Data Center Energy Procurement in Illinois

Data centers are among the largest and most distinctive commercial electricity accounts in Illinois: enormous, near-constant load with a very high load factor. Northern Illinois — the Elk Grove Village and I-88/Aurora/DeKalb corridors, largely in ComEd territory — has a growing footprint. For these facilities, procurement and capacity strategy are high-stakes.

Who this is for

Facility, engineering, and finance leaders at Illinois data centers and large computing facilities, and developers evaluating an Illinois site's energy profile.

The data center load profile

• Very high, very steady load. IT and cooling run continuously, producing a high load factor that can be favorable for supply pricing.
• Large, persistent capacity obligation. Because the facility runs near-flat, its capacity tag (PLC) in the ComEd/PJM zone is large and continuous, making capacity a major, ongoing cost component.
• Scale magnifies contract terms. At this size, pricing scope, pass-throughs, and volume terms have outsized dollar impact — small per-kWh differences are large absolute numbers.

Why the load is so flat — and why that shapes cost

A data center's electricity draw is dominated by two loads that never really stop: the IT equipment itself and the cooling required to reject the heat that equipment produces. Servers run continuously, and cooling scales directly with IT load, so the building draws a large, steady block of power hour after hour, day and night, with little of the day-versus-night or summer-versus-winter swing that shapes most commercial buildings. That flatness is the defining feature of the account. It tends to be favorable for supply pricing because the load is predictable and easy to hedge, but it also means the facility is drawing heavily during every regional system peak, which is exactly what sets the capacity obligation.

Capacity is a large, persistent cost — not an occasional one

In the ComEd/PJM zone, a facility's capacity tag (PLC) is fixed by how much it draws during the regional grid's peak hours, and that figure feeds the capacity component of supply cost for an entire delivery year. Most buildings can reduce their PLC by curtailing during peak windows; a data center generally cannot, because the load is the mission. So its capacity obligation is large and continuous, and capacity becomes one of the biggest ongoing components of the total energy cost rather than a footnote. This is the single most important reason data-center procurement cannot be reduced to shopping a per-kWh rate.

Why capacity and contract structure dominate

For a near-flat load this large, the supply rate, capacity treatment, and contract terms all matter enormously. A PJM auction clearing price is not a bill rate — capacity cost is filtered through delivery year, PLC, and the contract — so understanding those mechanics is central, not incidental. At this scale, how a contract handles capacity pass-through, how it defines the pricing scope, and how it treats other pass-through charges can outweigh a small difference in the headline energy rate, because a fraction of a cent per kWh becomes a large absolute number across a continuous multi-megawatt load. See commercial demand charges and the PJM capacity guide.

Procurement considerations specific to data centers

Because the account is so large and so capacity-driven, the analysis depends on good data. Interval data reconciled against 12–24 months of bills establishes the true load shape and the PLC, and for a development still under construction, a projected load profile stands in until real metering exists. Confirming the serving utility and the site's service arrangement early matters because it determines which market — PJM via ComEd, or MISO via Ameren — governs the capacity mechanics. Operators building or leasing across more than one site can treat the accounts as a multi-location procurement, coordinating renewals rather than negotiating each facility in isolation.

What to watch for

• Capacity treatment in the contract. Whether capacity is fixed, passed through, or blended into the rate has an outsized effect at this load — read how the contract handles it.
• Projected versus actual load on new builds. Pricing a development off a projection carries risk if the facility ramps differently than expected; revisit the account once real interval data exists.
• Reliability is engineered on site. Redundancy, backup generation, and UPS deliver uptime — the supplier does not. Supplier choice affects only the supply portion of the bill.

Getting started

Provide interval data and 12–24 months of bills for the facility (or projected load for a development), confirm the serving utility, and the account can be analyzed and priced on matched terms through the procurement process. No savings figure is promised in advance.