Ethanol-gasoline Blends Research Articles

Influence of ethyl acetate addition on phase stability and fuel characteristics of hydrous ethanol-gasoline blends

Hydrous ethanol or commercial ethanol is regarded as a promising additive for gasoline. Its low cost and many other advantages, such as increasing the octane number and reduction of harmful emissions, motivate the researchers to investigate its use as an economic octane booster. The most common drawback of using hydrous ethanol as a gasoline additive is the phase separation problem. In this study, the effect of adding ethyl acetate (EA) on the phase stability, distillation curve, vapor pressure, vapor lock index and octane number of hydrous ethanol-gasoline blends was investigated. The reference fuel blends were formulated by mixing hydrous ethanol (96%) with hydrocarbon-based gasoline in different percentages (5, 10, 15 and 20 vol%). For studying the effect of ethyl acetate on the fuel specifications, it was mixed with 15% hydrous ethanol-gasoline blend in different percentage (3, 6, 9 and 12 vol%). The experimental results indicated that ethyl acetate has a good ability to increase the phase stability and the octane number of the hydrous ethanol-gasoline blends without causing adverse impacts on the other studied specifications.

Characteristics of combustion and soot formation of ethanol-gasoline blends injected by a hole-type nozzle for direct-injection spark-ignition engines

In this study, the combustion and soot formation processes of mid-low level ethanol-gasoline blends (E0, E20 and E50) sprays injected by a hole-type nozzle were examined in a quiescently high-temperature and high-pressure constant volume vessel by various ignition strategies (e.g. ignition position, ignition timing and spark energy). High-speed imaging of OH* chemiluminescence and two-color pyrometry were employed to clarify the flame propagation and soot formation. The results show that a relatively favorable flame area is potential to achieve for both E20 and E50 at the EOI or slightly after EOI timing. Higher ethanol content blends show more sensitivity to the ignition energy due to the physical properties. The soot level tends to decrease with increasing ethanol content at EOI middle ignition, possibly attributed to the dilution effect of ethanol and the increase of oxygen content. At EOI downstream ignition, however, the soot formation increases in both E20 and E50, possibly as a consequence of the downstream fuel heterogeneity consisting of the inhomogeneous mixture and liquid droplets of highly sooting hydrocarbons. Retarding ignition timing can help to decrease the soot formation. Moreover, E20 shows not only comparably intense combustion to E0 but also less soot formation at EOI middle ignition.

Comparative studies on combustion, performance and emission characteristics of a two-wheeler with gasoline and 30% ethanol-gasoline blend using chassis dynamometer

Mid-level ethanol-gasoline blends such as E30 offers significant advantages in terms of higher octane number, desirable Reid vapor pressure and water tolerance characteristics compared to lower blends. An experimental study was undertaken on a motorcycle with commercial gasoline (E0) and 30% ethanol blended gasoline (E30) using a chassis dynamometer. Combustion, performance and emissions characteristics were investigated under steady state (wide-open throttle – WOT) and transient (Indian driving cycle – IDC) operating conditions. In the WOT test, carbon monoxide and hydrocarbon emissions decreased however oxides of nitrogen (NOx) increased with E30 compared to E0. The specific fuel consumption was higher with E30 but vehicle power decreased. Combustion analysis showed an increased combustion duration and delay in heat release rate with E30. The peak combustion pressure and maximum rate of pressure rise were also lower. Mass emission studies over IDC test show a decrease in CO and NOx emissions with E30 while hydrocarbon emission increased marginally. The notable point emerged from the study is that the operating conditions and change in air-fuel mixture regime impact the performance and emissions of two-wheeler significantly. The present work provides useful information for designing a dedicated spark ignition engine suitable for mid-level ethanol blends.

Experimental investigations to reduce unburned emissions in reactivity controlled compression ignition through fuel modifications

Reactivity Controlled Compression Ignition (RCCI) is a dual fuel LTC strategy wherein wider operating load range is achieved by utilizing low and high reactive fuels like gasoline and diesel, respectively. One of the major problems associated with RCCI is higher unburned emissions. The present work intends to reduce unburned emissions from RCCI combustion through fuel modifications. The investigated low and high reactive fuels include butanol- and ethanol-gasoline blends, gasoline-, butanol- and Karanja biodiesel-diesel blends. A production light duty diesel engine is modified to run in RCCI mode through suitable modifications. Based on PFI fuel sensitivity study, it is observed that 20% butanol and 80% gasoline blend (G80B20) results in lower HC, CO emissions and higher brake thermal efficiency. Similar results are obtained with 20% Karanja biodiesel and 80% diesel blend (D80K20) as the DI fuel. With G80B20 and D80K20 as PFI and DI fuels, respectively, the PFI to DI fuel ratio at each load conditions is optimized to further reduce unburned emissions in RCCI. Overall, it is concluded that by replacing gasoline and diesel with G80B20 and D80K20 as PFI and DI fuels, respectively, the HC and CO emissions are reduced by 50% along with 4.5% higher brake thermal efficiency.

