Overview

The Emissions and Fuels research team at CE-CERT, including national and international research leaders, is applying advanced technologies and methods to the measurement of emissions from all types of engines, including cars and light-duty trucks, heavy-duty freight trucks and construction equipment, and the large engines that power marine vessels. CE-CERT has considerable experience with successfully completing complex projects that involve elements of laboratory testing, fieldwork, activity measurements, and PEMS evaluations and implementations.

Research Projects

• Renewable Diesel for Off-Road Diesel Engines

  The purpose of this study is to better understand emissions and performance effects from renewable diesel and NOx-mitigated biodiesel relative to CARB ULSD. This study proposes to conduct detailed emissions testing on various renewable diesel blends (and potentially biodiesel blends) on heavy-duty off-road engines, with and without SCR exhaust treatment and diesel particulate filters (DPF) using an engine dynamometer. This study would focus on the physical and chemical characterization of particulate emissions and gaseous toxic pollutants from two off-road engines, one equipped with SCR and DPF aftertreatment systems and one older Tier 2 engine without aftertreatment system. SCAQMD will build upon the work UCR and CARB will be conducting in order to investigate the emissions of renewable diesel from newer technology off-road engines.

  Lead Researcher: Dr. Georgios Karavalakis Co-researcher: Dr. Kent Johnson

• Evaluation of PM and PN emissions from light-duty GDI vehicles using PEMS

  For decades, dynamometer based measurements of vehicle and engine emissions during driving cycles have been the standard method of verifying vehicles and engines are meeting current federal regulations. These same emissions measurements and driving cycles have been used as the basis to estimate emission inventories or the total pollutant emissions in a particular area due to the use of a given population of vehicles at a defined time and set of conditions. However, use of a set of average or typical driving cycles that were designed more than 20 years ago does not necessarily give an accurate estimate of everyday vehicle use. Nor do they provide typical power demands on the vehicle’s engine [1-2]. Currently, there is an increased concern in both the US and EU about the degradation of the actual atmospheric pollution levels of nitrogen oxides (NOx) and particulate matter (PM) in spite of the stricter vehicle emission limits in recent years. Differences between conditions for chassis or engine test cycles defined by vehicle emission regulations and real driving can contribute to the differences between expected and actual pollution levels. Recent air quality studies show significant exceedances for NOx and PM emissions, mainly in urban areas with high populations where emissions are mainly contributed by transport sources. Portable emission measurement systems (PEMS) were introduced and have been used for the purpose of investigating and regulating real driving emissions (RDE) of vehicles. PEMS are becoming an important regulatory tool, as evidenced by recent developments in the US and EU. The California Air Resources Board (CARB) and the Environmental Protection Agency (EPA) are also conducting tests with PEMS here in the US with heavy duty on-road and light-duty vehicles to determine their viability to measure real world on-road emissions. This is in addition to the normal Federal Test Procedure (FTP-75), Highway Fuel Economy Test (HWFET), and US06 Supplemental Federal Test Procedures (SFTP) chassis dynamometer testing. The goal of this study is to investigate the PM mass and particle number emissions from current technology GDI vehicles during on-road testing. Testing will be conducted on 3 GDI vehicles of different technologies and model years using state-of-the-art PM and PN-PEMS units. Emissions will be measured over different driving conditions mimicking urban, rural, and highway driving patterns. For each vehicle and for each test route, on-road testing will be performed three times to validate tailpipe emissions

  Lead Researcher: Dr. Georgios Karavalakis Co-researchers: Dr. Kent Johnson, Dr. Thomas Durbin 

• Evaluation of PM and PN emissions from a light-duty GDI vehicles with GPF using PEMS

  Currently, there is an increased concern in both the US and EU about the degradation of the actual atmospheric pollution levels of nitrogen oxides (NOx) and particulate matter (PM) in spite of the stricter vehicle emission limits in recent years. Differences between conditions for chassis or engine test cycles defined by vehicle emission regulations and real driving can contribute to the differences between expected and actual pollution levels. Recent air quality studies show significant exceedances for NOx and PM emissions, mainly in urban areas with high populations where emissions are mainly contributed by transport sources. Portable emission measurement systems (PEMS) were introduced and have been used for the purpose of investigating and regulating real driving emissions (RDE) of vehicles. The goal of this study is to investigate the PM mass and particle number emissions from a current technology GDI vehicle retrofitted with a gasoline particle filter (GPF) during on-road testing using state-of-the-art gaseous, PM, and PN-PEMS units. Emissions will be measured over different driving conditions mimicking urban, rural, and highway driving patterns. For the GPF-fitted vehicle and for each test route, on-road testing will be performed three times to validate tailpipe emissions.

