We can harness the wind to provide energy for boats, farms, homes, and cities. In this article, we look at the device behind them all; wind turbines. We answer the question; “How do wind turbines work?” and examine the benefits of harnessing the kinetic energy of the wind.
There’s no definite way to pinpoint the first time humans used wind energy. As early as 3100 B.C., Egyptians plied the Nile River using crafts that trapped the power of the wind with cloth sails10. By 10th Century A.D., Persia (now Iran) used windmills to grind grain, water their farms, and overall boost their agricultural produce.
As human needs grew more sophisticated, innovators continued to develop new machines that could utilize energy from the wind. Such demands are evident throughout the history of wind energy in the designs of the English post mill and the Persian horizontal mill. Eventually, those designs were either dismissed or upgraded, until we arrived at the standard wind energy machines of today; wind turbines.
How do Wind Turbines Work?
A wind turbine is a device that converts the kinetic energy of the wind into electricity7. The standard wind turbine is fitted with rotor blades, similar to helicopter blades, to intercept the wind. Developers install these wind turbines on land or water bodies like oceans and lakes. When over water they’re referred to as offshore wind energy.
They are usually placed in locations with high winds and installed on tall posts or towers for better wind reach. The rotors are connected to generators either directly or through a gearbox. It’s in these generators that the conversion from kinetic to electrical energy occurs.
There are different types of wind turbines in operation today. However, there are three main types which you are likely to encounter.
Is wind power efficient?
Wind power efficiency refers to how much energy is derived from the wind passing over the turbines. It’s virtually impossible for wind turbines to be 100% efficient, which would mean that no wind passed through to the other side, as it was all converted into sustainable energy. As such most wind turbines are around 30-45% efficient.
Further. a commercial wind turbine is normally spinning and therefore generating renewable power 70-80% of the time.
Most Common Types of Modern Wind Turbines
Here’s a simple breakdown of the most common types of wind turbines:
1. Horizontal-axis wind turbine
- The most popular type of wind turbine. Also considered as the most efficient.
- Turbines consist of three blades and resemble a giant fan.
- Their towers are made from tubular steel and stand as high as 300 ft.
- Can deliver power ranging from 10kW to more than 4.5M.W.
- Solely used for electricity generation.
Horizontal-axis wind turbines use an Anemometer to measure the strength of the wind. You’ll probably recognise these as 3 cups that spin around a central shaft. With this data, modern turbines are managed from a central control room. Here they can adjust the pitch of the blades so that the turbine does not spin too fast in high winds, managing the rotational energy. Increasingly this process can be automated too using the data to correctly position the turbines.
Another motor is found in the shaft, that can turn the turbine to the optimal position to harness renewable energy from the wind as it changes direction.
2. Darrieus vertical-axis wind turbines
- Named after George Darrieus, a French inventor who designed the prototype.
- Steel blades are curved around the tower vertically.
- Does not depend on the direction of the wind, which makes it ideal for places with unpredictable weather.
- Usually needs the help of another power source, e.g. a generator working as a motor to start.
- Ideal for (sturdy) rooftops.
3. Savonius vertical-axis wind turbines
- Named after its Finnish inventor, Sigurd Johannes Savonius.
- Made with a center rotating shaft which consists of several aerofoils.
- Intercepts wind from any direction.
- Self-starting, i.e. it doesn’t need another power source.
- Typically constructed of steel.
Small Scale Wind Turbines
We’re used to seeing wind turbines as massive contraptions. However, there are smaller-scale wind turbines designed using the same techniques above. They’re for people and organizations that need to generate energy on a smaller scale or to power machines and crafts (such as boats).
A small wind turbine can produce a yearly average of 7800 kWh2. Some of them can be installed on sturdy rooftops, while others need a pole rooted in the ground (about 20 – 30ft high).
Large wind turbines, on the other hand, require specific conditions to be viable. They are usually set up en-mass to create what is known as a wind farm. This is a select onshore or offshore area developed specifically for the production of wind energy.
