The Engineering of Industrial Hydropower


      The modern day hydroelectric turbine is widely credited as being the result of the water wheels of the industrial revolution.  In fact, many turbine designs developed in the industrial revolution are still in use today.  Although before the advent of cheap electric motors in the 1940s, water power was mainly used for producing mechanical power.  

How were the hydropower systems of the Industrial Revolution built?

    1. The first step in building the mill's water system was to build a trail race.  The trail race's purpose was to redirect any runoff and seepage away from the construction site that could slow the construction of the mill.  
    2. The second step in building the hydro-system was to start building the canal.  The key to not getting flooded was to start from down stream.  When you reach where the river's going to meet the canal, it is important to leave some ground between the two.  
    3. Third, line the canal with rocks so erosion is minimal.
    4.  The fourth step in building a dam is to make a temporary dam stretching half way across the river.  This will leave a spot directly behind the temporary dam which is dry.  From here, you will construct the actual mill dam. 
     5.  The construction of the dam varied from site to site.  The depth to bedrock, the materials at hand, the flow of the river, they all played a part in the construction of the dam.  Dams could be made out of many materials; wood planks, logs, iron, rough boulders, or shaped stone.  Although, shaped stone was by far the strongest material.  One major factor which played a part in the construction of the dam was how far it was to bedrock.  If it was more than about seven feet to the bedrock, the they would basically drive a thin wall of iron into the soil.  The purpose of this was to prevent seepage.  Seepage is potentially dangerous because it can structurally compromise the dam.  If there was only a couple of feet of silt, they would remove that.  Then they would build the dam right on the bedrock.  From there, they would construct a stone wall.  This is the actual mill dam.  From there, you would essentially make a ramp leading up to the dam so that some of the water pressure wold be directed to the ground, instead of the dam.
    6. Remove the temporary dam, and then place another temporary dam on the other side of the river.  
    7. Build the other half of the mill dam and then remove the temporary dam.  
    8. Build the stone foundation for the waterwheel.  This varies depending on the type of the wheel, but generally it includes a place for the shaft to rest, a stone canal bed to minimize erosion, and a shoot for the water to be directed onto the wheel.  
    9.  After you have finished adding those features on, build and install the waterwheel.  The wheel design varies depending on location, water flow, and drop of the river.  I'll get more in depth of the design of these turbines later on.
    10. After you've completed the waterwheel and the mill it's time to open up the canal.  Just dig the rest of the canal until you reach the mill pond. 

                    Congrats, you have finished building your mill!

Evolution of the Water Wheel
     The first water wheels originated in Greece around 400 BC.  They were basically grindstones mounted to a rough, horizontal wheel, and because of their simple design, their blue print changed little for hundreds of years.  In the first century AD the inefficient horizontal wheel was replaced by the more efficient vertical wheel.  In 1643, the first fulling mill was built in Rowley by John Pearson.  From there, as more and more people moved to America, more and more mills were built in order to satisfy the needs of those people.  Although the technology didn't evolve much until the industrial revolution.  As technology evolved, so did the waterwheels uses.  Instead of being used for just fulling, sawing and grinding, the waterwheel powered virtually all industry, making significant advances in technology possible.  When the steam engine was invented, waterwheels were used less and less for producing mechanical power.  Soon the mills moved from river-filled New England to areas closer to the cotton-growing regions of the south.  In the late 1800s, a new use for waterpower emerged from Europe; producing power.  The late 1800s and early 1900s was a very exciting time for innovation; Edison invented the light bulb, Tesla had discovered the amazing advantages of AC power.  Ultimately, waterpower would emerge as the major source of power until the advent of nuclear power in the 1950s.

Picture
Left:  This is one of the several types of overshot water wheels used in the mills of the industrial revolution.  The term "overshot" means that water travels over the water wheel spinning it clockwise.









Types of Waterwheels

Pitchback:  Efficiency: 90%
                        Characteristics:  The pitchback waterwheel is the most efficient waterwheel used in the industrial revolution.  This is because it captures virtually all of the waters kinetic energy.  Also when the water flows underneath it, it takes advantage of the energy as the water flows towards the river.  Compared to other designs, it requires little water.  Although, it does require a large drop of at least 15 feet. 


Overshot:  Efficiency: 70%
                      Characteristics:  The overshot waterwheel is a slightly less efficient waterwheel used in the industrial revolution.  This was a fairly rare design compared to other types of waterwheels for several reasons.  The first reason was because it required a large drop of  at least 17 ft.  Another reason why this was  fairly rare design was because it was a very complex design.  It took much more capital to build this type of waterwheel compared to other designs. 

Brestshot:  Efficiency: 50%
                       Characteristics:   The brestshot waterwheel is by far the most commonly used waterwheel of the industrial revolution.  This is largely because it only requires a drop of about 6 to 8 feet.  It generally wasn't as efficient as other designs because it did a poor job in transferring the kinetic energy of the water into mechanical power the mill can used.  Unlike other designs, the undershot waterwheel would be made of iron whenever possible.  This is because this design would face more strain than any other waterwheel.

Undershot:   Efficiency: 20%
                       Characteristics:  The undershot is the least efficient waterwheel design used in the industrial revolution.  It required large quantities of water in order to get a sufficient amount of power.  The main reason why this design was used was because it required virtually no slope.  This made it popular in flat areas where there were large sources of water.

Picture
Below: Unlike the overshot water wheels, undershot water wheels travel underneath the water wheel to spin it counter-clockwise.