Diesel fuel tends to conjure up images of smoke-belching vehicles sputtering down the road, but a University of Houston research team is trying to improve the fuel's soiled reputation in the transportation world.
As part of that effort, the UH Texas Diesel Testing and Research Center has received a $1 million grant from the Environmental Protection Agency to test a new technology designed to reduce the amount of ozone pollutants emitted by diesel-powered vehicles and equipment.
The grant money is being used to retrofit 10 school buses operated by the Houston Independent School District and then evaluate the equipment's performance over the next two years in the laboratory as well as on the road.
"Houston is an ozone non-attainment area due, in large part, to the significant amount of nitrogen oxides (NOx) and sooty particles released into the air by diesel-powered vehicles and equipment," said Rachel Muncrief, the grant's lead investigator and a UH research assistant professor of chemical and biomolecular engineering. "Retrofits have the potential to significantly reduce the total annual NOx emissions, and they also provide a cheaper alternative to completely replacing dirty diesel engines."
The EPA grant expands on the research and testing the diesel center has been doing since its inception in 2003.
Located in the UH Energy Research Park just south of the university's campus, the diesel center focuses on testing and conducting applied research on technologies designed to decrease emissions and improve fuel economy on heavy-duty diesel trucks and engines. Researchers test and evaluate how well a new technology performs in actual use and in the laboratory.
"We are focused on clean diesel research and technology development," said Mike Harold, M.D. Anderson professor of chemical engineering and the diesel center's principal investigator. "The public has misconstrued diesel as being dirty - that it's an old technology. What is not being recognized is that diesel is more fuel efficient. So if you can make it burn clean, you're kind of killing two birds with one stone. You save fuel and reduce CO2 emissions on the one hand, and you also have exhaust coming out that's a lot cleaner than it used to be.
"We are working with the federal government and state officials to develop technology from the ground up that would go onto existing diesel vehicles and new diesel vehicles intended to clean the emissions of these devices," he added. "And we wanted to help the state with the mission of cleaning up Houston's air."
The buses will be tested with and without the retrofit equipment to determine the actual reductions in emissions that are being obtained. The retrofit equipment was developed by Nett Technologies, a Canadian-based company.
If the EPA is satisfied with how the new technology works on the school buses, the agency could approve the technology's use on a larger scale, allowing fleets of diesel-powered vehicles to be equipped with the retrofits. The goal of the retrofits is to reduce NOx emissions by 65 percent.
The retrofits are designed to convert NOx into water and nitrogen gas, a naturally occurring substance in the air, by adding a reductant (urea) to the exhaust stream. Sensors measure the amount of NOx present in the exhaust stream and determine the quantity of the reductant needed to produce a chemical reaction that reduces the NOx as it passes over the catalyst, thus releasing a smaller amount of toxins into the environment.
As part of the analysis, UH researchers will conduct at least two on-road tests using their portable emission measurement system as well as attach the buses to the center's chassis dynamometer, a treadmill-like device for vehicles that allows researchers to measure emissions in-house but under simulated realistic conditions. Both tests will help researchers determine just how close the system can come to reducing NOx emissions and other pollutants.
"We're kind of an honest broker of sorts," Harold noted. "We bring in these new technologies, retrofit them on vehicles and then use our expertise to test the emissions of those vehicles with the technologies on them."
Harold said the emissions-testing work isn't a traditional research area for a university.
"We got involved in an activity that would normally be in an industrial venue," Harold said. "But having the capability at UH enables professors and graduate students to get involved in more real-world problems. So we're really complementing the basic research that we have ongoing with the more applied and larger scale testing.
"By bringing these two worlds together, I think we're producing some neat things."
About the University of Houston
The University of Houston is a comprehensive national research institution serving the globally competitive Houston and Gulf Coast Region by providing world-class faculty, experiential learning and strategic industry partnerships. UH serves more than 38,500 students in the nation's fourth-largest city, located in the most ethnically and culturally diverse region of the country.