The development of biomethane and hydrogen technology in the road transport in the EU countries is recommended, among the others, in the Directive of the European Parliament and of the Council 2014/94/EU of 22 October 2014. Under the provisions of the said Directive, it is recommended to EU countries to use biomethane and progressively ensure accessibility to hydrogen cars on their territories, and above all to ensure the possibility of driving hydrogen vehicles between the member States. The territorial accessibility for biomethane vehicles is determined by the availability of biomethane refuelling infrastructure in the first place in cities and then on the road network distances recommended in this directive. The territorial accessibility for hydrogen vehicles is determined by the availability of hydrogen refuelling infrastructure, in the first place along the TEN-T network. The article presents the possibilities of using these alternative fuels in Poland, presenting some of the results of research and analysis in this area.

Ammonia is a toxic exhaust component emitted from internal combustion engines. Both pure ammonia and the products of its reaction with nitrogen and sulfur compounds, being the source of particulate matter (PM) emissions, are dangerous for human health and life. The aim of the article was to demonstrate that NH₃ can be produced in exhaust gas after-treatment systems of spark-ignition (SI) engines used in light-duty vehicles. In some cases, NH₃ occurs in high enough concentrations that can be harmful and dangerous. It would be reasonable to collect research data regarding this problem and consider the advisability of limiting these pollutant emissions in future regulations. The article presents the results of the spark-ignition engine testing on an engine test bench and discusses the impact of the air–fuel ratio regulation and some engine operating parameters on the concentration of NH₃. It has been proven that in certain engine operating conditions and a combination of circumstances like the three-way catalytic reactor (TWC) temperature and periodic enrichment of the air–fuel mixture may lead to excessive NH₃ emissions resulting from the NO conversion in the catalytic reactor. This is a clear disadvantage due to the lack of limitation of these pollutant emissions by the relevant type-approval regulations. This article should be a contribution to discussion among emissions researchers whether future emission regulations (e.g., Euro 7 or Euro VII) should include a provision to reduce NH₃ emissions from all vehicles.

In this study, the authors assessed the road emissions of several passenger cars using specialised instrumentation, of the PEMS type, to measure particle number emissions in real traffic conditions. The tests were performed on a RDE test route developed and compliant with EU guidelines. The results of the tests were discussed in terms of the direct (created in the internal combustion engine) emission of particulate matter in various road conditions. Additionally, an index was determined that characterizes the number of particles according to their diameter in relation to the content of particles in the air. A characteristic of combustion engines (gasoline, diesel) is that during a cold start of the engine, the concentration of the number of particles with diameters around 100 nm increases more than 200 times (for hybrids—300 times). On this basis, it can be concluded that particle emissions with diameters smaller than 23 nm are significant in motor vehicles powered by combustion engines, regardless of whether they are conventional or hybrid vehicles. The share of particles with diameters less than 5 nm is 66% (for diesel engines) and 40% (for gasoline engines) of all the particles.

The article addresses the usage patterns of plug-in hybrid vehicles (PHEVs) under Polish conditions. The conventional approach to operating such vehicles assumes that they are used with a fully charged battery at the start. However, the economic circumstances of Polish users often do not allow for daily charging of vehicles from the domestic power grid. As a result, these vehicles are used not only in a mode powered solely by the internal combustion engine but also in a mode where the internal combustion engine is primarily utilized to charge the battery. An analysis was conducted on various ways of operating plug-in vehicles, evaluating not only harmful emissions but also fuel consumption (for battery states of charge: SOC = 100%, SOC = 50%, SOC = 0%, and SOC = 0 → 100%—forced charging mode). The study focused on the most characteristic vehicle segment in Poland, SUVs, and employed a methodology for determining exhaust emissions under real-world driving conditions. Results indicate that forced charging of such a vehicle’s battery leads to over a 25-fold increase in carbon dioxide emissions (fuel consumption) in urban areas compared to operating the vehicle with a fully charged battery (CO—25× increase, NOx—12× increase, PN—11× increase). Operating a plug-in SUV without charging it from the power grid results in a 13-fold increase in fuel consumption compared to using the vehicle with a fully charged battery (CO—10× increase, NOx—6× increase, PN—4× increase). The emission results were used to evaluate Poland’s charging infrastructure in the context of PHEV usage. The current state of the infrastructure and its development plans for 2030 and 2040 were analyzed. It was found that significant reductions in fuel consumption (by approximately 30%) and CO₂ emissions are achievable by 2040. Emissions of CO, NOx, and PN are expected to decrease by about 10%, primarily due to the internal combustion engine operating at high load conditions in non-urban or highway scenarios.

On-road driving tests are performed to determine the emission of harmful exhaust compounds from vehicles. These primarily include carbon dioxide, nitrogen oxides, and particle number. However, there is a lack of indicators that combine the first three substances that are the most important in assessing the environmental aspects of vehicles. The purpose of this article is to indicate the possibility of assessing emissions in real driving conditions from light-duty and heavy-duty vehicles of different categories. In order to do so, a portable emissions measurement system (PEMS) and an instrument for measuring the particle number were used. The tests were carried out on routes designed to comply with the requirements and regulations laid down in the European Union legislation. On-road emissions of carbon dioxide, nitrogen oxides and particle number have been determined. Factors have been determined as the multiplication of these compounds for each vehicle category in three phases of the test: urban, rural, and motorway. A new way of assessing emissions from vehicles using new factors has been proposed.