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Last week, the Port of Winona started receiving its most unusual cargo in recent history: 190-foot-long wind turbine blades strapped to the tops of barges with custom-designed holders. From a manufacturer in Brazil to a wind farm in the Dakotas, Winona is just one stop for the massive blades, and their journey requires feats of engineering all along the way.

Two cranes worked in tandem to offload the blades at a Riverview Drive dock and transfer them to specialized, oversized semi-tractors, which trucked the turbine parts down Riverview Drive to a staging yard on Theurer Boulevard. The super-long trucks include rear-wheel steering to help them make corners, and escort drivers temporarily stopped traffic on Pelzer Street to allow the trucks to make the corner at Pelzer Street and Theurer Boulevard.

As of last Thursday, Thomson Silvers of the shipping company Central Oceans said his crew and local contractors from Winona’s CD Corporation had offloaded around 19 blades. That left just 384 to go.

“We ran into some delays due to the flooding,” Silvers said. Central Oceans had hoped to start offloading the blades in June and finish before the city begins repaving Riverview Drive in late August, but persistent flood waters prevented barge shipping on the Mississippi River until this month. “All the barges this year have been affected by that. That delayed us by about a month … Unfortunately, it was something that was outside of everybody’s control,” he said. Silvers expected the final blades to be offloaded in November and outgoing truck shipments to continue leaving Winona through the end of the year.

The city plans to keep one lane of traffic open on Riverview Drive during the paving project, and Silvers said his team should be able to continue operating during construction. Needless to say, Winonans may want to avoid Riverview Drive once construction begins.

The gargantuan blades were manufactured in Brazil, shipped on ocean-going vessels to the Port of New Orleans, and transferred to barges for their voyage up the Mississippi River to Winona. From Winona, trucks will deliver them to wind-energy projects in North and South Dakota, where developers are racing to build new wind turbines before federal tax credits expire.

Winona State University Professor of Composite Materials Engineering Fariborz Parsi was one of several Winonans taking snapshots of the massive blades being offloaded last week, but he has more appreciation than the average citizen for the challenge of building the blades. “People see these things going down the road and think, ‘What the heck is that?’ Well, people get educated right here and go all over the world and all over the country making products that are similar,” Parsi said.

One of Parsi’s former students works for one of the top turbine repair companies in the U.S., and his current pupils practice some of the same fiberglass manufacturing and design principles that are used to produce the turbine blades like the ones being shipped to Winona. Parsi held up a cross-sectional mock-up of a turbine blade outside his office on campus. It looked like an airplane wing. “It has the same shape because it has to produce lift,” he explained.

The massive size of those blades would make them very challenging to design and build, Parsi said. The blades are likely all one single piece, he stated. “You make a mistake and mess up these big parts … you have to either repair it onsite or scrap the whole thing,” he said. The manufacturer might use a fiberglass production technique called hand layup, where workers place fiberglass textiles and apply resin by hand, which is extremely labor intensive. Alternatively, Parsi explained, the blade maker might use the filament winding technique, where a machine resembling a lathe wraps fiberglass around a rotating piece. “But imagine the size,” Parsi said, showing off winding equipment at Winona State’s composite materials engineering lab large enough to produce baseball bats. “You’d need a huge machine.”

Every step of the way, there are engineering and logistical challenges to producing and delivering such large components, but the people developing solutions to those challenges are helping make renewable energy possible. “It’s kind of nice to know that composites are part of the solution for energy, too,” Parsi said.