Automotive fuels provide the necessary energy to drive an internal combustion engine. While there are numerous brands and blends, at the end of the day, all of them exist do one thing: create measurable and controllable explosions in the engine that lead to motive force.
Let’s take a look at what automotive fuels do, what types of fuel are available, and how they are utilized.
What Are Automotive Fuels?
As an energy category, automotive fuels are combustible substances. They can be delivered in a range of forms ranging from liquid to gaseous variants.
Today’s primary fuel products are typically defined as being one of three types: gasoline, diesel, and natural gas.
Gasoline is a liquid created from traditional crude oil. It is primarily used in spark-ignition engines most associated with traditional consumer vehicles.
Diesel fuels are also created from crude oil, but are heavier and exhibit a higher energy density than gasoline. Diesel fuels are used incompression-ignition engines typically found in trucks and buses.
Natural gas is delivered in a gaseous form. This fuel variant is largely comprised of methane, and most often applied to natural gas vehicles (NGVs).
Other automotive fuels involve a hybrid of components like ethanol which is essentially defined by corn-based materials mated with traditional gasoline to develop a final product.
While the aforementioned categories are considered essential due to their long use as fuel types, various high technology efforts have created other variants worth noting, too.
These include:
Hydrogen which is used as a combustible in fuel-cell vehicles, and
Biodiesel which is being seen as a way to leverage renewable technology, while at the same time avoiding traditional diesel engine downsides like a significant emissions footprint.
Characteristics Of Different Automotive Fuels
A number of components define differences from one automotive fuel type to another. Here are the main ones you should know:
Energy Density, which refers to the amount of energy that can be obtained per unit of fuel. For example, diesel fuel offers a higher energy density than gasoline. This means that diesel produces more energy per unit of volume or weight.
Octane Rating which represents a measure of a fuel's ability to resist spurious detonation – also known as “knock.” This condition causes engine damage over time. Gasoline is rated by its octane number. The higher the number, the higher the knock resistance.
Cetane Rating which specifically relates to diesel engines, measures a fuel's ignition quality. The higher the Cetane number, the more efficient the ignition process.
Fuel Price which varies depending on factors such as supply and demand, production costs, and taxes. Gasoline and diesel prices fluctuate based on global oil prices.
Fuel Type, Usage & Characteristics
Fuel types generally apply to specific vehicles based on their design, intended use and unique characteristics. Like anything else, there are advantages and disadvantages to using certain automotive fuels. Here’s a short primer on what distinguishes each type – the good, the bad, and the vehicle most likely to have it in the tank.
Gasoline
The most common fuel used in passenger cars, SUVs, and light-duty trucks, gasoline is both widely available and convenient to use. It provides good power and acceleration in spark-ignition engines, and can be blended with ethyl alcohol to enhance octane rating.
While prices can be unpredictable and subject to sudden spikes, gasoline is generally less expensive than alternative fuel sources. However, since gasoline is derived from non-renewable sources, there is a limited supply of it to burn. That burning also releases pollutants into the air, contributing to negative environmental impacts and leading many governments around the world to eye up alternative options to better suit their ambitious climate goals.
Ultimately though, gasoline is a convenient, effective and versatile fuel source.
Diesel
Like gasoline, diesel is a petroleum-based fuel made from crude oil. However, the refining process is different and lengthier, as diesel is produced from the heavier, less volatile components of crude oil. This provides it with different characteristics, namely higher energy density and thereforebetter fuel economy, as well as different ignition qualities (i.e., compression rather than spark ignition).
Diesel engines can travel farther on the same amount of fuel, which partly explains why diesel fuel is largely used in trucks, buses and other heavy-duty vehicles and equipment.
While diesel engines are more fuel-efficient than their gas counterparts, and can also provide more torque and power at lower speeds, they are not necessarily “cleaner.” Diesel vehicles may emitless CO2over the course of their lifetimes, but they do produce more nitrogen oxides and particulate matter, which can also contribute to air pollution.
