Greenwashing or The Truth: Chicago’s 100% Renewable Energy Milestone Explained

On January 3, 2025, the City of Chicago announced that it is now powering all city-owned buildings with 100% renewable energy sources, including facilities like the O’Hare and Midway Airports and the Harold Washington Library. The initiative will reduce Chicago’s carbon emissions by 290,000 metric tons annually, or the equivalent of removing 62,000 cars from the road.

Where the energy comes from: 70% of the renewable energy is generated by the Double Black Diamond solar project in Southern Illinois. The other 30% is procured using renewable energy credits (RECs).

Chicago is the first of the United States’ major cities to lay claim to this achievement, but how much of it is real progress by environmental standards? We explore the exact meaning behind Chicago’s 100% renewable energy figure and how it builds on Chicago’s sustainability objectives.

Is all of Chicago being powered by renewables?

100% of municipal buildings under the City of Chicago’s jurisdiction, including libraries, police stations, and city hall, are powered by renewable energy. This does not include facilities like Chicago’s 7,000+ restaurants or 1.3 million housing units.

Where is Chicago getting the renewable energy from?

70% of the energy powering Chicago’s municipal buildings comes from the Double Black Diamond Solar farm in central Illinois. The solar project began in 2017 under former Chicago Mayor Rahm Emanuel, and each mayor since has collaborated with local project developers and energy suppliers to strike a deal where about half of the solar project’s energy is purchased by the city.

The relationship with Double Black Diamond Solar brings more than just environmental benefits to Chicago and Illinois residents. The outlook also favors the economy and job market, offering work opportunities during the construction of the project and engaging organizations like Chicago Women in Trades to offer free job training to women in construction and welding.

As far as the environmental benefits, however, claiming that 70% of Chicago’s facilities are directly powered by renewable energy can be misleading to those unfamiliar with the energy market. The energy from Double Black Diamond Solar does not go directly into the city, but is acquired through a Power Purchase Agreement.

What is a Power Purchase Agreement (PPA)?

Power Purchase Agreements (PPAs) are financial contracts between a customer and energy supplier. For an agreed-upon period at a fixed price, the customer will purchase the electric output of the solar farm while the solar developer handles operations and maintenance of the site.

Why PPAs are beneficial: price fluctuations in the energy market happen very frequently, which can pose risks for customers and energy suppliers alike. By entering a PPA structure, customers—like the City of Chicago—incur cost savings compared to traditional utility rates, and do not have to pay upfront capital costs to before reaping the benefits of the renewable energy project.

What PPAs don’t do: because PPAs are financial agreements, they do not physically dictate where energy is directed. The power is delivered to the broad electric grid based on demand. It is impossible to tell if the lights in Chicago, at any given time, are being powered by renewable energy, because once energy is generated—from coal, natural gas, solar or wind—it is all delivered to the grid in the same capacity.

What’s the alternative to a PPA? Realistically, PPAs are the only way large cities and corporations are able to utilize power generated by utility-scale energy projects. Our electricity grid is not sophisticated enough, nor would it be structurally efficient, to direct power from a specific energy source to a specific location. The only way the City of Chicago could lay claim to the physical delivery of renewable energy to its facilities would be if all buildings had their own renewable generation systems, like rooftop solar.

The bottom line: To the extent that PPAs financially support the operations and maintenance of clean energy projects and enable clean energy to be delivered to the electric grid, Chicago is doing its part to reduce 70% of its carbon emissions.

The other 30%: how do Renewable Energy Credits (RECs) work?

RECs are not a direct purchase of energy, but rather a certificate giving legal claim to the power generated by a renewable energy source.

The benefit of RECs: RECs can act as a signal to the energy market for increased demand for renewable energy projects. For businesses and other institutions, the main benefit of RECs is they offer the legal ability to claim their power is sourced from renewables.

What RECs don’t do: Unlike PPAs, renewable energy credits have nothing to do with new renewable power being added to the grid. For every megawatt of power that is added to a utility company’s generation capacity through clean energy projects, an REC is created for purchase. Therefore, having an REC is a claim to clean energy that is already part of the grid, and does not contribute to reduced carbon emissions.

The bottom line: RECs can be controversial because they allow entities to say they are powered by renewables, but they do not physically receive renewable energy nor does the purchase help to actually decarbonize the grid. No renewable energy is generated or financed by the purchase of RECs.

So, is Chicago really powered by 100% renewable energy?

Not entirely. Only the 400+ municipal buildings under the City of Chicago’s jurisdiction are included. And 30% of that energy is not energy at all, but a collection of RECs that allow the city to legally claim it is powered by renewable energy.

What’s important to remember: The electric grid is vastly interconnected, and once power is added to it you can no longer tell what kind of power plant the electricity was sourced from. So even though Chicago cannot say it is physically powered by just renewables, it can claim the next closest thing, which is that 70% of its energy consumption is covered by the purchase of power generated by the Double Black Diamond Solar project.

There’s still work to do: Angela Tovar, Chicago’s Chief Sustainability Officer, has acknowledged that RECs are not the endgame to Chicago being powered by 100% renewable energy. With a goal to be carbon-free by 2035, Tovar hopes that the purchases will encourage local renewable energy development and allow the city to bridge the REC gap.

Other resources: To learn more about what the City of Chicago is doing to reduce their carbon footprint and get involved yourself, check out their energy efficiency and renewable energy page.