Talk about irony: As 37-mile-per-hour gusts blasted downtown Minneapolis on Thursday, hundreds of wind-energy executives were inside the Minneapolis Hilton, discussing the challenges their industry still faces.

Chief among those challenges: weather-related down times and - perhaps more surprisingly - utilities unwilling to accept energy from wind farms because their high-voltage transmission lines can't accept any more power.

"The grid won't handle it, and (utilities) have to refuse wind power," said Scott McBride, regional site manager for Texas-based Padoma Wind LLC.

The 90-minute turbine-performance session was part of a three-day Wind Resource and Project Energy Workshop at the Hilton, which was sponsored by the Washington, D.C.-based American Wind Energy Association (AWEA).

As the primary trade group and lobbying arm for the U.S. wind-energy industry, the AWEA has pushed hard for a mixture of tax incentives and energy mandates that would result in wind farms generating 20 percent of U.S. electricity by 2030.

The Lone Star State installed 8,000 megawatts of wind turbines in the last year, said McBride, but grid capacity situations caused many Texas wind farms to shut down their turbines about 2 percent of the time.

Including that 2 percent, the turbines' down-time totals up to 7.5 percent during a year, or about 27.4 generation days, McBride told professionals attending the turbine-performance workshop.

Particularly in Texas, a huge state that ranks No. 1 among wind energy-producing states with 8,361 megawatts of wind energy connected to the grid, Weather issues and time-consuming repairs to wind turbine gearboxes contribute to times when wind farms are not producing energy for electricity users. McBride said wind-energy developers should have crews available round-the-clock to repair damaged turbines.

Minnesota, the fourth-ranked wind-energy state, has 1,805 megawatts of wind power plugged into the grid and is home to Xcel Energy Inc., the nation's No. 1-ranked utility in wind power.

Geographically, Minnesota is a key piece in many plans to build high-voltage transmission lines, connecting wind energy generated from wind-rich North Dakota and South Dakota to Chicago, and from there to heavily populated Eastern markets.

While many wind farms in the North Star State use 1.5-megawatt General Electric turbines, the workhorse of the domestic turbine fleet, most wind farm developers prefer German-manufactured Siemens wind turbines if they can afford them because they are reliable and durable.

Ioannis Antoniou, a measurement engineer for Siemens Wind Power, outlined his company's efforts to maximize the amount of energy a wind turbine can generate during the turbine-performance session.

To capture more wind than they currently do, Antoniou recommended that U.S. wind-energy developers build higher meteorological, or "met" towers that measure wind speeds before developing a wind farm.

Seasonal variances in wind speed, power generation and differences between daytime and generally windier nights must be considered to get the most out of wind farms, he said.

Depending on the height of the met tower, the strongest winds in Minnesota usually are felt from November through April, with May through October serving as an extended time of lower wind speeds and opportunities to repair turbines.