The effect of reduced idling on fuel costs, vehicle lifespan, emissions and other factors was studied in Anti-idling Technology on Fire Service Vehicles: An Evaluation of the Benefits, published in October by the University of the Fraser Valley (UFV) in British Columbia.
Authors Alex Zheng, John Lehmann, Keith Sharp, Kate Turcotte, Len Garis and Ian Pike investigated the benefits of equipping fire trucks with auxiliary power units (APUs), which provide an alternate power source for lights, lifts and other functions usually operated by a truck’s main engine. The authors also looked into potential sources of unnecessary idling.
“We anticipate this study will be of interest to many fire departments that are looking for ways to decrease costs and operate more sustainably,” said Zheng, the report’s lead author and a biostatistician/researcher at the BC Injury Research and Prevention Unit. “Based on our data, changes in both equipment and crew behaviours show promise in reducing truck idling time.”
The study involved 11 fire trucks at Surrey Fire Services in B.C., three of which were equipped with APUs. The trucks responded to a total of 2,236 incidents during the study period from May 1 to June 4, 2018. On average, each engine ran for 89.4 hours during the study period and idled for close to 42 per cent of the time.
The study’s key findings:
- APUs reduce idle time by 36.4 per cent and engine use by 15 per cent, equating to an estimated three additional years of vehicle service life. APUs are also 32 per cent more fuel efficient than a truck’s main engine (at the assumed 50-per-cent load), resulting in both cost savings and reduced greenhouse gas emissions. Their impact on maintenance costs is negligible, amounting to $1.58 a year.
- Using an APU would save $4,136 per year, taking into account the increased service life, fuel savings, carbon tax savings and impact on maintenance costs. This would result in a 20-year payback period for a $15,000 APU.
- The fuel savings alone are not enough to warrant the purchase of APUs. Removing the extended service life from the equation results in an annual savings of $221.26. At that rate, it would take almost 68 years to amortize a $15,000 APU.
- In addition to using APUs, key opportunities to cut down unnecessary idling include reducing on-scene time (particularly at medical and emergency incidents) and enforcing anti-idling policies.
Avoidable instances of idling, such as when an engine is left running while parked, add unnecessary fuel costs, GHG emissions and maintenance. As a result, more organizations with fleets are taking steps to reduce idling. Surrey Fire Services, for example, has equipped three trucks with APUs and encourages crews to turn off engines whenever possible.
When a fire truck with an APU is parked for more than three minutes, the APU automatically turns off the engine and starts running. Although APUs run on diesel, their fuel use and carbon dioxide emissions are 36 to 47 per cent lower than that of the main engine.
The UFV study compared the performance of the three Surrey trucks equipped with Smeal SG-09 Green APUs with that of its eight non-APU engines. All 11 trucks were powered by Cummins ISL nine-litre diesel engines, with Spartan Metro Star chassis and Smeal apparatus package. The trucks varied slightly in year of manufacture and maximum horsepower, but were otherwise equivalent in size, weight, configurations, duty cycles and load. All 11 trucks operated normally during the study period and were staffed by four unique crews.
When all 11 trucks were compared, no difference was found in fuel use during idling. However, the APU trucks spent between 21.7 and 45.6 per cent less time idling than the non-APU trucks. As well, the difference in idle time per on-scene hour, idle time per incident, and APU-use metrics were significant.
When the outliers (one APU truck and three non-APU trucks) were excluded, the two remaining APU trucks used 20.5 per cent less fuel when idling and spent 27 to 43 per cent less time idling than the remaining five non-APU trucks.
Ultimately, the data revealed that APUs reduce idle time by 36.4 per cent and reduce total engine use by 15 per cent, indicating a potential increase of three years of truck service life. This equates to an annual savings of $4,136 per year – based on the $605,400 cost of a new fire truck – and a full return of investment for a $15,000 APU in about 20 years. However, if only the savings related to fuel and maintenance costs are considered ($221.26 per year), the return on investment increases to almost 68 years.
B.C.’s carbon tax ($35/tonne of carbon dioxide-equivalent) was used to calculate the cost savings related to GHG emissions. APUs were found to reduce GHG emissions by 420 kilograms per year, based on the annual fuel savings and an emission factor of 2.63 kilograms of carbon dioxide-equivalent per litre for heavy-duty trucks.
In their investigation of sources of unnecessary idling, the authors determined that increased idling was linked to longer times spent on-scene, longer travel times, medical and emergency responses and, in some cases, which of the four crews responded to an incident.
Based on this, opportunities to reduce idling time include:
- reducing the amount of time crews spend at a scene
- reducing the amount of time crews spend traveling, idling in traffic or at intersections
- ensuring that all crews use anti-idling practices, such as turning off trucks while parked whenever possible
- using APUs when responding to medical and emergency incidents and other calls requiring the use of safety lights or equipment requiring auxiliary power
For example, the cost savings related to extended service life and reduced GHG emissions support the adoption of APUs for all fire trucks. Further, the discrepancies between the different crews’ idling times demonstrated the need for departments to widely enforce anti-idling policies.
The study can be downloaded for free from the UFV’s public safety and criminal justice research database at https://cjr.ufv.ca.