“If it is stored for too long, it can spoil”. These are Richard Stanley’s statements, while James Speight, author of Handbook of Petroleum Refining, argues that “it is not easy to generalize”. Although they differ in approach, both agree that it can be said that the condition of gasoline does not remain exactly the same over time. The raw fuel is not at all the same as the one that reaches the consumer. After the mixture of carbon and hydrogen atoms, hydrocarbons are formed. Gasoline undergoes several modifications until it reaches the desired octane rating.
One of the most common ingredients is ethanol, a biofuel that in Spain can be found in different proportions in gasoline. Modern engines have very delicate fuel injectors, so a dirty fuel could damage the engine. The storage of expired gasoline can pose a risk to the environment. If dumped on the ground, it can contaminate and generate volatile organic compounds (VOCs). These can leach into aquifers, contaminating water and air quality. In order to avoid such damage, degraded gasoline should be transferred to clean points or hazardous waste centers.
Does de gasoline expire?
According to James Speight, author of Handbook of Petroleum Refining, “Gasoline can be kept in good condition for months or years, depending on environmental factors such as heat, oxygen and humidity”. That is why it is not easy to answer this question. The final gasoline sold as fuel has nothing to do with the raw material, so there are many aspects that affect its composition.
Fuel transformation
The fuel passes through several stages until it reaches the final product. The initial phase consists of mixing a series of carbon and hydrogen atoms, which give rise to hydrocarbons. It is then refined and impurities such as sulfur dioxide are removed. Substances are then added to improve its performance and achieve the desired octane number. The higher the octane number, the less likely it is to ignite and detonate under pressure. According to Speight, “gasoline is made up of many different compounds, too many to be identified”.
What happens over time?
Stanley explains that over time, it stops behaving as expected. In addition to the fact that gasoline does not stay the same throughout the year, Stanley stated that “the lighter hydrocarbons start to evaporate and your car may not be prepared to take advantage of what’s left”. Depending on the weather, gasoline may react in one way or another. In winter, lighter hydrocarbon fuels are produced, so it is more volatile and flammable. This makes it easier to start a vehicle. On the other hand, in summer the hydrocarbons are heavier, to prevent it from evaporating in the heat.
Ethanol and humidity
One of the ingredients present in the fuel is ethanol. This is a hydrophilic biofuel, which binds its molecules to water. Stanley says, “If your blend has ethanol in it, it can start to absorb water vapor from the air and add it to the tank. That’s not desirable because water corrodes the system.
What about modern engines?
Modern engines work through injection and combustion systems, and that depends on milimetric precision. How is this achieved? By using clean, quality fuel. If out-of-date gasoline is used, it can contaminate the fuel filter and increase wear on sensors and catalytic converters. In addition, modern injectors are extremely delicate. They require the use of a quality, clean fuel. Otherwise, residues can clog the nozzles or corrode the metal.
Gasoline and environment
The storage of expired gasoline must be done in a rigorous manner. Otherwise, it can have serious consequences for the environment. Dumping or burning it emits volatile organic compounds (VOCs) into the environment, in addition to other carcinogens. The discharge of a single gallon can contaminate up to 750,000 gallons of groundwater. It is recommended to avoid these situations by taking expired gasoline to clean points or hazardous waste centers, where they collect this type of waste and know how to store it safely.
And if we no longer had to think about refueling our car with gasoline, but with… air?
