Yahoo Autos What is diesel fuel? Is it better than gasoline, and why is it so expensive?
Diesel fuel powers the country. If that sounds dramatic, think of all the trucks, buses, and ships you see every day. Most of them carry diesel engines instead of the gasoline engine or electric drivetrain that your car probably has. It’s also used in generators and to power agricultural vehicles, making it one of the most important fuels of our time.
Gas and diesel engines are both internal combustion, which use a mixture of air and fuel. The cocktail is compressed by the engine’s cylinders and ignites. Spark plugs are used in gasoline engines to create the spark for ignition, but diesel engines don’t have them. They do have something called glow plugs to get the engine started up, and after that they use high compression ratios to crank up the heat, which can damage gas engines.
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Because of this process, diesel engines are typically more fuel-efficient than gas engines. They also generate more torque at the same time, giving them pulling power that gasoline engines can’t muster. The extra rotating force at low speeds helps large trucks pull trailers up hills and start off the line.
Diesel fuel originated as a byproduct of the refining process for paraffin. At first, the fuel was discarded as waste, as no one could figure out what to do with it. It wasn’t until a man named Rudolf Diesel created an engine that could burn the stuff that it became useful as fuel.
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Today, diesel is refined from crude oil and averages between 11 to 12 gallons of production from a 42-gallon barrel of oil. The United States also produces a large quantity of biomass-derived fuels from materials like vegetable oils and animal fats. This is why you see people converting old Mercedes-Benz diesels to run on used deep-fryer oil and similar materials.
Why is diesel so expensive?
One major reason diesel usually costs more to purchase in the United States than gasoline is that diesel is taxed at a higher rate. The Federal tax rate for diesel sits at 24.3 cents per gallon, compared to 18.3 cents per gallon for gasoline. On top of that, individual states add their own taxes to fuel purchases, and while those amounts vary from state to state, many (but not all) have higher rates for diesel than other fuels.
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Supply and demand also plays a role in diesel fuel prices. While gasoline demand is relatively steady here in the United States, fuel supplier Cenex notes that diesel fuel prices are more likely to go up and down as demand rises and falls. The U.S. Energy Information Administration also notes that today's low-sulfur diesel formulations are costlier to produce than older fuels.
