Hydropower

Podcast Transcript

For thousands of years, humans have used the power of water to do work for them.

At first, it was very simple, then it gradually evolved to more complex and more efficient devices to harness the power of water.

Eventually, we were able to harness some of the world’s largest rivers to produce incredible amounts of power for millions of people.

Despite the advanced hydropower systems that exist today, there are still small-scale uses available as well.

Learn more about how humanity has harnessed the power of water on this episode of Everything Everywhere Daily.

I’ve gone over the history of many different technologies and inventions over the course of this podcast.

A common theme with many of these inventions is that they usually have an origin which traces back 3000 years or more, and more often than not, it started in China.

In the case of hydropower, as you’ll soon see, that doesn’t apply.

The very first evidence we have of water engineering dates back to around 4000 BC, when the Mesopotamians and Egyptians used irrigation canals to control the flow of water for agriculture.

These systems were very simple. They would create irrigation canals and small dams to get water where it needed to go. For the purpose of this discussion, they often needed to raise water from a lower level to a higher level.

This was initially done with buckets attached to a long arm to use the mechanical advantage of a lever. These early devices are called a Shaduf. Lifting water was a hugely important problem in the ancient world.

Archimedes screw, which is something you might be familair with, was his attempt to solve this problem.

Around 300 BC, we have evidence of the Greeks and the Egyptians using a wheel to lift water. In Arabic it is called a noria.

This seems odd because it is the exact opposite way water wheels were traditionally used. Human or animal energy was put into the wheel to raise water to a higher level.

It didn’t take too long after this that someone must have just let it run unattended and realized that the flow of water in a river or stream would turn the wheel, and maybe you could use that rotational movement to actually do something.

It was around this same period that the first water wheels were recorded.

These early Greek water wheels, which were used for mechanical energy, were actually horizontal water wheels.

Horizontal water wheels were used to turn a mill stone to grind grain. The water wheel and the grist stone were parallel to each other, and it didn’t require converting vertical rotation into horizontal rotation.

Around 200 BC, Philo of Byzantium wrote about early water wheels used to power grinding mills.

The problem was that horizontal water wheels were pretty inefficient.

By 20 BC, the great Roman architect and engineer, Vitruvius, described the vertical water wheel, which became widely used across the Roman Empire.

The vertical water wheel was a huge improvement over the horizontal wheel.

At first, the wheel was just put into a stream and the flow of the stream turned the wheel. This was an improvement, but it still wasn’t very efficient. A stream wheel is only about 20% efficient.

The first century BC saw a lot of innovation in a very short period of time when it came to water wheels.

One of the things that was figured out quickly was the concept of head.

“Head” refers to the vertical distance between the water source and the point where it exits or impacts a turbine or water wheel. It represents the potential energy available due to gravity and is a key factor in determining the efficiency and power output of a hydropower system.

They realized that, rather than putting a water wheel in the middle of a stream, you could get more power from it if you put it near a waterfall or some other location where there was a difference in water height.

Just divert the water along a channel and have it fall over the wheel.

This led to the development of what are known as undershot, breastshot, and overshot. These simply refer to where the water was first touching the wheel; low, medium, or high.

An overshot water wheel was the most efficient with the water falling down from the very top of the wheel.

The Romans were not what you’d call very inventive people. They didn’t have a great record of technical innovation. However, water wheels were the one thing they really excelled at.

With it they were able to create some truly innovative machines for the era.

The Barbegal Mill complex, built in the 2nd century, located in southern France, was an enormous water-powered flour mill consisting of 16 water wheels arranged in a cascading system, capable of grinding vast amounts of grain to feed the Roman population. This represents one of the earliest known large-scale industrial production sites.

The Hierapolis Sawmill, built in the 3rd century in present-day Turkey, was one of the earliest known examples of a machine using a crank and connecting rod mechanism to convert rotary motion into linear motion, allowing it to automate the cutting of stone and wood—a revolutionary advancement in mechanization.

I should note that about this same time in China, vertical water wheels also began to appear. By all accounts, it was an independent development.

When the Roman Empire fell, water wheel technology didn’t disappear. In fact, it expanded after the abolition of slavery when brute human labor couldn’t be used. Water wheel technology spread across Europe, the Middle East, and Asia, becoming a crucial energy source in medieval economies.

By the 11th century, water wheels were quite common across Europe.

In 1086, the Domesday Book, which was a survey taken of England by William the Conqueror, recorded more than 5,600 water mills. That was just in England. There were tens of thousands more scattered around the world.

Streams, rivers, and locations with a suitable head for a water wheel became prime locations for monasteries and mills.

While water wheels spread geographically, it wasn’t until the Renaissance that there were significant technical advancements in water wheels.

Leonardo da Vinci sketched designs for improved water wheels and gears. As with most of his inventions, they never got beyond his notebooks.

