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.

Many factors, such as climate change and the associated risk of increasing the average temperature on the globe, energy security and the finishing of fossil fuel deposits have caused other renewable energy sources to be sought. Transport, as a branch of industry largely responsible for air pollution and greenhouse gas emissions in large cities, requires the necessary changes in the way vehicles are powered. Until now, the fuels available at petrol stations use admixtures of first generation biofuels, such as bioethanol, as a 5% additive to motor gasolines and biodiesel (FAME) as a 7% additive to diesel oil. The article presents the idea of biorefinery installations, specifies the spectrum of substrates of the second and advanced generations, which may be a biorefinery input, including waste oils that can be used to produce hydrogenated HVO vegetable oils and other high-value products. The paper presents he existing biorefinery plant in Venice resulting from the transformation of a conventional oil refinery in which HVO fuel is produced. The article also presents the parameters of this new biofuel and compared them with the parameters of other fuels used to power self-ignition engines, such as FAME and diesel, along with discussing the prospects for HVO fuel development in Europe.