By LeventEryilmaz / Getty Images The city of Chicago has unveiled a program to power all of its public buildings with renewable energy, in the hope of driving down its carbon footprint. By 2025, Chicago’s city hall, libraries and airport will all run on electricity generated by wind or sun. The city of Chicago has unveiled a program to power all of its public buildings with renewable energy, in the hope of driving down its carbon footprint. By 2025, Chicago’s city hall, libraries and airport will all run on electricity generated by wind or sun. The mayor of Chicago, Lori Lightfoot, has announc…