Dive Brief:

• Arizona Public Service (APS) is studying the feasibility of generating power by burning forest biomass at one of its coal units in order to reduce wildfire potential, according to a letter sent to regulators on March 20.
• The Arizona Corporation Commission (ACC) had introduced biomass generation as part of its broader Energy Modernization Plan last year, adopting a separate policy in December that specifically called for at least 60 MW of biomass generation. APS would convert one 117 MW coal-fired unit at the Cholla Power plant to produce up to 70 or 80 MW by burning biomass, according to the Arizona Republic.
• The utility is seeking alternate lifelines for the Cholla plant, scheduled to close in 2025, after conversations of converting the facility to natural gas didn't pencil out, according to local press. If the analysis shows that converting Cholla to burn biomass "is more cost-effective than other alternatives, we will propose to move forward on the project" with the approval of state regulators, APS wrote in its letter.

Dive Insight:

The ACC has been considering biomass generation as a way to address the need to thin the overcrowded Ponderosa Forest that runs across the state and remains largely on federal land.

"Other states have wrestled with this issue from a utility standpoint, including California, to see if the avenue of energy production could be a means to also achieve this particular goal that could arguably be in the best interest of the state as a whole," Commissioner Boyd Dunn told Utility Dive.

APS is presenting a path forward on the ACC biomass policy by potentially taking on the goal through a retrofit of a Cholla unit, which would serve to maintain the facility's viability and protect local jobs.

"Previously, it had been a discussion of having smaller plants, maybe up to a half dozen or five of them, located along the Ponderosa forest that goes across northern Arizona," Dunn said.

The utility expects to issue a report to the ACC within 60 days of the March 20 letter.

"We are looking at all of the issues related to potentially converting the related unit from coal to biomass and certainly looking at the environmental impact, which would include looking at the need for how to manage any waste," Suzanne Trevino, spokesperson for APS, told Utility Dive.

APS and Salt River Project, a state-owned utility not regulated by the ACC, have been jointly experimenting with the use of biomass in energy production for a number of years, on a much smaller scale, said Dunn.

"APS must feel that there's certainly significant biomass in that area," Dunn said, adding that a conversion of the plant is going to require the utility to issue a request for proposals (RFP) and cooperation with the U.S. Forest Service to transport the underbrush and small trees that are removed to Cholla.

According to Dunn, the forest service has had to reallocate funds from managing the amount of underbrush that makes forests vulnerable to wildfire due to budget changes and the need to prioritize fighting fires rather than clearing up the forest.

"Our approach contemplates contracting with third party suppliers who would harvest and deliver the biomass feedstock to the power plant," APS wrote in their letter, noting that suppliers "would likely need" long-term contracts with the Forest Service for a minimum of 20 years.

"The bottom line is going to be the cost and whether this is going to be feasible or not," Dunn said. "There are many challenges."