Windmills are machines that harness wind energy to generate electricity. They’re considered one of the most sustainable and clean sources of energy available today.
Windmills are easy to construct and operate, providing a fun way for kids to learn about wind power firsthand.
Vertical Axis Windmills
Vertical axis wind turbines are becoming an increasingly popular type of windmill used to produce renewable electricity. These smaller machines boast major components closer to ground level than horizontal axis models, so maintenance workers don’t need to climb hundreds of feet up a tower for access.
These windmills are more cost-effective to construct than their horizontal counterparts, as well as having greater scalability – meaning they can be tailored to fit smaller spaces better.
VAWTs also boast higher power output than HAWTs, enabling wind farms to generate more energy. This is because the wind speeds up around each vertical axis turbine, increasing their capacity for producing power.
They offer lower maintenance costs than HAWT counterparts, making them a popular choice among wind developers. As such, they make perfect commercial applications and can even be utilized in offshore installations.
Furthermore, HAWTs feature a shorter design than their HAWT counterparts, making them ideal for wind farms that are clustered together. This increases the power generated by each turbine when placed in arrays.
Another reason they perform better is that they are designed for greater efficiency in high-speed wind flows. This is because they are less vulnerable to turbulence and aeroelasticity issues.
However, there are still some drawbacks to this type of turbine. For one thing, they do not start as readily as HAWTs and they also are less effective in strong winds.
Furthermore, HAWT windmills may not be as durable or reliable as their HAWT counterparts, leading to shorter lifespans and the inability to produce enough electricity as expected – thus why they are not used as frequently.
Vertical axis windmills are not as scalable as their HAWT counterparts, making them difficult to install on large roofs and harder to maintain since more parts must remain grounded for upkeep.
Horizontal Axis Windmills
Your choice of windmill has a major influence on its efficiency. If you live in an area with consistent winds, horizontal axis wind turbines are usually your best bet.
These turbines are highly efficient, capable of converting 40-50% of wind power into electricity. As the leading model in windmill research and development for decades, these mills have become widely used.
Horizontal-axis wind turbines feature their main rotor shaft and electrical generator at the top of a tower, oriented perpendicular to the wind. A gearbox converts the slow rotation of the rotor into faster rotation that can effectively drive an electrical generator.
Horizontal-axis wind turbines differ from vertical axis wind turbines in that their rotor is symmetrical, meaning the blades always catch the most favorable breeze, eliminating the need for artificial orienting.
The rotor of a wind turbine is specifically designed to capture more wind energy, enabling them to work in areas with reduced wind shear and higher energy yields. On average, they produce up to 34% more electricity than vertical-axis wind turbines.
However, they can be more expensive to operate than vertical axis wind turbines due to several issues. Firstly, the rotor is much heavier and requires a large tower for support; additionally, it needs to be pointed into the wind by means of a wind vane or other device.
Another drawback of this type of windmill is the extensive amount of time and money needed for installation. It typically requires a team of professional workers who spend months building the turbine and placing components inside its nacelle.
Maintenance on horizontal axis wind turbines can be particularly challenging due to their elevated location – often hundreds of feet off the ground. This is because key components like generator, gearbox, rotor, yaw system and other essential elements must all be serviced from above the tower.
Smock mills, also referred to as sloping tower mills, are an iconic type of windmill found throughout Europe; the Netherlands being particularly noted for their smock mills. Smock mills were most often employed for pumping and redistributing water but could also be built for other purposes.
Smockmills are composed of a wooden body sitting on top of a brick base to protect it from rot and support upright posts. The shape of these mills can range from an octagonal or hexagonal plan, constructed using slats or panels covered with horizontal weatherboarding.
Many smock mills were built during the 1650s and are mostly now abandoned; however, there are a few restored examples in England and USA. The oldest smock mill in Great Britain is Jack at Lacey Green near Princes Risborough (Chapter XII).
Nantucket Island’s Old Mill, built in 1746 and still operational today, serves as an example of a working smockmill. It has been restored multiple times and can now be visited as a tourist attraction.
Smockmills were invented long after post and tower mills became common in Europe, and soon became the most popular type of windmill worldwide. Smockmills boast a more robust body than post mills, which allows them to withstand wind more effectively. Plus, their rotating cap can be adjusted according to conditions for power generation – an essential feature in windy areas!
Smockmills may be costlier to construct than post or tower mills, but they also boast greater durability. As a result, smockmills are better protected from bad weather conditions and fires that could otherwise destroy other types of windmills.
Smockmills have long been a beloved export from the Netherlands to North America and Australia, as well as other countries bordering on the North Sea. The Netherlands is particularly renowned for its smock mills and their water management solutions.
Smock mills offer the benefits of both worlds – the efficiency of a windmill and the classic tower design. Although more costly to construct than tower mills, smock mills boast greater strength and longer life expectancies, making them popular in less wooded areas where building one was less costly than creating a tower.
Fan mills were a type of windmill popular during the 19th century. They were used for cleaning grain, which was essential in farming at that time. Early models were hand-powered and relied on wind power to separate grains from chaff, straw and dirt.
Fanning mills looked like miniature threshing machines, with a rotary fan moving air across sieves to separate lighter grains from heavier ones. Chaff and straw fell through holes in the sieves to a lower screen while heavier kernels stuck at the bottom were blown out via airlift.
Eventually, mills were upgraded with multiple layers of screens and an adjustable airblast into sieves that could be adjusted. This regulation was accomplished via an opening on the side of the machine which opened and closed with a handle attached to a toothed gear.
Power output regulation varies between machines and is dependent upon blade angle adjustment (also known as pitch control), turbine rotation speed, and wind speed. In some machines, yawing the blades vertically can be an efficient way to regulate power output.
For instance, one system designed in Western Australia involves gradually tilting the blades to align them with incoming wind. As they yaw, they present a small surface area to the wind which makes it easier for them to extract energy from it.
Therefore, this method of power output regulation can be more efficient than other approaches. It utilizes the rated power of the turbine to extract as much energy as possible.
The optimal control for a wind turbine is to maximize its energy capture in low, high and transition regions. In the first case, low wind speeds and low rated power force the turbine to extract maximum efficiency resulting in high energy capture and good power quality. Conversely, higher winds speeds and rated power cause the turbine to limit how much energy it can capture which reduces noise, rotor torque and overall gain.
Hi, I’m David. I’m an author of ManagEnergy.tv where we teach people how to save energy and money in their homes and businesses.
I’ve been a writer for most of my life and have always been interested in helping people learn new things. When I was younger, I would write short stories for my classmates and teach them how to do math problems.
I love traveling and have been lucky enough to visit some fantastic places around the world.