How Long do Wind Turbines Last?

The wind is infinite, but the lifespan of a wind turbine is very much finite. The materials they’re made of won’t last forever, and they’ll eventually need to be replaced. But how long do turbines really last? As the first wave of wind turbines is decommissioned, the question is becoming more relevant. Wind energy has exploded over the last ten years, and while turbines might seem like a permanent fixture on the landscape, eventually they’re going to have to come down. Entire communities have become dependent on wind for their energy needs, so it’s important to know just how long they will remain reliable alternative energy sources. While we’re familiar with the lifespan of other renewables, like solar panels, the question of how long a wind turbine will remain functional is one that has yet to be fully answered.

Life Expectancy of a Wind Turbine

Wind turbines are made to last between 20 and 30 years. Within its few decades of operation, a wind turbine will need to have some of its parts replaced, namely the gearbox and the blades.

Any object with moving parts will experience some wear and tear. It’s just like your car. While the paint might stay shiny for years on end, the engine will start to have mechanical issues early on. It’s the same for wind turbines. The gearbox will require the most maintenance and will have to be replaced after about ten years or so. The bearings of the gearbox are especially notorious for damage. Since they’re always moving, sometimes at great speeds, they tend to wear out pretty quickly.

The blades of a wind turbine may also need replacement. The blades may become delaminated, develop cracks, or become eroded on the leading edge. Blade speed often exceeds 100 mph at the tip, so everyday airborne objects like dust, dirt, and insects have a compounding effect on the blade’s surface over time. The least costly option is to repair the blade, but if the damage is severe enough, then it must be replaced. As it stands, the materials with which wind turbine blades are made are unfortunately non-recyclable.

All of this factors into the overall life of a wind turbine. Turbines that are properly maintained and occasionally have their parts replaced will last a full 25 to 30 years. But if the operators fall behind on maintenance, the turbines may face an early death. This is especially true for wind farms in harsh environments, such as those out at sea (whose replacement is much costlier, due to their geography).

Dangers to Wind Turbines

Turbines harness energy from the wind, which is nice when it’s breezy, but strong storms can pose a danger to wind energy infrastructure. Luckily, wind turbines are equipped to face the wrath of strong winds. For most turbines, 55 miles per hour is the cut-off, after which they go into a sort of “survival mode.” When the anemometer picks up high wind speeds, the rotor shuts down to prevent damage to the blades and gearbox. The blades protect themselves further by feathering, or flattening themselves out, to reduce the surface area facing the strong winds. The yaw mechanism remains engaged so the turbine still faces the direction of the wind. It remains in shutdown mode until the storm passes, when the turbine resumes its normal operations.

Heavy storms also bring lightning. Wind turbines struck by lightning can take on some serious damage. The outer coating of a wind turbine, and the materials used to make the blades, carry some resistance to lightning, but repeated strikes can still cause microfractures. Hail can also be a problem, especially in the Great Plains of the US. Pellets of ice pelting the turbine for a prolonged period is sure to cause damage.

Microfractures cause structural issues when they go undetected for too long. The constant wear and tear causes them to expand. Water and moisture then find their way into the cracks causing a host of problems. The excess moisture can accelerate the degradation of the materials. Worse, the water can freeze in cold weather, forcing microfractures to expand further and putting the entire structure at risk of failure.

Fire is an often overlooked threat to turbines. The parts inside the nacelle can reach high temperatures, and short-circuiting electronics can create sparks that can cause the machinery in the nacelle to burst into flames. Keep in mind that, like the engine of a car, the gearbox needs oil to run smoothly. And just like motor oil, these oils are flammable. While the chance of a wind turbine bursting into flames is rather low, the possibility is still a very real one if the turbine isn’t properly maintained.

Offshore wind turbines are subject to even harsher environments. The salty ocean air causes faster erosion on the blades when compared to onshore turbines. The possibility of storm surges and large waves also poses a threat. Their large size and remote location also makes repairs difficult and more costly.

