  Be careful to ground the generator housing
and ground wire in the water, and to keep people away who don't
know the dangers of 120-volts of electricity and wet feet in
water, etc.
Insulate all exposed wire.  Follow wiring instructions that come
with the generator, and run the cable down the anchor rope,
then along the river bottom (weight with rocks) to the shore.
Propeller Blade Tip Angle Adjustment.   At 4.7-ft/sec water
velocity, the propeller must turn at 60 to 70-rpm.   Twist the
propeller tip until the blade is angled as shown below.   All
blades must have a 9 [degrees] angle.
<FIGURE 1>      
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Grainger                     W. W. Grainer, Inc., 519 Potrero, San
                             Francisco, California U.S.A. [Phone:
                             (415) 861-48411]
Browning                     Browning Mfg. Division, Emerson Electric
                             Co., Maysville, Kentucky 41056 U.S.A.
Ryerson                      Ryerson Steel, Box 8427, Emeryville,
                             California 94608 U.S.A. (also, U.S.
Durkee Atwood                Durkee Atwood Co., Minneapolis, Minnesota
                             55413 U.S.A. [Phone:  (612) 332-0441]
Sears, Roebuck & Co.          Los Angeles, California 90054 U.S.A.
                             (NOTE:  Drill item 13 from .625" diameter
                             to .669" diameter.)
                             PARTS LIST
 Item      Quantity                                                            Cost      Total
Number     Needed              Description            Stock Number           Each        Cost        Where to Buy
   1           4           60" exhaust fan, 1" bore         3 CO 32              41.35     165.40      Grainger
   2          14           14" pulley, 1" bore              3 X 944              3.82      53.48       Grainger
   4          14          4" pulley, 1" bore              AS-40                 2.53       35.42      Browning
   5          14           "A" section "V"-belt             A 158                 6.43      90.02      Durkee Atwood
   6           1           Alternator, 1.2-kW,
                           115-Volt                       F32 KF 32054 N      119.00      119.00      Sears
   7           8           1" X 18" long shaft              Type 303 SS         61.00      61.00       Ryerson
   8           2           3" door hinge                                         1.20        1.20      (local)
   9        250 ft         Underground cable,
                           12 gauge, 5/8" bore           1 W 676             26.75       26.75       Grainger
  13           2           Variable pitch pulley           3 X 276               2.77        5.54      Grainger
  15           2           "A" section "V"-belt             A-75                  5.00      10.00      Durkee Atwood
  17        36 (14#)       4" X 8" X .125" thick            6061-T6 alum                     8.00      Ryerson
  18           12          1" flat washer                   plated steel                     1.00      (local)
  20        50 ft          1" diameter rope                                                25.00       (local)
  21        20 lb         4" long nails, plated wire                                      6.00      (local)
  22       300 ft          1/8" soft galvanized steel                                       5.00       Ryerson
                           Total cost of all purchased parts except wood    $612.81
                                                    Add tax and shipping

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