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Yu K, Li M, Harkins C, He J, Zhu Q, Verreyken B, Schwantes RH, Cohen RC, McDonald BC, Harley RA. Improved Spatial Resolution in Modeling of Nitrogen Oxide Concentrations in the Los Angeles Basin. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:20689-20698. [PMID: 38033264 PMCID: PMC10720381 DOI: 10.1021/acs.est.3c06158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 11/13/2023] [Accepted: 11/14/2023] [Indexed: 12/02/2023]
Abstract
The extent to which emission control technologies and policies have reduced anthropogenic NOx emissions from motor vehicles is large but uncertain. We evaluate a fuel-based emission inventory for southern California during the June 2021 period, coinciding with the Re-Evaluating the Chemistry of Air Pollutants in CAlifornia (RECAP-CA) field campaign. A modified version of the Fuel-based Inventory of Vehicle Emissions (FIVE) is presented, incorporating 1.3 km resolution gridding and a new light-/medium-duty diesel vehicle category. NOx concentrations and weekday-weekend differences were predicted using the WRF-Chem model and evaluated using satellite and aircraft observations. Model performance was similar on weekdays and weekends, indicating appropriate day-of-week scaling of NOx emissions and a reasonable distribution of emissions by sector. Large observed weekend decreases in NOx are mainly due to changes in on-road vehicle emissions. The inventory presented in this study suggests that on-road vehicles were responsible for 55-72% of the NOx emissions in the South Coast Air Basin, compared to the corresponding fraction (43%) in the planning inventory from the South Coast Air Quality Management District. This fuel-based inventory suggests on-road NOx emissions that are 1.5 ± 0.4, 2.8 ± 0.6, and 1.3 ± 0.7 times the reference EMFAC model estimates for on-road gasoline, light- and medium-duty diesel, and heavy-duty diesel, respectively.
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Affiliation(s)
- Katelyn
A. Yu
- Department
of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California 94720, United States
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
| | - Meng Li
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
- Cooperative
Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Colin Harkins
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
- Cooperative
Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Jian He
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
- Cooperative
Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80309, United States
| | - Qindan Zhu
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
- Department
of Chemistry, University of California,
Berkeley, Berkeley, California 94720, United States
| | - Bert Verreyken
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
| | - Rebecca H. Schwantes
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
| | - Ronald C. Cohen
- Department
of Chemistry, University of California,
Berkeley, Berkeley, California 94720, United States
| | - Brian C. McDonald
- Chemical
Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder, Colorado 80305, United States
| | - Robert A. Harley
- Department
of Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California 94720, United States
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2
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Wang H, Zhang S, Wu X, Wen Y, Li Z, Wu Y. Emission Measurements on a Large Sample of Heavy-Duty Diesel Trucks in China by Using Mobile Plume Chasing. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:15153-15161. [PMID: 37750423 DOI: 10.1021/acs.est.3c03028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
Real-world heavy-duty diesel trucks (HDTs) were found to emit far more excess nitrogen oxides (NOX) and black carbon (BC) pollutants than regulation limits. It is essential to systematically evaluate on-road NOX and BC emission levels for mitigating HDT emissions. This study launched 2109 plume chasing campaigns for NOX and BC emissions of HDTs across several regions in China from 2017 to 2020. It was found that NOX emissions had limited reductions from China III to China V, while BC emissions of HDTs exhibited high reductions with stricter emission standard implementation. This paper showed that previous studies underestimated 18% of NOX emissions in China in 2019 and nearly half of the real-world NOX emissions from HDTs (determined by updating the emission trends of HDTs) exceeded the regulation limits. Furthermore, the ambient temperature was identified as a primary driver of NOX emissions for HDTs, and the low-temperature penalty has caused a 9-29% increase in NOX emissions in winter in major regions of China. These results would provide important data support for the precise control of the NOX and BC emissions from HDTs.
