Illinois Commercial Energy: Business Electricity & Natural Gas
Illinois is a competitive energy state: eligible businesses in most of the state can choose who supplies their electricity and natural gas, while the local utility continues to deliver it. This page explains how that works, who your utilities are, what actually drives a commercial bill, and where to start — with links to deeper guides for each step.
Start here
Most commercial energy decisions in Illinois come down to three things:
- Commercial electricity — how supply, delivery, and demand work, and what a quote requires.
- Commercial natural gas — territories, supplier choice, and pricing basics.
- How procurement works — the step-by-step process from usage data to a signed contract.
If you're not sure where to begin, start with what a commercial energy quote requires — it lists exactly what to gather.
How commercial energy choice works
Illinois opened electricity to competition under the 1997 Electric Service Customer Choice and Rate Relief Law, administered by the Illinois Commerce Commission. The key idea is a split bill:
- Delivery — the utility owns the wires and meter, delivers the power, and handles outages. This is regulated and stays with the utility.
- Supply — the electricity itself, which an eligible business can buy from a competitive supplier (an ARES) or from utility default service.
Choice applies to the supply portion only. That distinction matters, because applying a supply-price difference to the whole bill overstates any change. Natural gas works the same way in the territories that offer choice. For a plain walkthrough, see how commercial electricity choice works and how commercial natural gas choice works.
Your utility territory
Illinois has distinct utilities for electricity and gas, and the right procurement path depends on which serve your address.
Electricity
- ComEd — much of northern Illinois, in the PJM market.
- Ameren Illinois — much of central and southern Illinois, in the MISO market.
Natural gas
- Peoples Gas — the City of Chicago.
- Nicor Gas — most of northern Illinois outside Chicago.
- North Shore Gas — parts of Lake County and the far-north suburbs (including Waukegan).
- Ameren Illinois — much of downstate; gas choice there is limited to Rider T transportation.
Where choice does not apply. Some cities own their electric systems and buy power on a full-requirements basis, so there is no separate supplier to choose — Naperville and Springfield (CWLP) are the clearest examples. Confirm your utilities from a recent bill; some communities sit on a boundary.
Browse all utility guides or service areas by location.
What drives a commercial energy price
There is no single "current commercial rate" that applies to every Illinois business. Cost depends on the account:
- Supply vs. delivery — a supplier prices supply; delivery, riders, and taxes stay with the utility.
- Usage and load shape — total kWh or therms, and when they are used.
- Demand charges — for demand-billed accounts, peak kW can be a large part of the bill, independent of the supply rate.
- Capacity — in the ComEd/PJM zone, an account's capacity tag carries peak behavior into supply cost.
To compare an offer against staying put, use the applicable utility benchmark — the price to compare — not a national average.
Contracts and procurement
Once you know your utility and usage, the decision is about structure and terms:
- Contract structure — fixed vs. index, or a block-and-index blend, each a different risk profile.
- Comparing offers — normalize proposals on matched terms; see how to compare commercial energy proposals.
- The terms behind the rate — contract review surfaces exclusions, tolerances, and renewal/holdover language.
- Timing — follow the renewal timeline so no account rolls to a post-expiration rate.
Multi-site owners can group accounts and align renewals through multi-location procurement.
By industry and location
Energy profiles differ by facility type and by where a business sits. See commercial energy by industry — from manufacturing and cold storage to hotels, restaurants, and data centers — and commercial energy by location for verified utility and market context in specific Illinois communities.
Where to start
A useful, account-specific comparison begins with a recent bill, 12 months of usage, and the current contract's end date — the full checklist is in what a commercial energy quote requires. Utility bills carry confidential account data, so share them only through a secure request.
Sources
- Illinois Commerce Commission — Electric Choice Basics (Plug In Illinois)
- Illinois Power Agency — Electricity Supply Rates
- Illinois Commerce Commission — Natural Gas Utility authority
- Ameren Illinois — Natural Gas Choice (Rider T transportation)
This page is a navigation guide; time-sensitive rate, tariff, and program details should be confirmed against the linked primary sources and a current bill. No savings outcome is promised in advance.
Frequently Asked Questions
QHow does commercial energy choice work in Illinois?
Illinois opened electricity to competition under the 1997 Electric Service Customer Choice and Rate Relief Law. In ComEd and Ameren Illinois territory, eligible commercial customers can buy their electricity supply from a licensed retail supplier (an ARES) or stay on utility default service, while the utility continues to deliver the power. Choice applies to the supply portion of the bill only; delivery stays with the utility.
QWhich utilities serve Illinois businesses?
For electricity, ComEd serves much of northern Illinois and Ameren Illinois serves much of central and southern Illinois. For natural gas, Peoples Gas serves the City of Chicago, Nicor Gas serves most of northern Illinois outside Chicago, North Shore Gas serves parts of Lake County and the far-north suburbs, and Ameren Illinois serves much of downstate. Confirm the utilities from a recent bill, since some communities sit on a boundary.
QCan every Illinois business choose an energy supplier?
No. Communities served by a municipal electric utility — such as Naperville or Springfield — buy power through the city and cannot choose a separate electricity supplier. And in Ameren Illinois gas territory there is no standard small-commercial supplier-choice program; only larger non-residential customers can self-supply through Ameren's Rider T transportation service.
QDoes switching suppliers affect reliability or outage response?
No. The delivery utility continues to own the wires or pipes and the meter, deliver the energy, and respond to outages and emergencies regardless of which company supplies it. Only the supply portion of the bill is affected by a supplier contract.
QWhat is the difference between fixed and index electricity contracts?
A fixed contract sets the supply price per kWh for the term, giving budget certainty for the components it includes. An index contract tracks a market index, offering potential savings with more month-to-month variability. Neither is universally cheaper — it depends on the account's risk tolerance and load.
QWhat are demand charges?
Many commercial rate classes bill a demand charge on the account's peak power draw (in kW) over a short interval, separate from the per-kWh energy charge. For demand-billed accounts it can be a large share of the bill, and it does not change when you switch supplier — managing demand is a separate lever from shopping supply.
QCan Illinois businesses choose a natural gas supplier too?
In Nicor Gas, Peoples Gas, and North Shore Gas territory, eligible commercial customers can buy gas supply from a licensed alternative gas supplier while the utility delivers it. In Ameren Illinois gas territory, supplier choice is limited to Rider T transportation for qualifying larger customers.
QWhen should an Illinois business shop for an energy contract?
For most accounts, begin 3 to 6 months before the current contract expires. That leaves time to gather usage, compare offers, and review terms — and to act before any auto-renewal or holdover rate takes effect.