In the case of wind turbines, bigger is always better. The larger the radius (or diameter) of the rotor blades, the better “The more wind the blades can convert into torque, the more torque the hub’s electrical generators can generate. Higher torque equates to more horsepower. By increasing the diameter, not only can more power be extracted, but it can also be extracted more efficiently.
Turbine blades that are larger and longer have a higher aerodynamic efficiency. When a turbine generates more power, less energy is lost when it is transferred to the transmission system and then to the electrical generator. Wind energy businesses are being pushed to build larger rotor blades due to economies of scale.
Because of the way wind flows around the planet, wind turbines are likewise getting taller. Because air is viscous (like a very thin honey) and has a high density, “The wind velocity at higher altitudes can be many times higher than at ground level, if it sticks to the ground.
As a result, placing the turbine high in the sky, where there is more energy to collect, is favorable. Wind may be distorted by hilly terrain (such as a mountain ridge), prompting engineers to create wind turbines that are even taller to capture the wind. Because of the higher levels of wind energy accessible at sea, offshore wind turbines are often larger and taller.
Onshore turbines (which are most widespread in Australia) typically feature blades that are between 40 and 90 meters long. The average height of a tower is around 150 meters. Offshore wind turbines (those that are located at sea and are widespread in Europe) are significantly larger.
General Electric’s offshore 12-megawatt Haliade-X wind turbine has 107m blades and a total height of 260m, making it one of the world’s tallest wind turbine designs. The Centrepoint tower in Sydney, for example, is 309 meters tall.
If the Robbins Island turbines are truly erected to 270 meters, as the media has speculated, they will dwarf General Electric’s behemoths. I can’t say whether this is likely, but I imagine engineers will have to choose the optimal turbine given the current wind conditions and infrastructure.
Challenging heights
The search for bigger and taller turbines is fraught with engineering difficulties.
Longer blades are more flexible than shorter blades, allowing vibration to occur. Vibration impacts performance and diminishes the life of the blades and whatever they’re coupled to, such as the gearbox or generator, if it’s not regulated.
Turbine blades are continually being improved in terms of materials and manufacturing procedures in order to make them longer and more durable.
Taller turbines generate more power, putting more strain on the gearbox and transmission system, necessitating mechanical engineers to devise novel methods for turning the rising torque into electrical power. Stronger support towers and foundations are required for taller wind turbines. The list of difficulties is extensive.
As the number of turbines increases, so does the amount of noise they produce. The outer edge of the blades is the primary source of noise. As it travels past the trailing edge, turbulence created by the blade itself makes a “hissing sound.” When the blade cuts through atmospheric turbulence as it blows into the tower, it makes more noise.
Noise isn’t just about volume. The sound of one turbine’s blades moving through the highly turbulent air created by the upstream turbine will be quite loud if it is located in the wake of another.
The silent-flying owl employs serrated feathers to reduce noise, and these are now being employed to make noisy turbines quieter.
Of course, engineering difficulties aren’t the only factors to consider when constructing wind farms. As with any significant infrastructure project, environmental implications, noise, visual impacts, and other community issues must all be considered. Wind turbines, on the other hand, are one of the most cost-effective and technologically advanced kinds of renewable energy, and as the industrialized world grapples with climate change, we will see an increase in their use.
The Conversation has given permission to republish this article under a Creative Commons license. Read the full article here.
What is a wind turbine’s typical height?
According to EIA data on utility-scale energy generators, wind turbines in the United States have increased in both average height and capacity during the last decade. Wind turbine capacity is mostly determined by the length of the blades, and taller turbines can not only have longer blades, but also benefit from the better wind resources available at higher elevations.
In 2016, wind turbines surpassed hydropower as the renewable technology with the most installed producing capacity in the United States, accounting for 8% of operating electric generating capacity.
However, due to the differences in how wind and hydroelectric electricity generators work, hydropower still delivers more electricity than wind, accounting for 7% and 6% of total electricity generation in the United States, respectively, in 2016. According to the EIA’s latest Short-Term Energy Outlook, electricity generation from wind is not likely to surpass that from hydro in 2017 or 2018.
The largest turbines in the United States today have a producing capacity of 6 megawatts (MW). These turbines are part of the Block Island Wind Farm in Rhode Island, which is home to the United States’ only operational utility-scale offshore wind turbines. The Icebreaker Offshore Wind project on Lake Erie near Cleveland, Ohio, is set to go online in 2018, and the Coastal Virginia Offshore Wind project in Virginia is set to go online in 2021.