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Affiliation(s)
- Hui Wang
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, PR China
| | - Shaojun Zhang
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, PR China
- State Environmental Protection Key Laboratory of Sources and Control of Ambient Pollution Complex, Beijing 100084, PR China
- Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China
| | - Xiaomeng Wu
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, PR China
| | - Yifan Wen
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, PR China
| | - Zhenhua Li
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, PR China
| | - Ye Wu
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, PR China
- State Environmental Protection Key Laboratory of Sources and Control of Ambient Pollution Complex, Beijing 100084, PR China
- Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China
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3
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Bishop GA, Haugen MJ, McDonald BC, Boies AM. Utah Wintertime Measurements of Heavy-Duty Vehicle Nitrogen Oxide Emission Factors. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:1885-1893. [PMID: 35044770 DOI: 10.1021/acs.est.1c06428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
There have only been a few wintertime studies of heavy-duty vehicle (HDV) NOx emissions in the United States, and while they have observed increased emissions, fleet characterization to identify the cause has been lacking. We have collected wintertime measurements of NOx emission factors from 1591 HDVs at a Utah Port of Entry in December 2020 that includes individual vehicle identification. In general, NOx emission factors for 2011 and newer chassis model year HDV are significantly higher than those for 2017 spring measurements from California. The newest chassis model year HDV (2017-2021) NOx emission factors are similar, indicating no significant emission deterioration over the 5 year period, though they are still approximately a factor of 3 higher than the portable emission measurement on-road enforcement standard. We estimate that ambient temperature increases NOx emissions no more than 25% in the newer HDV, likely through reductions in catalyst efficiencies. NOx emissions increase to a significantly higher level for the 2011-2013 chassis model year vehicles, where within the uncertainties, they have emissions similar to older precontrol vehicles, indicating that they have lost their NOx control capabilities within 8 years. MOVES3 modeling of the Utah fleet underpredicted mean NOx emissions by a factor of 1.8 but the MOVES3 estimate is helped by including a larger fraction of high-emitting glider kit trucks (new chassis with pre-emission control engines) than found in the observations.
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Affiliation(s)
- Gary A Bishop
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Molly J Haugen
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Brian C McDonald
- Chemical Sciences Laboratory, National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, United States
| | - Adam M Boies
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
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4
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Tan Y, Yoon S, Ruehl CR, Herner J, Henderick P, Montes T, Latt J, Lee A, Florea E, Lemieux S, Robertson W, Hu S, Huai T. Assessment of In-Use NOx Emissions from Heavy-Duty Diesel Vehicles Equipped with Selective Catalytic Reduction Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:13657-13665. [PMID: 34591445 DOI: 10.1021/acs.est.1c03042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This work evaluated the nitrogen oxide (NOx) emissions of 277 heavy-duty diesel vehicles (HDDVs) from three portable emission measurement system testing programs. HDDVs in these programs were properly maintained before emission testing, so the malfunction indicator lamp (MIL) was not illuminated. NOx emissions of some HDDVs were significantly higher than the certification standard even during hot operations where exhaust temperature was ideal for selective catalytic reduction to reduce NOx. For engines certified to the 0.20 g/bhp-hr NOx standard, hot operation NOx emissions increased with engine age at 0.081 ± 0.016 g/bhp-hr per year. The correlation between emissions and mileage was weak because six trucks showed extraordinarily high apparent emission increase rates reaching several multiples of the standard within the first 15,000 miles of operation. The overall annual increase in NOx emissions for the HDDVs in this study was two-thirds of what was observed in real-world emissions for HDDVs at the Caldecott Tunnel over the past decade. The vehicles at the Caldecott Tunnel would include those without proper maintenance, and the inclusion of these vehicles possibly explains the difference in the rate of emission increase. The results suggest that HDDVs need robust strategies to better control in-use NOx emissions.
