Wind turbines can function in a wide range of wind speeds, from very light to very strong. They produce approximately 80% of the time, but not always at full capacity. They shut off in extremely high winds to prevent damage.
Is it possible for wind turbines to be excessively powerful?
Wind turbines will be spinning on a windy day, providing tons of nice clean energy. The Met Office issued a yellow weather warning for wind in Scotland in the summer of 2016. A few bridges were closed, and ferries were canceled, but it was the day that wind turbines supplied 100% of Scotland’s electricity.
However, when severe weather and high winds strike, turbines must occasionally be turned down. If there is too much energy in the wind, all modern wind turbines are set to immediately stop turning. Some will shut down if the average wind speed exceeds a given threshold for an extended period of time, while others will shut down after a particularly severe gust (something like 100mph).
Strong enough winds to stop the turbines – let alone all of them – are extremely rare in the United Kingdom. Every ten years, high winds affecting 40% or more of the UK’s turbines would occur for around one hour (pdf).
Turbines shut down for safety reasons; if the wind is too strong, it can put a lot of stress on the blades and gears inside the turbine, producing a lot of friction and long-term damage. When the wind is a little slower and safer, it’s far safer to have the turbines stop and then restart.
It’s also quite easy to predict, so the National Grid knows when there will be a lot of wind power generated and when they will have to turn off. As a result, they can readily plan for the change.
On windy days, turbines may also cease whirling if there is too much renewable energy being sent into the National Grid. Instead of many tiny generators feeding into the system, it was originally structured around a few centralised power stations. When it’s too windy and turbines are producing a lot of renewable energy, the grid operators order some wind turbines to shut down to avoid overloading the grid. The true issue is with the grid, which has to be modernized to handle a new smarter energy system. Wind turbines aren’t the problem; they’re just doing their job.
When it comes to wind turbines, how much wind is too much wind?
The wind turbine is automatically turned off when the anemometer measures wind speeds more than 55 mph (cut-out speed varies by turbine).
What are the maximum wind speeds that wind turbines can withstand?
From June 1st to November 30th, the Atlantic hurricane season is officially defined. Tropical storms that originate in the Atlantic are expected to hit the northeast during this time, bringing severe winds, storm surge, heavy rains, and rip currents1. So, how do these storms affect offshore wind turbines?
Hurricane Irene is wreaking havoc on New England, New York, and Toronto, Canada, as seen from space. (Photo courtesy of NASA/NOAA GOES Project)
Wind turbines, on the other hand, have an anemometer that measures the present wind speed. The turbine controller receives this information. Based on these wind speeds, the turbine controller operates cut-in and cut-out intervals. Wind turbines are only turned on when wind speeds reach 8 to 55 miles per hour (mph)2. The blades restart regular operation and continue to supply renewable energy to the grid after the anemometer measures speeds at or below the turbine’s cut-out speed.
Can the turbines be damaged by severe winds?
Strong winds this winter are helping to alleviate a short-term energy shortage across Europe caused by rising gas prices. According to the United Nations Intergovernmental Panel on Climate Change, severe wind storms are predicted to become more regular in Northern Europe as global temperatures rise.
Storm Dudley is expected to hit Scotland and Northern Ireland with severe winds on Wednesday afternoon, causing the Met Office to issue a warning that roads, railroads, and ferries may be closed, as well as power outages. Another low-pressure system, Storm Eunice, is due to hit the country on Friday, bringing wind gusts of up to 70 miles per hour with the potential for heavy rain and snow in the Midlands and north.
Northern Europe’s significant wind speeds, especially in the winter, make it an ideal location for wind turbine installation. Winds can damage the turbine if they reach a specific speed around 90 kilometers per hour (56 miles per hour). A turbine will automatically cease spinning when the wind becomes too strong to protect itself. As a result, wind turbines are unlikely to be operational in areas where the storm is the most violent.
DWD, Germany’s national forecaster, has issued level-two warnings for the whole country “In some areas, “hurricane-like” wind speeds might approach 120 kilometers per hour. Beginning Wednesday night and lasting into Thursday morning, the storm will blow in from the west, with the threat of further severe weather over the weekend.
A weather warning was also issued by France’s weather forecaster “Wednesday’s forecast calls for a “strong wind” from the southwest, with gusts up to 85 kilometers per hour. People should avoid travel in areas affected by severe gusts, and electricity and telephone connections can be expected to be disrupted, according to Meteo France.
On Wednesday, August 11, 2021, wind turbines near the RWE-operated Garzweiler lignite mine in Grevenbroich, Germany. Alex Kraus/Bloomberg/Alex Kraus/Bloomberg/Alex Kraus/Bloomberg/Alex Kraus/B
On windy days, why aren’t the wind turbines spinning?
Why don’t the turbines spin all of the time? The most common reason for turbines stopping to spin is that the wind is not blowing fast enough. To operate, most wind turbines require a sustained wind speed of 9 MPH or higher. Turbines will also be shut down for scheduled maintenance or repairs.
