Estimating garbage truck GHG emissions is challenging since the same number of stops and road miles must be serviced, just with less trucks over less time. At ROC, we are estimating the reduction in CO2 from route optimization for waste collection as the net reduction in emissions from reducing the number of trucks utilized per day. Municipalities still have to service the same number of stops, just with less trucks. Thus, there are reductions in mileage only to drive to/from the route (to depot and disposal facilities). There are reductions in idling time with less trucks being utilized and the work being completed faster.
Reduced CO2 from Facility Trips = 1.4 hours per day at an average 20 mph = 27 miles divided by 3 mpg = 9 gallons multiplied by 22.2 pounds CO2/gallon = 200 lbs CO2 per day multiplied by 260 working days = 52,000 lbs CO2 per year per truck reduced (~5 passenger cars).
Reduced CO2 from Idling = 50% of workday is idling multiplied by in-truck workday average of 6 hours = 3 hours idling multiplied by 0.5 gallons/hour = 1.5 gallons of diesel multiplied by 22.2 pounds CO2/gallon = 33.3 lbs CO2 per day multiplied by 260 working days = 8,658 lbs CO2 per year per truck reduced (~0.9 passenger cars).
Total Annual CO2 Reduction per Garbage Truck Reduced from Route Optimization = 60,658 lbs CO2 (~6 passenger cars). If the disposal and/or depot locations are more distant, they have two dumps in a day, or the truck gets below average fuel consumption rates, the reduction could be 2-3 multiples of this baseline, i.e., 12 to 18 car equivalents per year for every truck reduced.
Potential Gross Impact on CO2 Reductions at Full Implementation = Half of the world’s population, 3.8 billion people (are serviced by garbage trucks) divided by each truck services about 2,500 homes/10,000 persons a week = 3.8B people divided by 10,000 persons per truck = 380,000 residential garbage trucks operating daily = average reduction in routes from route optimization of a minimum of 10% with a target utilization of 1% of all trucks = 380 trucks reduced = 23M lbs CO2 or ~10,500 tons CO2. If there are 9,900M metric tons from transportation annually, this reduction would represent a very small portion of total emissions generated.
Are we missing anything? It does not look like a significant impact on total emissions, but for a municipality, it would be a non-capital intensive way to reduce their climate emissions scorecard and save money in the process.
