We can harness the wind to provide energy for boats, farms, homes, and cities. This article looks at the device behind them all; wind turbines. We answer the question, "How do wind turbines work?" and examine the benefits of harnessing the wind's kinetic energy.
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 wind power with cloth sails10. By the 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.
A wind turbine is a device that converts the wind's kinetic energy into mechanical power or electricity8. 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, we refer to them 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 and creates electricity.
There are different types of wind turbines in operation today. However, there are three main types that you are likely to encounter when exploring how a wind turbine works.
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, meaning 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 usually spinning, even in a gentle breeze, and therefore generates renewable power 70-80% of the time.
How much electricity a wind turbine generates depends on the blades' size, the wind's speed and consistency, and how efficient all their moving parts are. More modern large-scale turbines, for example, generate around 2-8 megawatts.
Here's a simple breakdown of the most common types of wind turbines:
Horizontal-axis wind turbines use an Anemometer to measure the strength of the wind. You'll probably recognize these as 3 cups that spin around a central shaft. With this data, modern producers manage turbines from a main 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 position the turbines correctly.
Another motor in the shaft can turn the turbine to the optimal position to harness renewable energy from the wind as it changes direction.
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 power machines and crafts (such as boats).
Small wind turbines can produce a yearly average of 7800 kWh2 and can often meet most of the electricity demand for a household. Usually, you'll find a single wind turbine installed on sturdy rooftops, while others need a pole rooted in the ground (about 20 - 30ft high) to reach the optimal wind flow.
Smaller installations have become more popular as wind technology has reduced costs and increased the generation capacity. Furthermore, in some countries, utilities pay for surplus electricity fed back into the power grid.
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 wind energy production.
Large, commercial wind turbines can only function at an optimum level when installed in a suitable environment7. Smaller turbines need a lot less wind. However, they are best located in places with similar features to generate the optimal amount of energy. Here are a few key features that considered:
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 and wind flows 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 with no buildings to disrupt wind flow.
Some of the best places are open plains, at the top of rounded hills, or coastlines. Offshore wind farm locations also provide a steady supply of wind, which is why we have wind farms at sea.
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 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, especially when turning in high wind speeds, and consistent operations don't help either. To avoid a constant dispute with residents, a wind farm can benefit from being located in remote areas with a low (or no) human population.
The ideal land for onshore wind farms is not easy to come across. Government-backed wind farms make it significantly easier to secure the needed property. However, independent developers must find suitable areas and negotiate with the landowner(s).
A wind energy contract between the developer and the landowner may last for up to 80 years6. 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.
Since the prototype stage, wind turbine capacities are now significantly higher. The latest wind turbines can generate 100 times more energy than the early designs5. 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:
The process of generating electricity from wind is clean and non-polluting. This is unlike non-renewable sources (such as coal and oil), which require combustion, leading to pollution, carbon dioxide emissions, and other 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 when the wind blows. 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. Uneven heating of the sun's surface and the earth's rotation produced wind. 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:
While we use wind turbines 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 considered when discussing the use of wind turbines.
The annual average output of a small/micro wind turbine is 7800 kWh. Meanwhile, many manufacturing companies that produce turbines and other related equipment still operate on fossil fuels. 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 comparing the output of these small turbines to the environmental costs, some researchers argue that there's a significant loss in value which we cannot ignore.
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. These turbines stand in their migration pathways, posing a risk to flying creatures. One primary concern is birds and bats flying into rotors and being killed1.
There's also the concern that offshore turbine 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.
Several cases of boats and ships colliding with large wind turbines have occurred. 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, as we've answered the question, how does a wind turbine work? 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.
|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.|
|American Institute of Physics. (2019). Growth of wind energy points to future challenges, promise. ScienceDaily.|
|Curt Emanuel, Extension Educator, and Chad Martin, Renewable Energy Extension Specialist, Purdue University. A Landowner's Guide to Commercial Wind Energy Contracts.|
|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.|
|Wagner, H.-J. (2017). Introduction to wind energy systems. EPJ Web of Conferences. 148. 00011. 10.1051/epjconf/201714800011.|
|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).