Recent arguments for clean diesel are raising questions over the validity of propane autogas as an outstanding choice for school buses. This type of over-simplified information is being widely broadcast. But comprehensive, evidence-based reasoning is what school districts require to make important decisions. School administrators need truth-telling, not storytelling.

So, when it comes to clean diesel and propane autogas, what’s just talk and what’s the truth? Here are just a few factors to consider.

Duty Cycle and Maintenance
Today’s diesel engines are cleaner burning than older models, but claims about their efficiency must be put into a duty-cycle perspective. The complex emission systems that aid the diesel in achieving lower emissions strongly favor duty cycles with high, consistent power utilization, like over-the-road, long-haul applications. Propane autogas is a perfect fit for the duty cycle of school buses, which consists of stop/start at slower speeds with a tremendous amount of idle. This is because the simple and passive emission system on a propane autogas bus won’t degrade in efficiency under these conditions, whereas a modern diesel would likely need more frequent system regeneration or intervention by service personnel. See the full article here.