Allete Clean Energy is growing.

Standing in front of a TV in the lobby of the company's Downtown Duluth headquarters, Allete Clean Energy President Allan S. Rudeck Jr. pointed on a map to the six operational wind farms acquired since 2011. With turbines already spinning in Minnesota, Iowa, Oregon and Pennsylvania, projects in North Dakota and Montana will be added to that map as they come online in 2019.

The company, founded by its parent company Allete in 2011, has expanded so dramatically, in part, because of a rising demand for emission-free, renewable energy.

"The customer wants clean energy," Rudeck said

It helps that the cost of wind energy continues to fall too. According to the Department of Energy's 2017 Wind Market Reports, wind turbines are becoming larger and more powerful while technology costs continue to decrease. A report in November by investment firm Lazard said energy from wind farms is cheaper than energy from traditional coal plants.

"I almost think it's pierced that floor where it's now the most attractive and least-cost energy depending on regions," Allete Clean Energy's Director of Business Development Wells McGiffert said, adding that solar is more economical in sunny areas of the U.S. like the Southwest.

With those factors working in its favor, the company has grown from four to 82 employees in under eight years, and can currently provide 540 megawatts of wind generation to its customers but expects that to jump to 720 megawatts when its next two wind farms are operational later this year.

"How we've done this is through acquisitions," Allete Clean Energy CFO Laura L. Schauer said.

The company's business model combines buying, then refurbishing, existing wind farms while selling power to other companies; building and operating new wind farms, selling the power to other companies; and building new wind farms that will then, as a whole, be sold to another company.

"We were born out of a utility, understand the utility construct, but to date, our customer base has really been other utilities," McGiffert said.

But Allete Clean Energy doesn't sell its power or completed wind farms to the utility companies owned by its parent company.

Although Allete also owns Superior Water Light and Power and Minnesota Power, Allete Clean Energy sells the power produced by its wind farms to other utilities companies, like Minneapolis-based Xcel Energy, while the wind farms it builds are sometimes then sold to other companies, like Montana-Dakota Utilities.

Selling power to a sister company like Minnesota Power would create creates additional regulatory hurdles, or, as General Counsel and Secretary and Director of Compliance Maggie Thickens said, "there are more steps to it."

"We can do business with Minnesota Power, but it's a very different kind of situation and we thought it was best to work across the nation, and that's what we've done," Thickens said.

For now, Allete Clean Energy is a wind-only company, but it's looking into solar, natural gas and energy storage, company officials said.

"I don't know that when we started, we would have expected us to have only wind at this point," Schauer said. "I think we would have expected more, and so we're working to have more in our portfolio."

Nevertheless, the company still tries to keep its existing wind-only portfolio diverse.

A nationwide approach helps ensure that if the wind isn't blowing in Minnesota or Iowa on a particular day, it might be in Oregon or Pennsylvania.

"We're looking for greater diversity of transmission, of customers, of wind - and more broadly, to help create a more durable revenue stream so we can give our dividends to shareholders so they're happy," Rudeck said.

While Allete's regulated utilities - Minnesota Power, Superior Water Light and Power and a stake in American Transmission Company - still make up 80 percent of the company's overall revenue, 46 percent of that is dependent from industrial customers.

If any of those mines, paper plants or refineries shut down, company-wide revenue falls, potentially leaving residential customers with a higher bill so the company can remain profitable.

For stability and continued growth, Allete is using its energy infrastructure and services companies - Allete Clean Energy, U.S. Water and BNI Energy - to provide the other 20 percent of revenue.

According to Rudeck, Allete Clean Energy is in "a double -digit growth phase," helping ensure parent company Allete continues to grow by 5 to 6 percent, even as the utilities' traditional industrial customers remain "fickle."

"We're growing like crazy," Rudeck said.