Some of Arizona’s leading cities are trying to convert their fleets of buses for public transportation to low-emission or zero-emission fuel sources — such as electric power — to help the cause of promoting environmentally sustainable transportation. But Arizona State University isn’t stepping up to join in those efforts. High costs and short battery lifespans are among reasons the university isn’t making the conversion. Fulton Schools Research Professor Steve Polzin, a civil engineer who specializes in transportation, says schools and consumers may be hesitant because battery technologies are changing quickly. Consumers and transit services may be wary of investing in what will become obsolete technology when the next waves of a new and improved batteries and fuel sources emerge, Polzin says.