In a hurricane, what happens to wind turbines?
This post is part of a series on offshore wind technological issues in the United States that differ from those in other countries.
Offshore wind turbines on the Atlantic coast (and in the Gulf of Mexico) face a number of obstacles, including storms. The Energy Department is working on technologies to assist wind system designers in reducing the danger of offshore wind turbine systems in high-risk zones.
Although 13,000 megawatts of offshore wind have been deployed worldwide, the United States only has one commercial offshore wind farm in operation, as mentioned earlier in this blog series. The first blog explained that technology breakthroughs in floating foundations are required to make offshore wind economically viable in deep oceans off the shores of Maine and Hawaii in the United States.
This could be one of the reasons why the majority of near-term offshore wind development is being planned for the East Coast, from Massachusetts to North Carolina, where a large portion of offshore wind resources are shallow enough for fixed-bottom foundations. Offshore wind turbines on the Atlantic coast (as well as the Gulf of Mexico) have a different problem: storms, which we’ll discuss further below.
Irma and Maria, two recent hurricanes, wreaked havoc on infrastructure, particularly electrical infrastructure. When wind speeds exceed 55 miles per hour, wind turbines, whether land-based or offshore, have built-in mechanisms to lock and feather the blades (lowering the surface area pointing into the wind). In essence, the wind turbine is in use “It’s in “survival mode,” waiting for the storm to pass so it can resume electricity production safely.
Storms can be significantly more powerful off the coast. The turbine’s foundation must battle with enormous, violent waves in addition to the wind hitting it. Wind turbine engineers utilize models to determine how diverse stresses, such as winds and waves, will affect a wind turbine and its foundation. To estimate turbine loading in harsh situations, the models they utilize need to be modified further.
The National Renewable Energy Laboratory, which is part of the Energy Department, has historically financed research in this field (NREL). With the help of the University of Miami, NREL connected its existing wind turbine modeling software (named FAST) to the atmosphere-wave-ocean forecast model. It is used to conduct hurricane research and forecasting in order to develop a new hurricane model “Storm Environments with a Coupled Hydro-Aerodynamic Interface.” This tool aids wind system designers in reducing the danger of offshore wind turbine installations in high-risk zones.
In hurricane-prone areas of the United States, offshore wind developments have already been planned.
Indeed, one of the research priorities of a new DOE-funded offshore wind R&D consortium could be to better understand extreme metocean conditions, such as those experienced during hurricanes, in order to better predict potential failure modes of turbines operating in these areas, leading to the adoption of more robust engineering designs.
The twisted jacket foundation detailed in the previous blog in this series may be a promising design for hurricane-prone areas, despite the lack of data due to the small number of deployments. The oil and gas industry’s foundation weathered a direct strike from Hurricane Katrina (category 5) in 2005 and came out uninjured.
NREL built and analyzed a possible 500-megawatt offshore wind facility for deployment in 25-meter (over 80-foot) waters in the Gulf of Mexico as part of another DOE-funded study. A twisted jacket foundation from Keystone Engineering and a bespoke lightweight direct drive generator from Siemens were among the characteristics of this imagined wind farm.
Is it possible for a wind farm to withstand a hurricane?
As the offshore wind industry in the United States grows, more wind farms will be exposed to hurricanes throughout the country’s annual hurricane season. But how big of a threat do they pose?
Among the European companies trying to export their offshore wind development experience to North America are Iberdrola, rsted, and Statoil. However, there is one challenge that these businesses will be unfamiliar with in Europe: hurricanes.
Hurricanes’ threat to wind farms is a hot topic in the United States right now.
Hurricane Harvey, which hit the US mainland six months ago, was the first big hurricane to hit the US mainland in over a decade. Only one wind farm in Texas, E.On’s Papalote Creek complex, went offline, and it was due to transmission line damage rather than the turbines themselves.
However, as the North American offshore wind business grows, concerns have been expressed about what would happen offshore, where storms are more often, hurricane winds are stronger than onshore, and repairing a broken turbine is more difficult.
With this in mind, developers may be wondering how well current turbine technology stands up to extreme weather events that are rarely seen in Europe.
It’s fortunate that most US offshore wind farms are now planned in the northeast, given Hurricane Alley puts Florida and the southeastern states in the direct line of fire. Even still, as Hurricane Jose recently shown, the northeastern coastal states are not immune to the threat of extreme weather.
We also recall the devastation caused by Hurricane Sandy in New York in 2012. This hurricane caused an estimated $19 billion in economic losses in New York City and $33 billion across the state, in addition to flooding the subway system and closing the New York Stock Exchange for two days. Such occurrences don’t have to happen on a regular basis to be catastrophic.
This raises the question of what lessons may be learned from earlier hurricanes and other catastrophic weather occurrences if wind energy is introduced into US waterways.
