Impact of Heavy-Duty Diesel Truck Activity on Fuel Consumption and Its Implication for the Reduction of Greenhouse Gas Emissions

Abstract

Activity data from 79 line-haul and vocational trucks were analyzed to estimate trip-averaged fuel consumption per distance driven and per work performed. The 79 trucks had engine model years ranging from 2008 to 2015 and average (±standard deviation) miles per gallon of 5.5 ± 1.7, which is comparable to other large fleet studies. Engine output work used to overcome various forms of resistance was minimized at vehicle speeds between 54 and 60 mph, which led to best fuel economy. The average gallons-per-brake horsepower-hour (gal/BHP-HR) was 0.058 ± 0.0085. When comparing the gal/BHP-HR per trip speed, higher average trip speeds led to improved fuel economy (lower gal/BHP-HR). In the case of out-of-state line-haul trucks, fuel economy was also dependent on model year. The newer model year out-of-state line-haul truck (2014) had a significant improvement in fuel economy compared with the older model year trucks (2012 and 2013). This could be the result of more stringent CO2 emission standards beginning for model year 2014 trucks under the Phase 1 Greenhouse Gas rule, but data on more vehicles would further corroborate this. The trip-averaged CO2 emissions were calculated for each truck and it was found that some truck groups displayed consistent trip-averaged emissions whereas others displayed high variability despite belonging to the same fleet. Several of the trucks engaged in significant idling, with a median contribution to their CO2 emissions of 4.2%.

Analysis of the levelized cost of green hydrogen production for very heavy vehicles in New Zealand

“…This consumption rate was derived from 79 heavy-duty diesel trucks manufactured between 2008 and 2015. The consumption of 5.5  1.7 miles per gallon was reported to be consistent with other heavy-duty fleet studies (Collier et al, 2019). Travel distances were calculated using (1).…”

“…There is a general recognition that trucks are potentially the "low-hanging fruit" for hydrogen fuel (Concept Consultancy, 2019;Hydrogen Council, 2020;MBIE, 2019b). For instance, the fuel economy for heavy-duty diesel trucks is about 43 l/100km (Collier et al, 2019) and 8 kg/100km for hydrogen trucks (ESORO, 2017;Hyundai Motors New Zealand, 2019). Alternatively, a diesel truck runs at about 2.77 km/kg and a hydrogen truck at 12.5 km/kg.…”

“…The equivalent travel kilometres (Table 3.4) are determined from the consumed volume of diesel, assuming a constant fuel consumption rate of 5.5 miles per gallon, or 43 litres per 100 km. This method was adopted from Collier et al (2019). This consumption rate was derived from 79 heavy-duty diesel trucks manufactured between 2008 and 2015.…”

“…In terms of energy, the hydrogen demand is equivalent to 8.5 PJ 12 while for diesel it is 14.7 PJ (Concept Consultancy, 2019;MBIE, 2018). In terms of travel kilometre efficiency, diesel vehicles consume 16.6 kJ/km while hydrogen consumption is estimated at 9.6 kJ/km (Collier et al, 2019). This is an indication that hydrogen entails more efficient conversion of energy to useful motive power than diesel.…”

Investigating the Investments Required to Transition New Zealand’s Heavy-Duty Vehicles to Hydrogen

“…Only carbon dioxide emissions are considered for diesel trucks. This is because other emissions account for less than 1% of total emissions according to Collier et al [71].…”