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Conference report: 6th BOSMAL Emissions Symposium

28 June 2018

The 6th International Exhaust Emissions Symposium (IEES)—an event organized every two years by the BOSMAL Automotive Research & Development Institute—was held on June 14-15, 2018 at the BOSMAL facilities in Bielsko-Biała, Poland. The conference included 24 presentations and a poster session on topics including vehicle emission regulations and new EU testing procedures, CO2, GHG and air quality, emission control technologies, emission measurement, as well as electric powertrains. The symposium was attended by about 120 participants.

Regulatory Trends. The opening session of the conference was devoted to global trends in emission regulations, with a focus on European developments. The scene was set by Piotr Bielaczyc [Bosmal], who discussed the trends in the automotive industry and identified the upcoming regulatory challenges. Following the Volkswagen emission scandal, the diesel engine has experienced strong political headwinds in the EU. As a result of the regulatory uncertainty surrounding various local restrictions or “bans” on diesel cars considered by several European cities, the share of diesel cars has decreased from 55% in 2011/12 to 49% in 2016, and continues to decrease. Most customers who move away from a diesel car buy a gasoline vehicle instead. The share of alternatively fueled vehicles in the EU remains small: 1.8% for hybrids and 1.5% for electric vehicles (2016 data). The share of EVs is predicted to increase, but their sales strongly depend on government subsidies. The EVs share of new vehicle sales in the Netherlands—the leading EU member state for electric vehicle sales—has reached 6%, but fell significantly in 2016 once the tax incentives were cut. Nevertheless, some European countries are considering nation-wide restrictions on all conventional internal combustion powertrains, diesel and gasoline, in the 2030-2040 timeframe. These policies envision future mobility that relies on electric vehicles powered by renewable electricity—a narrative that seems largely based on wishful thinking. Carmakers—including Volkswagen—continue to support diesel as an effective and profitable way of meeting future CO2 emission reduction targets. However, support for EVs and hydrogen fuel cell vehicles (FCV) is likely to be built into future regulations. The EU proposal for post-2020 CO2 emission targets calls for a 30% emission reductions from 2021 levels by 2030—a target that cannot realistically be achieved by a combustion engine, gasoline or diesel. Under the proposed regulation, EVs and FCVs are considered—quite unrealistically—“zero-emission” vehicles and provided with special incentives, together with low-emission vehicles (50 g CO2/km, essentially plug-in hybrids).

European Commission [V. Franco] shared some of the initial thinking about the next, Euro 7 stage of emission standards. The European Parliament has called for a proposal for Euro 7 emission limits applicable by 2025 for all light-duty vehicles. The standards would be technology-neutral (e.g., the same emission limits for gasoline and diesel vehicles), would keep the tailpipe approach (no lifecycle emissions) and would focus on real-world emissions through WLTP + RDE testing and a new type-approval framework. The range of regulated pollutants could be extended, with possible additions including NH3, N2O, and non-exhaust particles (e.g., brake and/or tire particles). Euro 7 OBD should be effective in emission monitoring and tampering prevention. The use of remote sensing (RS) is considered for the detection of significant exceedance levels such as from a tampered DPF or SCR. Finally, the particle diameter cutoff for PN measurement could be lowered from 23 nm to 10 nm.

In the near-term perspective, the key regulatory issues include the transition to the WLTP testing procedure and the ongoing evolution of the Real Driving Emissions regulations [L. Hill, Horiba]. The regulations are very complex, and detailed specifications and requirements change rapidly, presenting a fast-moving target. The most recent batch of amendments, corrections and clarifications is included in the WLTP 2nd Act and the 4th RDE Package, which were adopted by the TCMV in May 2018, are expected to be finalized this year, and to become effective from 1 January 2019. The WLTP has been progressively introduced in the EU since 2017, with full implementation in 2021, when WLTP will replace the NEDC test for all type approvals. The WLTP 2nd Act includes new requirements for On Board Fuel Consumption Measurement (OBFCM), as well as electrical consumption in electric vehicles, to be stored in a standardized format to allow comparative analysis. The 4th RDE package brings numerous changes to the regulation. Importantly, RDE is to be applied to In Service Conformity (ISC) checks during the normal life of the vehicle, with type approval authorities to be responsible for performing RDE tests on a fixed percentage of approved vehicles. The RDE conformity factor (CF) for NOx has been tightened slightly to 1.43 from 1.5 (CF = 1 + margin NOx, with margin NOx = 0.43). RDE 4 also brings new changes to the calculation methods. The moving average window method will be used to verify the RDE trip dynamics, but will be replaced with a new method to calculate the RDE test results.

