Using portable emissions measurement systems (PEMS) to derive more accurate estimates of fuel use and nitrogen oxides emissions from modern Euro 6 passenger cars under real-world driving conditions

Data from portable emissions measurement systems (PEMS) and other sources have allowed the discrepancy between type approval and real-world fuel economy and nitrogen oxides (NOx) emissions to be both identified and quantified. However, a gap in the knowledge persists because identifying this discrepancy does not allow us to predict real-world fuel economy and emissions accurately. We address this gap in the knowledge using a bottom-up approach: a PEMS is used across a range of Euro 6 petrol and diesel vehicles, from which internally-consistent powertrain models are derived. These training vehicles are simulated over 20 real-world and regulated driving cycles. 26 metrics representing driving, vehicle and ambient characteristics are used to develop quantile regression (QR) models for three vehicle groups: direct-injection petrol vehicles with three way catalysts; diesel vehicles with selective catalytic reduction; and diesel vehicles with lean NOx traps. 95% prediction intervals are used to assess the predictive accuracy of the QR models from a set of validation vehicles. Across the vehicle groups, QR models for both fuel economy and NOx emissions depended on the dynamics of the driving cycles more than the engine characteristics or ambient conditions. The 95% prediction interval for fuel economy enclosed most of the observed values from the PEMS test, with similar prediction error to COPERT in most cases. The bene ts of the QR approach were more pronounced for NOx emissions, where the majority of PEMS observed data was enclosed in the 95% PI and median prediction error was up to two times lower than COPERT.EPSR

Real-world environmental impacts from modern passenger vehicles operating in urban settings

Real-world testing of a set of modern vehicles show most petrols meet their Euro standards for nitrous oxides (NO$_{x}$), while most diesel vehicles exceed them. However, that some diesel vehicles met their Euro standards implies exceedances are not peculiar to the fuel. Likewise, the compliance of the tested petrol vehicles with the standard does not mean all petrol vehicles do. Engine maps were synthesised which reproduced trip level emissions to within 10% of that gathered under real-world driving conditions. Average velocity alone, such as what is used in COPERT, is a poor predictor of emissions. Stepwise linear models showed NO$_{x}$ emissions could be predicted accurately by incorporating other metrics, such as maximum deceleration and the variance of velocity over the driving cycle. The models were validated on three driving cycles where all vehicles met their Euro standards, save Euro 6 diesel vehicles on the US highway cycle. COPERT overestimated NO$_{x}$ from all vehicles. More work is required to combine driving cycle metrics with vehicle characteristics, such as mass and peak engine torque, to identify the conditions under which vehicles exceed their Euro limits.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by WIT Press

Engine maps of fuel use and emissions from transient driving cycles

Air pollution problems persist in many cities throughout the world, despite drastic reductions in regulated emissions of criteria pollutants from vehicles when tested on standardised driving cycles. New vehicle emissions regulations in the European Union and United States require the use of OBD and portable emissions measurement systems (PEMS) to confirm vehicles meet specified limits during on-road operation. The resultant in-use testing will yield a large amount of OBD and PEMS data across a range of vehicles. If used properly, the availability of OBD and PEMS data could enable greater insight into the nature of real-world emissions and allow detailed modelling of vehicle energy use and emissions. This paper presents a methodology to use this data to create engine maps of fuel use and emissions of nitrous oxides (NO$_x$), carbon dioxide (CO$_2$) and carbon monoxide (CO). Effective gear ratios, gearbox shift envelopes, candidate engine maps and a set of vehicle configurations are simulated over driving cycles using the ADVISOR powertrain simulation tool. This method is demonstrated on three vehicles – one truck and two passenger cars – tested on a vehicle dynamometer and one driven with a PEMS. The optimum vehicle configuration and associated maps were able to reproduce the shape and magnitude of observed fuel use and emissions on a per second basis. In general, total simulated fuel use and emissions were within 5% of observed values across the three test cases. The fitness of this method for other purposes was demonstrated by creating cold start maps and isolating the performance of tailpipe emissions reduction technologies. The potential of this work extends beyond the creation of vehicle engine maps to allow investigations into: emissions hot spots; real-world emissions factors; and accurate air quality modelling using simulated per second emissions from vehicles operating in over any driving cycle.Engineering and Physical Sciences Research Council (Centre for Sustainable Road Freight Transport (EP/K00915X/1), Energy Efficient Cities Initiative (EP/ F034350/1)

Real world CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars.

