What is Clean Diesel?

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About Clean Diesel


Diesel moves approximately 70 percent of the nation's freight tonnage, and nearly all highway freight trucks are powered by diesel engines.

Today, there are 711,000 trucking companies that rely on 3.5 million drivers to deliver for the U.S. economy. Three out of four trucks on the road are powered by diesel and 98 percent of the large over-the-road Class 8 trucks are diesel. Over the last 20 years, emissions from heavy-duty diesel trucks, buses and other vehicles have been reduced by 95 percent for nitrogen oxides (NOx) - an ozone precursor - and 90 percent for particulate emissions. It would take 60 new trucks to generate the same emissions as a single truck manufactured in 1988!

60 trucks infographic


HD Benefits Infographic


The newest generation of clean diesel vehicles is a growing portion of the total diesel commercial truck population. About one in every three diesel commercial vehicles on the road in the United States is now equipped with the newest technology clean diesel engines - those manufactured beginning in model year 2010 that have near zero emissions of NOx and particulate matter.

A new generation of clean diesel technology is fueling those trucks that reduce emissions including greenhouse gas (GHG) emissions while saving fuel as more truckers invest in new technology clean diesel engines.

Over the past couple of years there has been a lot of speculation about a revolution in fuels and technology in the trucking industry. The 2018, year-end U.S. truck vehicles-in-use data shows that almost about 75 percent of all commercial vehicles are powered by diesel engines, and among the largest trucks (Class 8) diesel vehicles-in-use accounted for 97 percent of the overall population. So it appears that the ‘revolution’ is that truckers are choosing new clean diesel truck technology in increasing numbers over all other fuel sources.

In fact, the Fuels Institute predicts that diesel will continue to be the standard powertrain and fuel powering commercial vehicles in the future. Diesel also provides a unique technology platform suitable for expanded use of hybrid powertrains and lower-carbon renewable fuels - both strategies for reducing GHG emissions that will continue to expand in the future.

Diesel power is the driving force today of goods movement by truck in our economy and diesel will play a central role in efforts to reduce fuel consumption, promote energy security and lower GHG emissions in the years ahead. 

Clean Diesel Progress

While continuously making commercial trucks more fuel efficient, diesel engine and truck manufacturers have also been making them dramatically cleaner, a significant accomplishment considering that increased fuel efficiency and lower emissions are near opposite and competing forces in diesel engine design. In fact, diesel vehicles manufactured after 2010 achieve an average 5 percent improvement in fuel economy resulting in petroleum reduction equivalent to 5.8 billion barrels of crude oil. An owner of a single Class 8 truck powered by the latest clean diesel engine can expect to save about 960 gallons of fuel each year compared to previous generations of technology. Additional fuel-saving strategies are being developed to improve efficiency, including further engine refinements, vehicle aerodynamics and expanded use of hybrid technology for some applications.

New diesel vehicles are increasing their penetration in the marketplace because they are more fuel efficient, in part, due to meeting the requirements of Phase 1 of the U.S. Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) Fuel Efficiency standards that went into effect in 2014. Manufacturers are also investing new technologies including new engine designs to meet Phase 2 of these rules that kick-in in 2021.

In August 2011, U.S. EPA/NHTSA established a national program to reduce GHG emissions and establish new fuel efficiency standards for commercial vehicles beginning in 2014 through 2018. Because of the sheer magnitude of commercial vehicles operating in the United States, this regulation has the potential to result in significant emissions reduction and energy efficiency gains. The U.S. fleet of trucks consumes about 22 billion gallons of diesel fuel every year. Over the lifetime of the vehicles affected by the new rule, the program is expected to reduce oil consumption by more than 530 million barrels, result in more than $50 billion in net benefits, and reduce carbon dioxide emissions by 270 million metric tons.

Those Phase 1 rules are now implemented beginning with model year 2014. Manufacturers are meeting these targets through continued advancements in engine and aftertreatment technologies along with advanced aerodynamics, transmission, tire and other technologies that improve fuel economy. According to NHTSA, technologies deployed to meet these rules will improve fuel economy for a typical long haul tractor by 20 percent by 2018. Meanwhile fuel economy among many vocational vehicles will improve by 10 percent and many work trucks by 15 percent by 2018.

In October 2016, EPA and NHTSA announced the final rule for Phase 2 of fuel economy and greenhouse gas emissions reduction from the heavy-duty fleet. These proposed rules would apply beginning in 2021 through 2027 and are anticipated to further improve fuel economy and save 2 billion barrels of crude oil. Over the lifetime of the proposed rule, diesel is expected to remain the dominant powertrain and fuel. Technologies envisioned to attain the proposed standards will help further advance diesel's well established fuel efficiency credentials.

Read more - While All Eyes are on Phase 2 Let’s Not Forget About Phase 1

While new engines and vehicles are getting cleaner, technologies to reduce emissions from older vehicles are now widely available. Through the use of retrofit upgrades, older diesel engines can improve their performance and reduce key emissions by up to 90 percent. More information on retrofit technology and ongoing programs can be found in the Forum's Online Retrofit Tool Kit.

For additional information about engine certification standards and government regulations, visit the Truck & Engine Manufacturers Association (EMA) website.


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