Top executives of Xcel Energy, long a national leader in wind power, said Thursday that they see further investment opportunities in wind farms, including acquisition of older projects whose electricity the utility now purchases under long-term agreements.

"It's a great deal," Ben Fowke, chief executive of the Minneapolis-based electric and gas utility, said about wind energy.

He and other executives spoke at a New York investment conference where the company released a five-year, $15.2 billion investment plan for the eight states where Xcel operates. The plan could grow by another $1.6 billion with various optional investments, officials said.

It calls for building generating plants and transmission lines, and upgrading other infrastructure.

Xcel officials told analysts that the federal Clean Power Plan's call for a 30 percent cut in power-sector carbon emissions by 2030 is driving investment in natural gas-burning power plants and renewable energy. Natural gas emits about half as much carbon as coal, which has long been the dominant fuel for electricity in the Midwest.

"The Clean Power Plan … is a great opportunity," said Chris Clark, president of Xcel's Upper Midwest operations serving 1.4 million electric customers in Minnesota, North Dakota and South Dakota.

In October, Xcel announced plans to accelerate Minnesota-region wind and solar power investments and eventually close two Becker, Minn., coal-burning generators, replacing them with a gas-fired unit in the mid-2020s. In April, Xcel burned the last coal at its Black Dog power plant in Burnsville.

The company aims for a 60 percent cut in the electric utility's Upper Midwest carbon-dioxide emissions by 2030, compared with 2005 levels — well beyond the Clean Power Plan requirements.

Fowke said the transition away from coal requires investment in natural gas generators and renewable power, especially wind energy, which he said offers a hedge against future increases in the price of natural gas. That's because the cost of wind power, when calculated on a kilowatt-hour basis over the life of a project, is less than the cost of fuel burned in a natural gas power plant, he has said.

He calls this approach "steel for fuel" — wind turbines (made with lots of steel) offset the burning of fuel in power plants. Fowke also said he wants Xcel to own a greater share of the wind farms on its system.

Xcel owns 11 percent of its wind power capacity, and purchases the rest under contract from renewable energy companies.

Xcel's acquisition of wind farms could benefit investors because utility-owned assets are part of its rate base, for which it gets a regulated rate of return. By contrast, the cost of purchased wind power gets passed through to Xcel customers at no profit to the utility. Fuel costs at power plants are passed through in the same way.

For utility customers, the ownership of the wind farm makes little difference because they pay for the electricity one way or another.

"If you do it right, you can grow the rate base, and not increase customer cost because you just reduce your use of gas," Fowke of the plan to buy out wind power-purchase agreements.

Under the steel-for-fuel strategy, "you won't see us getting overly dependent on natural gas in the future even as we transition away from coal," Fowke said. "The reason is that we are replacing it with renewables." Gas-burning plants will back up intermittent wind and solar, "but the reality is that those gas plants are not going to be used as much," he added.

Xcel, which has been crowned by a trade group as the nation's most wind-reliant utility for 11 years in a row, already is shifting toward greater wind farm ownership. In its four most recent wind farm deals in Minnesota and North Dakota, Xcel purchased three of the projects from the developers, and signed a power purchase deal on the fourth.

But Xcel has more than 50 wind farm power-purchase agreements in Minnesota, according to state data. Xcel officials offered no details on which projects are potential acquisition candidates, or whether Xcel wants to make such deals before power purchase agreements expire. They can run for 25 years, and any changes require state regulators' approval.

In Minnesota, Xcel got 14 percent of its electricity from wind in 2014, and plans to boost that ratio to 25 percent by 2030. That increase, along with its other renewable energy goals, will mean doubling its Minnesota-region wind and solar capacity over the next 15 years, Clark said.

David Shaffer • 612-673-7090 • @ShafferStrib