Tuesday, February 21, 2006 TUSD testing bus with evap cooling LARRY COPENHAVER Tucson Citizen Swamp boxes on school buses? That's what Tucson Unified School District is considering in an attempt to cut down on the cost of keeping kids cool while reducing air pollution. The district has outfitted one school bus with an evaporative cooling system, complete with cooler pads, squirrel-cage fans, water-circulation pumps and water reservoir. The system is on loan from the Safer Corp, a business owned by a disabled veteran in northern California. It will be tested through the spring, summer and fall to see if it does a good job cooling bus interiors, said Bill Ball, the district's director of transportation. "To our knowledge, no one else in the country has done this," said Ball, who added that he's always looking to improve how kids get safely and comfortably to school and home again. The system comes with eight-speed fans and costs about $6,000 for four roof-mounted units, enough to cool the interior of a 75-passenger school bus, he said. A typical refrigeration-type of air conditioner for the same bus can set the district back about $15,000. The evap system operates on electric power generated by the bus's internal circuitry, which runs off the vehicle's battery even when the engine in not running, Ball said. This is different than refrigeration, which operates when the engine is running, although some buses carry an auxiliary engine to power the refrigeration unit. Just like a home evaporative cooler, windows have to be opened a bit to allow circulation, said Roy Gibson, a mechanic for 13 years with TUSD. Water reservoirs are monitored electronically so drivers know when to refill. The simplicity of the evap system makes it less apt to break down and easier and cheaper to repair, Ball said. "This could be a really nice thing." But does it cool well enough? That's what the testing over the next nine months will show, Ball said. The district expects the evap system will do the job during the heat, but not during the monsoon season, but most schools are not in session during that time. Introducing evap cooling to TUSD buses is just one idea on Ball's mind. Earlier this month, TUSD was among several districts recognized by the Arizona Department of Environmental Quality for cutting pollution and saving fuel through a new idle reduction program. And yesterday, TUSD received a nearly $500,000 grant from the U.S. Environmental Protection Agency to pay the $25,000-per-bus upgrade on 19 new buses so they can run on compressed natural gas, a clean-burning fuel. The grant, along with 36 others awarded across the nation by EPA, totals $7.5 million for compressed natural gas buses, EPA Administrator Stephen Johnson said during a ceremony in downtown Tucson. Collectively, the grants are expected to cut diesel particulate materials, a known cancer-causing pollution, by more the 500 tons a year.