Doing more with less, with bigger wind turbines

Shell Energy has completed a re-powering and site redesign on the Brazos Wind Farm in West Texas, which is now producing more power with far less turbines.

By Paul MacDonald

When you look at re-powering an existing wind power project, sometimes there’s no grey involved—the case for doing the repowering can be very strong. That was the situation for Shell Energy and its decision to re-power and do a site redesign on the Brazos Wind Farm in West Texas.

Today, Brazos has 182 MW of renewable power generation capacity, enabling the wind farm to produce enough electricity to power approximately 67,000 homes vs. the 48,000 homes it powered previously.

So the project has achieved a 14 percent increase in energy generation capacity versus site capacity pre-repower—and it has been able to achieve that production number with 122 fewer turbines on-site.

Before the repower, the project was originally equipped with 160 1-MW turbines, totaling 160 MW. Post-repower upgrade, the site now uses 38 next-generation Nordex 5 MW turbines, increasing the capacity to 182.4 MW. When you look at it, the company is now able to produce more with a lot less—less turbines, that is.

And there were some learnings along the way.
Although Shell Energy is one of the largest energy companies in the world, and a player in renewable energy, this marked the first wind project re-powering the company had ever done—and it went very smoothly, reports Dana Herrera, General Manager of Renewable Asset Management at Shell Energy.

Herrera explained that Brazos Wind was built in 2003, and equipped with 160 Mitsubishi turbines, so it was about 20 years old when Shell started to look at repowering the project, which is about 280 miles west of Dallas.

“At that time, we were reaching the point where we had to make some decisions: do we spend the money to keep the turbines operating? The life of the turbines at that point is down to five years or less. So you start watching the productivity of the turbines decline, and the cost to maintain them increase.”

At that point, it’s clear a decision has to be made on what to do with the project.

“We knew that time was coming,” says Herrera. They factor in items like where power prices are now, where they are expected to go in the future, among many other considerations, in doing a re-power.

One of the major factors working in favor of a re-power is that you already have a site, and a connection to the grid—the latter can be extremely important these days.

A recent study by the Lawrence Berkeley National Laboratory shows the backlog of new power generation and energy storage seeking transmission connections across the U.S. grew again in 2023, with nearly 2,600 gigawatts (GW) of generation and storage capacity now actively seeking grid interconnection. That is one heck of a long queue, to connect to the grid.

“The beauty of a re-power is you already have that connection to the grid,” says Herrera. “A project is already there—it’s been approved and built.” The flip side of that, though, is you have to de-commission the existing turbines, to install the new turbines.

There will also be negotiations to get new landholder agreements, and increase the power generation of the existing project and its connection, but an already-built project is still miles ahead vs. a greenfield project, which can face years of review, development and construction.

“With Brazos, all of that has already been completed,” says Herrera. “You already have your relationships with the local government, the landowner relationships are in place—you really do have a big leg up in doing a re-power vs. a new wind power project. You are so much further along.” She added that the community support Brazos has had, and continues to have, was integral to the re-powering project, which spans 10,000 acres between Borden and Scurry counties in West Texas.

It can be difficult to pinpoint it on each project, but there is kind of a clear time window when to consider a wind project re-power. And once the decision is made, the process can begin quickly, says Herrera.

“You start looking at what the technology looks like now, what turbines are you going to use—I would say it takes a year or so to get everything planned out and in order.” They started work planning the Brazos re-power in 2022, and it was completed in December 2023.

It can vary from project to project, and there are variables such as the size and age of turbines, but Herrera said there can be tipping points when looking at doing a repowering.

	The cattle on the Brazos Wind Farm site now have new turbines as neighbors, in the form of 38 next-generation Nordex 5 MW turbines, increasing the project’s capacity to 182.4 MW. Before the repower, the project was originally equipped with 160 1-MW turbines, giving it a capacity of 160 MW.

It’s a broad and extensive review process, she says. “We are looking at a 40-year life for these turbines, so it’s not just a matter of yesterday the power price was not ok, and today it’s ok, in terms of deciding to repower a wind project.” Other considerations would be equipment techno-logy and equipment lifespan.

There have been significant advances in turbine technology since the first turbines were installed on Brazos in 2003. Since an important part of a turbine involves its technology, perhaps a rough comparison might be looking at what your computer could do 20 years ago vs. what it can do now. The new Nordex turbines, for example, feature enhanced remote monitoring and data generation. The new turbines also include optimized features like a high-speed gearbox and design modifications for better reliability and serviceability in areas with medium to strong winds. The turbines have increased efficiency from larger, 155 meter rotors, across more than a 200,000 square foot area, and taller hubs reaching up to 120 meters.

