Zero and Near-Zero Emissions
Overview
The Emissions and Fuels Research team at CE-CERT includes nationally and internationally recognized experts. The team applies advanced technologies and methods to measure emissions from a wide range of engines. These include passenger vehicles, light-duty and heavy-duty trucks, construction equipment, and large marine engines.
CE-CERT has deep experience executing complex emissions research projects. These efforts often combine laboratory testing, field measurements, and vehicle activity analysis. The team also specializes in the deployment and evaluation of portable emissions measurement systems (PEMS) in real-world conditions.
Research Projects
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Medium and Heavy-Duty EV Deployment - Data Collection
Electric vehicle models in the medium-duty (MD) and heavy-duty (HD) categories have grown rapidly in recent years. As this market expands, more fleets are deploying—or considering—electric transit buses, school buses, trucks, and off-road equipment.
Reliable operational and performance data are needed to support research and provide insight into vehicle use and deployment strategies.
This project collects performance and operational data for MD and HD electric vehicles. A smaller subset of light-duty (LD) EVs will also be included. The project builds on deployments underway in several U.S. regions:
Electric transit buses (NY, IL, UT, and CA)
Electric school buses (NY and CA)
Electric trucks (fleet and goods movement operations in CA)
Electric off-road equipment (ports and logistics hubs in CA)
EVs for workplace and clean mobility programs
Data will be collected using onboard data loggers and standardized protocols. The project team will leverage its extensive experience in vehicle data collection.
Various types of loggers may be used. These include CALSTART and CE-CERT-owned units, OEM-installed systems, or third-party telematics. OEM participation will be encouraged to ensure consistent data access.
Collected data will include:
Vehicle performance
Charging activity from off-board chargers
Electricity consumption
Facility operational data
Climate conditions
Vehicle descriptors (make, model, year, battery capacity)
Data will be collected for at least 12 months. It will be stored on CALSTART and/or CE-CERT servers. After collection, it will be verified, cleaned, anonymized, and analyzed using standardized methods.
CE-CERT will work with NREL to define data formats and ensure compatibility with DOE national lab systems. Results will include tables, charts, and visuals. Data will be shared via FTP or secure access with authorized users.
Lead Researcher: Dr. Kent Johnson
Co-Researchers: Dr. Kanok Booriboonsomsin, Dr. Thomas Durbin -
OSAR: Phase 1 Sensor Evaluation on Heavy Duty Trucks
Heavy-duty vehicles are a major source of nitrogen oxide (NOx) and particulate matter (PM) emissions. In response, emissions standards have become more stringent. To meet these limits, many engines now use diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems.
While effective in certification testing, SCR performance often lags in real-world use—especially under low-load conditions. These gaps are especially concerning in the South Coast Air Basin. That region must meet strict ozone targets in 2023 and 2031.
SCR-equipped diesel engines that meet 2010 standards can reduce NOx by 90% in certification tests. However, under low-load conditions, in-use NOx emissions can be ten times higher (Dixit et al., 2017; Misra et al., 2013; Quiros et al., 2017; Lee et al., 2018).
Ultra-low NOx natural gas engines perform much better under similar conditions. They can emit NOx at levels 100 times lower than the standard (Johnson et al., 2017, 2018). Zero-emission and hybrid trucks also show strong potential, though adoption remains limited.
A dynamic compliance model—such as zero-emission or ultra-low NOx zones—could help reduce emissions in urban hotspots.
CARB has proposed a new low-NOx standard of 0.02 g/bhp-hr. This includes a low-power test cycle and updates to Not-To-Exceed (NTE) procedures. These changes aim to close the gap between certification and real-world emissions.
Another approach is continuous in-use emissions monitoring. This allows compliance to be assessed under actual operating conditions.
The Onboard Sensing, Analysis, and Reporting (OSAR) system builds on durable control sensors already installed in vehicle systems. These sensors have shown strong agreement with laboratory instruments—typically within ±15% (Montes, 2018; Yang et al., 2018).
NGK has developed NOx sensor prototypes that work below 250°C. Traditional sensors often fail under these conditions due to humidity damage. These low-temperature periods are when SCR systems produce the most NOx.
In OSAR testing, these prototypes achieved NOx measurements within ±10% of full PEMS systems. They performed well across cold-starts and a range of real-world conditions (Yang et al., 2018).
Phase 1 aims to develop and test a low-cost onboard monitoring system. It will track NOx and PM emissions from heavy-duty engines.
Future capabilities may include:
Dynamic calibration control
Fine-based in-use enforcement
Exposure mapping for the South Coast region
AQMD funding will be leveraged to attract additional industry support. This effort encourages onboard instrumentation in new trucks and supports potential retrofit solutions.
Lead Researcher: Dr. Kent Johnson
Co-Researcher: Dr. Thomas Durbin -
Zero-and-Near-Zero Emissions Freight Facility Grant
UC Riverside is supporting the Port of Long Beach (POLB) through its contract with CARB. UCR is contributing to the Zero- and Near-Zero Emissions Freight Facility initiative through data collection and testing.
UCR will provide data logging, portable emissions measurement system (PEMS) testing, and chassis dynamometer testing for advanced vehicle technologies.
For a selected group of vehicles and equipment, UCR will analyze:
Operating hours and days
Daily mileage and odometer trends
Speed and acceleration profiles
Time spent idling
Performance will also be assessed, including:
State of charge (SOC) during operation
Energy used per distance or work output
Energy or fuel use while idling
Two weeks of PEMS testing will be conducted, including travel, setup, and equipment installation. CE-CERT will also conduct chassis dynamometer testing at its Riverside facility.
Measurements may include:
Emissions from diesel, natural gas, and other fuel types
EV performance parameters are defined in UCR’s guidance
Combined EV and emissions data for hybrid vehicles
Lead Researcher: Dr. Tom Durbin
Co-Researchers: Dr. Kent Johnson, Dr. Kanok Booriboonsomsin, Dr. Wayne Miller -
200 Vehicle Study
UC Riverside is a national leader in emissions research using real-world testing. In the last five years, UCR has been a key contributor to validating portable emissions systems (PEMS). This work supports the EPA's Measurement Allowance Program for heavy-duty vehicles.
UCR conducted in-use testing with its Mobile Emissions Laboratory (MEL). The MEL is a 53-foot trailer with a full dilution tunnel and 1065-compliant system. It has been cross-validated with Southwest Research Institute.
UCR has led emissions characterization for a wide range of mobile sources:
Light- and heavy-duty vehicles
Construction and off-road equipment
Ships and port equipment
Trains and aircraft
UCR has developed advanced PEMS configurations, including:
A PM PEMS using the AVL microsoot sensor (MSS), paired with AVL or Sensor Inc. gas analyzers
A Horiba PG350 multi-gas analyzer system for ISO 8178 steady-state testing
These systems have been deployed in CARB and Caltrans studies and applied to ships, port vehicles, and generators. UCR has also established protocols for emissions control technology verification on marine vessels, generators, and rubber-tired gantry cranes.
Lead Researcher: Dr. Tom Durbin