By Ryan Randazzo, The Republic | azcentral.com 2015
The Sierra Club has filed a 57-page critique of a plan to upgrade a natural-gas fired power plant in Tempe with county air-quality regulators.
Arizona Public Service Co. plans to upgrade the Ocotillo Power Plant near Tempe Marketplace by replacing some of the old generators on the site with newer, faster-starting generators.
The Sierra Club said in its comments to the Maricopa County Air Quality Department that APS should consider adding battery storage for electricity, rather than the polluting gas generators.