In this study CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars were compared using a Portable Emissions Measurement System (PEMS). The models sampled accounted for 56% of all passenger cars sold in Europe in 2016. We found gasoline vehicles had CO2 emissions 13-66% higher than diesel. During urban driving, the average CO2 emission factor was 210.5 (sd. 47) gkm-1 for gasoline and 170.2 (sd. 34) gkm-1 for diesel. Half the gasoline vehicles tested were Gasoline Direct Injection (GDI). Euro 6 GDI engines <1.4ℓ delivered ~17% CO2 reduction compared to Port Fuel Injection (PFI). Gasoline vehicles delivered an 86-96% reduction in NOx emissions compared to diesel cars. The average urban NOx emission from Euro 6 diesel vehicles 0.44 (sd. 0.44) gkm-1 was 11 times higher than for gasoline 0.04 (sd. 0.04) gkm-1. We also analysed two gasoline-electric hybrids which out-performed both gasoline and diesel for NOx and CO2. We conclude action is required to mitigate the public health risk created by excessive NOx emissions from modern diesel vehicles. Replacing diesel with gasoline would incur a substantial CO2 penalty, however greater uptake of hybrid vehicles would likely reduce both CO2 and NOx emissions. Discrimination of vehicles on the basis of Euro standard is arbitrary and incentives should promote vehicles with the lowest real-world emissions of both NOx and CO2

Comparing real driving emissions from Euro 6d-TEMP vehicles running on E0 and E10 gasoline blends

Several governments are increasing the blending mandate of renewable fuels to reduce the life-cycle greenhouse gas emissions of the road transport sector. Currently, ethanol is a prominent renewable fuel and is used in low-level blends, such as E10 (10 %v/v ethanol, 90 %v/v gasoline) in many parts of the world. However, the exact concentration of ethanol amongst other renewable fuel components in commercially available fuels can vary and is not known. To understand the impact of the renewable fuel content on the emissions from Euro 6d-Temp emissions specification vehicles, this paper examines the real-driving emissions (RDE) from four 2020 to 2022 model-year vehicles run on E0 and E10 fuels. CO, CO2, NO, NO2, and NOx were measured through a Portable Emissions Measuring System (PEMS). In addition, N2O, formaldehyde, acetaldehyde, volatile organic compounds (VOCs), and other gaseous and particulate tailpipe emissions were measured and categorized in cold-start, urban, rural, and motorway segments with a proprietary system developed by Emissions Analytics. Engine-out emissions were also measured from a single-cylinder engine at steady-state low speed and load conditions. The results show that the aldehydes, VOCs, and N2O emissions were greatest at cold-start and lowest at motorway conditions. The formaldehyde real-driving emissions increased by 14 % on average between the E0 and E10 fuels. However, the formaldehyde engine-out emissions were reduced for E10. Acetaldehyde real-driving emissions were below the detectable threshold for both E0 and E10 fuels, whereas, engine-out emissions increased for the E10. Whilst CO emissions presented inconsistent results across the cars and driving phases, a reduction in CO2 emissions with the E10 fuel were observed across all conditions. NOx emissions increased for E10 compared to the E0 fuel in urban conditions and the opposite was observed for the motorway conditions. These findings highlight the need for the co-development of emissions regulations as greater ethanol and other renewable fuel content is blended into gasoline

Exposures to Particles and Volatile Organic Compounds across Multiple Transportation Modes

