Illinois has been deregulated since 2002. You'd think after more than two decades, every commercial business in the state would have this figured out. You'd be wrong.

Here's what makes Illinois genuinely interesting — and genuinely tricky: the state is split between two completely different wholesale energy markets. If you don't understand that distinction, your procurement strategy is basically a coin flip.

Two Utilities, Two Markets

This is the single most important thing to know about Illinois energy:

• ComEd territory (northern IL, including Chicago): Operates within PJM Interconnection. You're subject to PJM capacity costs, PJM transmission rates, and PJM wholesale energy prices.
• Ameren Illinois territory (central and southern IL): Operates within MISO (Midcontinent Independent System Operator). Different capacity rules, different transmission pricing, and generally lower wholesale energy costs.

A manufacturer in Peoria faces fundamentally different cost drivers than a distribution center in suburban Chicago. Same state, different worlds. If someone gives you a one-size-fits-all Illinois energy strategy, run the other way.

ComEd Territory: PJM Dynamics

If you're in ComEd's service area, you need to understand one thing above all else: PJM capacity costs. These have been one of the biggest cost drivers in the region, and PJM's Reliability Pricing Model (RPM) auctions produce capacity prices that swing wildly year to year. One year it's manageable; the next, it's eating your lunch.

For ComEd-area commercial customers, capacity can represent 20-30% of total electric costs. Twenty to thirty percent! And yet most businesses never actively manage it. Your capacity obligation is tied to your Peak Load Contribution (PLC) — your metered demand during PJM's five highest system peak hours each summer. Reduce your consumption during those hours, and you directly cut your capacity costs for the following planning year. This is probably the highest-value strategy available to you, and most businesses have never heard of it.

The competitive market in ComEd territory is robust, with dozens of Alternative Retail Electric Suppliers (ARES) licensed by the Illinois Commerce Commission. The best procurement windows tend to be fall and winter months, when forward PJM prices usually sit near their lows.

Ameren Territory: MISO Dynamics

If you're in Ameren territory, you've got a different situation entirely. MISO's energy costs run generally lower than PJM's, thanks to significant wind generation and cheaper natural gas relative to eastern markets. Nice perk.

But don't get too comfortable. MISO's own capacity construct — the Planning Resource Auction (PRA) — operates differently than PJM's RPM, and it's introducing its own cost pressures as coal plants retire and the grid transition accelerates. The era of dirt-cheap MISO capacity is not guaranteed to last.

The competitive supplier market downstate is smaller than ComEd's. Fewer ARES providers, less competition. But here's the flip side: suppliers who do serve the Ameren market value the volume, which means businesses who bother with structured procurement can often secure better-than-market terms. Scarcity has its advantages — if you're willing to do the work.

The CEJA Factor

Now, let's talk about the elephant in the room. Illinois passed the Climate and Equitable Jobs Act (CEJA) in 2021 — one of the most aggressive clean energy laws in the country. It mandates 100% clean energy by 2050, phases out fossil fuel generation, and creates new renewable subsidies, all funded partly through your utility rates.

What does this mean for you as a commercial buyer? It's a mixed bag, honestly:

• Rising distribution charges: Renewable subsidies and grid modernization are flowing through distribution rates. You can't avoid these by switching suppliers. They're going up for everyone. Period.
• Renewable energy supply options: The growing renewable fleet means competitive suppliers can now offer green products at increasingly competitive prices. If you have ESG goals, Illinois is becoming one of the most cost-effective states to buy 100% renewable electricity. That's a genuine silver lining.
• Demand response value: More intermittent renewables means more complex grid management, which means more compensation for businesses that can flex their load. If you can shift or curtail when the grid needs help, people will pay you for it.

Natural Gas in Illinois

On the gas side, Illinois lets commercial customers choose their supplier through programs like Nicor Gas's Customer Select, Peoples Gas's Choices for You, North Shore Gas, and Ameren Illinois. The competitive gas market is active, with fixed, variable, and blended structures all available.

Illinois sits near major pipeline infrastructure and storage facilities, so basis differentials stay moderate. For businesses burning significant gas — restaurants, manufacturers, large commercial buildings — competitive procurement typically yields 10-15% savings over default utility rates. Not life-changing, but not nothing either. Especially when you multiply it across 12 months and multiple locations.

Our Advice for Illinois Businesses

Three things. First: know which wholesale market you're in. Seriously. A PJM strategy applied to a MISO account is a mistake, and vice versa. If your broker doesn't immediately ask whether you're ComEd or Ameren, get a new broker.

Second: stop ignoring non-supply costs. Capacity, transmission, and distribution charges collectively often exceed the supply component of your bill. And with CEJA pushing the clean energy transition, these costs are actively changing. If you're only focused on the energy rate per kWh, you're looking at less than half the picture.

Third: timing matters more in Illinois than in most states. PJM capacity auction results, MISO planning resource auction outcomes, seasonal gas price swings — these all create windows where forward prices are more favorable. Working with someone who watches these cycles means you're buying when the market favors buyers, not when your contract happens to expire.