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Affiliation(s)
- Yi Tan
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Seungju Yoon
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Chris R Ruehl
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Jorn Herner
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Paul Henderick
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Tom Montes
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Jenna Latt
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Abraham Lee
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Elena Florea
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Sharon Lemieux
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - William Robertson
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Shaohua Hu
- California Air Resources Board, 8340 Ferguson Avenue, Sacramento, California 95828, United States
| | - Tao Huai
- California Air Resources Board, 8340 Ferguson Avenue, Sacramento, California 95828, United States
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5
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Ruehl C, Misra C, Yoon S, Smith JD, Burnitzki M, Hu S, Collins J, Tan Y, Huai T, Herner J. Evaluation of heavy-duty vehicle emission controls with a decade of California real-world observations. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2021; 71:1277-1291. [PMID: 33576718 DOI: 10.1080/10962247.2021.1890277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 06/12/2023]
Abstract
Over the past decade, efforts to reduce emissions of particulate matter (PM) and oxides of nitrogen (NO + NO2, or NOx) from heavy-duty diesel vehicles (HDDVs) have led to the widespread adoption of both Diesel Particulate Filters (DPFs) to control PM and Selective Catalytic Reduction (SCR) to control NOx. We evaluated the performance of DPFs and SCR with 13,327 real-world fuel-based Black Carbon (BC) and NOx emission factors from 9,167 unique heavy-duty vehicles (primarily HDDVs) measured at four sites in California (two ports, two highways) from 2011 to 2018. BC emission factors have decreased by 90% during the past decade. At the same time, BC distributions have become increasingly skewed toward "high-emitters" - e.g., the portion of the HDDV fleet responsible for half of all BC emissions has decreased from ~16% to ~3%. NOx emission factors have also decreased over the past decade, but by only 31%. They remain roughly five times greater than in-use thresholds.We examined changes in BC and NOx emissions with engine age. BC emissions from DPF-only trucks decreased slightly but insignificantly, by 6 ± 15 mg/kg fuel per year, while for DPF+SCR trucks they increased by 5 ± 3. These changes are less than 5% of in-use thresholds. The annual increase in NOx emissions with age was much greater: 1.44 ± 0.28 g/kg for older SCR trucks without on-board diagnostic (OBD) capabilities and 0.48 ± 0.35 for newer trucks with OBD, roughly 20- 50% of in-use thresholds. Paired t-tests on the over 600 vehicles that were observed in multiple campaigns were consistent with these results. Observed changes in BC emissions with age were best fit with a "gross emitter" model assuming an annual DPF failure rate of 0.83 ± 0.01% for DPF-only trucks and 0.56 ± 0.01% for DPF+SCR trucks.Implications: These observations of real-world HDV emission factors have several major implications for regulatory efforts to reduce them. The increasing importance of a relatively small number of high BC emitters suggests that widespread sampling of the on-road fleet will be necessary to identify these vehicles. On the other hand, the much more ubiquitous deterioration in NOx control measures may be better addressed by incorporating on-board diagnostic systems, with telematic data transfer when possible, into inspection and maintenance programs. These NOx observations also highlight the need for strengthening heavy-duty SCR durability demonstration requirements.
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Affiliation(s)
- Chris Ruehl
- Research Division, California Air Resources Board, Sacramento, CA, USA
| | - Chandan Misra
- Office of Community Air Protection, California Air Resources Board, Sacramento, CA, USA
| | - Seungju Yoon
- Research Division, California Air Resources Board, Sacramento, CA, USA
| | - Jeremy D Smith
- Monitoring and Laboratory Division, California Air Resources Board, Sacramento, CA, USA
| | - Mark Burnitzki
- Mobile Source Laboratory Division, California Air Resources Board, Sacramento, CA, USA
| | - Shaohua Hu
- Mobile Source Laboratory Division, California Air Resources Board, Sacramento, CA, USA
| | - John Collins
- Research Division, California Air Resources Board, Sacramento, CA, USA
| | - Yi Tan
- Research Division, California Air Resources Board, Sacramento, CA, USA
| | - Tao Huai
- Mobile Source Laboratory Division, California Air Resources Board, Sacramento, CA, USA
| | - Jorn Herner
- Research Division, California Air Resources Board, Sacramento, CA, USA
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6
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Hamilton SD, Harley RA. High-Resolution Modeling and Apportionment of Diesel-Related Contributions to Black Carbon Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:12250-12260. [PMID: 34505515 DOI: 10.1021/acs.est.1c03913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Exposure to diesel-related air pollution, which includes black carbon (BC) as a major component of the particulate matter emitted in engine exhaust, is a known human health hazard. The resulting health burden falls heavily on vulnerable communities located close to major sources including highways, rail yards, and ports. Determination of source contributions to the overall pollution burden is challenging due to collinearity in the exhaust composition profiles for relevant sources including heavy-duty diesel trucks, railroad locomotives, cargo-handling equipment, and marine engines. Additionally, the impact of each source depends not just on the magnitude of emissions but on its location relative to receptors as well as on meteorology. We modeled source-resolved BC concentrations in West Oakland, California, at a high (150 m) spatial resolution using the Weather Research and Forecasting model. The ability of the model to predict hourly and 24 h average BC concentrations is evaluated for a 100-day period in summer 2017 when BC was measured at 100 sites within the community. We find that a community monitoring site is representative of population-weighted average BC exposure in the community. Major contributing sources to BC in West Oakland include on-road diesel trucks (44 ± 5%) and three off-road diesel sources: ocean-going vessels (19 ± 1%), railroad locomotives (16 ± 2%), and harbor craft such as tugboats and ferries (11 ± 1%).
