The Chicago Tribune reports that starting Jan. 1, all 411 Chicago city-owned buildings will transition to 100 percent renewable energy, a move that will reduce annual carbon dioxide emissions by 290,000 metric tons. This reduction is equivalent to removing 67,500 passenger vehicles from roads each year, according to the city’s Chief Sustainability Officer Angela Tovar.

The Tribune explains that the city has entered a five-year power purchase agreement with Constellation, marking the company’s largest municipal contract to date. Starting in 2025, 70 percent of the municipal buildings’ electricity will come from Double Black Diamond, a 4,100-acre solar farm in Sangamon and Morgan counties, which is the largest solar project east of the Mississippi River.

According to the newspaper, the remaining 30 percent will be sourced through renewable-energy certificates purchased by Constellation. While some critics view these certificates as potential “greenwashing” since they don’t guarantee local renewable energy generation, Tovar told the Chicago Tribune this approach was intentional to allow for future rooftop solar installations on city buildings. The Tribune reports that this transition affects public facilities including City Hall, Harold Washington Library, O’Hare and Midway airports, and local libraries. The agreement is expected to maintain stable utility bills with potential cost savings, according to Tovar’s statement to the paper.

The publication notes that Double Black Diamond’s construction created approximately 450 jobs and is projected to generate $100 million in new tax revenue for Sangamon and Morgan counties. Additionally, Constellation and Swift Current Energy have committed to annual donations of $400,000 to Chicago nonprofits supporting workforce development in the green economy.

The Tribune mentions that the city joins other cities like Houston and Burlington, Vt., in transitioning municipal buildings to renewable energy. The city initially sought to create a solar farm in Cook County, but land costs proved prohibitive. The paper notes that only half of Double Black Diamond’s power will go to Chicago’s municipal buildings, with the remainder contributing to Illinois’ clean-energy infrastructure. Cook County and Loyola University Chicago have already agreed to purchase some of this power.

Looking ahead, the Tribune reports that City Hall has committed to powering all buildings, not just municipal ones, with renewable energy by 2035. This transition represents a significant step in Chicago’s broader sustainability efforts, as detailed by Eric Lammers, CEO of Swift Current Energy, who told the paper that Double Black Diamond will serve as a roadmap for future clean energy initiatives.