Either anti-coal activists in Boulder don't know that Governor Bill Ritter recently signed one of the nation's most aggressive renewable energy bills , or they want the rest of the state to know that even Boulder is burning plenty of dirty-ol', high-polluting coal. Several protesters assembled Sunday at a Boulder County Valmont Industries Incorporated coal plant run by Xcel, holding up a banner reading "RENEWABLES NOW" and two mock wind-turbines to symbolize clean energy, according to The Denver Post . "Boulder is ready to move forward with 100 percent renewable electricity. If Xcel is not willing to partner with the city to make this happen, then Boulder officials and citizens need to take our energy future into our own hands," protestor Tom Weis says. But authorities decided the protest got out of hand, and deputies arrested several activists, along with a photojournalist, according to The Daily Camera , which quotes Sheriff Joe Pelle as saying the event "was peaceful" and "everything was fine until they climbed over the fence." Xcel spokesman Mark Stutz says when protesters decided to get atop a coal pile, the event left the "realm of reasonable discussion and entered a world, quite frankly, of stupidity." Environmental journalist and activist Bill McKibben, in town to speak about his new book, "Eaarth: Making a Life on a Tough New Planet," says that these kinds of actions are needed around the world. McKibben, who was not arrested, is the founder of the 350.org  movement, which battles carbon dioxide emissions. "Keep this up, and keep the pressure on. It's starting to work, slowly but surely," he tells followers.