Additionally, diesel fuel is more expensive than gasoline due to high demand, high taxes, and high refining costs.
Natural Gas
Compressed natural gas (CNG) and liquefied natural gas (LNG) are used in heavy-duty trucks and buses, as well as in some passenger cars. Natural gases are cleaner-burning than gasoline or diesel and therefore produce less emissions. Additionally, natural gas is in abundant domestic supply and is often less expensive than gasoline or diesel.
Natural gas is extracted from underground deposits using various drilling and extraction techniques. The resulting gas is filter-processed to remove unnecessary impurities like water and sulfur. Afterwards, it is compressed and then stored in high-pressure tanks for transportation.
As such, there are some challenges associated with using natural gas as an automotive fuel, including the need for a specialized fueling infrastructure, the lower energy density it has compared to gas or diesel, and the added weight and cost of fuel storage tanks which could require modifications to the vehicle's engine and fuel system.
Ethanol
Ethanol is a more environmentally-sustainable fuel created from renewable sources, including corn, sugarcane, and other similar plant products. It is typically blended in various concentrates with gasoline to create E10 (10% ethanol, 90% gasoline) or E15 (15% ethanol, 85% gasoline) fuel.
Some ethanol blends contain up to as much as 85% ethanol and 15% gasoline. Known as E85, this blend is used primarily in flexible fuel vehicles (FFVs), which are designed to run on a range of ethanol blends. E85 is typically less expensive than gasoline, but it has lower energy content so may result in lower fuel efficiency and higher overall fuel costs.
While ethanol has a higher octane rating than gasoline, it also has different properties that can affect engine performance and durability, particularly at higher concentrations. This is why running an ethanol blend in an engine not designed for it (like in an older vehicle) can cause damage to fuel lines, gaskets and seals.
Another challenge that ethanol presents is in its production. Harvesting the necessary crops to create ethanol requires significant land use, which can compete with food crops.
Hydrogen
Car manufacturers and law makers consider hydrogen to be a promising alternative fuel, as it only produces water vapor when burned, making it zero-emission. Additionally, hydrogen can be produced from renewable sources such as wind or solar power and it possesses a high energy density.
Hydrogen fuel cell vehicles (FCVs) are a relatively new technology and are not yet widely available. Contributing to this is the high cost of producing, storing, and transporting hydrogen. Additionally, the fueling infrastructure is still very limited and vehicle’s must be intentionally built or adapted to accept the fuel.
Racing Fuels
When it comes to automotive fuels, performance and racing applications should be considered as an additional matter of note. These fuel types are highly dependent on individual racing organizations and their related rules and regulations, but here are some examples:
Gasoline
is used in sports car racing, particularly in production classes and some drag racing.
Diesel
is most typically seen in tractor pulls and truck racing.
Methanol
is specifically applied to drag racing, particularly in the Top Fuel and Funny Car classes.
Nitromethane
is another fuel only utilized in drag racing and specifically in the Top Fuel class.
Ethanol
is quickly becoming the primary fuel for most non-drag racing applications including NASCAR, IndyCar, IMSA, and Sprint Car Racing.
In addition to the aforementioned fuel types, there are also some specialized racing fuels designed for high-performance engines.
The Future of Automotive Fuels
As one might suspect, new technologies continue to impact the development of various fuel types and their engine processes. Here are just a few ways that innovative fuel technologies may involve themselves in the future:
Hydrogen Fuel Cell Vehicles.
Fuel cell vehicles (FCVs) could offer a zero-emission alternative to gasoline and diesel vehicles, with the added benefit of fast refueling times and long driving ranges.
This fuel type is derived from renewable sources like corn, soybeans, and sugarcane, and could offer a low-carbon alternative to gasoline and diesel.
Advanced Formulizations.
Advances in engine technology and fuel formulations continue to improve fuel efficiencies while reducing emissions associated with gasoline and diesel vehicles.