Replacing aging wind farms in Europe with new turbines is preferable to extending project lifetimes due to the higher yield of the latest machines, industry group WindEurope said.

Some 14 GW of wind capacity in Europe is already more than 20 years old and, by 2030, the figure will have reached 78 GW, the trade group said in a Dec. 1 news release.

In relative terms, Denmark, Spain and Portugal have the oldest wind fleets, with their average turbine at over 12 years old. The potential for repowering — replacing older turbines with newer machines — is largest in Germany, with 17 GW now older than 15 years, WindEurope said.

Across Europe, 170 wind farms have already been repowered, over half of which are in Germany. The country has Europe's largest onshore wind fleet, and new projects have faced opposition from locals concerned about visual impact and wildlife protection.

Rebuilding existing projects with bigger machines is usually easier, with locals already used to the machines.

"In the midst of the energy crisis, repowering wind farms makes sense," said Nicolas Wolff, executive vice president and general manager of Canadian power producer Boralex Inc.'s European division. Boralex recently repowered a site in Somme, France, increasing its capacity by more than 50%.

"Given the positive environmental impact, the production gains from technological advancements, the extension of our engagement with territories accustomed to wind power and the rapid speed of deployment, wind farm repowering is a concrete response to the [French] government's stated aim of accelerating renewable energy production," Wolff said in a Nov. 21 statement.

Yet, repowered wind farms are still considered new projects and require many of the same administrative steps as a brand-new site.

The European Union wants to ease permitting bottlenecks for wind and solar projects, and as such has categorized renewables as being in the overriding public interest. In emergency legislation related to the energy crisis, the European Commission has set a maximum planning time limit of six months.

"Repowering is a win-win-win game," WindEurope CEO Giles Dickson said in a statement. "The oldest wind farms are usually on the best wind sites but have the least efficient turbines. Repowering them makes the best use of the sites. You can triple the output with 25% fewer turbines."

Countries that need to work harder on plans for repowering are Spain, Italy and Denmark, according to WindEurope.

Offshore wind repowering promising

Many wind farms today opt for lifetime extension instead of repowering, with the industry observing that turbines are often still in good shape after 20 years of operations.

Extensions are often done because legislative frameworks for repowering are not in place, WindEurope said. However, on average, repowering reduces the number of turbines in a wind farm by a quarter while increasing installed capacity by 2.7 times and tripling the electricity output, the trade group said.

WindEurope's repowering analysis focuses on onshore wind, with most offshore projects developed post-2000 and still operating with their original turbines. While the issue of repowering will become relevant for offshore wind, WindEurope has not yet produced data on the benefits, according to spokesperson Christoph Zipf.

"My feeling would, however, be that the business case for offshore wind repowering will be even more compelling, as the nameplate capacity difference between legacy turbines and modern ones is even bigger," Zipf said in an email.

Today's largest offshore wind turbines have a capacity of 15 MW, and can reach capacity factors of 50%, while the oldest models in the water are smaller than 4 MW.

"Repowering should be a no-brainer," said Alon Carmel, energy transition expert at PA Consulting. Because the oldest sites have good wind speeds and low environmental and social impacts, it will be "the logical next step for the industry," Carmel said Dec. 1.

Investors are also set to benefit, Carmel said. "Repowering enables them to significantly boost their returns by increasing energy yield and reducing operations and maintenance costs," the consultant said.

Even without repowering, the offshore wind sector is grappling with supply chain constraints, especially around the availability of vessels large enough to install the new generation of mega-turbines. "There will be a supply chain squeeze, and that will continue for a few years as the supply chain scales up," Carmel said.

Repowering is unlikely to take away those resources from new projects, however. "I actually think because of the timing it won't be so much of an issue," Carmel said.

Offshore wind farms will only start reaching their 20th anniversary en masse in about five years time, meaning the supply chain will have time to respond to the projected surge in demand, Carmel said.

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