Saving diesel fuel while reducing emissions? Thank SCR and DEF

Allen Schaeffer, Engine Technology Forum
4 hours ago
2 min read

It hurts. Pain at the pump is widespread, with the national average for regular gasoline reaching $4.50 per gallon, up $1.38 from a year ago.

For truckers, farmers and anyone pumping diesel, the national average is $5.64 per gallon, up $2.16 from a year ago, according to the latest data from the U.S. Energy Information Administration.

Higher fuel prices are trickling through the economy and bringing a renewed focus on fuel savings.

Ninety-seven percent of all commercial trucks are powered by diesel, making it the lifeblood of the economy.

The largest big rigs haul about 40,000 pounds of cargo per trip, travel roughly 120,000 miles each year, and consume more than 15,000 gallons of fuel annually.

Today, more than two-thirds of all Class 3-8 vehicles are 2010-model-year or newer.

These advanced engines feature fully integrated selective catalytic reduction (SCR) systems that require the use of diesel exhaust fluid (DEF).

According to numerous studies and reports, advanced diesel engines equipped with SCR/DEF technology achieve 3 percent to 5 percent better fuel economy than older engines without this system.

At any price, the savings are significant for truckers using 5 percent less diesel fuel than older generations while consuming more than 15,000 gallons of diesel annually.

Since about 2014, off-road engines and equipment have also utilized SCR/DEF technology in roughly half of all machines, creating savings for farmers using tractors and other equipment with SCR systems as well.

The technology is effective because it enables engines to be tuned and optimized for fuel economy and performance while relying on the efficient SCR/DEF system to reduce emissions at the tailpipe.

Rising fuel prices are not the only issue today.

Recent changes in vehicle-emissions policy have raised concerns about maintaining clean-air progress while still meeting federal health-based standards.

Here, SCR/DEF technology delivers more than just fuel savings—it also helps provide cleaner air across the country.

SCR/DEF is a major contributor to clean air, helping reduce 79 percent of smog-forming emissions.

In 2010, heavy-duty diesel vehicles accounted for 65 percent of all U.S. nitrogen-oxide (NOx) emissions, which contribute to ozone formation.

By 2022, the introduction of advanced diesel engines with SCR led to a 76 percent reduction in NOx emissions from highway vehicles and a 42 percent reduction from off-highway engines and equipment.

Combined, the NOx-emissions reductions from these two sectors account for 79 percent of the total U.S. NOx emissions reduction since 2010. (See 2005 and 2022 maps below.)