All About Wind Power

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Podcast Transcript

For thousands of years, humans have been using the power of the wind to do useful work.

At first, the wind was just used for sailing ships, but eventually, the wind’s power was harnessed to do mundane tasks like milling grain and pumping water. 

Unlike many ancient energy sources, wind power is still used today, and it has become a major source of electrical generation.

Learn more about how humans conquered the wind and made it useful on this episode of Everything Everywhere Daily.

The wind is something that humans have dealt with for as long as there have been humans. 

Outside of perhaps drying meat and hides after a hunt, there is no evidence of paleolithic people doing anything to harness the power of the wind. 

The first real evidence we can find in the archeological record of humans using the wind goes about 7,000 years to ancient Egypt, where we found the earliest sailboats. 

The early sailboats were very simple, but they provided power to move up and down the Nile River and, later, along the coast of the Mediterranean Sea. 

About 5,000 years ago, we know that early Austronesian people used sails. These were the ancestors of the Polynesians and Micronesians, who probably originated from the island of Taiwan

Despite the existence of warships with teams of oarsmen propelling the vessel, usually for speed in combat, the sail was by far the most popular means of propulsion for thousands of years. 

Despite how popular and widespread sailing had become, there was shockingly little evidence for wind power being harnessed for anything else. 

The Babylonian king Hammurabi had reportedly planned or built a wind-powered water pump to power his irrigation network in the fertile crescent. If he did build it, it never caught on. 

Around 300 BC, the Persians were using wind to power grain mills. This is believed to be the first example in history of wind being used for such a purpose. 

The Persian windmills looked very odd if you are familiar with modern windmills. They were horizontal, so they didn’t require gears to transmit the rotational energy in a different direction. It also didn’t use sails or vanes. 

The windmill was just a vertical wooden pole with horizontal poles sticking out of it. It would then the placed in a brick tower with an opening that would channel air into it. 

The lack of sails was rather astonishing, considering that sails were used on ships to catch the wind. 

One of the first people to build a practical device to run a machine is someone whose name has appeared on this show before: Hero of Alexandria. The same person who also created the first crude steam-powered device. 

He created a wind-powered organ that could play music. As with his steam engine, it was more of a toy, but it did show that wind power could be harnessed to do something useful.

The Romans did almost nothing with wind power other than sailing ships. This seems rather odd given that they did a lot of grain milling and pressing of olives, both of which are tasks that use rotational energy. 

The best reason I’ve come across was that the Roman use of slave labor stunted their technological development. They probably could have developed windmills, but why bother when you can just throw cheap human labor at a problem? 

The first widespread use of wind didn’t really develop until around the 8th century in what is today Iran and Afghanistan. They created a better version of the Babylonian horizontal windmill but used it to pump water. These horizontal windpumps used sails to power the rotation of the main axle, vastly increasing their power compared to ancient versions.  

These Persian windpumps spread rapidly across the Islamic world and eventually to India and China. The rotational energy they created was easily adopted for milling grain as well. 

The horizontal windmill arrived in southern Spain around the early 11th century via the Caliphate of Corduba.

The horizontal windmill was simple, but it had serious problems. Given its orientation, there was a limit to how much wind it could catch. The wind would blow the blades or sails on one side and then would move into the wind on the other side. 

The next big innovation in windmill design was the vertical windmill. This is a windmill that looks like the windmills that you are familiar with. The blades all faced the wind and deliver much more energy than horizontal windmills.

The first vertical windmills appeared in the 12th century. The first known vertical windmill was in the village of Weedley in Yorkshire, England

This was a huge improvement in windmill design, so much so that it has persisted for almost 900 years. 

However, there was still a problem. It worked great if the wind happened to hit the blades head-on. But what if the wind changed directions and now was coming in from the side or even from behind?

The solution to this problem was the development of the post mill.

As the name suggested, the post mill had everything mounted on a single vertical pole. This allowed the entire apparatus to be rotated to always face the wind.  The farmer who operated the windmill would have to push a giant handle outside the windmill to turn it. 

You can still see post mills scattered around Europe today, and many of them are still functioning.

The post mill then led to the hollow post mill, where the center pole was hollow, and a drive shaft could be put inside. This allowed the windmill to turn and still move whatever machinery was attached to it at the bottom. 

The 13th century saw much of this innovation in windmills in Europe. This was the high technology of this period. 

Turning an entire windmill was still pretty inefficient, and it also limited the size of how big a windmill could be if you had to turn the entire edifice. 

This led to the creation of the tower windmill. If you’ve seen old windmills in Europe, this is the type they probably are. Tower windmills were built on masonry towers, allowing them to be much larger and taller than post windmills.

The key to the tower windmill was that only the top of the windmill, connected to the blades, had to rotate. That means a single person could move a much larger windmill and do it inside the tower regardless of weather conditions. 

Perhaps the biggest user of windmills in Europe was the Dutch. In fact, windmills were so ubiquitous in the Netherlands that they have become the country’s symbol. 

The reason for the extensive use of windmills by the Dutch was to pump water. A great deal of agricultural land in the Netherlands is below sea level. In order to keep the land productive, it has to be pumped almost constantly. 

This necessitated an extensive network of windmills to keep the fields, known as polders, from flooding. 

