More than 70% of the nation’s freight is transported by large commercial trucks. While ground transportation may be a popular choice for delivery, it isn’t the cleanest. According to the U.S. Environmental Protection Agency, medium- and heavy-duty vehicles such as tractor-trailers, buses and vocational vehicles are the largest mobile source of nitrogen oxide (NOx) emissions. NOx is known for creating air pollutants such as smog, carbon monoxide and other toxins.

However, an environmentally friendly solution may emerge within the next decade with the help of a UCF researcher.

Engineering Professor Subith Vasu is working with commercial truck manufacturer PACCAR, owner of the Peterbilt and Kenworth brands, to create a hydrogen-based combustion engine for heavy-duty vehicles. The project is funded through a $3.5 million grant from the U.S. Department of Energy and is the agency’s first effort to develop hydrogen combustion engines for commercial trucks.

“We’re fortunate to be part of this project,” Vasu says. “It’s a very prestigious effort for UCF, to be part of this project that’s highly relevant in the decarbonization of transportation efforts around the globe. It will also be a great opportunity for students to get involved with an industry-funded project.”

The Demand for Hydrogen

For decades, diesel has been the fuel of choice for large commercial vehicles. But in recent years, the government has pushed for a cleaner alternative. In 2021, President Biden appropriated $62 billion to the DoE, including $9.5 billion for clean hydrogen solutions as part of the Bipartisan Infrastructure Bill. Over this past year, the Environmental Protection Agency also tightened its NOx emissions standards for heavy-duty commercial vehicles beginning with 2027 model year equipment.

While Tesla has developed a semi-truck that runs on electric motors, Vasu says there are some limits to the weight it holds and the distance it can travel.

“Tesla is developing electric supercars and semi-trucks, but there are limits to the batteries,” Vasu says. “They’re fine for driving down to the nearest town but driving from Seattle to Miami, you need significant battery power, also you don’t have time to wait until it is fully charged since most of these freightliners are under time pressure.”

Building a Better Engine

Hydrogen can solve the problem of a longer-lasting battery, but PACCAR currently has more questions than answers. How will hydrogen behave in the extreme temperature and pressure of an engine? Under what conditions will it ignite? Alternatively, what conditions will prevent ignition?

Vasu and his team of researchers will find these answers through experiments run in their state-of-the-art shock tube. The data collected will be used to create computational models to share with PACCAR.

Vasu received his doctorate in mechanical engineering from Stanford University and joined UCF’s Department of Mechanical and Aerospace Engineering in 2012. He is a member of UCF’s Center for Advanced Turbomachinery and Energy Research and is an associate fellow of the American Institute of Aeronautics and Astronautics. Vasu is a recipient of DARPA’s Director’s Fellowship, DARPA Young Faculty Award, the Young Investigator grant from the Defense Threat Reduction Agency, American Chemical Society’s Doctoral New Investigator, American Society of Mechanical Engineers Dilip Ballal Early Career award, and the Society of Automotive Engineers SAE Ralph R. Teetor Educational award. He has received many of the highest honors at UCF, including the UCF Luminary and Reach for the Stars awards.