What is Clean Diesel?

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About Clean Diesel

What is Clean Diesel?

Cleaner diesel fuel, advanced engines and effective emissions control technology make up a new generation of diesel. It's clean diesel.

What is clean diesel?

What makes it different from regular diesel?

Clean diesel is the new generation of diesel technology.

Today’s cleaner diesel fuels, advanced engines and effective emission controls combine to achieve near zero emissions for fine particles and smog forming compounds like oxides of nitrogen (NOx). Clean diesel’s proven energy efficiency and ability to use renewable fuels position diesel as a key technology achieve cleaner air, lower greenhouse gas emissions and a sustainable environment around the world.

Cleaner diesel fuel, advanced engines and effective emissions control make up a new generation of diesel. It's clean diesel.

Cleaner Diesel Fuels

Today, ultra-low sulfur diesel fuel - containing 97 percent less sulfur - is now the standard for both on-highway and off-highway diesel engines nationwide. Using this cleaner diesel (ULSD) immediately cuts soot emissions from diesel vehicles and equipment by 10 percent. Reducing the sulfur content of diesel fuel is similar to removing lead from gasoline during the 1970s.

Cleaner diesel fuel enables the development of a new generation of advanced engines and emission control devices that can't operate effectively with higher sulfur content in diesel fuel. 

Cleaner diesel fuel is more than just cleaner petroleum diesel. Diesel engines are capable of operating on advance biofuels like biodiesel and renewable diesel fuels that are capable of reducing greenhouse gas emissions by at least 50 percent.

Why is diesel technology so fuel efficient?

A combination of the energy-rich properties of the fuel and the completeness of the combustion of fuel to create useful mechanical energy. ULSD is a petroleum-based fuel with the highest energy density among transportation fuels - that's more energy per gallon than other alternatives. The U.S. Energy Information Administration states that few transportation fuels surpass the energy density of diesel. Even advanced biofuels including biodiesel and renewable diesel have energy densities far superior than other alternatives.

Energy Density Graph

Read DTF's Diesel Fuel Study - Diesel: Fueling the Future in a Green Economy.

Advanced Engines

Diesel is the world's most efficient internal combustion engine. It provides more power and fuel efficiency than alternatives such as gasoline, compressed natural gas or liquefied natural gas. Read more about the history of the diesel engine.

Fuel combustion is the primary difference between gasoline and diesel engines. Gasoline engines ignite fuel with spark plugs, whereas diesels ignite fuel with compression. Inside the engine, the combustion of air and fuel takes place under pressure and heat created by compressing the air-fuel mixture so intensely that it combusts spontaneously, releasing energy, that is transmitted to powering the wheels on a vehicle, the piston's motion and creating mechanical energy.

Advanced new technologies such as electronic controls, common rail fuel injection, variable injection timing, improved combustion chamber configuration and turbocharging have made diesel engines cleaner, quieter and more powerful than past vehicles.

Effective Emissions Control

After decades of research and innovation, a variety of emission controls are available to deliver near-zero emissions standards. 

Introduction of cleaner diesel fuels for both on- and off-road applications is a central part of the clean diesel system designed to meet near zero emissions standards. With the introduction of lower sulfur diesel fuel came the ability to use a number of exhaust aftertreatment options such as diesel particulate filters (DPF), exhaust gas recirculation (EGR), diesel oxidation catalysts (DOC), and selective catalyst reduction (SCR) with the use of diesel exhaust fluid (DEF) that can be sensitive to the sulfur levels in the fuel.

The installation of various emission control technologies may also improve emissions from older diesel engines through retrofit capabilities. Read more about retrofit capabilities to reduce emissions from older vehicles and equipment.


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