Easy Ways to Reduce School Bus Emissions: Q&A with John Gonzales

Almost 10 years ago, School Bus Fleet chatted with John Gonzales on alt-fuel trends and the potential of electric buses. A lot has changed since then, with a surge in EV interest fueled by the EPA’s funding opportunities, followed by the stabilized market that we see today.

Let’s check back in Gonzales, who is now the senior engineer for the Center for Integrated Mobility Sciences at the National Laboratory of the Rockies (formerly NREL).

Q: For a school district ready to reduce fleet emissions that can’t transition to electric buses, where should they start?

Gonzales: Maintenance upkeep on the current fleet would be the first place to start. Confirm that the existing equipment utilizes components that are operating within the manufacturer’s specifications. Diesel particulate filter (DPF) systems can fail without providing trouble codes. Ensure that the tailpipe is clean with no carbon residue. For example, black residue in the tailpipe can indicate a failing DPF filter.

Q: Which maintenance and operational practices — such as reducing idling, preventive maintenance, tire management, driver practices, or route efficiency — offer the greatest opportunities to reduce fuel consumption and emissions?

Gonzales: All of these practices on their own provide opportunities to reduce fuel costs and are considered standard maintenance practices. The most overlooked item is driver training. How a driver operates the bus can provide considerable savings on both fuel and maintenance costs.

Training can have a direct impact on how they accelerate, how they stop the bus, and if they choose to limit their idle times. There are fleets that utilize their GPS systems to create driver rewards programs. In some cases, they take this data and encourage drivers to have somewhat of a competition to see who could do better and provide some type of reward monthly. This internal competition can create a life of its own.

Q: When it's time to replace a bus, what lower-emission options do you recommend districts consider if going electric isn't practical? 

Gonzales: It is best to evaluate your current routes to determine what fueling options might be optimal for your fleet. There are times when traditional diesel would be the best option. Though with thorough evaluation, there may be prime opportunities to look at other fuels like propane to power part of the bus fleet.

Propane offers an opportunity for long-term pricing stability that might not be found with traditional fuels. Propane engines also do not require the complex aftertreatment systems that traditional diesel vehicles require. This can provide lower overall maintenance costs, along with the potential for a greater return on investment for the school district.

Q: You previously managed a school bus fleet yourself. From an operator's perspective, where do you think districts sometimes leave easy emissions or fuel savings on the table?

Gonzales: The status quo is an easy path to follow. Change can provide for some risks and fleet management is traditionally a risk adverse environment. Introducing new fuel choices brings concerns about the tooling required to work on them. Training and driver buy-in require time and planning.

These are all items that need to be explored before new fuel technology is deployed. Fuel costs are a major driver within school transportation, and propane can offer school districts a strong return on investment over the life of the vehicle.

Q: How should a district measure emissions-reduction efforts? What data should operators track?

Gonzales: Good preventive maintenance practice is key to operating an effective fleet program. Following manufacturer guidelines and beyond can reduce downtime and provide for longer fuel system component reliability. High idle times are quite detrimental to modern diesel aftertreatment systems. This can accelerate component failure and have a negative impact on vehicle performance.

Q: If you were advising a transportation director with a limited budget to create a three- to five-year emissions-reduction plan, what would you prioritize?

Gonzales: Updating the fleet with the best available technology is the key. Getting rid of older vehicles would be the first choice, especially pre-2010 and 2007 diesel vehicles (since after 2010 is when the current emissions rules were enacted). This provided increased reduction in both NOx and hydrocarbons.

All fuels must meet the same emissions requirements, and some can offer greater benefits in certain criteria pollutants. For example, propane is certified by the EPA to provide lower NOx than is required by the standard without the need for complex aftertreatment components. When maintenance costs are a driving factor for fleets, these items make a considerable difference moving forward.