R/emi_europe_emep_wear.R
emi_europe_emep_wear.RdReturns a list or data.table of emissions for urban buses based on Tier 2 of EMEP/EEA air pollutant emission inventory guidebooks (2019). The function concerns the emissions of particulate matter (PM), encompassing black carbon (BC) (1), which arises from distinct sources, namely, road vehicle tire and brake wear (NFR code 1.A.3.b.vi), and road surface wear (NFR code 1.A.3.b.vii). It is important to note that PM emissions exhaust from vehicle exhaust are excluded. The focus is on primary particles, which refer to those that are directly emitted due to surface wear, rather than those generated from the resuspension of previously deposited material. See more in @details.
emi_europe_emep_wear(
dist,
speed,
pollutant,
veh_type,
fleet_composition,
load = 0.5,
process = "tyre",
as_list = TRUE
)units; Length of each link in 'km'.
units; Speed in 'km/h'.
character; Pollutant, classified in "TSP"(Total Suspended Particles), "PM10","PM2.5", "PM1.0","PM0.1". Please note that emissions factors for "PM1.0" and "PM0.1" are not available for road surface wear process.
character; Bus type, classified in "Ubus Midi <=15 t", "Ubus Std 15 - 18 t", "Ubus Artic >18 t", "Coaches Std >18 t", or "Coaches Artic >18 t".
vector; Fleet composition, which is a distribution of fleet based on frequency. If there is only one, 'fleet_composition' is 1.0.
numeric; Load ratio, classified in 0.0, 0.5 and 1.0. Default is 0.5.
character; Emission process sources, classified in "tyre","brake" and/or "road".
logical; Returns emission factors as a list, instead of data.table format. Default is TRUE.
List. emission in units 'g' (list or a data.table).
The following equation is employed to evaluate emissions originating from tyre and brake wear
TE(i) = dist x EF_tsp(j) x mf_s(i) x sc(speed),
where:
TE(i) = total emissions of pollutant i (g),
dist = distance driven by each vehicle (km),
EF_tsp(j) = TSP mass emission factor for vehicles of category j (g/km),
mf_s(i) = mass fraction of TSP that can be attributed to particle size class i,
sc(speed) = correction factor for a mean vehicle travelling at a given speed (-)
Tyre
In the case of heavy-duty vehicles, the emission factor needs the incorporation of vehicle size, as determined by the number of axles, and load. These parameters are introduced into the equation as follows:
EF_tsp_tyre_hdv = 0.5 x N_axle x LCF_tyre x EF_tsp_tyre_pc
where
EF_tsp_tyre_hdv = TSP emission factor for tyre wear from heavy-duty vehicles (g/km),
N_axle = number of vehicle axles (-),
LCF_t = a load correction factor for tyre wear (-),
EF_tsp_tyre_pc = TSP emission factor for tyre wear from passenger car vehicles (g/km).
and LCF_tyre = 1.41 + (1.38 x LF),
where:
LF = load factor (-), ranging from 0 for an empty bus to 1 for a fully laden one.
The function considers the following look-up table for number of vehicle axes:
| vehicle class (j) | number of axes |
| Ubus Midi <=15 t | 2 |
| Ubus Std 15 - 18 t | 2 |
| Ubus Artic >18 t | 3 |
| Coaches Std <=18 t | 2 |
| Coaches Artic >18 t | 3 |
The size distribution of tyre wear particles are given by:
| particle size class (i) | mass fraction of TSP |
| TSP | 1.000 |
| PM10 | 0.600 |
| PM2.5 | 0.420 |
| PM1.0 | 0.060 |
| PM0.1 | 0.048 |
Finally, the speed correction is:
sc_tyre(speed) = 1.39, when V < 40 km/h; sc_tyre(speed) = -0.00974 x speed + 1.78, when 40 <= speed <= 90 km/h; sc_tyre(speed) = 0.902, when speed > 90 km/h.
Brake
The heavy-duty vehicle emission factor is derived by modifying the passenger car emission factor to conform to experimental data obtained from heavy-duty vehicles.