Azeotrope formation in gasoline–ethanol blends. Part 1 – Impact of nonionic on E10 distillation curve

Blending 10 vol% of ethanol into hydrocarbon base gasoline (HBG) increases significantly the vapour pressure of the blend (E10), and exhibits near-azeotrope behaviour that severely affects the shape of E10 distillation curve. The distillation curves of HBG and E10 fuel blend, were constructed using ASTM D86 distillation data, and the areas under each distillation curve, were calculated through the numerical trapezoid rule (NTR) and calculus definite integration (CDI) methods. Consequently, the area due to azeotrope formation (ADAF), was estimated. In this paper, we present the impact of small concentration of nonionic surfactant on the area under distillation curve (AUDC) of E10 fuel blend and the area due to azeotrope formation (ADAF). Also, the influences of the added surfactant on the volatility criteria of the investigated E10 fuel blend were discussed.

Near-azeotropic volatility behavior of hydrous and anhydrous ethanol gasoline mixtures and impact on droplet evaporation dynamics

After fermentation, the concentration of bioethanol is only 8–12 wt%. To produce anhydrous ethanol fuel, a significant amount of energy is required for separation and dehydration. Once the azeotrope composition is reached, distillation can no longer be exploited for purification and more expensive methods must be used. Replacing anhydrous ethanol fuel with hydrous ethanol (at the azeotrope composition) can result in significant energy and cost savings during production. The goal of this study was to characterize the volatility behavior and the droplet evaporation dynamics of hydrous and anhydrous ethanol gasoline blends. Three hydrous ethanol-gasoline blends (10, 15, and 30 vol%) in which the hydrous ethanol was composed of the azeotropic proportions of ethanol and water, and three anhydrous ethanol gasoline blends (10, 15, and 30 vol%) were prepared and analyzed with the advanced distillation curve method. Distillation curves were obtained for all test fuels and distillate samples were taken during the distillation process. A droplet evaporation model validated with the distillation data was exploited to understand how the non-ideal volatility behavior of these blends, the high heat of vaporization of water, and altered fluid properties can affect the transient droplet evaporation phenomena and thus the fuel's potential to effectively mix with air in direct injection internal combustion engines. Minor differences in the distillation curves and vapor-liquid equilibrium between the hydrous and anhydrous fuels were measured. Droplet modeling results showed that the higher heat of vaporization and viscosity of water relative to ethanol can lead to significant differences in the net droplet evaporation time between the two types of blends, especially at the higher blending ratios evaluated. These results suggest that the presence of water in ethanol-gasoline blends may extend droplet lifetimes and increase the susceptibility of the fuel to form particulate matter emissions. This is the first study to use distillation methods to gain a better understanding of evaporation behavior and the role of water's non-linear vapor-liquid equilibrium on droplet evaporation dynamics.

Impact of ethanol blending on particulate emissions from a spark-ignition direct-injection engine

Particulate formation due to combustion of a wide range of ethanol-gasoline blends was investigated in a spark-ignition direct-injection (SIDI) engine. This study is a follow-up to a previous study done by the authors in which particulate formation for ethanol-gasoline blends was examined under fully premixed combustion, eliminating physical effects of the fuel. In this study, fuel was injected directly into the cylinder to investigate how the physical properties of the blended fuels influence particulate formation. The engine was operated at a fixed load, phasing, and equivalence ratio while end of injection timing was varied. The results of this work show that increasing ethanol content leads to a decrease in engine-out particulate in spite of, sometimes significant, changes in fuel properties. However, it was also shown that particulate results can be affected by engine operating history which, if not taken into account, could have implications for research and real world applications.