The Dutch also modified the tower windmill design and created what is known as a smock windmill. This is basically the same as a tower windmill, except above a short masonry foundation, everything is made of wood. This is to make the windmill lighter, so it didn’t sink into the very soft ground of the polder. 

If you are ever in the Netherlands and want to see how the Dutch windmill system operated, there is a historical site outside of Rotterdam called Kinderdjik. It is a UNESCO World Heritage site and is easily accessible via water taxi from the Rotterdam city center. 

This was pretty much the state of windmills entering the industrial revolution. A windmill was usually inferior to a water wheel simply because water flowed almost continuously, but they were still very common throughout Europe.

Peak windmill probably occurred around 1850, when there were 200,000 windmills in Europe and 500,000 waterwheels.

The development of the steam engine made the windmill mostly obsolete. Some places might have used them if they had them, but machines were far more powerful and efficient for whatever you wanted a windmill to do. 

There was still occasional windmill uses in remote areas. On the Great Plains in the United States, windmills would be set up to pump water for cattle. An estimated 6 million of these small windmills were installed across the United States.

However, just as machines rendered windmills obsolete, a new technology emerged. Electricity.

All you needed to do to create electricity was turn an electric dynamo. This was usually done with water or steam, but it could also be done with a windmill. 

The first windmill to generate electrical power was built in 1887 by Prof James Blyth of Anderson’s College of Glasgow, Scotland. He used his windmill to generate power for his cottage on the seashore.  He offered to power the street lights of the nearby village of Marykirk, Scotland, but the people there declined the offer as they thought electricity was the work of the devil. 

Throughout the 20th century, wind-powered electrical generation remained  niche. It was mostly used in places that couldn’t get access to the electrical grid. 

It wasn’t until 1941 that the first megawatt electrical windmill was built. It was erected on Grandpa’s Knob Mountain in Castleton, Vermont.

Unfortunately, it only operated for 1,100 hours before one of the blades broke. It was never fixed due to wartime rationing. It was to remain the largest electrical windmill in the world for 48 years. 

What really changed with wind-powered electrical generation was the OPEC embargo in the 1970s. Energy prices rose, and people began looking for cleaner energy alternatives. 

Moreover, technological changes also made wind power far more feasible than before. 

The key to creating cost-effective electricity from wind is scale. When it comes to wind, bigger is better. 

The reason why has to do with the area covered by a windmill versus the size of its blades. 

As a windmill turns, it is being turned by wind flowing through a circle the size of the rotating blades. If you remember back to your geometry courses, the area of a circle is pi times the radius squared. So for every increment a windmill blade increases in size, the power it can generate is roughly increased by the square of the length of the blade. 

The bigger a windmill gets, the more efficient it becomes. This is the exact same reason why it is always more cost-effective to buy the largest pizza possible. 

On top of the efficiencies of size, the higher up you go, the faster the wind usually is, so there is more energy to capture. 

The problem is that the bigger the windmill gets, the heavier it becomes. The angular velocity of the tips of the blades starts moving incredibly fast.  

Pretty much any metal is too heavy to use for the creation of massive windmill blades. 

The development of synthetic materials such as fiberglass and carbon fiber allowed for extremely large, strong, and lightweight windmill blades to be produced. 

The other big innovation was putting gearboxes in the turbines. Just like you would switch gears on your bicycles when going uphill, so too did gears allow for the windmill to adjust the speed of the turbine in different wind conditions. 

The critical factor in electrical generation from wind is obviously… wind. Not everywhere on Earth has an equal amount of wind. The Great Plains has an enormous amount of wind potential, which is why you will see so many wind turbines in states like Texas, Iowa, and North Dakota. 

Likewise, many coastal regions have a great deal of wind as well. This is behind the move to create offshore wind farms, which would be located, potentially, several miles from land.

With higher winds and no people, you can set up almost as many as you like. 

Electrical generation from wind has become big business. Today the global production of wind power is estimated to be over 600 gigawatts. The country that produces the most wind power is China, followed by the United States, Germany, India, and Spain. 

The world’s largest wind turbine, as of the time I am recording this, is the General Electric Haliade-X turbine outside of Rotterdam. It stands 260 meters or 853 feet tall and has blades that are 107 meters or 351 feet long. Each blade is longer than a football field.

It can produce, by itself, produces between 12 to 13.6 megawatts of electricity. 

Unlike solar power, the challenges for wind power are mostly engineering, not advances in material science. 

The big problem with wind power is the obvious one that has plagued it since its inception. The wind doesn’t always blow. 

When the wind is blowing, wind power actually works great. When it doesn’t blow, it doesn’t work at all. 

This is why, unless you can create an enormous amount of energy storage, wind power can only contribute to an electrical system and not run it entirely.

There are other issues facing wind power as well, including noise, birds that are killed by rotating blades, and disposal problems with blades that have been retired.

Nonetheless, the future of wind power looks good. More offshore wind farms are under development, there will soon be wind turbines that produce 17 megawatts of power, and the costs of wind power is projected to drop anywhere from a third to a half over the next 10 to 20 years. 

That isn’t even considering the high cost of alternatives like natural gas and oil. 

Wind power is one of the only ancient sources of power that is still regularly used today.  Through centuries of incremental improvements and innovations, the technology used to pump water in ancient Perisa is now used to provide electricity to people’s homes.