Travellers may be exposed to a wide range of different air pollutants during their journeys. In this study, personal exposures within vehicles and during active travel were tested in real-world conditions across nine different transport modes on journeys from London Paddington to Oxford City Centre, in the United Kingdom. The modes tested covered cycling, walking, buses, coaches, trains and private cars. Such exposures are relevant to questions of traveller comfort and safety in the context of airborne diseases such as COVID-19 and a growing awareness of the health, safety and productivity effects of interior air quality. Pollutants measured were particle number (PN), particle mass (PM), carbon dioxide (CO2) and speciated volatile organic compounds (VOCs), using devices carried on or with the traveller, with pumped sampling. Whilst only a relatively small number of journeys were assessed—inviting future work to assess their statistical significance—the current study highlights where a particular focus on exposure reduction should be placed. Real-time results showed that exposures were dominated by short-term spikes in ambient concentrations, such as when standing on a train platform, or at the roadside. The size distribution of particles varied significantly according to the situation. On average, the coach created the highest exposures overall; trains had mixed performance, while private cars and active transport typically had the lowest exposures. Sources of pollutants included both combustion products entering the vehicle and personal care products from other passengers, which were judged from desk research on the most likely source of each individual compound. Although more exposed to exhaust emissions while walking or cycling, the active traveller had the benefit of rapid dilution of these pollutants in the open air. An important variable in determining total exposure was the journey length, where the speed of the private car was advantageous compared to the relative slowness of the coach

Synthesis of Learning from a Decade of CGIAR Research Programs

The objective of this forward-looking synthesis was to bring together learning from a decade of experience with CGIAR research programs (CRPs), based on existing evaluative evidence. The purpose of this meta-review is to review lessons from the CRP experience to inform the development of future research programs of One CGIAR. The 2021 Synthesis and Lessons Learned from a Decade of CRPs is delivered in response to the request of the CGIAR System Council and aligned with the synthesis terms of reference endorsed by SIMEC in February 2021. The synthesis examined evidence from the two phases of CRP implementation: 2011–2016 and 2017–2019. Four key issues were addressed: (1) patterns and trends between the two phases of CRPs related to the quality of science (QoS) and research for development, achievement of sustainable development outcomes, and management and governance; (2) systemwide issues affecting CRP achievements; (3) recommendations for the future orientation of CGIAR research and innovation; and (4) key evidence gaps and needs for future evaluations. A narrative synthesis approach was used, employing secondary source data from 47 existing evaluations and reviews. External evaluations were systematically coded and analyzed by senior subject matter experts (SMEs) using a standardized analytical framework. A bibliometric trend analysis was carried out, and findings were triangulated against earlier syntheses and validated by members of the Independent Science for Development Council (ISDC), CRP leaders, and expert peer reviewers

The “I” in us, or the eye on us? Regulatory focus, commitment and derogation of an attractive alternative person

When individuals are highly committed to their romantic relationship, they are more likely to engage in pro-relationship maintenance mechanisms. The present research expanded on the notion that commitment redirects self-oriented goals to consider broader relational goals and examined whether commitment interacts with a promotion and prevention focus to activate derogation of attractive alternatives. Three studies used cross-sectional and experimental approaches. Study 1 showed that romantically involved individuals predominantly focused on promotion, but not prevention, reported less initial attraction to an attractive target than single individuals, especially when highly committed to their relationship. Study 2 showed that romantically involved individuals induced in a promotion focus, compared to those in prevention focus, reported less initial attraction, but only when more committed to their relationship. Regardless of regulatory focus manipulation, more committed individuals were also less likely to perceive quality among alternative scenarios and to be attentive to alternative others in general. Finally, Study 3 showed that romantically involved individuals induced in promotion focus and primed with high commitment reported less initial attraction, than those primed with low commitment, or than those induced in prevention focus. Once again, for these latter no differences occurred according to commitment prime. Together, the findings suggest that highly committed promotion focused individuals consider broader relationship goals and activate relationship maintenance behaviors such as derogation of attractive alternatives to promote their relationship