Energy factors for flexible fuel engines and vehicles operating with gasoline-ethanol blends

This work investigates the energy factors for fuel conversion from the analysis of brake specific fuel consumption (BSFC) maps of a sample of 15 engines, representative of 75% of current models available in the Brazilian market. The method also employs the engine driving patterns of power output versus crankshaft speed obtained from bench dynamometer tests. The energy factors obtained from the engine analysis was validated against experiments carried out with two production vehicles in laboratory tests following the 1975 US Federal Test Procedure (FTP-75) procedure and road tests following 16 different urban and highway routes. The fuels used in the tests were hydrous ethanol (E100, 6 v/v % water) and a blend of 22 v/v % anhydrous ethanol and 78 v/v % gasoline (E22). The energy factors found from the 3D engine BSFC map analysis were higher than those obtained from the Willans line, currently adopted as a standard, by 52% for E22 and 57% for E100. The results from the 3D engine BFSC maps and the first vehicle following the FTP-75 cycle and 15 road routes were similar, also close to the results from the second vehicle, qualifying them to be representative of modern flexible fuel spark ignition engines and vehicles.

Impact of bio-alcohol fuels combustion on particulate matter morphology from efficient gasoline direct injection engines

The requirements for controlling particulate emissions in gasoline direct injection (GDI) engines, particularly in hybrid vehicles (where frequent cold-start event impact on both, particles characteristics and catalytic aftertreament efficiency), nesesitates the need for understanding their formation mechanism and their morphological characteristics. The findings described in this investigation have significance in the design of efficient Gasoline Particulate Filters (GPFs) and the development of computational models that predict particle filtration and oxidation processes.Morphological analysis of the particulate emissions from the combustion of commercial gasoline and two bio-alcohol blends: of 25% v/v ethanol in gasoline and 33% v/v butanol and 67% v/v gasoline, in a modern GDI engine has been carried out using a transmission electron microscopy. The primary particle size distribution from the combustion of butanol-gasoline blend was slightly smaller compared to gasoline, while the mean primary particle diameter was 3 nm smaller from the combustion of ethanol-gasoline fuel. This decrease in primary particle size for ethanol-gasoline blend was also reflected in a reduction of the mean radius of gyration and mean number of primary particles per agglomerate.The combustion of butanol-gasoline blend induced improved particle oxidation rates during the combustion process and post-oxidation stage, and led in 80% and 60% reduction in particle concentration in the engine exhaust when compared to the combustion of gasoline and ethanol-gasoline blend, respectively. Additionally, the estimation of the particle fractal dimension through the use of fractal equation, minimum bonding rectangle method and root form factor showed comparable results for butanol-gasoline and gasoline, with the particle agglomerates being more compact than the ethanol-gasoline fuel, where more chain like particles are seen. Therefore, particles emitted from the combustion of ethanol-gasoline fuel are easier to be trapped (lower fractal dimension) and present a higher reactivity (high surface/volume ratio) compared to particles emitted from gasoline combustion.

Evaluation on physicochemical properties of iso-butanol additives in ethanol-gasoline blend on performance and emission characteristics of a spark-ignition engine

In this study, experiments were conducted on a four-cylinder spark-ignition engine to investigate the effects of iso-butanol additives in ethanol-gasoline blend on fuel properties, performance and emission characteristics of a SI engine. The engine tests were carried out at 50% wide open throttle and variations of engine speed from 3000 to 5000 RPM with an interval of 1000 RPM. The engine was fueled with base gasoline fuel, ethanol-gasoline blended fuel at 10% volume percentage of ethanol (E10) and three different fuel blends of iso-butanol additives; 5%, 10% and 15%, in E10 blended fuel denoted as E10B5, E10B10 and E10B15, respectively. Physicochemical properties tests were conducted in this study to evaluate the fuel heating value, kinematic viscosity and density, which have been selected due to their influences on engine performance and exhaust emissions. Results of heating value showed a decreasing pattern for the blended fuel samples compared with that of base gasoline fuel as E10, E10B5, E10B10 and E10B15 produced 2.33%, 3.14%, 5.06%, and 5.31%, respectively. However, as alcohol concentration increases in the blended fuel samples, the density and kinematic viscosity were both increased with maximum values of 0.767 g/cm3 and 1.15 mm2/s, respectively obtained for E10B15. In terms of engine performance, the blended fuel samples exhibited higher brake power than that of base gasoline fuel with mean increase of 7.71%, 10.21%, 10.89% and 11.54% for E10, E10B5, E10B10 and E10B15, respectively. Significant reduction in brake specific fuel consumption obtained with E10, E10B5, E10B10 and E10B15 by mean of 3.57%, 5.15%, 7.14% and 10.89% respectively, compared to base gasoline fuel. Noticeable improvement of brake thermal efficiency observed with the blended fuel at a maximum increment of 18.91% achieved by E10B15. High combustion temperature produced by the blended fuel samples have been contributed to the higher exhaust gas temperature. Accordingly, the emissions of carbon monoxide and hydrocarbon were all reduced; except for carbon dioxide and nitrogen oxide, with the addition of iso-butanol additive compared to those of ethanol-gasoline blend and base gasoline fuel.

