The Illinois Commerce Commission approved a sustainable energy plan for Commonwealth Edison and Ameren that will lead to the state generating 8 percent of its electricity from renewable and generally non-polluting sources by 2013. That is roughly equal to the electrical output of three nuclear power plants.

"It's a step in the right direction toward Illinois becoming a leader in clean energy development, if Commonwealth Edison and Ameren live up to their agreements," said Howard Learner, executive director of the Environmental Law & Policy Center.

The idea of reaping more electricity from renewable sources such as methane recovered from landfills and wind turbines got a big push earlier this year from Gov. Rod Blagojevich. His plan was largely the one adopted by the ICC.

It calls for the state's electric utilities to acquire 2 percent of their electricity from renewable sources like wind, photovoltaic cells, crops grown for energy production and waste methane by the end of 2006. That is to grow gradually until it reaches 8 percent in 2013. The plan limits the cost to consumers.

ICC Commissioner Robert Lieberman was appointed earlier this year to study the idea of renewable energy.

"This plan begins to set Illinois on a path to lower energy bills," Lieberman said. "It's in everybody's interest to do it."

Wind turbines are key to the plan. Arrays of the turbines are expected to generate 75 percent of the 3,000-megawatt capacity in place seven years from now.

Several small wind farms are already located in Illinois, and a large project is planned for the area around Ellsworth, about a 25- minute drive east of Bloomington, where 243 wind turbines would be scattered over 50 square miles.

Backers of wind energy, and they include Lt. Gov. Pat Quinn, note that farmers can earn $3,000 to $5,000 a year in lease payments for each wind turbine located on their property.

Invenergy LLC, a Chicago-based energy company with a wind farm in Tennessee and others under construction in Montana, Idaho and Colorado, is interested in several sites in its home state.

"Illinois has lagged behind the rest of the U.S. as far as pushing forward on renewable energy," said Kevin Smith, senior vice president of Invenergy.

He said Invenergy could complete one or more projects in Illinois before the end of 2006, a key date for wind turbine energy.

Although their fuel is free, the 40-story-tall wind turbines are not financially viable without federal tax subsidies. Those subsidies are set to expire at the end of 2006, though backers in Congress have in the past repeatedly extended them.

ComEd and Ameren have agreed to the plan and are working on how to implement it.

ComEd no longer generates electricity, instead buying it from other companies or from its corporate sister at Exelon, which operates nuclear plants. So ComEd plans to buy electricity from renewable sources from other companies.

"We are going to go out and ask developers to bid," said Arlene Juracek, vice president of energy acquisition for ComEd. "We have developers who have been responding."

Although energy from wind turbines is non-polluting, the turbines' spinning blades and high towers can be lethal to avian life. It is important that wind turbines not be located too close to bodies of water, landfills or other features that attract large numbers of birds or bats.

"Before any project is built, they have to do a very serious assessment of what the bird mortality would be," said Rebecca Stanfield, director of the Illinois Public Interest Research Group.

Stanfield is a big supporter of wind energy, however, and she said Tuesday's decision will help Illinois catch up with the 18 states that have already mandated that utilities buy power from renewable sources.

While environmentalists were pleased by the plan, they remained a little wary about how ComEd will try to meet it. The utility is to file with the ICC next month, explaining how it will meet the goals.

"It's not clear what happens next if the utilities' proposals fall short," the Illinois Sierra Club said in a statement.