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What are Fuel Emissions?

Daniel Liden
Daniel Liden

Nearly every fuel, when consumed, emits various substances into the air. These fuel emissions, especially when they come from fossil fuels, can be very harmful to the environment and to the lives of humans, animals, and plants. When a fossil fuel is burned, it tends to release a significant amount of carbon dioxide into the air; it can also release other harmful substances such as sulfur dioxide or carbon monoxide. Fossil fuels are burned around the world for countless purposes which range from powering automobiles and airplanes to providing electrical energy. The mass burning of fossil fuels releases massive quantities of fuel emissions which can have wide-ranging effects on many different things.

One of the major concerns people have about fuel emissions is the effect that such emissions have on the environment. Many of the gases released through the burning of fuels, such as carbon dioxide, are greenhouse gases that cause the greenhouse effect and contribute to global warming. Carbon dioxide is one of the primary fuel emissions resulting from the burning of fossil fuels, so the effect on the environment is significant. Fossil fuels are primarily hydrocarbons, so burning them breaks the bonds between carbon and hydrogen, carbon atoms bond to oxygen, and carbon dioxide is released.

The EGR valve recirculates vapors to help prevent excess pollutants from being released in a car.
The EGR valve recirculates vapors to help prevent excess pollutants from being released in a car.

Carbon monoxide emissions are another dangerous type of fuel emissions, but carbon monoxide emissions are more directly harmful to humans. Carbon monoxide emissions result from the incomplete combustion of fossil fuels, which happens in the chemical processes in automobiles. As a result, automobiles are equipped with catalytic converters that oxidize carbon monoxide into carbon dioxide, which is less harmful directly. Catalytic converters also cause other chemical reactions which make some of the other products of burning fossil fuels somewhat less dangerous.

Fuel emissions are a result of burning fossil fuels.
Fuel emissions are a result of burning fossil fuels.

Fuel emissions lead to a dangerous and harmful process known as acid rain in which chemicals released into the atmosphere through the burning of fossil fuels return to the ground in the form of acidic precipitation. This can be very harmful to plants, water supplies, aquatic creatures, and some man-made objects. Sulfur dioxide is the compound that is most commonly associated with acid rain; it dissolves in the moisture of the atmosphere and becomes sulphurous acid. Nitrogen oxides can also contribute to acid rain and are common in car exhausts. Lead compounds can also be released by the burning of fossil fuels; in high concentrations, these fuel emissions can lead to impairment in children.

Discussion Comments


@submariner- Vehicle emissions are a tricky thing to regulate. What has happened with the increase of fuel economy has been a sort of rebound effect. The average consumer does not reduce vehicle miles traveled when they get better fuel economy. They actually increase the number of miles they travel because the opportunity cost per mile has decreased. More fuel-efficient cars also have smaller gas tanks so there is a perceived decrease in costs when filling up at the pump.

Consumers respond best to price. If you look at the recent recession and the two major gas spikes that occurred during that time, you would see that the price spikes drove fuel prices down (increased conservation) more than any increase in fleet efficiency.

The most effective way to regulate emissions or increase fuel economy is to drive consumer demand for those vehicles. This is done by increasing the price through price regulation or gasoline taxation. If people knew that gas would never drop below $4.00 per gallon, you would likely have large growth in the auto industry and a significant increase in fuel efficiency standards. This is just my opinion, but I have studied the issue extensively.


From what I know about fuel economy and emissions, it seems like the two are tied to each other. Emissions go up as economy goes down and vice versa. What I do not understand is why fuel emissions in the United States have not gone down considering fuel economy standards have gone up considerably.

Why is this the case? It makes it seem futile to regulate fuel economy standards when they do little for reducing greenhouse gas emissions. Is there a better way to regulate emissions in vehicles besides increasing fuel economy standards?


@babalaas- Fuel cells produce very few emissions, but what they produce depends largely on the type of fuel the fuel cell uses. I am speaking strictly on demand side output of emissions for fuel cells so keep that in mind.

Two types of fuel cell vehicles are under development; those that run on hydrogen and those that run on methanol. In the case of hydrogen, the only emission produced is pure water. Hydrogen fuel cell vehicle emissions produce no carbon dioxide, nitrous oxides, carbon monoxide, or sulfur dioxides. Hydrogen fuel cell vehicles also use no hydrocarbons per mile.

Methanol fuel cell vehicles extract their hydrogen from fossil fuel so they do produce some emissions, but considerably fewer than gas or diesel. On a per mile basis, Methanol fuel cell vehicles produce the same amount of water vapor as hydrogen fuel cell vehicles. Methanol fuel cells produce about 15 percent the carbon dioxide, and less than one percent the carbon monoxide and nitrous oxides of the average gasoline powered car.

Additionally, they only consume one tenth of one percent the mass of hydrocarbons of a conventional car for every mile it is driven. From an energy efficiency and conservation standpoint, fuel cell vehicles use much less fossil fuels than other technologies.


How do fuel cells work and what kinds of emissions do they produce? They must produce some type of by-product from the chemical reaction that takes place within them. How do the emissions from fuel cells compare with those of fossil fuels? Do fuel cells create CO2 emissions or are they different, less harmful emissions? I think the prospect of fuel cell vehicles sounds promising, but I do not know enough about the technology to make my own opinion.

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    • The EGR valve recirculates vapors to help prevent excess pollutants from being released in a car.
      By: Negaro Imaging
      The EGR valve recirculates vapors to help prevent excess pollutants from being released in a car.
    • Fuel emissions are a result of burning fossil fuels.
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      Fuel emissions are a result of burning fossil fuels.
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