Influence of EGR and ethanol blending on soot formation in a DISI engine

Soot formation and in-cylinder soot oxidation in an optically accessible DISI-engine is analysed for gasoline–ethanol mixtures under part load operating conditions. A volumetric extinction measurement technique was used both for the determination of the liquid fuel distribution and quantitative soot measurements. Toliso, a mixture containing isooctane and toluene (65 vol% isooctane and 35 vol% toluene) was utilised as a surrogate gasoline fuel. The EGR (EGR-exhaust gas recirculation) rate-dependence and the effect of ethanol blending (0, 20 and 40% ethanol, E0–E40) were studied at part load operation with two different injection timings. Operating point 1 (OP1) represents an early injection with piston wetting and pool fire, operating point 2 (OP2) represents a late injection timing with reduced time for mixture formation. Soot formation is more pronounced for OP1 and for E20 and E40 as compared to E0. Here the pool fire due to the fuel-dependent liquid wall film formation plays a major role in soot formation and oxidation. Late injection timing leads to increased soot formation for E20 compared to Toliso, while E40 shows lowest soot formation. Here the fuel–wall wetting is less pronounced, but mixture inhomogeneities exist, and the soot cloud covers a larger region in the cylinder. An EGR addition leads to a higher soot formation for Toliso for both operating points. The ethanol-blends show a reduction of the soot formation with EGR, which is explained by reduced combustion temperatures and the chemically bound oxygen for E20 and E40 leading to locally leaner mixtures at constant global air–fuel ratio. The study shows optimisation potentials of injection strategies for ethanol-blended gasoline in combination with EGR in DISI-engine applications.

Physiochemical Property Characterization of Hydrous and Anhydrous Ethanol Blended Gasoline

Water removal during the production of bioethanol is highly energy intensive. At the azeotropic point, the mixture can no longer be separated via fractional distillation, so expensive and energy intensive methods are required for further purification. Hence, there is an interest in using hydrous ethanol at the azeotropic point to improve the energy balance of ethanol fuel production. Currently there is a lack of available thermophysical property data for hydrous ethanol gasoline fuel blends. These data are important to understand the effect of water on critical fuel properties and to evaluate the potential of using hydrous ethanol fuels in conventional and optimized spark ignition engines. In this study, gasoline was blended with 10, 15, and 30 vol % of anhydrous and hydrous ethanol. The distillation curve, Reid vapor pressure, vapor lock protection potential, viscosity, density, haze and phase separation points, and lower heating value were measured for each blend, and the results were compared to ASTM D...

Progress in regulated emissions of ethanol-gasoline blends from a spark ignition engine

ABSTRACTOne of the major sources of increased air pollution is the continuous and rigorous emissions from gasoline engines, which are generating a threat to our environment. Different methods are explored to reduce these emissions. Emissions are formed due to the incomplete combustion of fuel caused by the lack of oxygen content during combustion. Gasoline has no oxygen content so oxygen for the combustion process for a gasoline engine is derived from the intake air, resulting in incomplete combustion; however, additional oxygen can be supplied through ethanol blended with gasoline. Ethanol has the additional advantage of reducing harmful emissions when used a fuel in a spark ignition (SI) engine. On altering the fuel blending ratio in varying percentages the harmful emissions can be checked, which demonstrates the potential of using ethanol-gasoline blends. The aim of this review is to study and analyze the range of opportunities and future prospects for introducing blends of gasoline-ethanol, gasoline with all other alcohols, and derivative and subsequent alternative fuels in varying percentage ratios in existing SI engines by diagnosing various aspects such as air-fuel ratio, operating cylinder pressure, ignition timing and compression ratio related to the emission parameters only.

