Implementing the ACE Rule

Arizona G&T Cooperatives’ Michelle Freeark Chairs Subgroup that Provides Guidance
on How States Can Implement Affordable Clean Energy Rule


For Immediate Release


Geoff Oldfather, (520) 586-5465, C: (520) 444-3473,

J.D. Wallace, (520) 586-5157, C: (520) 235-4203,

This image shows the boiler in operation on ST3 at Apache Generating Station. The subcommittee chaired by AzGT’s Michelle Freeark produced a “Guidance Document” that can be used by state environmental regulatory agencies to navigate the technical requirements of the Affordable Clean Energy (ACE) rule.

BENSON – When the U.S. Environmental Protection Agency issued the Affordable Clean Energy (ACE) final ruling on June 29, 2019, Michelle Freeark knew the hard work was just beginning. The EPA provided minimal guidance when it came to state regulators knowing how to implement the rule.

The National Rural Electric Cooperative Association asked Michelle Freeark, Arizona G&T Cooperatives’ executive director of regulatory affairs and corporate services, to chair a subgroup to develop guidance, which it presented to NRECA’s Environmental Policy Council in February 2020.

“As far as we can determine, NRECA is the first industry trade association to put out a guidance document on the ACE rule,” Freeark said, adding that other utilities and agencies are already asking for copies. “We wanted something people could use, not just put on the shelf and forget—and that’s what we achieved.”

The Obama-era Clean Power Plan (CPP), a rule with extensive compliance requirements, would have made many coal plants too expensive to operate. The CPP was repealed when ACE became final. The ACE rule focuses on improving efficiency at power plants to achieve carbon dioxide reductions. It returns the responsibility of implementing the rule to states and is potentially more flexible and cost-effective for those generating power.

But it leaves state regulatory agencies at a loss when it comes to implementation. In Arizona, the Arizona Department of Environmental Quality (ADEQ) will implement and enforce the rule for Arizona G&T Cooperatives and other power providers.

“This is more complicated than putting in a traditional control device and walking away and seeing reductions,” Freeark explained. “There are a lot of technical issues that state regulators don’t fully understand, so we provided a tool that they could utilize as they implement ACE.”

The project involved meeting sometimes twice a week for months, coordinating so everyone could be heard. The subgroup ended up with a document that steps through what a state must consider when implementing ACE for any generating unit, whether owned by cooperative members, investors or municipalities.


About Arizona G&T Cooperatives

Arizona Electric Power Cooperative (AEPCO) and Sierra Southwest (Sierra) together comprise the Arizona G&T Cooperatives ( AEPCO owns and operates the 605-megawatt (combined gross) Apache Generating Station, located at Cochise, east of Benson. AEPCO also owns, operates and maintains 829 miles of electric power transmission line—including line owned in part with other utilities— and 27 substations to provide wholesale electric power from Apache to six member distribution cooperatives in southern Arizona, western New Mexico, northwestern Arizona and California.

Sierra is the vehicle to develop new ways to serve the renewable energy needs of our Member cooperatives and customers, and helps maximize solar and other renewable tax credits that are available. Sierra has initiated two utility scale solar projects; the 20 MW Apache Solar project on AEPCO property adjacent to and northeast of AGS, and SunAnza, the 2 MW solar array adjacent to the Anza EC headquarters in Anza, California.

Combined, the distribution cooperatives that receive AEPCO’s wholesale power serve more than 161,000 meters representing more than 420,000 individual residential, commercial, agricultural, and industrial member/consumers.

The Class A member cooperatives that receive wholesale power from AEPCO include Duncan Valley Electric Cooperative, Duncan; Graham County Electric Cooperative, Pima; Mohave Electric Cooperative, Bullhead City; Sulphur Springs Valley Electric Cooperative, Willcox; Trico Electric Cooperative, Marana; and our California member, Anza Electric Cooperative, Anza, California.

These member cooperatives own the AzGT and, by extension, the G&T Cooperatives are owned by their members—the people at the end of the line who use the power