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Affiliation(s)
- Sofia D Hamilton
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
| | - Robert A Harley
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720-1710, United States
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7
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Yu KA, McDonald BC, Harley RA. Evaluation of Nitrogen Oxide Emission Inventories and Trends for On-Road Gasoline and Diesel Vehicles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:6655-6664. [PMID: 33951912 DOI: 10.1021/acs.est.1c00586] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
On-road vehicles continue to be a major source of nitrogen oxide (NOx) emissions in the United States and in other countries around the world. The goal of this study is to compare and evaluate emission inventories and long-term trends in vehicular NOx emissions. Taxable fuel sales data and in-use measurements of emission factors are combined to generate fuel-based NOx emission inventories for California and the US over the period 1990-2020. While gasoline and diesel fuel sales increased over the last three decades, total on-road NOx emissions declined by approximately 70% since 1990, with a steeper rate of decrease after 2004 when heavy-duty diesel NOx emission controls finally started to gain traction. In California, additional steps have been taken to accelerate the introduction of new heavy-duty engines equipped with selective catalytic reduction systems, resulting in a 48% decrease in diesel NOx emissions in California compared to a 32% decrease nationally since 2010. California EMFAC model predictions are in good agreement with fuel-based inventory results for gasoline engines and are higher than fuel-based estimates for diesel engines prior to the mid-2010s. Similar to the findings of recent observational and modeling studies, there are discrepancies between the fuel-based inventory and national MOVES model estimates. MOVES predicts a steeper decrease in NOx emissions and predicts higher NOx emissions from gasoline engines over the entire period from 1990 to 2020.
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Affiliation(s)
- Katelyn A Yu
- Department of Civil and Environmental Engineering, University of California, Berkeley 94720-1710, California, United States
| | - Brian C McDonald
- Chemical Sciences Laboratory, NOAA Earth System Research Laboratories, Boulder 80305-3328, Colorado, United States
| | - Robert A Harley
- Department of Civil and Environmental Engineering, University of California, Berkeley 94720-1710, California, United States
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8
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Sugrue RA, Preble CV, Kirchstetter TW. Comparing the Use of High- to Low-Cost Black Carbon and Carbon Dioxide Sensors for Characterizing On-Road Diesel Truck Emissions. SENSORS 2020; 20:s20236714. [PMID: 33255331 PMCID: PMC7727720 DOI: 10.3390/s20236714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/18/2020] [Accepted: 11/22/2020] [Indexed: 11/30/2022]
Abstract
The exhaust plume capture method is a commonly used approach to measure pollutants emitted by in-use heavy-duty diesel trucks. Lower cost sensors, if used in place of traditional research-grade analyzers, could enable wider application of this method, including use as a monitoring tool to identify high-emitting trucks that may warrant inspection and maintenance. However, low-cost sensors have for the most part only been evaluated under ambient conditions as opposed to source-influenced environments with rapidly changing pollutant concentrations. This study compared black carbon (BC) emission factors determined using different BC and carbon dioxide (CO2) sensors that range in cost from $200 to $20,000. Controlled laboratory experiments show that traditional zero and span steady-state calibration checks are not robust indicators of sensor performance when sampling short duration concentration peaks. Fleet BC emission factor distributions measured at two locations at the Port of Oakland in California with 16 BC/CO2 sensor pairs were similar, but unique sensor pairs identified different high-emitting trucks. At one location, the low-cost PP Systems SBA-5 agreed on the classification of 90% of the high emitters identified by the LI-COR LI-7000 when both were paired with the Magee Scientific AE33. Conversely, lower cost BC sensors when paired with the LI-7000 misclassified more than 50% of high emitters when compared to the AE33/LI-7000. Confidence in emission factor quantification and high-emitter identification improves with larger integrated peak areas of CO2 and especially BC. This work highlights that sensor evaluation should be conducted under application-specific conditions, whether that be for ambient air monitoring or source characterization.
