Salt River Project has a nearly $1 billion expansion plan in the works for a Coolidge natural-gas burning power plant that officials say is necessary to maintain reliability on the Phoenix power grid.
SRP’s plans calls for the Coolidge Generating Station to more than double, with 16 new generators added in the expansion. The quick starting generators can react to fluctuations on the grid, including intermittent power from renewable sources like solar and wind.
Environmentalists are concerned that the investment in gas plants moves the utility in the opposite direction of its climate goals. SRP officials said the gas plants are necessary to help integrate more intermittent solar and wind on the grid.
The Power Committee of the SRP board approved the deal on Tuesday, with an estimated project cost of $830 million. In case the project costs more, the approval included a cap on expenses at $953 million. It will need an affirmative vote from the full board to proceed.
“The primary driver is the significant near-term growth we are seeing,” said Grant Smedley, director of resource planning, acquisition and development for the utility.
SRP is pursuing additional solar, battery and even a new wind project, he said, and the company still plans to hit its target of reducing carbon emissions 65% in 2035 and by 90% in 2050 when compared with 2005 numbers.
SRP also plans to add 2,025 megawatts of new solar from large power plants by 2025, plus substantial capacity from large, utility-scale batteries. Officials describe a megawatt of power is enough electricity to supply 250 homes at once.
“We are pursuing an all-of-the-above energy strategy,” Smedley said.
California has experienced energy constraints the past two summers, prompting concerns about supply throughout the West.
“It really serves as additional motivation for us to pursue this,” Smedley said of California’s supply issues. “What you see from that is increased risk we would have relying on (buying energy on) the market for those peak summer afternoons. For us, we’d like to have our own resources that we can count on that we can build to serve our customers’ needs.”
According to SRP, the gas units would operate during the hottest hours of summer or other times when energy demand is highest, therefore make a “relatively small contribution” to overall carbon emissions.
Coolidge power plant currently has 12 generators on site, and the capacity to power about 150,000 homes when running at full capacity. The power plant will grow significantly under the plan.
The planned expansion adds another 820 megawatts, or an equivalent to power about 200,000 homes when running at full capacity.
SRP explained the expansion is necessary because the Phoenix area is growing tremendously with additional homes and businesses. The plan is for the first eight units to be running in summer of 2024 and second eight in summer 2025.