Above: TRC Graduate Scholar Tyler Feralio (top right) explains his work in the TAQ Lab

Are biodiesel vehicle emissions less damaging to human health than burning petroleum-based diesel?  Do hybrid vehicles have lower tailpipe emissions compared to traditional gas-fueled vehicles?  These are the types of questions that students in UVM’s Transportation Air Quality (TAQ) Laboratory are taking big strides to answer.  As part of an ongoing effort of the TRC Graduate Scholars to learn about each other’s work and find opportunities to utilize the expertise and experience of their peers, on December 7, 2012, the scholars took a peer-guided tour of UVM’s TAQ Lab.  The TAQ Lab is supervised by Associate Professor Britt Holmén in the School of Engineering (environmental engineering) who specializes in measurement and modeling real-time, real-world vehicle emissions from alternative vehicles and fuels.

TRC Graduate scholar Tyler Feralio, a PhD candidate in civil and environmental engineering and this year’s UVM TRC Student of the Year, and Karen Sentoff, M.S. candidate, also in civil and environmental engineering, led the group through their respective work in the TAQ lab.  Using advanced particle and gas pollutant sampling equipment, the TAQ lab researchers focus on quantifying transient emissions from alternative vehicle types under real-world operating conditions.   Two types of vehicles are studied - a gasoline-powered hybrid-electric vehicle and a light-duty diesel engine running different blends and feedstocks of biodiesel.   

As part of the TAQ Lab team, Sentoff’s research measured tailpipe emissions from a model year 2010 Toyota Camry hybrid electric vehicle and its conventional counterpart.   Over an 18-month campaign, she drove the vehicles along the same real-world route while instrumented with state-of-the-art equipment measuring gas- and particle-phase emissions every second.  The results of this research will provide needed information on tailpipe emissions contributions of the hybrid vehicle to air quality over broader ranges of road grade and temperature encountered in regions like Vermont with steeper terrain and wider seasonal temperature fluctuations than current data sources.

 Above: (Left) TAQ Lab sampling equipment utilized in light-duty diesel engine emissions testing

(Right) Particle spectrometer for high-speed (1 Hz) tracking of exhaust particle size distributions

Feralio’s ongoing research in the TAQ Lab includes the comparison of transient tailpipe emissions from a light-duty diesel engine resulting from the combustion of both petroleum-based diesel fuel and blends of different feedstock (soy and waste grease) biodiesel fuels.  Feralio has developed a system to accurately collect transient tailpipe emissions data from a 1.9L Volkswagen diesel engine coupled to an eddy current dynamometer.  He is currently preparing to embark on a 20-week data collection campaign to compare the particulate emissions generated by the engine running on petroleum based diesel and multiple blends of both used cooking oil (UCO) and soybean oil methyl ester (SME) biodiesels.  Using the data collected during this period, Tyler will build and test an artificial neural network (ANN) model to predict the size and abundance of ultrafine particles emitted based on standard onboard diagnostics (OBD-II) parameters that the engine’s computer monitors.  This model is expected to be capable of running in real time.  If this is realized, such a model could be utilized for more advanced pollution control and engine management systems.

Above: John Kasumba, PhD candidate in environmental engineering, explains his work in testing emissions

The tour group next visited a nearby laboratory, where Feralio’s work meets with that of John Kasumba, a PhD candidate in environmental engineering.  Kasumba works as a graduate research assistant with Professor Holmén to characterize the specific organic compounds created by engines burning petro-diesel versus vegetable oil-based biodiesel. He is particularly interested in testing for compounds that may have negative effects on human health and examining their levels in combustion products from biodiesel fuel blends. Kasumba looks to expand on limited research on potential harmful emissions from biodiesel, such as carbonyls, which may be produced in higher quantities from biodiesel than petro-diesel.  His work has included developing methods for some of these testing procedures and will soon proceed to testing particle samples generated by Feralio.

Through their efforts, these TAQ Lab graduate students contribute to research on vehicle emissions, creating critical knowledge in this area, covering the use of biodiesel and petro-diesel fuels, as well as hybrid and conventional gasoline vehicles.

For more information about the TAQ Lab research, contact Professor Britt Holmén at bholmen@uvm.edu.