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Affiliation(s)
- Rebecca A. Sugrue
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA; (R.A.S.); (C.V.P.)
- Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Chelsea V. Preble
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA; (R.A.S.); (C.V.P.)
- Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Thomas W. Kirchstetter
- Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720, USA; (R.A.S.); (C.V.P.)
- Energy Technologies Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Correspondence:
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9
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Preble CV, Harley RA, Kirchstetter TW. Control Technology-Driven Changes to In-Use Heavy-Duty Diesel Truck Emissions of Nitrogenous Species and Related Environmental Impacts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:14568-14576. [PMID: 31686501 DOI: 10.1021/acs.est.9b04763] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Emissions from thousands of in-use heavy-duty diesel trucks were sampled at a highway and an arterial street location in the San Francisco Bay Area, spanning a time period when use of diesel particle filters (DPFs) and selective catalytic reduction (SCR) increased rapidly. At the highway site where a diverse mix of trucks is observed, SCR systems on 2010 and newer engines reduce emitted nitrogen oxides (NOx) by 87 ± 5% relative to pre-2004 engines. SCR also mitigates DPF-related increases in nitrogen dioxide (NO2) emissions. However, a majority of trucks had in-use NOx emission rates that exceeded applicable emission standards. SCR systems increase emissions of nitrous oxide (N2O) and ammonia (NH3) from near-zero levels to 0.93 ± 0.13 and 0.18 ± 0.07 g kg-1, respectively. Emissions of all nitrogenous species and especially NH3 are skewed; 10% of trucks contribute 95% of the on-road fleet's total NH3 emissions. Similar emission changes are observed at the arterial street site where exclusively drayage trucks operate. The environmental effects of decreased black carbon, NOx, and carbon dioxide (CO2) emissions and increased N2O and NH3 emissions due to the rapid adoption of DPF and SCR systems by the California truck fleet are: (1) a 65% net decrease in the social cost of statewide exposure to diesel truck emissions (-3.3 billion 2018 US dollars per year), and (2) a 3% net decrease in the global warming potential-weighted emission factor (-27 g CO2-eq km-1).
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Affiliation(s)
- Chelsea V Preble
- Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States
- Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Robert A Harley
- Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States
- Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Thomas W Kirchstetter
- Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States
- Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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10
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Tan Y, Henderick P, Yoon S, Herner J, Montes T, Boriboonsomsin K, Johnson K, Scora G, Sandez D, Durbin TD. On-Board Sensor-Based NO x Emissions from Heavy-Duty Diesel Vehicles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:5504-5511. [PMID: 30995015 DOI: 10.1021/acs.est.8b07048] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Real-world nitrogen oxides (NO x) emissions were estimated using on-board sensor readings from 72 heavy-duty diesel vehicles (HDDVs) equipped with a Selective Catalytic Reduction (SCR) system in California. The results showed that there were large differences between in-use and certification NO x emissions, with 12 HDDVs emitting more than three times the standard during hot-running and idling operations in the real world. The overall NO x conversion efficiencies of the SCR system on many vehicles were well below the 90% threshold that is expected for an efficient SCR system, even when the SCR system was above the optimum operating temperature threshold of 250 °C. This could potentially be associated with SCR catalyst deterioration on some engines. The Not-to-Exceed (NTE) requirements currently used by the heavy-duty in-use compliance program were evaluated using on-board NO x sensor data. Valid NTE events covered only 4.2-16.4% of the engine operation and 6.6-34.6% of the estimated NO x emissions. This work shows that low cost on-board NO x sensors are a convenient tool to monitor in-use NO x emissions in real-time, evaluate the SCR system performance, and identify vehicle operating modes with high NO x emissions. This information can inform certification and compliance programs to ensure low in-use NO x emissions.