However, the idea of adding gears to mills was a powerful one that did catch on.

Advances in gearing mechanisms allowed water wheels to be used for more than just grinding grain. They allowed for water to power hammer mills for metalworking, fulling mills for textiles, and paper mills for producing paper.

Water wheels were used to power bellows for furnaces and pumps to drain mines.

Georgius Agricola, a 16th-century German mining expert, described these applications in his work De Re Metallica.

Hydropower was the dominant form of industrial power used by humans up until the invention of the steam engine.

With the development of the steam engine, it liberated factories and mills from having to be next to a water source with a large head. Factories could now be located anywhere that coal could be delivered.

However, the industrial revolution didn’t cease the use of water power. In fact, in a few cases, water wheels reached their logical conclusion.

If you visit the Isle of Man, you can see the Great Laxey Wheel.

The Great Laxey Wheel is a massive water wheel built in 1854 to pump water from the Great Laxey Mine, one of the island’s most important lead and zinc mining operations. Designed by Robert Casement, the wheel is an overshot water wheel with a diameter of 72 feet 6 inches or 22.1 meters, making it the largest working water wheel in the world.

Still operational, it can rotate at a speed of three revolutions per minute.

Just when it looked like the steam engine might forever displace hydropower, in the 19th century an invention gave it new life: the water turbine.

Unlike traditional water wheels, which rely on direct impact, turbines use curved blades or vanes to efficiently harness both the speed and head, of flowing water.

The first practical water turbine was developed in 1827 by Benoît Fourneyron, followed by significant improvements such as James Francis’ Francis turbine in 1849.

The 19th century saw many quick improvements in the water turbine, including the development of the Pelton wheel in 1876, which is used in high-head, low-flow situations, and the Kaplan turbine in 1913, for low-head, high-flow conditions.

Turbines were reaching efficiencies over 90% in the late 19th century.

Of course, the water turbine proved to be great for the new form of power that would revolutionize the world: electricity.

In 1872, the world’s first hydroelectric power system was built in Cragside, England. However, it wasn’t really much as it was designed to power a single arc lamp.

The world’s first commercial hydroelectric plant was the Appleton Edison Light Company, which was built on the Fox River in Appleton, Wisconsin in 1882. The location of that first hydroelectric plant is less than a mile from where I’m recording this very episode.

This first hydroelectric plant had an output of 12.5 kilowatts. There is a hydroelectric plant right outside my window, which is pretty small, that has an output of 525 kilowatts.

To put that into perspective, the largest hydroelectric facility in the world, the Three Gorges Dam, has an output of 22.5 GW.

By 1889, just seven years after the first hydroelectric plant, there were over 200 in the United States.

In 1895, the Niagara Falls Power Station began operating, supplying electricity to Buffalo, New York, demonstrating, for the first time, the large-scale potential of hydropower.

Hydroelectricity quickly became an important part of electrical production. By the 1920s, hydropower accounted for nearly 40% of the world’s electricity.

The world’s insatiable demand for electricity led to the development of more water turbines for electrical production and the creation of massive hydroelectric dams.

Dams create more power for turbines than a regular river because they increase the “head” and regulate water flow, maximizing the energy available for conversion. In a natural river, water flow is variable and often lacks the height necessary to generate substantial pressure.

A dam stores water in a reservoir, allowing it to accumulate potential energy. When released, the water flows through channels at high pressure, striking the turbine blades with greater force, which significantly improves efficiency and power output compared to a free-flowing river.

The Dnieper Hydroelectric Station built in 1932 was one of the largest projects in the Soviet Union.

Hoover Dam built in 1936 and the Grand Coulee Dam in 1942 were some of the largest hydropower plants in the world at the time.

In previous episodes, I’ve mentioned other massive dam projects around the world like the Aswan High Dam and the Grand Ethiopian Renaissance Dam.

However, there isn’t nearly as much dam building going on as there was almost 100 years ago. Environmental concerns and burgeoning costs have made them less attractive, especially considering that many dams have a very finite lifespan due to silting.

However, there are other sources of hydropower that are being explored.

One is harnessing tidal power. This would involve putting massive turbines anchored below the surface of the water that would turn whenever the tide went in or out.

On the other end of the spectrum is microhydro.

Microhydro is a small-scale hydropower system that generates electricity using the natural flow of water, typically producing less than 100 kilowatts of power. It is designed for individual homes, farms, or small communities, often in remote areas where grid electricity is unavailable. Unlike large hydroelectric dams, microhydro systems usually operate on a run-of-river basis, meaning they do not require large reservoirs or significant environmental disruption.

Despite being thousands of years old, we are not done with hydropower yet. From the extremely large dams on some of the world’s largest rivers to microhydro powering a cabin in the woods, hydropower will probably play a role in humanity’s energy mix for centuries to come.