“There is a whole new level of technology that we now have in place on Brazos compared to what we had before,” said Herrera. “There is also a lot of work behind all of this, looking at the features of the various turbines, and making sure it connects with what we already have at the facility.”

In terms of power, Herrera emphasized that the project went from 160 turbines to 38, and was still able to increase power generation by 14 percent.

Herrera noted that the decommissioning of the existing turbines is a project in itself. “We took out all those 160 turbines, and took that land down to its natural state. Landowners want their land returned to pristine condition for agricultural reasons, hunting reasons, so we went through that process with them.”

	The benefits of installing new turbines comes on the human side, too. The folks who do the maintenance now only have to maintain 38 turbines vs. 160, before the re-power. The new, larger turbines have more space for the service technicians, and are more ergonomically friendly, recognizing that the techs spend a fair bit of time doing servicing in the turbines’ nacelle spaces.

“When you are replacing a 1 MW
turbine with a 5 MW turbine, you can’t keep any of the original turbine infrastructures,” explains Herrera. “We can keep all of the power lines, a lot of the Balance of Plant, the interconnection, but because the turbines are being completely replaced, we had to remedy all the concrete bases.”

The benefits, though, of installing new turbines comes on the human side, too. “The folks who do the maintenance now only have to maintain 38 turbines vs. 160. Every time you climb a turbine, you have a safety risk, so we have been able to reduce that considerably.”

She noted that the older turbines had a climb assist system, that helped the service technicians climb the ladders. “Now we have something similar to an elevator in the new turbines, so it’s much safer.”

She added that there was very little space to manoeuver in the nacelles of the old turbines. The new, larger turbines have more space for the service technicians, and are more ergonomically friendly, recognizing that the techs spend a fair bit of time doing servicing in that nacelle space. “So it has a direct beneficial impact for the people who work on the turbines day in, day out,” she said.

She noted that in West Texas, temperatures can reach 120 degrees F., so the more efficient the work space, and the less time techs have to spend inside the turbine, the better.

“The turbine manufacturers make the turbines as reliable and maintenance free as possible, but turbines are still big, complicated and require maintenance—and that maintenance work has to be done—it’s not like putting off an oil change on your pick-up truck.”

When they are considering a repower, Shell’s extensive review process includes making sure that the grid operator, in this case the Electric Reliability Council of Texas (ERCOT), is fully in the loop with their plans. ERCOT depends on power from projects such as Brazos, and it will be without that power while the project is being re-powered.

The local community is also fully informed. “It’s eight truckloads to bring a single wind turbine to the site, so we are creating some traffic,” says Herrera. “We worked out agreements with the county.” Shell Energy arranged to repave a number of roads that were used to transport wind components.

As mentioned, Brazos actually marked the first time Shell Energy has done a re-powering of a wind project, but it went smoothly, says Herrera. Clearly, the company’s depth of experience and its resources helped to deliver a well-managed project.

“When Shell does any kind of major capital project like Brazos, there is so much research done on all the technical components, the permitting—there are a lot of people involved with a major project like this. All of it is worked out in great detail before we even break ground.”

Shell and all of its contractors were very safety conscious—at one point, when it looked like safety could become an issue on site, the company and its 200 contractors took a day, and went through a thorough safety review, and addressed the situation. “I have to give the contractors credit for doing that—they all committed to doing it immediately.”

In terms of major contractors, IEA did the turbines on the project, and Bianchi Electric was the high voltage contractor.

Of course the Brazos site has a good wind resource—Herrera said there are two to three months when the wind is particularly strong, and the turbines are able to produce more power.

The site is on top of what the company refers to as a “cap rock”, kind of a plateau. The wind can sweep up the side of the cap rock, and pack a punch. This actually caused some damage to turbines that were sited near the edge in the original project, so the turbines in the re-build were located further back from the edge.

In terms of the existing 160 turbines, Shell Energy contracted with a local company for the removal and repurposing of 2,100 tons of fiberglass from the decommissioned turbine blades. The material will be repurposed to support the creation of products for concrete, asphalt, composites, and/or bulk molding applications.

The process starts with a site assessment, which determines the best strategy for removing and decommissioning the wind turbines. From there, a team is brought in to disassemble the wind turbines, load them into large trucks, and transport them to a facility where components are either recycled or repurposed.

While doing a re-power certainly offers some advantages over a greenfield project, Herrera noted these projects, of course, still have their challenges—and sometimes they involve people, as in landowners. In parts of Texas, the land has been in the same family for generations, and landowners are very protective. Shell Energy’s approach is to involve the local people who will be working on the project in discussions with landowners. “We’ve been members of the community for 20 years and intend to be there for a long time,” she emphasizes. “That shows we care about them, about their land, and that there will be local folks around when the project is built, and to help keep it operating.”

Q4 2024