Since taking ownership of nearly 30 propane-powered vehicles last year, most of them school buses, Mesa Unified School District No. 4 near Phoenix reported saving more than $5,600 in fuel, or 32 cents less per mile compared to diesel.
The findings are part of a case study recently released by ROUSH CleanTech and Blue Bird of the school district's alt-fuel operations. ROUSH CleanTech provides the propane fueling system. Twenty-one of the new propane vehicles are Blue Bird Micro Bird G5 Type A school buses and six are 2012 model-year Blue Bird Propane-Powered Vision Type Cs. Mesa is also using a 2012 Ford F-250 propane-run pick-up truck.
The savings equate to a 60-percent increase when compared to diesel. ROUSH said the 28 new propane vehicles also reduce the district's carbon footprint by about 7,200 pounds of carbon dioxide each year.
"After finding school districts across the country — from Texas to Los Angeles to Oregon — successfully switching their school buses to run on propane autogas, we knew it could work for Mesa, too," said Director of Transportation Ron Latko.
Latko approached the school board in 2009 to "double up" on school bus purchases. In return for paying the premium for the new buses, Latko said he would forgo buying new buses the following school year so the district could remain within budget. The objective was to allow the district to learn from other districts that purchased diesel engines that utilize either EGR or SCR to comply with 2010 EPA emission standards.
He said the first question asked by the school's governing board was, "How fast can we convert the entire fleet?"
Latko said he used the ThyssenKrupp Elevators "Five Cs" approach to identify propane as the most viable alternative fuel to meet Mesa's needs. ThyssenKrupp developed its Five Cs two years ago to develop a protocol for analyzing the best alternative fuels for the company's fleet. He added that some school districts have fueled with propane autogas for as long as 30 years.
Last year, Blue Bird dealer Canyon State Bus Sales shared a propane Vision for Mesa technicians to test drive. Latko said his teams developed a fuel savings calculator that found that each bus could save as much as $2.06 per gallon compared to diesel, which equates to $61,130 per year, a figure arrived at before the federal tax credit of $0.50 per gallon expired.
Mesa uses an 18,000-gallon, on-site fueling station and an additional 2,000-gallon fueling station at a satellite yard. The district operates a total of 514 school buses, the largest fleet in Arizona, to transport 19,000 students each day.