Texas has the largest onshore turbines in the US, each with a capacity of 4 MW. The Horse Hollow Wind Energy Center in Texas has 420 wind turbines spread out over 47,000 acres, making it one of the world’s largest wind farms. The project’s total energy generation capacity is at 735 MW.
Turbines are now significantly taller than they were in prior decades.
In the United States, the average height of wind turbines constructed since 2012 has been around 280 feet, or 80 meters. Before 2006, just a few wind turbines could reach a height of 280 feet.
Wind speed rises with height and in open locations where there are no windbreaks such as trees or buildings. The tops of smooth, rounded hills, broad plains and lakes, and mountain gaps that funnel and increase wind are all good places for wind turbines.
What is a typical wind turbine size?
What is the size of a wind turbine? Onshore turbines are currently built in sizes ranging from 2.5 to 3 MW, with blades ranging from 50 to 60 meters in length.
What is the height of onshore wind turbines?
In any case, the goal is to keep making turbines bigger and bigger. When it comes to land-based (onshore) turbines, there are a number of non-technical issues to consider, such as transportation and infrastructure bottlenecks, land use difficulties, concerns about vistas, huge birds, shadows, and so on.
However, wind power is increasingly moving out to sea, particularly in Europe. And out in the middle of the ocean, where land is barely visible, the only restriction to size is engineering. As a result, offshore turbines are now growing at a higher rate than onshore turbines over the last decade.
In March of this year, a clear example of this pattern emerged (when I first published this story). GE Renewable Energy said that it will invest $400 million in the development of a new monster turbine called the Haliade-X, which will be the world’s biggest, tallest, and most powerful turbine (at least until the next big announcement).
It’s a remarkable engineering achievement, but the significance of increasing turbine size goes far beyond that. Turbines that are larger gather more energy and do so more consistently; the larger they are, the less variable and predictable they become, and the easier they are to integrate into the grid. On wholesale energy markets, wind is already outcompeting traditional sources. It won’t even be a competition after a few more generations of expansion.
What wind turbines are getting up to
Let’s start with some comparisons to get a sense of the size of this new GE turbine.
To gather the most up-to-date information on wind turbine sizes, I called Ben Hoen, a research scientist at Lawrence Berkeley National Laboratory. (He emphasizes that they are estimates.) In a few months, LBNL will provide a report on this, but he doesn’t expect the figures to alter much, if at all.)
In 2017, the average overall height (from base to tip) of an onshore US turbine was 142 meters, according to Hoen (466 feet). The median turbine height was at 152 meters (499 feet). In fact, according to Hoen, the median is getting close to the maximum. In other words, onshore wind turbines in the United States appear to be gradually approaching that height. Why? Because if you build higher than 499 feet, the FAA demands certain more steps in their clearance process, which most developers don’t seem to think is worth the trouble.
The Hancock Wind project in Hancock County, Maine, houses the world’s tallest onshore wind turbines. If you must know, thoseVestas V117-3.3s are roughly 574 feet tall.
So that’s all for the onshore. What about a trip to the islands? So far, the US has only one operational offshore wind farm, the Block Island Wind Farm off the coast of Rhode Island. Its turbines reach a height of about 590 feet.
How does the Haliade-X stack up against all of that? It will be 853 feet tall, according to GE.
That would be the world’s tallest wind turbine, as far as I’m aware. The previous record holder, as far as I can gather from searching (as I said, these things change frequently), is an 809-foot onshore turbine in Germany.
Bigger turbines mean more power, more often
However, height isn’t the only factor to consider. There are a few other accolades for the Haliade-X.
The whole sweep of the turbine’s blades is measured by the rotor diameter (the diameter of the circle they define). When all other factors are equal, a larger rotor diameter means the turbine can capture more wind.
According to Hoen, the average rotor diameter of US wind turbines was 367 feet in 2017. The rotor diameter of the Haliade-X will be 722 feet, which is almost double the average. The blades will be massive, measuring 351 feet in length each, longer than a football field and longer than any other offshore blade to date, according to GE.
The Haliade-X will have a very high capacity factor because to its huge rotor diameter, steady offshore wind, and 12MW turbine (onshore averages approximately 3MW; offshore around 6MW).
The following excerpt from the 2016 Wind Technologies Market Report by the Department of Energy illustrates how wind capacity factors have changed over time: “The average 2016 capacity factor for projects completed in 2014 and 2015 was 42.5 percent, compared to 32.1 percent for projects completed between 2004 and 2011, and just 25.4 percent for projects completed between 1998 and 2001.
