Pinnacle West Capital Corporation

Pinnacle West Capital supplies electricity to 1.7 million customers across 35,000 square miles of Arizona through a grid anchored by Palo Verde Nuclear Station, which runs three reactors continuously at around 3,900 megawatts using treated municipal wastewater piped from Phoenix-area cities — the only cooling arrangement of its kind at any commercial nuclear plant in the United States, because no river or lake exists near the desert site. Because those reactors cannot be throttled back during mild weather without violating fuel-cycle economics, every utility-scale solar farm Pinnacle West adds to the same grid makes the surplus problem worse, forcing the company to curtail its own solar output or sell the excess power into regional wholesale markets already depressed by California's midday solar exports. The Arizona Corporation Commission sets what the company can charge residents and industrial customers like Freeport-McMoRan copper smelters and semiconductor fabs, so the cost of managing that surplus — along with every transmission and nuclear infrastructure decision — flows directly into regulated rate cases rather than being absorbed as a private loss. The entire structure depends on Phoenix-area municipalities continuing to supply the treated wastewater that cools the reactors, because if that supply were reduced or redirected through Colorado River allocation disputes or municipal repurposing, no alternative coolant source exists at the site and Palo Verde's output could not be maintained.