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Affiliation(s)
- Yi Tan
- California Air Resources Board, 1001 I Street , Sacramento , California 95814 , United States
| | - Paul Henderick
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2 , El Monte , California 91731 , United States
| | - Seungju Yoon
- California Air Resources Board, 1001 I Street , Sacramento , California 95814 , United States
| | - Jorn Herner
- California Air Resources Board, 1001 I Street , Sacramento , California 95814 , United States
| | - Thomas Montes
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2 , El Monte , California 91731 , United States
| | - Kanok Boriboonsomsin
- College of Engineering - Center for Environmental Research and Technology , University of California at Riverside , 1084 Columbia Avenue , Riverside , California 92507 , United States
| | - Kent Johnson
- College of Engineering - Center for Environmental Research and Technology , University of California at Riverside , 1084 Columbia Avenue , Riverside , California 92507 , United States
| | - George Scora
- College of Engineering - Center for Environmental Research and Technology , University of California at Riverside , 1084 Columbia Avenue , Riverside , California 92507 , United States
| | - Daniel Sandez
- College of Engineering - Center for Environmental Research and Technology , University of California at Riverside , 1084 Columbia Avenue , Riverside , California 92507 , United States
| | - Thomas D Durbin
- College of Engineering - Center for Environmental Research and Technology , University of California at Riverside , 1084 Columbia Avenue , Riverside , California 92507 , United States
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11
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Haugen MJ, Bishop GA, Thiruvengadam A, Carder DK. Evaluation of Heavy- and Medium-Duty On-Road Vehicle Emissions in California's South Coast Air Basin. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:13298-13305. [PMID: 30406648 DOI: 10.1021/acs.est.8b03994] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Emission measurements were collected from heavy-duty (HDVs) and medium-duty vehicles (MDVs) at the Peralta weigh station long-term measurement site near Anaheim, CA, in 2017. Two Fuel Efficiency Automobile Test units sampled elevated and ground-level exhaust vehicles totaling 2 315 measurements. HDVs (1844 measurements) exhibited historical reductions in fuel specific oxides of nitrogen (NOx) from the 2008 measurements (55%) with increased use of exhaust gas recirculation and selective catalytic reduction systems. However, as these technologies have aged, the in-use benefits have declined. Infrared % opacity measurements of tailpipe soot decreased 14% since 2012 with increased diesel particulate filter (DPF) use, DPF longevity, and fleet turnover. Sixty-three percent of the HDV fleet in 2017 was chassis model year 2011+ compared to only 12% in 2012. The observed MDV fleet (471 measurements) was 1.4 years older than the HDV fleet with average NOx 14% higher. A significant reduction in MDV NOx occurred ∼2 model years prior to similar HDV reductions (2014 versus 2016 chassis model year). MDV chassis model years 2014+ were able to meet their corresponding NOx laboratory certification standards in-use, whereas HDVs remain slightly above this threshold. Similar MDV NOx emission trends were also observed in data previously collected in Chicago, IL.
