My interests are
broadly in energy and environmental systems, including: modeling and evaluation of advanced
energy conversion (e.g.,combustion, gasification)
and environmental control systems; measurement and modeling of real-world
fuel use and emissions of onroad and nonroad vehicles; development and
application of methods for quantification of variability and uncertainty
and for sensitivity analysis in systems models; and exposure and risk
analysis. Air pollutant emissions of
interest include criteria pollutants, hazardous air pollutants (“air
toxics”), particulate matter, and greenhouse gases. More details on my teaching, current and past research activities, publications,
activities, research group, and computer laboratory are available in the links above.
[link to CCEE department webpage for Dr. Frey]
Follow Dr. Frey on LinkedIn, ResearchGate, ORCID, Scopus, and Google Scholar.
Dr. Frey spoke as an invited lecturer in the 2015 Warren
Lecture Series at the University of Minnesota on October 16, 2015. His lecture regarding “Measurement and
Modeling of Real-World Onroad Vehicle Activity and Emissions” is available
as a YouTube video.
Dr. Frey, who chaired the EPA Clean Air Scientific
Advisory Committee (CASAC) and the CASAC Ozone Review Panel, answers some
of the most frequently
asked questions about the scientific review completed in 2014 of the
National Ambient Air Quality Standard for Ozone. EPA Administrator Gina McCarthy announced
the final ozone rule
on October 1, 2015.
Many of Dr. Frey’s current and recent students were active participants and presenters at the June 2015 Annual Meeting
of the Air & Waste Management Association, held
at the Raleigh Convention Center.
Dr. Frey was chair of the Student Program for this meeting.
Dr. Frey’s research on the effect of biofuels on emissions from diesel railroad
locomotives was featured in CCEE News.
Dr. Frey shared a best paper award at the 2015 Annual
Meeting of the Transportation Research Board.
Dr. Frey and colleagues developed a new modeling framework for estimating the
effect of transportation infrastructure, traffic control measures, and
traffic operations on vehicle emissions.
Five recently published journal papers:
Che, W., H.C. Frey, and A.K.H. Lau, “Comparison of
Sources of Variability in School Age Children Exposure to Ambient PM2.5,”
Environmental Science and Technology, 49(3):1511–1520, DOI:
Liu, B., and
H.C. Frey, “Quantification and Application of Real-World Light Duty Vehicle
Performance Envelope for Speed and Acceleration,” Transportation Research
Record, 2503:128-136. DOI: 10.3141/2503-14 (2015)
Liu, B., and
H.C. Frey, “Variability in Light Duty Gasoline Vehicle Emission Factors
from Trip-Based Real-World Measurements,” Environmental Science &
Technology, “Just Accepted” publication, published online September 24,
2015. 10.1021/acs.est.5b00553 (2015)
N.M. Rouphail, H.C. Frey, B. Liu, and B.J.
Schroeder, “A Simplified Method for Comparing Emissions at Roundabouts and
Signalized Intersections,” Transportation Research Record, 2517:48-60. DOI:
Zhou, X., S. Tanvir, H. Lei, J. Taylor, B. Liu, N.M. Rouphail, and H.C. Frey, Integrating a Simplified
Emission Estimation Model and Mesoscopic Dynamic Traffic Simulator to
Efficiently Evaluate Emission Impacts of Traffic Management Strategies,
Transportation Research – Part D, 37(2015):123-136 doi:10.1016/j.trd.2015.04.013