- Associated Press - Friday, October 28, 2016

PHOENIX (AP) - An Arizona water and power utility is conducting an experiment to add forest-thinning debris to coal burned by an electricity-generating plant, hoping to make thinning more economical to help avoid devastating wildfires producing runoff that would contaminate reservoirs.

A test conducted Wednesday at the Salt River Project’s Coronado Generating Station near St. Johns in eastern Arizona showed that the plant’s machinery can handle mixing woody biomass material with coal, SRP officials said.

That sets the stage for stage for two 10-day periods of burning biomass in November, said SRP water strategy analyst Ron Klawitter.

Klawitter said SRP then will study costs and other data collected during the planned biomass burns before deciding whether to using forest debris to augment coal as a fuel source on a regular basis.

“This test is all about a market-driven solution to forest restoration in northern Arizona,” Klawitter said.

The forest debris used in Wednesday’s test burn was chipped from cuttings from an existing thinning project on state land near Flagstaff. Several state agencies, including the Land and Forestry departments, are partnering with SRP in the project, which is partly federally funded.

Though fire is part of the natural ecosystem, thinning is important for forest health because fires that otherwise would just burn low-lying vegetation and leave large trees unharmed can instead act as torches in overgrown forests and ignite the tops of trees and then spread unchecked across huge areas.

Large wildfires can produce erosion and ash runoff in watersheds such as those of the Salt and Verde rivers, which feed SRP reservoirs and provide water to millions of Phoenix-area residents and other water users.

Larger tree trunks cut down during thinning projects can be sold for lumber but that leaves tons of branches and other low-value material that often is placed in large piles and burned.

At Coronado, the chipped biomass was mixed into the fuel supply by pouring it onto coal on a conveyor belt feeding fuel to the plant’s boiler.

Biomass isn’t a “fuel of choice” for Coronado because the woody material is less efficient and more expensive than coal, SRP said in a statement on the project.

While SRP said the experiment represents the first “co-burning” of biomass with coal in Arizona, biomass is the planned sole fuel source for a new wood-burning plant planned in Eagar, also in eastern Arizona.

A waste management company, Los Angeles-based Concord Blue Energy Inc., has received a state environmental permit for that plant. It plans to sell power to the Navopache Electric Co-Op, which operates in eastern Arizona and western New Mexico.

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