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Affiliation(s)
- Molly J Haugen
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States of America
- Department of Engineering , University of Cambridge , Cambridge , United Kingdom CB2 1PZ
| | - Gary A Bishop
- Department of Chemistry and Biochemistry , University of Denver , Denver , Colorado 80208 , United States of America
| | - Arvind Thiruvengadam
- Mechanical and Aerospace Department , West Virginia University , Morgantown , West Virginia 26505 , United States of America
| | - Daniel K Carder
- Mechanical and Aerospace Department , West Virginia University , Morgantown , West Virginia 26505 , United States of America
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Preble CV, Cados TE, Harley RA, Kirchstetter TW. In-Use Performance and Durability of Particle Filters on Heavy-Duty Diesel Trucks. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:11913-11921. [PMID: 30153019 DOI: 10.1021/acs.est.8b02977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Diesel particle filters (DPFs) are standard equipment on heavy-duty diesel trucks with 2007 and newer engines in the U.S. This study evaluates the performance and durability of these filters. Black carbon (BC) emission rates from several thousand heavy-duty trucks were measured at the Port of Oakland and Caldecott Tunnel over multiple years as California regulations accelerated the adoption of DPFs. As DPF use increased, fleet-average BC emissions decreased, and emission factor distributions became more skewed. Relative to 2004-2006 engines without filters, DPFs reduced BC emission rates by 65-70% for 2007-2009 engines and by >90% for 2010+ engines. Average BC emission rates for 2007-2009 engines increased by 50-67% in 2015 relative to measurements made 1-2 years earlier. Some trucks in this cohort have become high-emitters, indicating that some DPFs are no longer working well. At the Port, where DPFs were universal in 2015, high-emitting 2007-2009 engines (defined here as emitting >1 g BC kg-1) comprised 7% of the fleet but were responsible for 65% of the total BC emitted. These observations raise concerns about DPF durability and the prospects for fully mitigating adverse effects of diesel particulate matter on human health and the environment.
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Affiliation(s)
- Chelsea V Preble
- Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States
- Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Troy E Cados
- Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States
- Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Robert A Harley
- Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States
- Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Thomas W Kirchstetter
- Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States
- Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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Quiros DC, Smith JD, Ham WA, Robertson WH, Huai T, Ayala A, Hu S. Deriving fuel-based emission factor thresholds to interpret heavy-duty vehicle roadside plume measurements. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2018; 68:969-987. [PMID: 29652244 DOI: 10.1080/10962247.2018.1460637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 06/08/2023]
Abstract
UNLABELLED Remote sensing devices have been used for decades to measure gaseous emissions from individual vehicles at the roadside. Systems have also been developed that entrain diluted exhaust and can also measure particulate matter (PM) emissions. In 2015, the California Air Resources Board (CARB) reported that 8% of in-field diesel particulate filters (DPF) on heavy-duty (HD) vehicles were malfunctioning and emitted about 70% of total diesel PM emissions from the DPF-equipped fleet. A new high-emitter problem in the heavy-duty vehicle fleet had emerged. Roadside exhaust plume measurements reflect a snapshot of real-world operation, typically lasting several seconds. In order to relate roadside plume measurements to laboratory emission tests, we analyzed carbon dioxide (CO2), oxides of nitrogen (NOX), and PM emissions collected from four HD vehicles during several driving cycles on a chassis dynamometer. We examined the fuel-based emission factors corresponding to possible exceedances of emission standards as a function of vehicle power. Our analysis suggests that a typical HD vehicle will exceed the model year (MY) 2010 emission standards (of 0.2 g NOX/bhp-hr and 0.01 g PM/bhp-hr) by three times when fuel-based emission factors are 9.3 g NOX/kg fuel and 0.11 g PM/kg using the roadside plume measurement approach. Reported limits correspond to 99% confidence levels, which were calculated using the detection uncertainty of emissions analyzers, accuracy of vehicle power calculations, and actual emissions variability of fixed operational parameters. The PM threshold was determined for acceleration events between 0.47 and 1.4 mph/sec only, and the NOX threshold was derived from measurements where after-treatment temperature was above 200°C. Anticipating a growing interest in real-world driving emissions, widespread implementation of roadside exhaust plume measurements as a compliment to in-use vehicle programs may benefit from expanding this analysis to a larger sample of in-use HD vehicles. IMPLICATIONS Regulatory agencies, civil society, and the public at large have a growing interest in vehicle emission compliance in the real world. Leveraging roadside plume measurements to identify vehicles with malfunctioning emission control systems is emerging as a viable new and useful method to assess in-use performance. This work proposes fuel-based emission factor thresholds for PM and NOx that signify exceedances of emission standards on a work-specific basis by analyzing real-time emissions in the laboratory. These thresholds could be used to prescreen vehicles before roadside enforcement inspection or other inquiry, enhance and further develop emission inventories, and potentially develop new requirements for heavy-duty inspection and maintenance (I/M) programs, including but not limited to identifying vehicles for further testing.