Emission Testing & Measurements. It is expected that the WLTP procedure will have a significant effect on certified CO2 emissions and their representativeness of average real-world emissions [B. Giechaskiel, JRC]. One of the problems with the NEDC test has been an increasing gap between the NEDC type approval CO2 values and real-world CO2 emissions. This gap—at around 7% in 2001—has reached nearly 40% in 2016. The WLTP will address a number of test boundary and margin issues, such as fixed temperature, electric auxiliaries, battery charge, or optimal tires. In addition to the WLTP procedure, the in-use CO2 gap is expected to be controlled through CO2 monitoring and conformity testing. The objective is not necessarily to eliminate the gap, but to ensure that it remains constant and that CO2 emission improvements reported during type approval are reflected in real world operation.

Politecnico di Torino [L. Ronaldo] investigated the impact of the WLTP test on CO2 emissions from two conventional passenger cars. The WLTP, due to the higher test mass and road load (RL), leads to an increase of 45% and 49% in the cycle energy demand, while the average CO2 emissions increased only by 10% and 24%, respectively, for vehicle 1 (SI) and vehicle 2 (CI). The increase in CO2 emissions is limited because of the lower impact of the engine warm-up over the WLTP, compared to NEDC. The stop-start technology had a limited benefit (less than 2%) on CO2 reduction on WLTP, which includes less idling than NEDC.

JRC [B. Giechaskiel] also summarized their activities related to EU particle number measurements. Some of the important future oriented activities include:

German National Metrological Institute (PTB) [A. Terres] analyzed PN measurements, including the PMP laboratory procedure and PN PEMS measurements, with a focus on measurement accuracy, calibration aerosol standards, and calibration and validation procedures. It was found that variation of PN measurement in the field is much larger than that of gas measurements, while new PN-PEMS devices have brought additional uncertainty. A number of calibration aerosols are evaluated in an ongoing inter-laboratory comparison under the PMP framework.

Emission Control. The session on emission control and aftertreatment was opened by Ameya Joshi [Corning] who discussed the emission challenges presented by worldwide emission regulations and the respective aftertreatment solutions. As cold start emissions continue to be a challenge, low-temperature three-way catalysts are developed for gasoline applications. Another trend in gasoline engine aftertreatment is the adoption of gasoline particulate filters (GPF), driven by PN regulations in the EU and, in the future, in China and India. GPFs may also be adopted to meet the 2025 California LEV III mass limit of 1 mg/mi. High PN emissions have been also measured in hybrids (PFI & GDI), especially under urban driving conditions. Another challenge with hybrid powertrains are emissions related to the catalyst cool-down during engine stop-start operation.

Under the RDE regulation and the updated AES/BES (auxiliary/basic emissions systems) requirements, wider environmental boundaries must be covered in engine calibrations, and the engine and aftertreatment system requires emission optimization over a wider part of the engine map. Software tools are used to develop and optimize Euro 6d calibrations. Nissan [M. Alonso] presented their new, model based calibration (MBC) methodology for the development of future engines. To assist carmakers in RDE development, AVL [K. Engeljehringer] has developed Road-to-Lab traffic and driver simulation tools.

Latest results from the Concawe Diesel Emissions Project were presented by Jon Andersson [Ricardo]. The study examined emissions from three Euro 6 vehicles with a DPF and different types of NOx aftertreatment (urea-SCR, SCRF-SCR, NOx adsorber & passive SCR). The testing was conducted over laboratory test cycles and on the road (PEMS). All vehicles were compliant with Euro 6c over NEDC. While the urea-SCR vehicles were also compliant over the WLTC, the NOx adsorber system had NOx at 1.9 × the limit. However, the vehicle with a NOx adsorber produced less NOx in the initial, low temperature segment during urban RDE driving. This confirms that the NOx adsorber + urea-SCR configuration—used in several Euro 6d models—may provide the optimum diesel emission configuration. The study found valid correlations between all emissions from PEMS and lab analyzers—the correlation was especially good for NOx and PN emissions.

Amminex [T. Johannessen] presented an update on their solid ammonia SCR technology, where gaseous NH3 is released on demand from rechargeable ammonia cartridges. The Amminex system has been deployed on some 300 city buses in Copenhagen, and 155 buses in London. Recently, the system has been also installed on garbage trucks in Sweden. Another retrofit NOx control system, called the NOxBuster®, has been developed by Proventia [T. Kinnunen]. The system, which combines a DPF and a urea-SCR catalyst, has been installed on over 3000 vehicles in London, Germany, Norway, Sweden, Finland, and Korea.

