The Apache Generating Station, one of the last remaining power plants in Arizona that use coal, is among 66 power plants nationwide granted exemptions by the Trump administration from updated standards on mercury, arsenic, lead and other toxic pollutants.
Environmentalists worry that allowing plants to avoid compliance with the new standards could harm air quality, public health and the environment.
Power companies have been phasing out coal plants in Arizona for years. The last is targeted for closure in 2032, when federal rules kick in that require 90% capture of carbon emissions.
But Arizona’s intense summer heat puts a strain on the supply of electricity, and power companies have long turned to older, dirtier technology when demand peaks.
At issue are Environmental Protection Agency standards known as the MATS rule, part of the Clean Air Act, which President Richard Nixon signed in 1970. Congress updated it in 1977 and 1990.
The Apache Generating Station’s waiver allows its owner and operator, Arizona Electric Power Cooperative, to comply with the 2012 version of the federal standards rather than stricter caps issued by the EPA in April 2024.
The MATS rule was originally aimed at coal-burning plants. The EPA has expanded it to apply to natural gas; Apache, a 408-megawatt plant about 80 miles east of Tucson, uses both.
Natural gas generates far less toxic material and particulate matter than coal. But it does create carbon dioxide, and the Biden administration also issued rules aimed at curbing those greenhouse emissions.
AEPCO says the older EPA standard is stringent enough to avert hazardous pollution levels and that complying with the updated caps would be “technically unworkable” and “significantly more expensive.”
“The Presidential Variance ensures that Apache can continue to operate to provide power to Southeast Arizona and rural electric utility members,” Carolyn Turner, director of communications and member services at Arizona G&T Cooperatives, which includes AEPCO, said by email. “We do not believe that the issuance of this variance will result in any increase in particulate or particulate hazardous air pollutant emissions. AEPCO is committed to environmental excellence and continued compliance with MATS.”
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Turner cited a 2020 EPA study that she said indicated the “prior MATS standards were sufficient to protect the public from any health risks.”
When the EPA issued tighter standards in April 2024, it said that “technologies and/or methods of operation are available” to further control pollution “at reasonable costs.”
The agency said the 2012 standards had “driven sharp reductions” in pollution from power plants and that the updated standards will go further, cutting annual emissions by 1,000 pounds of mercury and at least 7 tons of other hazardous materials by 2028.
“AEPCO requested the exemption to avoid unnecessary financial burden on rural consumers,” Turner said, adding that available monitoring systems aren’t sensitive enough to measure fine particulate matter at the level required by the EPA’s latest standard.
President Donald Trump signed an order shortly after taking office that rolled back Biden-era EPA regulations. In April, he signed multiple executive orders promoting coal.
His cost-cutting effort, led by billionaire Elon Musk, has also aggressively curtailed the EPA’s staff and mission.
Trump-appointed EPA Administrator Lee Zeldin gave power companies until March 31 to request a waiver allowing them to operate under the older rules.
If approved, companies get a two-year exemption, with the possibility of two-year extensions.
Last September, AEPCO announced plans to stop using coal for power generation by 2027 at the Apache Generating Station, shifting entirely to natural gas after that.
Arizona has two other coal plants in operation besides Apache: Springerville Generating Station and Coronado Generating Station, both northeast of Phoenix near the New Mexico state line.
Springerville, operated by Tucson Electric Power, generates nearly 1,800 megawatts. Environment Arizona Research & Policy Center listed it as the state’s most polluting power plant in 2020.
TEP owns two of the four units at Springerville. The others are owned by Salt River Project and the Tri-State Generation and Transmission Association.
All have publicly committed to phasing out coal by 2032 and being more environmentally conscious.
According to Pam Syrjala, SRP’s senior director of supply and trading, demand can triple in the summer, when temperatures can soar past 110 degrees. Rapid growth in Arizona’s cities has added to pressure on suppliers.