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Affiliation(s)
- David C Quiros
- a California Air Resources Board , Sacramento , CA , USA
| | - Jeremy D Smith
- a California Air Resources Board , Sacramento , CA , USA
| | - Walter A Ham
- a California Air Resources Board , Sacramento , CA , USA
| | | | - Tao Huai
- a California Air Resources Board , Sacramento , CA , USA
| | - Alberto Ayala
- a California Air Resources Board , Sacramento , CA , USA
| | - Shaohua Hu
- a California Air Resources Board , Sacramento , CA , USA
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Haugen MJ, Bishop GA. Long-Term Fuel-Specific NO x and Particle Emission Trends for In-Use Heavy-Duty Vehicles in California. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:6070-6076. [PMID: 29692175 DOI: 10.1021/acs.est.8b00621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Two California heavy-duty fleets have been measured in 2013, 2015, and 2017 using the On-Road Heavy-Duty Measurement System. The Port of Los Angeles drayage fleet has increased in age by 3.3 model years (4.2-7.5 years old) since 2013, with little fleet turnover. Large increases in fuel-specific particle emissions (PM) observed in 2015 were reversed in 2017, returning to near 2013 levels, suggesting repairs and or removal of high emitting vehicles. Fuel-specific oxides of nitrogen (NO x) emissions of this fleet have increased, and NO x after-treatment systems do not appear to perform ideally in this setting. At the Cottonwood weigh station in northern California, the fleet age has declined (7.8 to 6 years old) since 2013 due to fleet turnover, significantly lowering the average fuel-specific emissions for PM (-87%), black carbon (-76%), and particle number (-64%). Installations of retrofit-diesel particulate filters in model year 2007 and older vehicles have further decreased particle emissions. Cottonwood fleet fuel-specific NO x emissions have decreased slightly (-8%) during this period; however, newer technology vehicles with selective catalytic reduction systems (SCR) promise an additional factor of 4-5 further reductions in the long-haul fleet emissions as California transitions to an all SCR-equipped fleet.
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Affiliation(s)
- Molly J Haugen
- Department of Chemistry and Biochemistry MSC 9020 , University of Denver , Denver , Colorado 80208 , United States
| | - Gary A Bishop
- Department of Chemistry and Biochemistry MSC 9020 , University of Denver , Denver , Colorado 80208 , United States
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Abstract
Emissions of nitrogen oxides (NOx) have a large impact on air quality and climate change as precursors in the formation of ozone and secondary aerosols. We find that NOx emissions have not been decreasing as expected in recent years (2011–2015) when comparing top-down estimates from satellites and surface NO2 measurements to the trends predicted from the US Environmental Protection Agency’s emission inventory data. The discrepancy can be explained by the growing relative contribution of industrial, area, and off-road mobile sources of emissions, decreasing relative contribution of on-road gasoline vehicles, and slower than expected decreases in on-road diesel NOx emissions, with implications for air-quality management. Ground and satellite observations show that air pollution regulations in the United States (US) have resulted in substantial reductions in emissions and corresponding improvements in air quality over the last several decades. However, large uncertainties remain in evaluating how recent regulations affect different emission sectors and pollutant trends. Here we show a significant slowdown in decreasing US emissions of nitrogen oxides (NOx) and carbon monoxide (CO) for 2011–2015 using satellite and surface measurements. This observed slowdown in emission reductions is significantly different from the trend expected using US Environmental Protection Agency (EPA) bottom-up inventories and impedes compliance with local and federal agency air-quality goals. We find that the difference between observations and EPA’s NOx emission estimates could be explained by: (i) growing relative contributions of industrial, area, and off-road sources, (ii) decreasing relative contributions of on-road gasoline, and (iii) slower than expected decreases in on-road diesel emissions.
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