Predicting Octane Number Using Nuclear Magnetic Resonance Spectroscopy and Artificial Neural Networks

Machine learning algorithms are attracting significant interest for predicting complex chemical phenomenon. In this work, a model to predict research octane number (RON) and motor octane number (MON) of pure hydrocarbons, hydrocarbon-ethanol blends, and gasoline–ethanol blends has been developed using artificial neural networks (ANNs) and molecular parameters from 1H nuclear magnetic resonance (NMR) spectroscopy. RON and MON of 128 pure hydrocarbons, 123 hydrocarbon–ethanol blends of known composition, and 30 FACE (fuels for advanced combustion engines) gasoline–ethanol blends were utilized as a data set to develop the ANN model. The effect of weight percent of seven functional groups including paraffinic CH3 groups, paraffinic CH2 groups, paraffinic CH groups, olefinic −CH═CH2 groups, naphthenic CH–CH2 groups, aromatic C–CH groups, and ethanolic OH groups on RON and MON was studied. The effect of branching (i.e., methyl substitution), denoted by a parameter termed as branching index (BI), and molecular w...

Study of Corrosion Effects of Oxidized Ethanol–Gasoline Blends on Metallic Materials

Bioethanol added into gasolines significantly changes the physical and chemical properties of the resulting fuels and can have a considerable influence on their overall thermo-oxidative stability. During fuel oxidation, different oxidation products such as water, acidic substances, and peroxides are formed and these can have corrosive effects on metallic construction materials of the storage and transportation equipment, engines, and fuel lines of automobiles, etc. In this work, we tested the laboratory prepared ethanol–gasoline blends (EGBs) E10, E25, E40, E60, and E85, which were artificially oxidized depending on their induction period. The oxidized fuels were used to study their corrosion aggressiveness after their thermal load in the presence of oxygen or after the expiry of their shelf life. The corrosion properties of these fuels were tested on steel, copper, aluminum, and brass using electrochemical methods such as electrochemical impedance spectroscopy and Tafel curve analysis. For comparison, st...

From actual ethanol contents in gasoline to mid-blends and E-85 in conventional technology vehicles. Emission control issues and consequences

The study investigated the combustion and emissions of gasoline engines using four ethanol–gasoline blends ranging from 10 to 85 volume percent ethanol, and an E0 control Performance were compared in single cylinder engine and tested in a chassis dynamometer using two Tier I vehicles. The octane sensitivity of the fuels increases with the addition of ethanol from 7.8 for a non-oxygenated fuel to 23 for the 85% ethanol blend. Fuel sensitivity have a direct relationship with the latent heat of vaporization, because charge cooling is one of the way alcohols increases Research Octane Number. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease in aromatic BTEX compounds was detected as the amount of ethanol in the fuel increased. Both vehicles operated without engine fault code display except when the E-85 was used. The engine could be started stably with E10, E20, and E45. However, for E85 the engine idling became unstable because the air–fuel mixture was too lean making impossible the reduction reactions necessary for NOx emission control in the catalytic converter.

Exhaust noise, performance and emission characteristics of spark ignition engine fuelled with pure gasoline and hydrous ethanol gasoline blends

The exhaust noise, performance and emission characteristics of a gasoline engine fuelled by hydrous ethanol gasoline with 10%, 20% hydrous ethanol by volume (E10W and E20W) and pure gasoline (E0) were experimentally investigated. The tests were performed at full load and different engine speeds varying from 1500 rpm to 5000 rpm. The results showed that compared with E0, E10W and E20W had much lower exhaust noise at low engine speeds. With the increase of engine speed, E0 showed an advantage in low exhaust noise. However, engine fuelled with three fuels displayed comparable noise emissions at high speed. In addition, better thermal efficiency, significantly decreased CO and HC emissions were achieved by hydrous ethanol gasoline at all tested operating conditions. However, significant NOx emission and slight BSFC were observed for E10W and E20W. Compared with E20W, E10W showed decreased BSFC, HC and NOx emissions with the increase of engine speed, while CO emission was only slightly increased. Hydrous ethanol gasoline was capable of realizing comparable torque and power with E0 at all operating conditions. From the results above, hydrous ethanol gasoline could be considered as a promising alternative for SI engine. What's more, E10W exhibits enhanced performance.

