Problems with 'green' energy you may not have heard about

...in regions where homeowners have long rolled their eyes at shoveling driveways, add another cold-weather chore: cleaning off the solar panels. "At least I can get to them with a long pole and a squeegee," said Alan Stankevitz, a homeowner in southeast Minnesota.

In January 2007, a bus stalled in the middle of the night on Interstate 70 in the Colorado mountains. The culprit was a 20 percent biodiesel blend that congealed in the freezing weather, according to John Jones, the transit director for the bus line, Summit Stage.

Winter may pose even bigger safety hazards in the vicinity of wind turbines. Some observers say the machines can hurl chunks of ice as they rotate.

"It's like you throw a plate out there and that plate breaks," said Ralph Brokaw, a cattle rancher in southeast Wyoming who has 69 wind turbines on his property. When his turbines ice up, he stays out of the way.

Operators of the electrical grid do not worry much about the seasonal swings, because the percentage of production from renewable energy is still so low - around 1 percent of the country's power comes from wind, and less from solar panels. ...

But as renewable energy becomes a bigger part of the nation's power mix, the seasonable variability could become more of a problem. Already, power developers are learning that they must make careful plans to avoid the worst impacts of ice and snow.