Alcohol Engines: Pollution Solution Or Problem?

Alcohol engines are those that use alcohol, such as ethanol and methanol, as fuel. Alcohol has been used as an alternative to gasoline since the early years of automobile production, particularly in Brazil. Alcohol contains oxygen in its structure, which means more thorough combustion, and it does not contain the same pollutants as gasoline additives such as lead and sulfur. However, alcohol-diesel blends at cold start produced higher pollutant emissions, and low-level ethanol blends can increase evaporative emissions in vehicles. Nevertheless, ethanol auto-ignition only occurs at temperatures above 677°C, and ethanol and methanol blends with gasoline may cause reductions in CO and HC emissions.

Ethanol and methanol blends with gasoline can cause reductions in CO and HC emissions

Alcohol engines are less polluting than gasoline engines. Gasoline is a complex mixture of hydrocarbons, which can include lead, sulfur, and other noxious materials. These substances produce contaminative exhaust fumes when burned in an engine.

On the other hand, alcohol burns much cleaner. Although it also never combusts completely, the volume of noxious fumes is significantly reduced in an alcohol-burning engine. This is because alcohol contains oxygen in its structure, allowing for more thorough combustion, and lacks the additional pollutants present in gasoline.

However, it is important to note that ethanol blends have been associated with increased emissions during cold engine starts. Additionally, increasing the additive concentration beyond 0.5% has been shown to deteriorate engine performance and emissions.

Alcohols can cause corrosion of some metals and alloys

Alcohols, particularly ethanol and methanol, have been used as engine fuels since the early years of automobile production, especially in Brazil. They are considered promising alternative transportation fuels as they can be derived from biological matter and are compatible with modern engines.

However, one concern with the use of alcohols is their potential to cause corrosion in metals and alloys commonly used in auto parts. Research has shown that ethanol can cause pitting corrosion in stainless steel, with higher ethanol concentrations leading to deeper pits. This is due to the increased solubility of oxygen in the alcohol-containing solution, which results in the generation of iron oxides with high oxidation states. Additionally, ethanol, in the presence of halides, can attack steel and cast iron. The introduction of ethanol also leads to a decrease in the saturated metal cation concentration, which influences the pitting corrosion susceptibility.

Furthermore, studies have found that anhydrous ethanol may cause cracking of some alloys, such as Ti-6Al-4V. The presence of water can help prevent this type of corrosion. Similarly, the corrosion of aluminum by ethanol can be prevented by the elimination of chlorides.

The corrosive effects of ethanol and other biofuels on auto parts are important to consider due to their impact on the durability of these components. Evaluating the long-term effects of biofuels on the performance and integrity of metallic materials used in engine components is crucial to ensure the safe and efficient operation of vehicles.

Alcohol engines produce less noxious fumes than gasoline engines

Alcohol engines produce fewer noxious fumes than gasoline engines. This is because alcohol contains oxygen in its structure, which allows for more thorough combustion. Conversely, gasoline is a complex mixture of many substances, including hydrocarbons, lead, sulfur, and other noxious materials, which contribute to the contaminative effects of the engine's exhaust fumes.

When gasoline is burned in an engine, it produces carbon monoxide and other poisonous fumes, largely due to the fact that the fuel never combusts completely and is subjected to extreme temperatures and pressures. Alcohol, on the other hand, burns much cleaner, even though it also doesn't combust fully. The volume of noxious fumes produced by alcohol is significantly reduced compared to gasoline.

The use of alcohol as an engine fuel has been explored as a promising alternative to gasoline. Alcohol fuels have been used since the early days of automobile production, particularly in Brazil, where ethanol has a long history as an automobile fuel. Alcohol has a high "octane" rating, which prevents engine detonation under load, and it can withstand greater compression ratios, resulting in equivalent or even superior performance compared to gasoline engines.

However, it is important to note that alcohol blends may face challenges during cold starts, as they have been shown to produce higher concentrations of certain pollutants, such as NOx, THC, and CO, compared to diesel fuel. Nevertheless, during warm engine starts, alcohol blends have a positive effect on reducing smoke opacity and particle concentration.

The reduction in noxious fumes from alcohol engines contributes to a cleaner and less polluting driving experience. This is particularly important in reducing air pollution, which is a major concern in many cities and has been linked to various health issues, including respiratory problems and an increased risk of certain cancers.

Alcohol-diesel blends at cold start produced higher pollutant emissions

Alcohol has been used as an engine fuel since the early years of automobile production, particularly in Brazil, where ethanol has a long history as a vehicle fuel. Alcohols can be derived from biological matter via established and new processes, making them an attractive alternative to fossil fuels.

Alcohol is considered a promising alternative to gasoline because it burns much cleaner. Although alcohol, like gasoline, never combusts completely, the volume of noxious fumes is drastically reduced in an alcohol-burning engine. This is because alcohol contains oxygen in its structure, allowing for more thorough combustion, and doesn't contain the pollutants necessary as additives in gasoline, such as lead and sulfur.

However, one study found that alcohol-diesel blends at cold start produced higher pollutant emissions. The starting of compression engines is a complex process where the instability of the combustion process favors high levels of emissions, and because the catalyst is only efficient when the engine works at warm conditions. This process is particularly critical at cold temperatures because very low crank speeds and high blow-by levels are caused by the increase in oil viscosity and the decrease in battery performance. The study found that alcohol blends tested at "cold" start produced combustion instabilities with higher concentrations of NOx, THC, and CO compared with diesel fuel used as a reference.

It is important to note that higher alcohols, such as butanol and pentanol, have been shown to reduce smoke emissions and improve engine efficiency. The combination of higher alcohols, high exhaust gas recirculation (EGR) rates, and late injection timing enabled low-temperature combustion (LTC) in diesel engines, simultaneously reducing smoke and NOx emissions.

Ethanol auto-ignition occurs at temperatures above 950 K

Alcohol, specifically ethanol, has been considered as an alternative to gasoline as an engine fuel. Ethanol is a grain-derived alcohol that has been used as an automobile fuel in countries like Brazil. It has a high octane rating, a low cetane rating, a high latent heat of vaporization, and a low calorific value relative to hydrocarbon fuels.

The use of ethanol as a fuel has several advantages. Firstly, it burns much cleaner than gasoline. While neither fuel combusts completely, ethanol produces fewer noxious fumes because it contains oxygen in its structure, allowing for more thorough combustion. Secondly, ethanol mixes well with water, solving the problem of water settling at the bottom of the fuel tank during winter and freezing. Finally, ethanol is derived from biological matter, making it a renewable and non-petroleum-based fuel source.

However, there are also challenges associated with using ethanol in engines. Compression ignition of ethanol is difficult and requires high temperatures and/or the use of ignition improvers. Additionally, ethanol has a high affinity for water, corrosivity, and poor lubricity. During cold engine starts, ethanol blends have been shown to produce higher pollutant emissions and combustion instabilities, with increased concentrations of NOx, THC, and CO compared to diesel fuel.

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