August 27, 2021

To Refit or Repower Aging Wind Farms?

by PowerHub Editor

Wind farm evolution has been nothing short of impressive in the last three decades. From innocent 50KW structures to mammoth 8MW machines, turbines have seen tremendous change in size, structure and strength. And as every change came in, it left a previously cherished fleet of turbines at the end of its life – waiting for a decision on its fate.  

End-of-life management is an important part of smart wind asset management. With a power generating life of 20 to 30 years, turbines that no longer meet performance standards have to be decommissioned. Unless, the great minds in wind have a better plan.  

Turns out, they do.  

According to the Global Energy Wind Council, there are 341,000 wind turbines around the world. And presently, about 65% of the turbine fleet in the United States is more than 10 years old. 

With many of these headed towards the 20-30 year mark, wind farm owners and developers aren’t quite ready to give up on them. They know it’s time. Time to make strategic decisions for at least 30,000 of those graceful, tall structures at aging wind farms. 

They’re exploring two possible options. Either refit old wind farms with upgrades or repower them with new turbines. Both these options are life extension strategies that, experts suggest, add productive years to the life of existing wind farms.  

Let’s discuss these options, their implications and the way wind farm developers are breathing life into aging turbines.  

Repowering Old Wind Farms with New Turbines  

Repowering wind farms has gained a lot of traction in the last few years. This strategy is seen as giving wind farms a whole new life. It includes a complete makeover of the turbines with the aim to generate more, or at least the same, power at existing sites.  

Repowering can be done in two ways, partially or fully. Partial repower is what most developers are interested in because it presents a financially viable solution. Such strategies target the blades, arguably the most important component in power generation.  

As the U.S. turbine fleet ages, each year, 8000 blades are being taken down across the nation. Developers invest considerable resources to bring down these old blades, and install bigger, lighter versions that have a great ‘sweeping’ power. The older counterparts are then either recycled or buried in municipal landfills.  

On the other hand, a full repower means taking down the turbine completely; blades, tower and all. Definitely a bigger investment. However, with most ideal wind farm locations already taken up, the cost of a full repower is quite justifiable.  

Oh, and since the best-in-class turbines are now installed, a developer will likely meet production targets with fewer units than before. And all this while he can take advantage of existing permits, PPAs and infrastructure. There you go, savings. Savings. Savings.  

Case in point: complete repowers have been a go-to strategy for most aging wind farms in California. Since the state was one of the early adopters of wind power, turbines installed before 1990s were taken down in favor of higher and mightier machines.   

More Power. Better Power. 

Many a times, a repowering strategy is implemented 10-15 years into a wind farm’s life. A number of factors come in play here. First, wind capacity factors – the average out of turbines – decline by 1.6% each year post installation. Hence, as these years go by, the output of a turbine may decline substantially, making a case for a repowering project.  

Second, this decision is partly governed by 10-year tax credit policies. Once expired, a wind portfolio may go through a hand-off for change in ownership. If the new stakeholders fancy new technology, wind farms are then repowered.  

Moreover, most manufacturers have an 8-20-year warranty on turbine components. Keeping the declining capacity factor in mind, developers often choose to repower before the end of life mark to avoid costly repairs.  

No mater what the reason, repowering aging wind farms is on the rise. According to the National Renewable Energy Laboratory, repowering investments will reach an all time high of $25 billion by 2030. 

Refitting Old Wind Farms with Upgrades  

Refitting is another life extension strategy that is less invasive than repowering. Developers who do not want to invest into a considerable makeover for a wind farm can choose to refit it with technological upgrades.  

Since these turbines have been functioning for a good 20-25 years, it’d be safe to say that a few upgrades would do them a world of good. It can make them function at an acceptable level of performance again, without the hefty price tag.  

So, what parts of the turbine are upgraded? Good question. Refitting a turbine is quite similar to upgrading the software on your computer. When you feel your machine would use a boost to enhance its speed and general functionality, you go about looking for technological advancements in the software space.  

Similarly, when wind farms are reaching the end of their useful life, or beginning to show signs of aging, they can be upgraded for better performance and load control. Most of these upgrades come in the form of better monitoring software. Programs that can help the turbine balance periods of high winds and high performance, with those of high equipment load.  

In essence, this balance really is the most important indicator of turbine wellbeing.  

When Refit Is The Way Forward 

There are instances when a wind farm owner or developer may not be able to repower a site, even if he’s willing to make the investment. Local land permits come into consideration here. Sites that have aesthetic value or very strict local regulations often prohibit installation of taller structures as part of wind asset management agreements.  

In such an instance, repowering a wind farm may be off the table. If this site has a favorable PPAs and wind conditions, refitting aging turbines is usually the only option. 

Moreover, refitting proponents argue that they see this strategy as an extension of their own management of the turbine, requiring little to no change on their part. Continuous and timely repairs and maintenance drills are a prominent part of wind asset management. So, when OEM executes refitting on a turbine to up its performance, the expectations remain the same.  

Implementing upgrades may be a wise strategy to save costs, but does it have an overall impact on performance? Most experts are tempted to say yes. They believe refitting instead of repowering may result in increasing maintenance costs. After 20 years of service, simply upgrading technology may not be the solution to the physical wear and tear experienced by these machines.  

According to proponents of this strategy, continuous and rigorous maintenance can battle this problem, all the while keeping capital costs low. However, this isn’t a sure shot answer simply because there are a lot of variables, decisions, stakeholders and natural factors involved. If refitting is what suits these conditions best, it’s a strategy worth a try.  

So, Where’s the Wind Blowing? 

So, do we refit or repower? Well, there isn’t a short and solid answer to this question. I know, it would’ve made life easy for wind farm asset managers, but it’s the truth. 

It’s safe to say that wind asset owners, developers and OEM teams will have a lot to think about over next few years. They’re taking mixed approaches to aging turbines, basing their decisions on a host of factors.  

What makes this decision even harder is the individuality of turbine history. Two turbines on the same farm may experience varying loads and maintenance cycles throughout their lives. Should they be treated the same way at end of their useful period?  

As they experiment with both options, we’ll soon have clear roadmap for aging wind farms. What is clear, though, is the fact that repowering and refitting mean well for local communities as well. Not only do they extend landowner’s leases, they also lead to job creation within the Operations & Maintenance sector.  

No doubt, extending the life of these powerful machines makes wind farms a truly renewable source of electric power.  

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