In 2016, the nuclear fleet in the United States had an average capacity factor of roughly 92 percent. (Nuclear is only economically viable in today’s markets when it is used as a baseload generator.) Coal and natural gas accounted for 55 and 56 percent of the total. (Natural gas is so cheap because it is routinely ramped up and down to match demand swings.) Coal used to be close to 80 percent, but it is becoming increasingly uneconomic to operate coal plants.)
So, in the United States today, wind energy accounts for 42.5 percent of total energy consumption, whereas natural gas accounts for 56 percent. According to GE, the Haliade-X would have a capacity factor of 63 percent. That’s insane, even if it isn’t the highest in the world. The Hywind Scotland project’s floating offshore turbines recently reached a 65 percent completion rate.
When you add it all together, each Haliade-X turbine will produce roughly 67GWh annually at a “typical German North Sea site,” according to GE, “enough clean power for up to 16,000 people per turbine, and up to 1 million European households in a 750 MW windfarm configuration.” (It goes without saying that the number would be lower for energy-sipping American households.) That’s it “According to the business, the turbine produces 45 percent more electricity than any other offshore wind turbine now available.
In Rotterdam, the Netherlands, the first Haliade-X is now being built. In April, GE said that it would start producing electricity later this year.
Bigger turbines that run more often are going to crush all competitors
This 2015 piece by energy researcher Ramez Naam on the ultimate potential of wind power is one of my favorites. “Even at today’s price per kwh, wind at 60% capacity factor would be considerably more useful than it is currently, with fewer constraints to how much of it we might utilize,” he wrote.
- The more volatile a source is, the more backup is required to solidify and ensure its reliability. (At the moment, backup is mostly provided by natural gas plants, however batteries are becoming more common.) Higher capacity factors lower backup costs by making wind less variable and more reliable.
- Renewable energy that is variable (sun and wind) has a tendency to “eat its own lunch.” The next increment of capacity added lowers the clearing price for all the other increments since it all produces energy at the same time (when the sun shines or the wind blows). The lower the price, the more energy comes online at once. A turbine with a 60 percent capacity factor blunts and reduces this price-suppressing effect by dispersing its energy over a longer period (about twice the 32 percent of 2011-vintage turbines).
Although a capacity factor of 60% or more isn’t precisely “baseload,” it does appear to be less variable. Even if the price of wind energy remained constant, turbines like the Haliade-X would be more valuable.
It won’t stay the same, though; it’s down 65 percent since 2009. According to a recent NREL analysis, advancements in wind power technology (including larger turbines) could reduce it by another 50% by 2030. (University of Virginia researchers are working on a design for an offshore turbine that will be 1,640 feet taller than the Empire State Building.)
Assume that by 2025, new wind turbines in the United States have an average hub height of 460 feet, which is substantially in line with current forecasts. According to NREL research, such turbines may have capacity factors of 60 percent or higher across more than 750,000 square miles of US land and 50 percent or higher across 1.16 million square miles.
With expected developments in wind technology, that much wind, at that capacity factor, will create power cheap enough to demolish all competitors. And the year 2025 isn’t all that far away.
In feet, how tall is a wind turbine tower?
Industrial wind turbines are significantly larger than those found in a playground or behind a home.
For example, the widely used GE 1.5-megawatt model has 116-foot blades atop a 212-foot tower, for a total height of 328 feet. The blades cover just under an acre of vertical airspace.
On a 262-foot tower, the 1.8-megawatt Vestas V90 from Denmark has 148-foot blades (sweeping more than 1.5 acres) and a total height of 410 feet.
The 2-megawatt Gamesa G87 from Spain, with 143-ft blades (just under 1.5 acres) on a 256-ft tower, totaling 399 feet, is another model that is becoming increasingly popular in the United States.
In meters, how tall is a wind turbine tower?
Wind turbines come in a variety of sizes, from tiny micro turbines to massive utility-scale power plants. Large turbines may have blades that are more than 50 meters long, implying that the rotor diameter is greater than 100 meters (more than a football field)! Commercial-scale turbines are frequently mounted on 100-meter towers, with blade tips reaching up to 160 meters (525 feet) in the air.
Smaller turbines for the home or farm have rotor diameters of up to 15 meters (50 feet) and can be mounted on 30- to almost 50-meter towers.
What is the height of a wind turbine blade?
The blades can be as short as 4 feet and as long as 50 feet, and they can be mounted on a 165-foot (50-meter) tall metal lattice tower. These turbines can reach heights of 120-200 feet when one of the blades is standing straight up.
Where is the world’s largest wind turbine located?
At Siemens Gamesa’s test center in sterild, Denmark, the third and final 108-meter blade was placed on the SG 14-222 DD prototype offshore wind turbine.