Wind Turbine Locations
Large, commercial wind turbines can only function at an optimum level when installed in a suitable environment8. Smaller turbines need a lot less wind. However to generate the optimal amount of energy they are best located in places that share similar features. Here are a few key features which are often considered:
Strong wind speed
For a large wind turbine to be economically viable, it is installed somewhere with a wind speed of at least 6-8 meters per second (m/s). This wind speed should ideally be consistent so that energy generation is not interrupted often. As such helping to ensure the turbine blades as spinning regularly. This is why many wind farms are located in remote locations where there are no buildings to disrupt the flow of wind.
Some of the best places are open plains, at the top of rounded hills, or coastlines. Offshore locations also provide a steady supply of wind, which is why we have wind farms at sea.
Road or ship access
Wind turbines, gearboxes, and additional equipment need constant maintenance. They have a lot of moving parts and handle extreme pressure regularly. Wind farms benefit from easy access so that maintenance teams can carry out their duties on time.
Also, many of the parts needed to fix large-scale commercial wind turbines are sizeable. A maintenance team will need access to carry them back and forth.
Wind turbines can be large, noisy, and unsightly. Residents often dispute the changes that wind turbines bring to their landscape9. The noise of moving turbines and consistent operations don’t help either. To avoid constant dispute with residents, a wind farm can benefit from being located in remote areas with low (or no) human population.
The ideal land for wind farms is not easy to come across. Government-backed wind farms make it significantly easier to secure the needed property. However, independent developers will have to find suitable areas and negotiate with the landowner(s).
A wind energy contract between the developer and landowner may last for up to 80 years5. Before signing the contract, both parties must also agree on how much construction and changes are allowed. The developer must gain all the rights needed to build and operate a fully-functional wind farm.
The Growth of Wind Energy as a Renewable Source
Since the prototype stage, wind turbine capacities are now significantly higher. The latest wind turbines can generate 100 times more energy than the early designs6. With these advancements, the cost of generating wind energy is also dropping (from $500 per megawatt-hour to $50). The main reason for this fast-paced advancement in wind energy is that it is one of the most promising types of renewable energy.
Wind energy sources naturally replenish themselves creating a clear renewable energy advantage. Regardless of how much we use, they can replace the portion depleted through natural reproduction or recurrence in a finite amount of time. We can use as much wind as possible to create electricity without reducing its future supply. Therefore, wind energy is renewable.
Some of the benefits of wind energy are:
Clean energy production
The process of generating power from wind is clean and non-polluting. This is unlike non-renewable sources (such as coal and oil) which require combustion, leading to pollution and greenhouse gases.
For many decades, countries had no choice but to depend on OPEC – Organization of the Petroleum Exporting Countries- and oil-producing countries for their energy needs. OPEC has the power to influence oil prices, and consequently, world economies. With renewable sources like wind energy, every country has the opportunity to generate its energy independently. For example, Denmark produced 41% of its electricity from wind energy in 2018.
As long as the earth’s natural processes continue to occur, we can always harmlessly generate energy. The wind is produced through the uneven heating of the sun’s surface and the earth’s rotation. Since we can’t deplete the sun or cause the earth to stop rotating, we’ll have enough wind for a long time.
With the world’s ongoing pivot to renewable energy, wind energy is one of the most reliable energy sources available. The top 10 countries, according to their installed wind power capacity11 (last data from 2018) are:
- China (211,312 MW)
- United States (96,665 MW)
- Germany (59,311 MW)
- India (35,129 MW)
- Spain (23,494 MW)
- United Kingdom (20,970 MW)
- France (15,309 MW)
- Brazil (14,707 MW)
- Canada (12,816 MW)
- Italy (9,958 MW)
Environmental Concerns Regarding Wind Turbines
While wind turbines are used to create renewable energy, they also pose a few risks to the environment. Some of these risks have been addressed in the past. Developers are continually making changes to the design and installation of wind turbines. However, there are still some environmental concerns to be taken into account when discussing the use of wind turbines.
Small Scale Wind Turbines
Output may not make up for the use of fossil energy during manufacturing
The annual average output of a small/micro wind turbine is 7800 kWh. Meanwhile, many of the manufacturing companies which produce turbines and other related equipment still operate on fossil fuel. The production of steel, which is the material used in making turbines, is an energy-consuming process.
