Ethanol fuel is a sustainable energy resource that is intended
to provide a more environmentally and economically friendly
alternative to petroleum-based fuels, such as gasoline. Recent
interest in ethanol has increased due to the fact that it can be
combined with gasoline at different percentages: from low
percentages with not specially modified gasoline vehicles up to 85%
of ethanol, and even up to 100%, in flexible-fuel vehicles.
There is much debate and a considerable amount of concern among
automakers and consumers regarding the environmental friendliness
of ethanol, mainly due to the lack of complete knowledge about the
effects of its use on direct pollutants from exhaust vehicle
emissions such as CO, CO₂, NOx, HCs and particulates and on the
fuel consumption of the vehicle. Furthermore, there is concern
regarding the impact that ethanol could have on the different
VOC's, principally because they are ozone precursors due to
their reaction in the atmosphere with nitrogen oxides (NOx) in the
presence of sunlight, which contributes to ground-level ozone
formation.
This paper aims to evaluate the impact of adding ethanol to
gasoline on exhaust emissions and fuel consumption, measuring
regulated and non-regulated pollutants. To achieve this objective,
exhaust emissions tests adapted to the use of ethanol blends were
performed using a Euro 4 vehicle running with E0, E5 splash and E10
and a flexible-fuel vehicle running with E0 and E85. An analysis of
the automotive engine exhaust for standard pollutants (CO, CO₂ HC,
NOx, particulates) was performed. Then these regulated measurements
were completed with the speciation of the exhaust emissions
determining the different contributions of some aldehydes, ketones,
ethanol and different individual hydrocarbons, determined by
HRGC-FID and HPLC-UV. This long list of pollutants and their
particular ozone-forming potential were used to estimate
ground-level ozone formation and the effect of different
ethanol-gasoline blends on it.
The paper concludes with an evaluation of the results obtained
in order to determine the effects of adding different percentages
of ethanol to gasoline on exhaust emissions (regulated and
non-regulated) and fuel consumption as well as to determine the
impact on ground-level ozone formation.