The production of hydrocarbon fuel from waste engine oil is an excellent way to produce alternative fuels. The aim of the research in this paper is obtaining fuel with a mixture of waste engine oil (WMO) and diesel fuel that can be used as an alternative fuel for internal combustion engines and low power heat generators. With this goal in mind, tests were conducted to estimate the combustion parameters and emissions at a low heat output of 40 kW. Waste motor oils (WMO) and four of its diesel mixtures were used, varying in weight from 20% WMO to 50% WMO. Test results were analysed and compared with diesel fuel. Higher NO, CO and CO₂ emissions were determined for WMO and its mixtures compared to diesel fuel. The flue gas temperature in the kiln was high for all WMO and diesel blends, which indicates the efficiency of the input energy. The absorption of flue gases in the scrubber with distilled water showed higher presence of sulphates, sulphides, nitrates and nitrites compared to allowable values.

This paper presents the basic characteristics of gaseous combustion products (CO2, CO, NOx, SOx, NH3, etc.) in internal combustion engines (ICE) and their harmful impact on the environment, i.e., the ecological context. Special attention is given to the formation of CO2and CO, specifically the reaction kinetics CO2=CO+0.5·O2 as the dominant gases in the exhaust gases of ICE. At an ambient temperature of 298K, the considered reaction ΔH=282990 kJ is endothermic and the equilibrium constant at normal pressure (1.013∙105Pa) is much less than one Kp’=1.40·10-45, which means that the equilibrium of the reaction is shifted to the left, towards the reactant CO2. This practically means that the formed CO2 in the exhaust gases remains stable and, as a greenhouse gas, has an impact on the 'greenhouse effect.' Only at significantly high temperatures, above 2000K, does a slight formation of CO and reduction of CO2 occur. JEL classification: Q53, Q42