Hydropower
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For thousands of years, humans have used the power of water to do work for them. At first, it was pretty simple, and 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. But despite the advanced hydropower systems that exist today, there are still small-scale uses available.

Learn more about how humanity has harnessed the power of water on this episode of Everything Everywhere Daily. This episode is sponsored by Mint Mobile. I don't know about you, but I like to know where my money is going. The problem is that big mobile companies like money too.

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I've gone over the history of many different technologies and inventions over the course of this podcast. And a common theme with many of these inventions is that they usually have an origin that traces back about 3,000 years or more, and more often than not, it started in China. In the case of hydropower, as you'll see, that doesn't quite apply.

The very first evidence we have of water engineering dates back to around 4000 BC, when the Mesopotamians and the 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 the water where they needed it 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, which can still be found in use in the world today, are called a shadduf. Lifting water was a hugely important problem in the ancient world. The Archimedes' screw, which is something you probably are familiar 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's called a noria. This seems odd because it's the exact opposite way water wheels are traditionally used.

human or animal energy was put into the wheel to raise water to a higher level. Well, it didn't take long after this that someone must have realized that if you just let it run unattended, that the flow of water in a stream or river would turn the wheel. And maybe you could use that rotational movement to actually do something. It was around the same time 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 millstone to grind grain. The water wheel and the grist stone were parallel to each other and didn't require converting vertical rotation into horizontal rotation or vice versa. Around the year 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 water wheel. At first, the wheel was just put into a stream and the flow of the stream would turn 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 time when it came to water wheels. One of the things that was figured out relatively 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 it's 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 then have it fall directly over the wheel. This led to the development of what are known as undershot, breastshot, and overshot wheels. And they simply refer to where the water was first touching the wheel, low, medium, or high. An overshot water wheel was the most efficient, with water falling right down from the very top of the wheel.

The Romans were not what you'd call a very inventive people. They didn't have a great track record of technical innovation. However, water wheels were one thing that they really did excel at. With it, they were able to create some truly innovative machines of that era.

The Barbigal 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. And 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 of the Greeks and Romans.

When the Roman Empire fell, waterwheel technology didn't disappear. It, in fact, expanded after the abolition of slavery when brute human labor couldn't be used. Waterwheel technology spread across Europe, the Middle East, and Asia, becoming a crucial energy source in medieval economies. By the 11th century, waterwheels were quite common all across Europe.

In 1086, the Dom's Day 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 any location with a suitable head for a water wheel became a prime location for monasteries and mills. While water wheels spread geographically, it wasn't really until the Renaissance that there were significant technical advancements in water wheels.

Leonardo da Vinci sketched designs for improved waterwheels and gears. And as with most of his inventions, they never got beyond his notebook. However, the idea of adding gears to mills was a powerful one that did catch on. Advances in gearing mechanisms allowed waterwheels to be used for more than just grinding grain. They allowed for water to power hammer mills for metalworking, fulling wheels for textiles, and paper mills for producing paper.

Water wheels were used to power bellows for furnaces and pumps to drain mines. 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 where 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. Today, if you visit the Isle of Man, you can see the Great Laxley Wheel. The Great Laxley Wheel is a massive water wheel built in 1854 to pump water from the Great Laxley 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 maximum speed of 3 revolutions per minute. Just when it looked like the steam engine might forever displace hydropower, in the 19th century a new invention gave it new life, the water turbine.

Unlike traditional water wheels, which relied on direct impact, turbines used curved blades to effectively harness both the speed and head of flowing water. The first practical water turbine was developed in 1827 by Benoit Forneron, 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 for high-head, low-flow situations, and the Kaplan turbine in 1913 for low-head, high-flow conditions. Turbines were now starting to reach efficiencies over 90% in the late 19th century. Of course, the water turbine proved to be great for the next 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 really wasn't 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 very first hydroelectric plant is less than a mile from where I'm recording this very episode. That first hydroelectric plant had an output of 12.5 kilowatts.

And there's a hydroelectric plant right outside my window right now, which is pretty small, that has an output of 525 kilowatts. And to put that into perspective, the largest hydroelectric facility in the world, the Three Gorges Dam, has an output of 22.5 gigawatts. 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 the 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 Antoine 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 still 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 tides went in or out. And 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's 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 that they do not require large reservoirs or significant environmental disruption. Despite being thousands of years old, we're 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 have a role in humanity's energy mix for centuries to come.

The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Austin Oakton and Cameron Kiefer. I want to thank everyone who supports the show over on Patreon. Your support helps make this podcast possible. I'd also like to thank all the members of the Everything Everywhere community who are active on the Facebook group and the Discord server. If you'd like to join in the discussion, there are links to both in the show notes. And as always, if you leave a review or send me a boostagram, you too can have it read on the show.