There are widespread
policy assumptions that the phase-out of gasoline
and diesel internal combustion engines will over time lead to much
reduced emissions of Volatile Organic Compounds (VOCs) from road transport
and related fuels. However, the use of real-world emissions measurements
from a new mobile air quality monitoring station demonstrated a large
underestimation of alcohol-based species in road transport emissions
inventories. Scaling of industry sales statistics enabled the discrepancy
to be attributed to the use of ancillary solvent products such as
screenwash and deicer which are not included in internationally applied
vehicle emission methodologies. A fleet average nonfuel nonexhaust
VOC emission factor of 58 ± 39 mg veh–1km–1was calculated for the missing source, which is greater
than the total of all VOCs emitted from vehicle exhausts and their
associated evaporative fuel losses. These emissions are independent
of the vehicle energy/propulsion system and therefore applicable to
all road vehicle types including those with battery-electric powertrains.
In contrast to predictions, vehicle VOC emissions may actually increase
given a predicted growth in total vehicle kilometers driven in a future
electrified fleet and will undergo a complete VOC respeciation due
to the source change.