Arizona Public Service expects its peak demand to grow about 3.4 percent a year for the next 15 years, mainly because of industry and data centers, and it wants roughly 4,000 MW of new gas generation to cover part of it. The figures come from the integrated resource plan APS filed with the Arizona Corporation Commission at the end of October, reported by Utility Dive on 4 November, the day after parent company Pinnacle West published its third-quarter results.
Another Record Summer
According to the earnings release, the APS system reached an all-time peak of 9,166 MW on 2 August. Demand went above 9,000 MW three times in the quarter and beat last year's record of 8,648 MW a dozen times; it is the fourth year in a row with a new summer record. Commercial and industrial sales rose 14.5 percent in the quarter. In the resource plan APS projects a peak above 14.5 GW in 2041, about 60 percent over today's record, and retail sales of about 80,600 GWh against roughly 34,200 GWh in 2025.
What The Plan Builds
The gas part, as Utility Dive lists it:
- 1,107 MW of new combustion turbines at existing APS sites, plus uprates of tolling units, between 2026 and 2030;
- the Cholla site repowered as a 387 MW gas plant by 2030;
- Desert Sun, a 1,238 MW combined cycle plant planned for 2032 to serve what the plan calls large-customer subscription load.
Next to that come about 2 GW of utility-scale solar and 2.5 GW of battery storage in the next two years. APS also wants to keep the Four Corners coal plant running to 2038 instead of retiring it in 2031, which it says could save customers close to $1 billion. Environmental groups criticised that part of the plan.
The utility treats data center demand with some caution. It calls the record interest from large customers a risk of loads that never arrive, and protects itself with minimum demand terms, collateral and exit fees. Chief executive Ted Geisler summed up the company's line in the release: growth should pay for growth, meaning a data center or factory pays for the infrastructure built to serve it.
Heat Is Part Of The Plan
Arizona is one of the hardest places to run thermal plant in summer, and the records above were set in exactly those weeks. Combustion turbines lose output as the inlet air gets hotter, and engines and generator sets need cooling that still works at the site's highest ambient temperature, not at a rating-point figure. Anyone planning backup or bridging power for a desert data center while the utility's plants are still years away should put the hottest-day case at the top of the enquiry. More on these installations on our gas turbine and power plant pages.
Sources: Utility Dive, Pinnacle West (SEC filing)