Emission estimates for an on-road flex-fuel vehicles operated by ethanol-gasoline blends in an urban region, Brazil

Vehicle emissions have become the dominant source of air pollutants in many cities. Relatively few studies have examined the impact of different ethanol concentrations into fuel on exhaust emissions from flex-fuel vehicles on real-time traffic conditions. In this study, emissions analyses of carbon monoxide, carbon dioxide, nitrogen oxides and hydrocarbons were carried out in a flex-fuel vehicle in an urban route in the Fortaleza city/Brazil. The vehicular exhaust emissions of the pollutants above mentioned were measured through a portable analyzer. Route was performed with different ethanol/gasoline blends (27%, 85%, and 100% ethanol). VSP methodology was used in this work. On-board system data used could register instantaneous emissions as a function of vehicle dynamics. It was observed that the acceleration operation mode was the major responsible for highest emissions of CO, CO2 and NOx for all blends tested. CxHy emissions of <0.005 g km−1 were registered. The results show the relevance of performing sampling in real-time traffic conditions, since the emission standards set by approved real-time traffic conditions do not often represent local reality.

Comparative analysis of the Performance and Emission Characteristics of ethanol-butanol-gasoline blends

Global warming and energy security being the global problems have shifted the focus of researchers on the renewable sources of energy which could replace petroleum products partially or as a whole. Ethanol and butanol are renewable sources of energy which can be produced through fermentation of biomass. A lot of research has already been done to develop suitable ethanol-gasoline blends. In contrast very little literature available on the butanol-gasoline blends. This research focuses on the comparison of ethanol-gasoline fuels with butanol-gasoline fuels with regard to the emission and performance in an SI engine. Experiments were conducted on a variable compression ratio SI engine at 1600 rpm and compression ratio 8. The experiments involved the measurement of carbon monoxide, carbon dioxide, oxides of nitrogen and unburned hydrocarbons emission and among performance parameters brake specific fuel consumption and brake thermal efficiency were recorded at three loads of 2.5kgs (25%), 5kgs (50%) and 7.5kgs (75%). Results show that ethanol and butanol content in gasoline have decreased brake specific fuel consumption, carbon monoxide and unburned hydrocarbon emissions while the brake thermal efficiency and oxides of nitrogen are increased. Results indicate thatbutanol-gasoline blends have improved brake specific fuel consumption, carbon monoxide emissions in an SI engine as compared to ethanol-gasoline blends. The carbon dioxide emissions and brake thermal efficiencies are comparable for ethanol-gasoline blends and butanol-gasoline blends. The butanol content has a more adverse effect on emissions of oxides of nitrogen than ethanol.

The Effect of Using Ethanol-Gasoline Blends on the Mechanical, Energy and Environmental Performance of In-Use Vehicles

The use of ethanol in gasoline has become a worldwide tendency as an alternative to reduce net CO2 emissions to the atmosphere, increasing gasoline octane rating and reducing dependence on petroleum products. However, recently environmental authorities in large urban centers have expressed their concerns on the true effect of using ethanol blends of up to 20% v/v in in-use vehicles without any modification in the setup of the engine control unit (ECU), and on the variations of these effects along the years of operation of these vehicles. Their main concern is the potential increase in the emissions of volatile organic compounds with high ozone formation potential. To address these concerns, we developed analytical and experimental work testing engines under steady-conditions. We also tested carbureted and fuel-injected vehicles every 10,000 km during their first 100,000 km of operation. We measured the effect of using ethanol-gasoline blends on the power and torque generated, the fuel consumption and CO2, CO, NOx and unburned hydrocarbon emissions, including volatile organic compounds (VOCs) such as acetaldehyde, formaldehyde, benzene and 1,3-butadiene which are considered important ozone precursors. The obtained results showed statistically no significant differences in these variables when vehicles operate with a blend of 20% v/v ethanol and 80% v/v gasoline (E20) instead of gasoline. Those results remained unchanged during the first 100,000 km of operation of the vehicles. We also observed that when the vehicles operated with E20 at high engine loads, they showed a tendency to operate with greater values of λ (ratio of the actual air-fuel ratio to the stoichiometric air-fuel ratio) when compared to their operation with gasoline. According to the Eco-Indicator-99, these results represent a minor reduction (&lt;1.3%) on the impact to human health, and on the deterioration of the ecosystem. However, it implies a 12.9% deterioration of the natural resources. Thermal equilibrium analysis, at the tailpipe conditions (~100 °C), showed that ethane, formaldehyde, ethylene and ethanol are the most relevant VOCs in terms of the amount of mass emitted. The use of ethanol in the gasoline reduced 20–40% of those emissions. These reductions implied an average reduction of 17% in the ozone formation potential.