EF_tsp_brake_hdv = 1.956 x LCF_brake x EF_tsp_brake_pc
where:
EF_tsp_brake_hdv = heavy-duty vehicle emission factor for TSP,
LCF_brake = load correction factor for brake wear,
EF_tsp_brake_pc = passenger car emission factor for TSP,
and LCF_brake = 1 + (0.79 x LF),
where:
LF = load factor (-), ranging from 0 for an empty bus to 1 for a fully laden one.
The size distribution of brake wear particles are given by:
| particle size class (i) | mass fraction of TSP |
| TSP | 1.000 |
| PM10 | 0.980 |
| PM2.5 | 0.390 |
| PM1.0 | 0.100 |
| PM0.1 | 0.080 |
Finally, the speed correction is:
sc_brake(speed) = 1.67, when V < 40 km/h; sc_brake(speed) = -0.0270 x speed + 2.75, when 40 <= speed <= 95 km/h; sc_brake(speed) = 0.185, when speed > 95 km/h.
Road Wear
Emissions are calculated according to the equation:
TE(i) = dist x EF_tsp_road(j) x mf_road
where:
TE = total emissions of pollutant i (g),
dist = total distance driven by vehicles in category j (km),
EF_tsp_road = TSP mass emission factor from road wear for vehicles j (0.0760 g/km),
mf_road = mass fraction of TSP that can be attributed to particle size class i (-).
The following table shows the size distribution of road surface wear particles
| particle size class (i) | mass fraction of TSP |
| TSP | 1.00 |
| PM10 | 0.50 |
| PM2.5 | 0.27 |
References
#' EMEP/EEA data and reports can be accessed in the following links:
Other Emission factor model:
ef_brazil_cetesb(),
ef_europe_emep(),
ef_scaled_euro(),
ef_usa_emfac(),
ef_usa_moves()
emi_europe_emep_wear(dist = units::set_units(1,"km"),
speed = units::set_units(30,"km/h"),
pollutant = c("PM10","TSP","PM2.5"),
veh_type = c("Ubus Std 15 - 18 t","Ubus Artic >18 t"),
fleet_composition = c(0.5,0.5),
load = 0.5,
process = c("brake","tyre","road"),
as_list = TRUE)
#> $pollutant
#> [1] "PM10" "TSP" "PM2.5"
#>
#> $veh_type
#> [1] "Ubus Std 15 - 18 t" "Ubus Artic >18 t"
#>
#> $fleet_composition
#> [1] 0.5 0.5
#>
#> $speed
#> 30 [km/h]
#>
#> $dist
#> 1 [km]
#>
#> $emi
#> PM10_brake_veh_1 PM10_brake_veh_2 TSP_brake_veh_1 TSP_brake_veh_2
#> <units> <units> <units> <units>
#> 1: 0.01674622 [g] 0.01674622 [g] 0.01708798 [g] 0.01708798 [g]
#> PM2.5_brake_veh_1 PM2.5_brake_veh_2 PM10_tyre_veh_1 PM10_tyre_veh_2
#> <units> <units> <units> <units>
#> 1: 0.006664313 [g] 0.006664313 [g] 0.00936999 [g] 0.01405498 [g]
#> TSP_tyre_veh_1 TSP_tyre_veh_2 PM2.5_tyre_veh_1 PM2.5_tyre_veh_2
#> <units> <units> <units> <units>
#> 1: 0.01561665 [g] 0.02342497 [g] 0.006558993 [g] 0.009838489 [g]
#> PM10_road_veh_1 PM10_road_veh_2 TSP_road_veh_1 TSP_road_veh_2
#> <units> <units> <units> <units>
#> 1: 0.019 [g] 0.019 [g] 0.038 [g] 0.038 [g]
#> PM2.5_road_veh_1 PM2.5_road_veh_2
#> <units> <units>
#> 1: 0.01026 [g] 0.01026 [g]
#>
#> $process
#> [1] "brake" "tyre" "road"
#>