“We need to lean on all of our resources a lot more in summer,” she said. “Coal plants are an extremely reliable resource. We’re able to store fuel on site, so that’s a very good reliability aspect. But we do still continue to have plans to retire those assets and continue to grow our sustainable resources.”
Coronado generates 822 megawatts. SRP says it will stop burning coal there by 2032.
SRP announced in 2020 that Coronado would run seasonally starting this year, revving up only to help meet summer demand.
Arizona companies also own a majority of the Four Corners Power Plant, located on Navajo land in New Mexico just east of the state border. Four Corners produces up to 1,179 megawatts and is the largest coal plant that supplies power to Arizona.
Three of the five units at Four Corners have been retired. Decommissioning for the others is planned by 2031.
In 2021, Arizona Public Service Co. said Four Corners would shift to seasonal operations that “will bring substantial environmental benefits” while allowing for surge production needed “during Arizona’s notoriously hot summer months.”
But in a securities filing last year, APS said it “elected not to begin seasonal operation due to market conditions.”
APS spokesperson Yessica del Rincón affirmed that “Four Corners Power Plant operates as a year-round source of energy to meet customers’ needs.”
APS ended operations last month at the Cholla Power Plant, about 80 miles east of Flagstaff. Del Rincón said the company is reviewing its options following Trump’s executive orders easing restrictions on coal plants.
“We plan to preserve the site for potential future generation uses, including the possibility of nuclear power. At this time, APS has already procured reliable and cost-effective generation that will replace the energy previously generated by Cholla Power Plant,” she said by email.
The Coronado Generating Station in St. Johns, in eastern Arizona, is a coal-fired power plant owned by Salt River Project, a Phoenix-area utility. (File photo courtesy of SRP)
The Navajo Generating Station, a coal plant on tribal land in northern Arizona, shut down in 2019 and has since been demolished.
Navajo President Buu Nygren said recently that the Navajo Nation has lost $40 million per year due to the closure and cited the widespread job losses as a warning against moving too quickly to close aging power plants.
On April 8, state Rep. David Marshall, R-Snowflake, and 22 other Republicans in the Legislature sent a letter to Interior Secretary Doug Burgum, urging him to “stop the retirement of coal-fired power plants in Arizona and support the reactivation of those already shut down.”
The lawmakers said they want the Navajo Power Plant reopened – an idea decried by Tó Nizhóní Ání, a Navajo environmentalist group.
According to the group’s executive director, Nicole Horseherder, rebuilding the plant would create environmental and logistical problems.
“Firing up new coal plants does not happen overnight. … Trump will be out of office before one is even permitted, let alone built and ready to come online,” she said in a statement.
Horseherder also noted that coal isn’t cost-effective compared to alternatives, which is a big reason why power companies have been phasing it out for years.
In an interview with Cronkite News, Horseherder recalled the long history of health problems suffered by Navajo workers at coal plants and mines.
The Navajo Nation should “intentionally and aggressively” move to cleaner sources of energy, she said, though she agrees with Nygren and others on the need to blunt the impact on workers.
“Is there a plan? That’s a question that nobody is asking,” she said.
The dangers of coal are well established.
According to the National Institutes of Health, “Coal-burning power plants are a major source of fine particulate matter … associated with increased risk of death.”
Coal mining is especially dangerous. Ongoing exposure to coal dust is associated with coal workers’ pneumoconiosis, also known as black lung disease.
The American Lung Association says that “the burning of fossil fuels like oil, gas, and coal at power plants emits a host of harmful air pollution, including carbon dioxide that drives climate change and other emissions like particulate matter, carbon dioxide, mercury, sulfur dioxide and nitrogen oxides.”
Arizona has no active coal mines.
The last two were the Black Mesa and Kayenta mines, both owned and operated by Peabody Energy on Navajo land. Black Mesa closed in 2005, around the same time as the Mohave Generating Station in Nevada. Kayenta operations ceased in 2019 when the Navajo Generating Station closed.