CHICAGO -- Plants cool 3 million square feet of rooftops throughout the city. Wind, hydropower and biofuels provide one-fifth of its energy. And last year, the mayor announced one of the country's most ambitious plans to slash greenhouse-gas emissions.
So when Chicago promises to host the greenest Summer Olympics ever if it's awarded the 2016 games, organizers say it's not a gimmick. It's an extension of efforts that have been transforming this former Rust Belt city for years.
"We've got a real opportunity to take the best aspects of our city, the parks, the lakefront and the environmentalism and bring a real asset to the table," Chicago 2016 spokesman Patrick Sandusky said. "It's certainly one of the great strengths of the city of Chicago that we have to offer."
In Chicago's official Olympic bid book, released earlier this month, organizers tout a low-carbon "blue-green" event, with most venues along Lake Michigan, which is lined with parks, and a focus on environmentalism.
Organizers say vehicles provided by the games would run on low-carbon fuels or electricity and event sites would be powered by renewable energy. Storm water would be collected for reuse; the venues would use recyclable or reusable products. And sites would adhere to green building standards and coexist with natural habitat.
The other bid cities -- Madrid, Rio De Janeiro and Tokyo -- also are highlighting environment-friendly plans to the International Olympic Committee, which will choose the host city in October.
Madrid promises to promote bicycle use and Rio De Janeiro says 3 million trees would be planted in nearby rain forests to offset carbon emissions. Tokyo plans a zero-waste Olympics.
Though such plans are an important consideration for the IOC, it's more crucial for bid cities to have good organization for athletes, officials and the media and a strong financial plan, said A.D. Frazier, chief operating officer of the 1996 Summer Olympics in Atlanta.
Regardless of whether Chicago gets the Olympics, Mayor Richard M. Daley says he'll continue to focus on a goal he set a long time ago: to make his city the greenest in the United States.
"When I started planting trees they thought it was a waste of money," Daley said during an interview at his City Hall office. "We started planting a green roof. They said, 'Oh, this is silly. What are we doing that for?'"
The city's green-roof program, which helps cool buildings and slow storm water runoff, began about 10 years ago and now is the most extensive in the U.S. The city has planted thousands of trees and roadside plants, designated nearly 140 miles of bicycle lanes, and is buying hybrid buses and studying whether to designate bus-only lanes.
In September, city officials vowed to reduce emissions of carbon dioxide to three-fourths of 1990 levels by 2020 by making buildings more energy-efficient, using renewable energy, improving transportation and reducing industrial pollution.
Such efforts -- touted in the Olympic bid -- have put Chicago on the national environmental map.
"Years ago, Chicago could never have competed with Seattle, Portland or San Francisco with trying to be green," said Warren Karlenzig, author of "How Green is Your City?"
But Chicago still has a long way to go to match those cities, which frequently rank among the greenest in the U.S. because of successful recycling programs, high public transit ridership and use of renewable energy.
Chicago air quality, for example, still does not consistently meet federal standards. It was rated moderate or unhealthy near half the time by the Illinois Environmental Protection Agency for 2006, the latest numbers available.
Perhaps the biggest challenge to meeting long-term environmental goals -- and keeping its green Olympic promise -- is improving the city's troubled public transit system, said Howard Learner, president of the Environmental Law and Policy Center in Chicago.
Chicago's century-old subway tracks are so dilapidated in some stretches that trains sometimes must travel at the pace of a horse at trot, though the city is working to eliminate slow zones. The city also has added 113 hybrid buses and expects another 57 by late summer.
"As a practical matter you can't have a green city if you don't have an effective public transit system that works well," said Learner. "No first class public transit, no green city."
The IOC has cited problems with Chicago's transportation network. Daley rode Beijing's modern transit system when he attended last summer's Olympics and said Chicago needs to create the same safe, clean and friendly system.
Chicago officials acknowledge the challenges, but are undaunted.
"By no means are we perfect and we don't say that we are," said Suzanne Malec-McKenna, commissioner of the Chicago Department of the Environment. "I think that we're bold. I think we're willing to take risks and hopefully create a market to make it accessible to residents and businesses."
But make no mistake, Chicago wants the Olympics -- in a big way.
The international exposure would go a long way toward helping dispel the image of a pollution-belching factory town and replace it with a gleaming, modern -- and green -- metropolis.
"We want to make the greenest Olympics ever," said Sadhu Johnston, Chicago's chief environmental officer. "We think that makes sense in the greenest city."