UCR’s CE-CERT Study Highlights Natural Gas for Emissions Reduction in Heavy-Duty Trucks

September 7, 2018

An ACT News Executive Interview with Kent Johnson, Assistant Research Engineer, University of California, Riverside College of Engineering Center for Environmental Research and Technology (CE-CERT), Riverside, California

The last week of August, CE-CERT and Southern California Gas (SoCalGas) announced the results of a new study on ultra-low emission natural gas heavy-duty engines. Tests of a new 11.9-liter engine, made by Cummins Westport (CWI), have shown it is the only heavy-duty engine in this category to not only meet, but exceed, the California Air Resources Board’s cleanest optional low-NOx standard of 0.02 g/bhp-hr.

Kent, who has worked in CE-CERT’s research and emissions testing laboratories since 1993, led the tests on the near-zero emission natural gas engine, demonstrating that the ISX12N near-zero engine achieves California’s lowest smog-forming emissions standard, and maintained those emissions during all types of driving.

Kent joined CE-CERT’s research faculty in 2009 after serving on the Center’s staff as Principal Development Engineer and manager of the Mobile Emissions Laboratory (MEL) for 16 years. He received his Ph.D. in Chemical and Environmental Engineering from UC Riverside where his doctoral research focused on the impact of real world emissions on ambient air quality.

Kent led the tests on the near-zero emission natural gas engine, demonstrating that the ISX12N near-zero engine achieves California’s lowest smog-forming emissions standard, and maintained those emissions during all types of driving.

During his career, Kent has created a comprehensive program for the evaluation of portable emissions monitoring systems (PEMS) that has had impacts at both the national and international levels. He manages research programs that involve emissions from all mobile sources under real world conditions (heavy and light duty vehicles, marine, locomotive, and many others). He also manages research programs that include operation of specialized equipment such as chassis and engine dynamometers and various advanced measurement methods.

ACT News caught up with Kent to learn more about the study on a day he was headed to the San Pedro Bay Ports for a meeting. This led him to comment on how air quality near ports and in urban settings can benefit from the ISX12N engine fueled with natural gas in heavy-duty trucks by lowering NOx emissions.

ACT News: The UCR report that was released the last week of August, 2018, titled “Ultra-Low NOx Near Zero Natural Gas Vehicle Evaluation ISX12N 400” was based on testing the Cummins Westport ISX12N (Near-zero) 11.9-liter ultra-low NOx natural gas engine in a heavy-duty Class 8 truck. What was the goal and how was the testing approached?

Kent Johnson: The goal with this 12-liter engine was to look at how heavy-duty trucks operate in urban areas, and how do we lower NOx emissions. Our world is becoming very urban; most of the population is living in urban areas, because that’s where the work is.

We chose to use test engine duty cycles from port activities, as ports are central to many urban settings, with some of the biggest industries and businesses close to ports. Emissions are always higher in regions close to ports; one reason is all the heavy-duty trucks and diesel engines.

The results of the UCR study really underscore how important it is to employ engine technologies that help clean the air like these near-zero natural gas engines.

We wanted to test the duty cycles that are representative of the South Coast Air basin, which includes the Ports of Long Beach and Los Angeles. We evaluated regulated and non-regulated emissions, ultrafine particles, and global warming potential. Fuel economy was also considered. The testing was done with a dynamometer that simulated various driving conditions. We simulated port drayage duty cycles, due to the industry pattern of idling, low speeds, and short regional distances.

We use laboratories to test and compare between engine technologies. I’ve tested other technologies on these port cycles, to see how representative they would be operating in the Southern California ports. Natural gas is the solution for lowering NOx.

ACT News: You’ve done groundbreaking work on the Cummins Westport near zero engines, finding both the 9-liter and 12-liter engines achieved California’s lowest smog-forming emissions standard, and maintained those low emissions during all types of driving. What key message do you have for the industries who drive Class 8 trucks in California?

Kent Johnson: Natural gas is a great choice for heavy-duty trucks, when you look at the technologies we have available today. It’s a great 10-year choice for now. Other technologies are being tested, we aren’t sure yet which will become commercially viable in real world use. Maybe a mix of technologies is the way to go now. If you were hypothetically going to buy 100 trucks, maybe purchase 90 natural gas trucks, and 10 electric trucks, as we see how technologies advance.

When you look at the impacts of poor air quality on human health, it’s a problem we have to solve.

From an academic point of view, after testing these natural gas engines, combined with the availability of renewable natural gas in California, the data shows for NOx reductions that natural gas is the safe, wise choice.

ACT News: Why is it important to note the testing showed the NOx emissions did not increase with lower power duty cycles, in fact, showing the opposite trend, as compared to diesel engine counterparts?

Kent Johnson: The natural gas engine operates the same for NOx, no matter what speed the truck is driving. When you are 2 miles out from the port and most likely driving in congestion, or 10 miles out, or 100 miles out, the NOx remains the same.

That isn’t true for diesel engines in heavy-duty trucks. When diesel trucks operate in low-speed, low-load operations, the engines don’t get hot enough, which puts a lot of burden on the truck. The engines emit more NOx in these conditions.

ACT News: How can driver behavior contribute to lowering NOx emissions while driving a truck with this engine?

Kent Johnson: With the CWI engine emissions level at 0.02, anything the driver does that is aggressive while driving will exceed this number. If a driver is accelerating hard or braking hard, it will add to the NOx emissions.

How important is it for California to find ways to reduce smog and emissions from the transportation sector?

Kent Johnson: When you read the reports from the agencies such as South Coast Air Quality Management District (SCAQMD) and the Alternative Fuel Data Center (AFDC), they stress the impact that transportation has on air quality and the atmosphere. As an academic, there is some debate on the models being used to measure what is happening regarding air quality and the ozone. But, we know we have a problem. When you look at the impacts of poor air quality on human health, it’s a problem we have to solve. The results of the UCR study really underscore how important it is to employ engine technologies that help clean the air like these near-zero natural gas engines.