Assessing the Damage

Wind turbines are an expensive endeavour. While operations and maintenance costs are the cheapest expenses, they can still rack up pretty quickly. (Thankfully, wind turbines tend to pay for themselves well before they reach the end of their shelf-lives.)

It’s often the case that damage on the inner machinery like the gearbox and generator aren’t immediately visible, so engineers often spend valuable time and energy assessing possible issues. Because of this, they’ve come up with several methods to diagnose structural and mechanical problems within the turbine.

Mechanics and engineers have several different tools at their disposal to find potential issues. For the gearbox, workers might use visual inspections, stethoscopes, video endoscopes, or vibrational analyses to find mechanical flaws. This gives the engineers a multifaceted view of the conditions inside the gearbox.

When blades are damaged, it’s usually visible. But microfractures and internal weaknesses may go undetected. In these cases, engineers may use ultrasound or thermal imaging to get a peek at the inner structure of the blades. They may also employ digital shearography using lasers to scan the surface of the blade for cracks.

Catastrophic Failures

The worst-case scenario for a wind turbine is a complete failure of the structure. Wind turbines may fail for several reasons. Extreme weather can push turbines to their limit. Mechanical failures can cause fires or send the rotor spinning out of control. Incorrectly installed turbines have fallen right off their foundation. While it doesn’t happen often, wind energy experts have seen their fair share of failures. Wind turbines are constantly under a ton of stress, literally. Poor maintenance or bad engineering can end up taking a heavy toll, and in some cases, more than just the turbine is lost.

In 2019, a wind turbine in Washington State caught fire. The generator got too hot and caused the nacelle to burst into flames. At first, the fire was contained to the top of the turbine, but as parts of the turbine started to melt, burning pieces fell to the ground and ignited the grass. This started a wildfire, which was exacerbated by dry conditions and strong winds. Over 300 acres were burned. Luckily, no one was injured.

Unfortunately, sometimes lives are lost. A wind turbine that caught fire in the Netherlands killed two workers when it exploded into flames during routine maintenance. Because the turbine was so tall, firefighters were unable to reach the nacelle and save the workers.

One of the most dramatic failures took place in Hornslet, Denmark, in 2008. A combination of strong winds and a speed brake failure caused the rotors to spin out of control. When engineers saw that catastrophe was imminent, they evacuated the turbine and set up a massive perimeter. When the winds picked up, the rotor began spinning at breakneck speeds until the turbine exploded, destroying the structure and sending debris flying. The Hornslet incident is one of the only complete structural failures caught on video.

Wind Energy Waste

When a wind turbine reaches the end of its lifespan, it gets decommissioned. Currently, the first wave of wind turbines installed in the 1990s are at or near the end of their useful lives. While larger and more efficient turbines are taking their place, wind companies now have another question to answer; what are we going to do with all the old turbines?

Some parts of a wind turbine are recyclable. The tower and hub are made of steel and so can be melted down and repurposed. The components of the gearbox and generator can also be scrapped and reused. The real problem are the blades. The blades of a wind turbine are made of a composite material consisting of glass fiber and plastic resin. They aren’t easily broken down and recycled. This has created a massive waste problem in the wind industry.

Because wind energy is still new, there still isn’t a way to recycle or repurpose turbine blades. They don’t fit in landfills, and they’re too big for even the largest industrial compactors. For now, old blades are being stored in wind turbine “graveyards” across the Midwest. In Europe, a few creative companies have resorted to repurposing them as playgrounds, bridges, benches, or public art. But until a concrete solution is found, the turbine cemeteries will keep growing.

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Conclusion

Wind energy is becoming a larger part of the global energy portfolio, and while turbines appear to be monolithic and everlasting structures, they will eventually need to be replaced. After 20 to 30 years, wind turbines become a liability. Turbines erected in the 1990s are just now being decommissioned, and wind industry experts are better learning how to guard against mechanical issues and structural failures to help increase turbine lifespans. The problem of disposing of turbine blades is becoming a growing concern, as landfills aren’t big enough to handle the load. With wind power growing at an ever-increasing rate, now is the time to plan for the next generation of decommissioned turbines.