The Aristotle University [S. Geivanidis] discussed the development of a physical sensor model and OBD implementation of a resistive, accumulating soot sensor for DPF monitoring.

Real Driving Emissions. Gordon Andrews [University of Leeds] presented a wealth of data on emissions from congested traffic, concluding that congestion is a major source of NO2 emissions contributing to the air quality problems in many UK cities. While current RDE limits exclude journeys with speed below 15 km/h, air quality in cities could benefit by including low speed congestion in the RDE by lowering the lowest journey speed to 5 km/h or eliminating the lower speed limit altogether.

Cambustion [M. Duckhouse] adapted their fast gas analyzers—including a fast FID HC, as well as fast CO and NOx analyzers—for on-vehicle use and conducted several tests on a Euro 6 plug-in hybrid vehicle (PHEV) with a 1.8 L PFI gasoline engine. The analyzers can resolve engine transients, such as during engine start-up or acceleration, in real time providing interesting insights into the emission behavior. For instance, even though the initial acceleration of the PHEV relied on the electric motor, rich excursions at engine-on caused a 7% CO breakthrough. A number of high NOx emission episodes were also identified. Over the tested RDE route, the vehicle emitted 0.09 g/km NOx, compared to the Euro 6 NEDC limit of 0.06 g/km. Some 70% of the NOx emissions occurred at three areas, including a heavy congestion area with several traffic lights, and two speed bump sections. Two NOx spikes were registered after each speed bump—one at start of combustion and one at acceleration.

TNO [S. van Goethem] introduced their Smart Emissions Measurement System (SEMS). SEMS is a light-weight, simple on-board emission analyzer that utilizes an automotive NOx/O2 sensor, a thermocouple, a CAN bus OBD II and J1939 interface, as well as an optional NH3 sensor. The collected data is sent via Wi-Fi to the server, which calculates the fuel consumption, CO2, NOx and NH3 (g/s) and performs binning of data (g/kWh or g/km).

Electric Vehicles. For the first time in the history of the Bosmal conference, one of the sessions was devoted to electric powertrains. The first talk provided an overview of electric powertrains [Piotr Bielaczyc, Bosmal]. Surprisingly, the history of electric vehicles pre-dates that of internal combustion engine vehicles, with first electric cars built around 1830. The sales of EVs peaked around 1910, when they started to lose market share to the less expensive ICE cars. By 1935, EVs become all-but-extinct due to the dominance of ICEs fueled by cheap gasoline. Fast forward to today, the world is facing climate change and a looming oil depletion problem, with electric vehicles perceived by many as the most promising technology for future mobility. While many carmakers announced ambitious plans to transition from ICE to EV powertrains, a number of barriers remain, including the charging infrastructure, charging time, battery capacity, and the vehicle cost. The major underlying technical issue is energy density—the energy density of Li-ion battery is approximately 4% of the energy density of fossil fuels, i.e., 125 kg of Li-ion battery is equivalent to 4.5 liters of gasoline.

The EV charging infrastructure—a seemingly under-appreciated aspect of electrical mobility—involves both the addition of a new generating power and an expansion of the grid. Each EV needs at least 40 kWh per charge, which translates to 5 kW × 8 hrs of slow charging [M. Sutkowski, Horus]. To enable fast charging, with 30-40 min giving a reasonable driving range, at least 100-150 kW (and preferably 350 kW) is required per stand. Considering that the fast charging time is 2-3 times longer than refueling, some 20-30 stands and several MW of power would be needed per station. Today, the overwhelming majority of gas stations in Poland have inadequate power supply to support a charging stand for even 3-4 EVs and would require an upgrade to the electric service. The Polish government’s plans call for 1 million EVs by 2030. To support this target with a mix of slow and fast charging infrastructure, about 3.0-6.3 GW of extra power would be needed—an increase of 12-25% relative to the ~25 GW peak capacity of the current Polish generation system.

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There are no plans for the IEES Symposium in 2020, as BOSMAL will be involved in the organization of the SAE Powertrain, Fuel & Lubricants Meeting to take place in Cracow, Poland, September 22-24, 2020. The meeting is jointly organized by the SAE, BOSMAL and the PTNSS.

Conference website