The primary focus of the pupil transportation industry is to get children to and from school safely, and there are many facets involved in this: Bus drivers must be properly trained and certified; the buses must be in good condition; students must know how to properly board and disembark their buses — the list is extensive.
In recent years, another component has been added to this list: The air students breathe should be free of pollutants. To help reduce the harmful components of exhaust, pupil transportation administrators can retrofit their buses with particulate traps or diesel oxidation catalysts.
Another option to achieve cleaner running buses is to transition to units that can operate on an alternative fuel, such as propane or compressed natural gas (CNG). Ted Olsen, alternative fuels manager for propane provider Delta Liquid Energy in Paso Robles, Calif., says that vehicles powered by propane emit virtually no particulate matter and 50-percent less nitrogen oxide compared to vehicles powered with a gasoline or diesel engine.
Natural gas-powered vehicles also generate a low level of nitrogen oxide and particulate matter, according to Jim Harger, chief marketing officer for natural gas provider Clean Energy in Seal Beach, Calif.
While improved air quality is a benefit of running fleets on CNG and propane, there are factors that operations should consider if they are thinking about working toward a “greener” fleet with the help of these fuels.
Weigh the potential for cost savings
Officials in the alternative fuels industry say that it is important for pupil transporters to first determine what the cost savings will be as a result of operating their buses on propane or CNG as opposed to diesel or gasoline.
Olsen says that his years working in the propane industry have shown him that propane will save operators money due to its lower cost compared to other fuels.
Harger says that powering vehicles with natural gas will also save pupil transporters money. “Natural gas-powered buses cost more, but the fuel is substantially less,” he explains. “The fuel cost savings over the life of the bus will far outweigh the additional cost up front.”
Consider the size of your facility and your equipment needs
Moreover, think about how you will want to refuel your school buses. Bus drivers can fill up at a company’s network of stations in the area that their district serves, or the district can house refueling infrastructure at its facility.
Operations that would like to have refueling equipment in their bus lot must make certain that there is sufficient space to accommodate the infrastructure.
Olsen says that the complete footprint for Delta Liquid Energy’s refueling equipment is 15 feet by 15 feet.
“We’ve put in vertical tanks, which enabled operators to have more space onsite,” he adds.
Pupil transportation operations will need an approximately 30-by-30-foot plot to house a compressor, dryer, the switch gear and a single storage vessel from Clean Energy.
Harger also notes that the equipment has to be 10 feet away from buildings, and it cannot be located underneath any power lines.
Selecting the type of fuel dispensing equipment (i.e., time-fill or fast-fill) that will best meet a fleet’s needs is just as important as ensuring that there is sufficient space for the infrastructure.
In working with school districts to have Delta Liquid Energy’s propane refueling infrastructure installed onsite, Olsen has found that many operations request a fast-fill system.
“We know that school bus operators need to be able to fill the vehicles in less than 10 minutes, so we’ve put in equipment that will fill the buses in a timely fashion,” Olsen says.
Aside from finding out whether an alternative fuel provider can fulfill your dispensing equipment needs, Olsen says pupil transporters considering switching to propane should ask themselves the following questions:
• Do I want to be able to fill the bus only, or do I want to be able to fill the bus and have a record of the transaction?
• Do I want to integrate my propane dispensing equipment with my gasoline or diesel dispensing equipment?
“We did a job for a district, and they wanted the propane dispenser integrated with their gasoline and diesel fuel islands,” Olsen explains. “The drivers can fill the buses with propane the same way they do with gasoline and diesel.”
The system also enables the district to receive a complete report on how many gallons of propane were used during a refill, which bus was refilled, its mileage and the time that the refill occurred.
Harger suggests that operations thinking about powering their school buses with CNG use a time-fill dispensing system. He feels that this type of system is ideal for filling a school bus fleet because buses are typically parked in the bus lot for an extended length of time.
“When the bus comes back to the yard, you can hook it up and have it fuel overnight, for instance, instead of having a driver sit at a pump,” he says.
By extension, Harger notes that having a dispensing system that does not require that the drivers spend time refueling the buses can result in substantial labor savings over the life of a bus.
NGVAmerica’s Stephe Yborra offers a different outlook on refueling equipment for school bus operations.
“NGVAmerica recommends that if there is refueling infrastructure that is nearby, convenient and has the ability to accommodate the additional fuel load, use existing fueling stations,” Yborra says. “If that’s not economical or convenient, you need to make sure that you have enough throughput with the buses that you’re buying for the volume of fuel to justify investing in a refueling station onsite at your facility.”
This means that, ideally, operations should run 10 or more buses on CNG. Yborra says that school districts could work with other entities that have fleets with natural gas-powered vehicles.
“If there’s an arrangement where the fueling meets everyone’s needs, it will create enough fuel throughput to improve the station economics. The bigger the station, the larger the fuel throughput and, therefore, the better the cost per gallon will be,” he says.