What’s Even Better Than Building New Wind Farms?

It’s not easy to build a wind project. Many of the best spots for generating wind power are already occupied by turbines. Even if you do find a good one, then comes everything else — inflation in the supply chain, convincing a local community that they want a wind farm near them, leasing the land, and so on and so forth. The whole process can take as long as five years.

But what about just making an existing wind farm … better.

This option, known as repowering, is becoming more attractive to wind developers and operators as existing wind assets age — operators get a more efficient wind farm, and developers get to avoid the many headaches of starting from scratch. The topic came up Tuesday, in fact, at the American Council on Renewable Energy’s 2024 Finance Forum. There are “some real opportunities for repower,” said David Giordano, BlackRock’s global head of climate infrastructure, on a panel about scaling capital to meet demand growth for renewables.

“When you repower a project, oftentimes you can utilize some of the existing infrastructure. And that means that you can add new equipment without the full cost of a greenfield development,” Eric Lantz, director of the Wind Energy Technologies Office at the Department of Energy, explained to me. When you install more modern equipment, he said, “you have higher hub heights, you have larger rotors — you can capture more energy from that site.”

Even if you tear down everything and rebuild from the ground up, Lantz told me, repowering still means you can use the existing transmission and interconnection, meaning developers can get more generation without having to deal with infamously long interconnection queues, which can impose yet more years on the energy development timeline.

Lantz collaborated on a 2020 research paper with a trio of Danish wind researchers (Denmark has one of the largest and most advanced wind power industries in the world) and found that from 2012 to 2019, 38% of all wind energy development projects in the country involved replacing old equipment as opposed to building on new sites. Repowering can be attractive to both developers and local communities, the researchers explained, because larger and more efficient turbines can actually reduce the net number of turbines on a given site while generating the same or even more power, with less visual disruption and less maintenance required.

Last year, Wood Mackenzie estimated that repowering onshore wind assets would lead to more installed capacity than new offshore wind in 2025 and 2026. In 2022, the U.S. repowered 1.7 gigawatts of wind plants, mostly by upgrading rotors (blades) and nacelle components like gearboxes and generators, upping their total capacity to 1.8 gigawatts, according to the Department of Energy. Average rotor diameter increased from 93 meters to 112 meters, adding on about the length of an 18-wheeler to the typical rotor.

Repowering has been a favored strategy of some of the biggest renewable developers, who have large and aging fleets of wind turbines that often already occupy prime spots. At the massive Shepherds Flat site in Oregon, for instance, Brookfield Renewable Partners replaced more than 300 turbines — i.e. over 900 blades — with new ones that were about 90 feet longer, upping the site’s total generation by some 20%.

At a proposed repowering in Southern California, Brookfield wants to replace around 450 turbines with just eight, while a New York repowering increased generation by almost 30% “while maintaining the same number of units to minimize ground disturbance,” the company said.

The rationale for repowering, like everything in energy, is a mixture of mechanical and financial. Over time, wind turbines tend to degrade, with actual power generation falling off. Even just by restoring a wind farm’s initial generating capacity, repowering can increase output, with newer, more advanced equipment, capacity can notably increase. And when renewable developers have to answer to investors, that cheaper generation can look quite attractive.

The energy developer NextEra plans to repower 1.4 gigawatts of its wind projects through 2026, the company’s chief financial officer said in an April earning call, and in January said that it had repowered a quarter of its existing 24 megawatts of wind. At that time, NextEra chief executive John Ketchum told analysts that the cost had been “roughly 50% to 80% of the cost of a new build and starting a new 10 years of production tax credits, resulting in attractive returns for shareholders.”

“With over a decade to potentially qualify for repowering,” he added, “it represents a great opportunity set.”

Looking at wind projects from before and after 2012, Scott Wilmot, an executive vice president at Enverus Intelligence Research, calculated that average capacity factor increased from around 30% to around 40%. “Swapping new equipment right off the bat, you can get a plus-10 percentage point gain on capacity factor,” he told me.

And then there’s the tax incentives. Repowering “resets” the production tax credit that’s the lifeblood of the wind industry, allowing owners and developers to claim it for another 10 years. When Enverus looked at a hypothetical project that had been operational since 2011 and repowered in 2023, it was possible that its production tax credit for an additional 10 years could increase from $22 per megawatt to almost $28. “It really does make the economics look quite attractive,” he told me.

“If you can get close to 10 percentage point capacity factor gain, you blow pretty much any greenfield, new build project out of the water.”