To begin with, it isn’t always a terrible thing. Extreme weather can be used to create energy for wind farms. More wind implies more electricity production, but only up to a point: the turbine continues to create power until it reaches a cut-out speed, at which point it shuts down to avoid strain on the rotor.
When wind speeds exceed 55 miles per hour, both onshore and offshore wind farms have the ability to withstand category 3 storms, thanks to built-in mechanisms that lock and feather the blades, twisting them so they no longer catch the wind and rotate. The turbine resumes normal operation once the storm has passed.
When Hurricane Harvey reached the Texas coast, wind farms proved remarkably resilient: not only did they survive, but they mostly remained active throughout the storm.
What can we learn from Hurricane Harvey?
Nonetheless, according to post-Hurricane study, turbines need to be fine-tuned to cope with higher-strength winds. This is especially true when high wind speeds are combined with other factors: pressure from both the wind and the waves during a severe weather event, for example, could be problematic for offshore wind. Furthermore, if a project uses floating foundations, this adds another variable.
The University of Colorado published research into the limitations of existing turbine design in withstanding higher-strength winds in the aftermath of Hurricane Harvey. Current models, according to computer simulations, are unprepared for the worst-case scenario: a category 5 hurricane. This is due to the fact that present standards do not take into consideration a veer, which is a shift in wind direction across a vertical span.
Changes in wind direction between the rotor’s tip and hub caused a potentially harmful strain on the blade during the simulation. These findings may encourage manufacturers to improve existing turbine designs so that they may be utilized in hurricane-prone areas, or developers to look for other risk mitigation options, such as insurance.
The US Department of Energy is presently financing research into more durable designs to this purpose.
For example, a twisted jacket foundation similar to those used in the oil and gas industry could be utilized in offshore wind: one of these foundations survived a direct strike from Hurricane Katrina (category 5) in 2005. Overall, there is a growing case that developers can build wind projects even in storm-prone places, albeit the true test will come when any of these are put to the test.
Furthermore, some evidence suggests that wind power could even help reduce the impact of extreme weather events.
People on land could be protected from hurricanes by offshore turbines, according to a 2014 Stanford study: 78,000 huge wind turbines scattered across 35,000 square kilometers of ocean outside of New Orleans would have reduced Hurricane Katrina’s category 3 winds at impact by 129 to 158 kilometers per hour and 79 percent of the storm surge. This is due to turbines’ ability to absorb energy from the cyclone as it passes along their path, lowering the hurricane’s strength.
In some ways, the study is a bit ludicrous. According to a report released last week by WindEurope, there were 92 offshore wind farms in operation in 11 European countries at the end of 2017, with a total of 4,149 turbines. To reduce a category 5 hurricane to a category 3, New Orleans would require nearly 19 times the number of offshore turbines now in operation across Europe. However, it does demonstrate a principle.
Hurricane Sandy’s winds would have been decreased by 125 to 140 kph and the surge by up to 34% if the same group of turbines had been installed offshore of New York City.
The researchers also suggested that, unlike seawalls, this type of protection would be able to pay for itself through electricity generation.
However, this does not ring true to us. It is contingent on the turbine not shutting down in severe winds or being damaged by the hurricane before reaping the benefits of those winds. And I doubt many owners of offshore wind farms would see it as a financial benefit if they were forced to pay for the repair of a damaged offshore wind farm. But let’s get on with it.
In any case, this is a topic that developers, producers, and researchers are finally interested in.
As wind energy grows in popularity across North America and in its oceans, there is an opportunity to develop technology so that wind turbines can withstand whatever the US hurricane season throws at them.
Is it possible for windmills to resist hurricanes?
Offshore wind farms are fast growing in popularity. According to a new study published in Geophysical Research Letters that predicts the worst-case scenarios generated by category-5 storms, most wind turbines are not equipped to withstand a direct hit from the worst hurricanes.
Is there enough wind for a turbine in my area?
To start generating, a conventional turbine needs wind speeds of around 10 miles (15 kilometers) per hour. The cut-in speed of a wind turbine is defined as the minimal wind velocity. To achieve the optimum results, a wind turbine should be installed in a location where the wind speed is consistently higher than the minimum cut-in speed before power is generated. Winds, on the other hand, are three-dimensional, and their features are heavily influenced by their elevation above and over the earth.
If you reside in a low-wind environment, you may need turbine blades with a larger surface area, which can be achieved by using several blades. The majority of commercial wind turbines have three blades, but employing a rotor with more than three blades will help catch more wind energy. However, increasing the blade’s surface area will increase the blade’s drag in the air at higher speeds, resulting in a substantially slower start-up or cut-in speed. Low-wind locations gain the most from multi-blade designs.
The three-bladed Popsport wind generator, which generates 12 or 24 volts from its light and strong 400W DC generator, is one of the most frequent low-wind-speed turbine designs, making this wind generator kit perfect for home use.