There are still very few wind-powered factories, and the existing ones consume energy on a smaller scale. The factories which produce mini turbines contribute to both air pollution (greenhouse gases) and land pollution (transfer of metals such as chromium into the soil). When the output of these small turbines is compared to the environmental costs, some researchers argue that there’s a significant loss in value which we cannot ignore.
Large Commercial Wind Turbines:
Wind turbines are massive, often standing up to 328 ft. Some people consider them unappealing to the eyes or complain that these wind turbines disrupt the aesthetics. Often, residents can’t stand the change when their skylines are suddenly filled with huge metal constructions.
Large onshore and offshore wind farms pose threats to wildlife. One primary concern is birds and bats flying into rotors and being killed1. These turbines stand in their migration pathways, posing a risk to flying creatures.
There’s also the concern that offshore turbines construction and use generate a lot of underwater noise3. This represents a risk of hearing impairment in some marine mammals and a change in their migration patterns.
There have been several cases of boats and ships colliding with large wind turbines. These accidents usually happen at night when the captains may not see the structures until it is too late4. Such collisions happen too many times for comfort. Such events are a considerable threat to both the environment and human life.
While wind turbines may not cause air pollution, they are often responsible for noise pollution. Some wind turbines are very noisy and could inconvenience residents up to a mile away. In areas with high winds, they work almost non-stop, which means that the noise is constant.
Wind turbines are some of the most important inventions in the energy industry. How wind turbines work, their growth and their possibility for near-endless renewable energy have made wind energy one of the fastest-growing energy sources in the world. As explained above, wind turbines still pose some environmental concerns. However, both private and government organizations continue to work on improving the interaction between wind turbines and the environment.
- The History of Wind Energy
- Advantages and Disadvantages of Wind Energy
- The 10 Biggest Wind Farms in the World
- What is Offshore Wind Energy?
- Renewable Energy Trains and the Railways
- Uses of Renewable Energy in Daily Life
Sources & References:
|National Wind Coordinating Collaborative (2010). Wind Turbine Interactions with Birds, Bats, and their Habitats: A Summary of Research Results and Priority Questions.|
|Benjamin Greening, Adisa Azapagic. (2013). Environmental impacts of micro-wind turbines and their potential to contribute to UK climate change targets.|
|Madsen, Peter & Wahlberg, Magnus & Tougaard, Jakob & Lucke, Klaus & Tyack, Peter. (2006). Wind turbine underwater noise and marine mammals: Implications of current knowledge and data needs. Marine Ecology Progress Series. 309. 279-295. 10.3354/meps309279.|
|Biehl F., Lehmann E. (2006) Collisions of Ships with Offshore Wind Turbines: Calculation and Risk Evaluation. In: Köller J., Köppel J., Peters W. (eds) Offshore Wind Energy. Springer, Berlin, Heidelberg.|
|Curt Emanuel, Extension Educator, and Chad Martin, Renewable Energy Extension Specialist, Purdue University. A Landowner's Guide to Commercial Wind Energy Contracts.|
|American Institute of Physics. (2019). Growth of wind energy points to future challenges, promise. ScienceDaily.|
|Wagner, H.-J. (2017). Introduction to wind energy systems. EPJ Web of Conferences. 148. 00011. 10.1051/epjconf/201714800011.|
|Biswal, Dr. Gouranga & Shukla, Dr Soorya. (2015). Site Selection for Wind Farm Installation. INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN ELECTRICAL, ELECTRONICS, INSTRUMENTATION AND CONTROL ENGINEERING Vol. 3, Issue 8, August 2015. 3. 2321-2004. 10.17148/IJIREEICE.2015.3814.|
|Environmental Impacts of Wind Energy (2007). Chapter: 4 Impacts of Wind-Energy Development on Humans.|
|Pasqualetti, Martin & Righter, Robert & Gipe, Paul. (2004). History of Wind Energy.|
|GWEC | GLOBAL WIND REPORT 2018 (2019).|