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In this study, the NOx emissions of four Euro 6 diesel passenger cars ranging from Euro 6 b to Euro 6 d-TEMP in different ambient conditions and driving routes were investigated with a Portable Emissions Measurement System (PEMS) and continuous NOx concentration monitoring device. A model was also generated for translating NOx concentration values into a gram basis. The results suggest that there is a marked difference in NOx emissions based on the Euro 6 step for the car is type approved. The study showed that the conformity factor for NOx emissions on a route in a city environment (“City route”) changed from 0.65 to 5.2 depending on the Euro 6 step and car. Surprisingly, a Euro 6 b car equipped with Selective Catalytic Reduction SCR system and updated engine control unit (ECU) software for lower tailpipe NOx emissions provided lower average NOx emissions than a Euro 6 d-TEMP diesel car equipped with dual lean-NOx traps. Results for the City route also showed that the road infrastructure (crossroads and speed limitations) can have a noticeable effect on promoting driving that leads to higher NOx emissions even with a Euro 6 d-TEMP car. Estimations of NOx emissions with modelling based on continuous NOx concentration monitoring suggested that Euro 6 b diesel cars can provide NOx emissions close to the current RDE legislation. In addition, the modelling suggested that the Euro 6 b car with updated ECU software and the Euro 6 d-TEMP diesel car are capable of extremely low daily average NOx emissions, even close to 20 mg/km, in normal daily usage. Nevertheless, the monitoring results and model also suggest that cold ambient temperature has a high effect on the NOx emissions reduction performance of these vehicles, occasionally increasing their daily average emissions to as high as 900 mg/km.

Due to agricultural engines' high average workload and operation in rural areas, substituting internal combustion engines in non-road sector is still a challenge. Utilizing sustainable solutions are therefore in key position for decarbonizing the non-road sector. To this day, the diesel engines dominate the markets because of their high efficiency. However, the simplicity and cost effectiveness of the spark-ignited engines together with renewable fuels are suggested to bring several advantages compared to the diesel engine. E.g. ethanol and bio methane are relatively simple to produce from agricultural residuals and wastes, and the raw materials are easily available around the world. Additionally, stoichiometric engines would only require a three-way catalyst (TWC) to fulfil Stage V emission regulations. A bi-fuel (BF) and dual-fuel (DF) engine operating on both ethanol and biogas could potentially offer a flexible option for e.g. farmers, as they could produce the fuels locally and simultaneously increase the sources of income. The largest technical challenges concerning spark-ignited (SI) engines compared to its diesel counterparts are mainly related to lower engine efficiency. Furthermore, the differences in SI fuels characteristics set limitations on regular SI engines for flexible fuel operation. The main focus of this paper was therefore to study possible methods for developing a flexible spark-ignited non-road engine fulfilling Stage V emission requirements. The studied test engine was a port fuel injected (PFI) SI-conversion based on a commonly used non-road diesel engine for agricultural applications. The engine was equipped with two injectors per cylinder, one directed into the swirl port, the other to the tangential flow port. Additionally, a single gas injection mixer was added to distribute gaseous fuel for all cylinders at once. Four different injection methods were studied: Single liquid fuel injection separately in both swirl and tangential ports, dual port liquid injection and dual-fuel mode, utilizing simultaneously ethanol and methane. The results are compared against Stage V requirements.

PTAs have the possibility to act as trendsetters for sustainable mobility. Helsinki Region Transport (HSL) already has managed to cut both local and greenhouse gas emissions of buses significantly. The goals are quite ambitious;by 2025 HSL wants to achieve a reduction of 90 % or more for emissions of carbon dioxide and pollutants, compared to the year 2010. Within the partnership with HSL, VTT has tested more than 200 buses, and conducted several field tests. The technologies and fuels covered include diesel, renewable diesel, ethanol, methane (natural gas, biogas), hybrids and battery electric vehicles, creating a comprehensive database. This paper discusses theprogress in the performance of buses with conventional powertrains. Furthermore, it presents the actions taken by HSL to introduce advanced biofuels as well as electric buses in Metropolitan Helsinki. Finally, it presents HSL’sfleet strategy going towards 2030.

In this study, the NO

Since 2013, Euro VI heavy-duty on-road vehicles have been on the market in the Europe. Regulated exhaust emissions, including nitrogen oxides and particulate matter, have been cut down to a very low level, independent of fuel (diesel or natural gas). Multiple research papers have shown that the regulated emissions from the Euro VI and US 2010 heavy-duty on-road vehicles tested on chassis dynamometers really deliver emission levels which correspond the type approval requirements, independent of the test cycle used. In-service conformity (ISC), which is included in the Euro VI legislation, requires heavy-duty on-road engine manufacturers to test and prove their engines to comply with the emission legislation during the engine in-use period. The measurements are carried out in the field using PEMS (Portable Emission Measurement System) equipment. This kind of testing, depicting real-world emissions is the final stage to confirm low real-life emissions. Although there is evidence that the exhaust aftertreatment systems of Euro VI heavy-duty on-road engines work well on an average, there is only a limited data of city buses covering their functionality over longer operation periods, especially not at lower ambient temperatures. Especially reduction of nitrogen oxides in the SCR-system (Selective Catalytic Reduction) is sensitive to SCR catalyst operation temperature, and also to impurities transferred from engine oil or fuel. This paper present results of a unique combination of chassis dynamometer measurements, on-road PEMS measurements and continuous NOx-emission monitoring during operation in winter condition from four Euro VI diesel city buses operating in the Helsinki metropolitan area. Based on the research done, four Euro VI city buses monitored and measured during the project showed decreased NOx conversion rate and increased tailpipe NOx emissions when operating in ambient temperatures below 0 °C. Especially in ambient temperatures below -10 °C, the continuous monitoring showed dramatically increased tailpipe NOx concentrations.

Energy use and emissions from non-road mobile machinery need to be reduced. Various mobile machinery are used in multiple diffeerent use cases. Their share of Finland’s CO2 emissions is about 4 % and the most common fuel used is light fuel oil. New alternative energies are partly already compatible with today’s machines, but some require renewal of machinery fleets and building energy infrastructure. In the short term, distribution obligation of biofuel fraction is an effective measure to cut CO2, but at the same time it will increase fuel price for consumers. Including biogas on the distribution obligation was assessed not to be beneficial. Currently, there is no CO2 regulation on mobile machinery and this is slowing down development towards alternative energies. Such regulatory framework should be implemented at European level. Alternative energy solutions for nonroad mobile machinery have potential to develop towards competitive products withing the decade. This shift requires a comprehensive set of policy measures: product development and its funding, trials and pilot projects, incentives for machine and infrastructure investments, review of taxation, collection and sharing of information. Deficiencies were identified in current data collection and statistics on mobile machinery; improving these will support renewal of mobile machine fleets and reducing emissions.