Solar is squeezing out nuclear energy in Arizona, but a hydrogen project could help

Ryan Randazzo
Arizona Republic
Rather than turn Palo Verde down or off, the surplus electricity on sunny, cool days could be diverted from the grid and used to create hydrogen.

The Palo Verde Nuclear Generating Station 50 miles west of Phoenix is licensed to run into the 2040s, but officials there say they will need to get creative to keep it going that long, or beyond.

The nuclear plant has a problem that is unique to the Southwest: The growing amount of solar power on the regional power grid eventually will displace the nuclear plant's power at certain times of the year.

In the summer, when people run lots of air conditioners, Palo Verde and other large plants meet the heavy electricity demand.

But on mild spring and fall days, there’s lots of power in the Southwest from solar power plants and solar panels on hundreds of thousands of rooftops from Texas to California, but little demand for electricity for air conditioning.

“Some days we still end up with more energy being produced because of Palo Verde and all that solar than what we can really use,” said Jack Cadogan, senior vice president of site operations at Palo Verde for Arizona Public Service Co.

One idea is to use some of the big plant’s electricity to produce hydrogen fuel that can be used in power plants or even vehicles. The concept is being tested with Idaho National Laboratory.

Rather than turn Palo Verde down or off, the surplus electricity on sunny, cool days could be diverted from the grid and used to create hydrogen.

That can be done with something called “reverse-operable electrolysis,” where electricity is used to separate water into oxygen and hydrogen gas.

Hydrogen gas can be used to power fuel-cell cars and trucks. Or it could be piped to nearby natural-gas plants, blended with that gas, and burned to make electricity at times when the solar power is not available and the grid needs the electricity.

Another option is to store it in tanks and reverse the process to make electricity for the grid when the sun is down and solar power is unavailable.

“So it is a battery,” Cadogan said. “It is a fancy, alternate battery.”

APS officials are working with Idaho National Laboratory to research the economic feasibility of a hydrogen generator near Palo Verde. If it pencils out, a small test facility could be built near the nuclear plant in 2021.

Ohio-based FirstEnergy Solutions and Minneapolis-based Xcel Energy also are participating in aspects of the U.S. Energy Department’s research into nuclear plants and hydrogen.

Making Palo Verde more flexibility

Utilities including APS are planning to add substantial amounts of solar to their systems, and that eventually will force Palo Verde to either shut down or run at partial capacity during mild weather.

“We know that will only grow over time,” Cadogan said. “We are trying to project, how do we make Palo Verde more flexible to still be the anchor point or cornerstone of our clean-air energy mix in Arizona and the whole desert Southwest? We really do need to fit into the environment that is changing.”

The Palo Verde Nuclear Generating Station 50 miles west of Phoenix is licensed to run into the 2040s, but officials there say they will need to get creative to keep it going that long, or beyond.

APS runs the nuclear plant for seven owners including Salt River Project, El Paso Electric Co., Southern California Edison, Public Service Co. of New Mexico, Southern California Public Power Authority and the Los Angeles Department of Water and Power.

The plant makes more electricity than any other facility in the U.S.

Power plants fueled by natural gas can be turned down on mild-weather days to make room for the energy from sunshine, and turned back up quickly in the evening when the sun sets. Nuclear plants don’t do that very well.

The three generators at Palo Verde are each made to run at essentially full power for 18 months straight until they need to be turned off for maintenance and refueling.

“Running it at 100%, it is the sweet spot for this plant,” Cadogan said.

While shutting the plant down for extended periods of time is an option, it’s not the most economical one. That’s because the plant would put out less electricity, but the expenses wouldn't be reduced much. Utilities value Palo Verde because each unit of energy it produces is among the lowest cost in the region.

Turning the nuclear plant up and down also could threaten the plant’s reliability, because doing so involves more input from the plant operators than if the plant runs at a steady state for months at a time, Cadogan said.

The U.S. Department of Energy approached APS with the hydrogen concept, he said.

“They came to us on this one and said, it seems like you have a unique issue with solar kind of pinching nuclear,” he said. “We said, 'We do.'”

Creative ideas worthwhile, expert says

Producing hydrogen as a side business to Palo Verde makes sense if it keeps the nuclear plant running, said John Hofmeister, who retired as president of Shell Oil Co. in 2008 and has written about energy and lectured at the School of Sustainability at Arizona State University.

“I think there is a critical role for nuclear for the future,” Hofmeister said in a recent interview with The Arizona Republic.

In his 2011 book, “Why We Hate the Oil Companies: Straight Talk from an Energy Insider,” Hofmeister predicted the country’s energy future will rely on nuclear, solar and hydrogen.

“I have no qualms about any of those,” he said. “They are the future. They are CO2 free.”

Carbon emissions from coal, natural gas and oil that produce CO2 are warming the earth's atmosphere and contributing to climate change. While nuclear energy is not renewable like solar or wind, it doesn't emit carbon.

It’s best to make use of the nuclear plant that’s already built, Hofmeister said. Closing and decommissioning the nuclear plant would cost utility customers billions, he said, and they’d also have to pay for whatever replaces the plant to supply energy in the summer.

“Take away Palo Verde and Arizona consumers are going to have to fork over enormous amounts of cash to build (energy) storage capability,” he said. “Or turn to gas, or continue to rely on coal, which are CO2 rich.”

Because of those costs, Palo Verde officials should find some arrangement, whether producing hydrogen or something else, to remain open, he said.

“If we don’t solve it, Arizona will lose an incredibly valuable resource,” he said.

Other efforts to extend operations

APS is investing in other measures to ensure Palo Verde doesn’t run into obstacles that keep it from running into the 2040s, including a possible alternative water source and equipment upgrades.

Palo Verde is the only nuclear plant in the world that uses reclaimed wastewater for cooling rather than a river or seawater.

The plant uses an average of 65 million gallons of treated wastewater every day — more than 23 billion gallons a year — to generate electricity.

The water, used for cooling at the power plant, is produced by a wastewater treatment plant owned by five Valley cities, which sell the reclaimed water to Palo Verde's owners under an agreement that was renewed in 2010 and runs through 2050.

But the water gets more expensive in the latter years, particularly after 2025, so APS is considering alternative water sources.

APS officials also don’t want a minor mechanical issue to derail the plant, so the company preemptively is replacing key components around the plant.

As the individual generators undergo their usual refueling shut downs, APS has replaced equipment dating to the plant’s opening in the 1980s to ensure all the parts work.

That includes approximately $15 million cranes inside the three circular containment domes. The cranes are used during refueling to move big pieces of equipment.

Replacing them is the heaviest lift ever done at the power plant, Cadogan said. All the nuclear fuel is taken out of the containment domes and placed in a nearby storage pool while the cranes are replaced, he said.

“If you drop it, you could damage the plant really beyond repair,” Cadogan said of the crane replacement, which is taking place in Unit 3 during a fall refueling at Palo Verde.

Preemptively replacing the cranes is sensible because if they break and unexpectedly prolong a fueling outage at the plant, it would cost about $1 million a day in lost energy production, he said.

APS really doesn’t want that kind of unexpected expense late in the plant’s life when it might not make economical sense to fix.

“We get that done so we don’t, late in the plant’s life, run into a big project that would maybe kind of end the life of the plant,” he said.

Reach reporter Ryan Randazzo at or 602-444-4331. Follow him on Twitter @UtilityReporter.

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