  Lead Researcher: Dr. Georgios Karavalakis

• SOA Forming Potential from HD Diesel Vehicles and HD Natural Gas Vehicles

  This program will investigate the physical and chemical composition of secondary emissions from 2 natural gas trucks and 2 modern technology diesel trucks over realistic driving conditions. The proposed study will complement the major 200 vehicle program funded by SCAQMD. Primary organic aerosol (POA) will be measured for all heavy-duty vehicles over different driving cycle using a chassis dynamometer. The primary emissions testing using CE-CERT’s Mobile Emissions Lab (MEL) and heavy-duty chassis dynamometer will be covered under the base SCAQMD program. Emission measurements will include regulated pollutants, PM mass, total particle number, solid particle number in accordance to the PMP protocol, black carbon, and particle size distributions, as well as carbonyl compounds. For each vehicle, the exhaust will be collected in CE-CERT’s mobile chamber and subsequently photochemically aged. This proposal will expand on SCAQMD’s funding for evaluating in-use emissions from current technology natural gas and diesel trucks and for evaluating secondary organic aerosol (SOA) formation from GDI vehicles, including ethanol fueled GDI vehicles. The proposed work will use the mobile environmental chamber with on-line gas and particle phase instrumentation to include detailed physical and chemical characterization of primary and secondary aerosol (e.g., POA and SOA) from heavy-duty vehicles. There are three novel aspects for this program: (1) characterizing current generation heavy-duty vehicles, since most previous studies have focused on light-duty vehicles/engines, and (2) characterizing the SOA forming potential from natural gas trucks. To the best of our knowledge, this will be the first study looking at the impacts of natural gas heavy-duty vehicles on SOA formation and ultimately their impact in air quality. Characterizing aerosols from heavy-duty diesel and natural gas vehicles is an important step in understanding air quality in our region. Heavy-duty trucks are important sources of volatile and semi-volatile organic compounds (VOCs and SVOCs), NOx, CO, and particulate matter (PM) that represent a significant contribution to SOA and ozone formation in the atmosphere. Secondary organic aerosol formed from atmospheric reactions of volatile and semi-organic compounds in the presence of NOx constitutes an important component of suspended fine atmospheric particulate matter that impacts visibility, climate, and health. Studies have shown that in California diesel emissions from heavy-duty vehicles contribute to primary organic aerosol (POA), but not detectably to SOA, while gasoline vehicles are the main source of SOA formation (Bahreini et al., 2012). However, there is a gap in the literature about the actual effects of primarily natural gas heavy-duty vehicles and diesel trucks.

  Lead Researcher: Dr. Georgios Karavalakis Co-researcher: Dr. David Cocker 

• Real-world tire and brake wear emissions

  The RFP calls for diverse expertise in vehicle emissions, real time particle measurement, filter sampling, source apportionment, and dispersion modeling. The main aim of this project is to understand chemical and physical nature of non-exhaust PM specifically brake and tire wear PM in the real-world measurement in comparison to well-controlled laboratory characterization. The team, composed of five leading experts, aims to tackle a multitude of questions regarding brake and tire wear PM. A literature survey will be conducted to identify knowledge gap in estimating real-world tire and brake wear PM contributions. Measurements will be conducted at two roadside locations representing light and heavy duty vehicle corridors, respectively. Particle size distribution, mass concentration and elemental composition will be acquired in real-time, and filter samples will be collected for detailed characterization of PM composition. Road dust, tire wear, and brake wear PM samples will be obtained to derive source profiles. Detailed traffic information analysis will be conducted to translate traffic information into the composition of vehicles and brake activities. A novel hybrid environment receptor model with combined benefits of positive matrix factorization (PMF) and effective variance chemical mass balance (EV-CMB) models will be used to apportion measured concentrations to contributing sources, including tire and brake wear PM. Emissions factors will be determined based on carbon balance and distance traveled. Detailed dispersion modeling will be performed to assess impact of brake and tire wear PM to nearby downwind communities.

  Lead Researchers: Dr. Heejung Jung Co-researcher: Guoyuan Wu

• Pollutant Emission Rates from Maritime Sources

  The task includes quantifying real-world emissions from individual CHC operating in California. Previously, CARB staff has assumed real-world emissions follow the measurements recorded during the engine certification cycle; however, DPM and NOx emitted from CHC may be higher in the real world than during certification even when accounting for expected deterioration of emission control systems. A Portable Emissions Measurement System (PEMS) will be used to characterize emissions from three (3) CHC vessels for CARB’s inventory modeling. In an effort to choose the most appropriate vessels to characterize in more detail using PEMS, UCR will work with CARB staff to choose vessels based on emission factor data from the pool of vessels characterized using remote sensing methods done by other team members with separate budgets. UCR will measure DPM and NOx emissions over transient operation conditions over 2 consecutive weeks for three CHC vessels. UCR will analyze the data and report the result to ARB and the team. This project includes UCB, USC and UCR. UCB is a leading institution (and others are subcontractors) for contract purpose and each institution has a separate SOW. The above is SOW for UCR.

  Lead Researcher: Dr. Heejung Jung