This article discusses the problems of exhaust gas emissions in the context of the possibility of their reduction through the use of fuels with hydrogen as an additive or hydrotreatment. These fuels, thanks to their properties, may be a suitable response to more and more demanding restrictions on exhaust emissions. The use of such fuels in reactivity controlled dual fuel engines (RCCI) is currently the most effective way of using them in internal combustion (IC) engines. Low-temperature combustion in this type of engine allows the use of all modern fuels intended for combustion engines with high thermal efficiency. Thermal efficiency higher than in classic engines allows for additional reduction of CO₂ emissions. In this work, the research on this subject was compiled, and conclusions were drawn as to further possibilities of popularizing the use of these fuels in a wide spectrum of applications and the prospect of using them on a mass scale.

This paper presents a theoretical analysis of the selected properties of HCNG fuel calculations and a literature review of the other fuels that allow the storage of ecologically produced hydrogen. Hydrogen has the most significant CO₂ reduction potential of all known fuels. However, its transmission in pure form is still problematic, and its use as a component of fuels modified by it has now become an issue of interest for researchers. Many types of hydrogen-enriched fuels have been invented. However, this article will describe the reasons why HCNG may be the hydrogen-enriched fuel of the future and why internal combustion (IC) piston engines working on two types of fuel could be the future method of using it. CO₂ emissions are currently a serious problem in protecting the Earth’s natural climate. However, secondarily, power grid stabilization with a large share of electricity production from renewable energy sources must be stabilized with very flexible sources—as flexible as multi-fuel IC engines. Their use is becoming an essential element of the electricity power systems of Western countries, and there is a chance to use fuels with zero or close to zero CO₂ emissions, like e-fuels and HCNG. Dual-fuel engines have become an effective way of using these types of fuels efficiently; therefore, in this article, the parameters of hydrogen-enriched fuel selected in terms of relevance to the use of IC engines are considered. Inaccuracies found in the literature analysis are discussed, and the essential properties of HCNG and its advantages over other hydrogen-rich fuels are summarized in terms of its use in dual-fuel (DF) IC engines.

The problem of global warming and related climate change, as well as rising oil prices, is driving the implementation of ideas that not only reduce the consumption of liquid fuels, but also reduce greenhouse gas emissions. One of them is the use of natural gas as an energy source. It is a hydrocarbon fuel with properties allowing the reduction of CO₂ emissions during its combustion. Therefore, solutions are being implemented that allow natural gas to be supplied to means of transport, which are trucks of various categories and purposes. This article presents the results of tests of an engine from a used semi-truck, to which an innovative compressed natural gas (CNG) supply system was installed. This installation (both hardware and software), depending on the engine operating conditions, enables mass replacement by natural gas (up to 90%) of the basic fuel—diesel oil. During the tests, on the basis of the obtained results, the influence of the diesel fuel/CNG exchange ratio under various engine operating conditions on the concentration of toxic CO₂, CO, NO, NO₂, CH_4, C₂H_6, NMHC, NH₃ and exhaust smoke was assessed. The test results confirm that, compared to conventional fueling, the diesel/CNG-fueled engine allows for a significant reduction in CO₂ concentration even in a car operated for several years with diesel fuel and with high mileage. The use of a non-factory installation significantly increased the concentration of methane CH₄, nitrogen dioxide NO₂ and carbon monoxide CO in the exhaust gas. It was found that the smoke content and the temperature of exhaust gases did not decrease with increasing ratio of fuel replacement. The concentration of CO, NO_X, CH₄ and NMHC was increased, while the concentration of CO₂, C₂H₆, NH₃ and the consumption of diesel fuel by the engine, decreased significantly. The innovation of the research is based on the use of a modern and unique engine gas fuel system control system where the original fuel supply system with unit pumps is able to reduce diesel oil consumption by up to 90%.

Nowadays, internal combustion engines are being developed in the directions that allow to maximize the efficiency of their work, in order to make the most economical use of fuels. The low-temperature method of burning fuels in HCCI engines - Homogenous Charge Compression Ignition - allows to improve the efficiency of the engine, thanks to the reduction of energy lost during cobustion process. For the further development of engines with this type of mixture auto-ignition, with increasing the range of fuels used for that king of engines, it is necessary to develop the RCCI engines. Reactivity-Controlled Compression Ignition - RCCI - is the way to control the air-fuel mixture auto-ignition by using the injection of second fuel injected into the combustion chamber before the combustion begins. The development of modern compression ignition engines is strongly dependent on engines with this type of ignition. Using two fuels with different physicochemical properties makes it possible to control the time of compression ignition and allows to use engine in full range of operation. RCCI is a special type of HCCI engine that allows to use many types of fuels with high combustion efficiency and low emission of harmful exhaust components. The paper analyzes the issues related to the adoption and development of engines with this method of ignition.

The constant development of civilization increases environmental pollution as a result of industrial activity and transport. Consequently, human activity in this area is restricted by regulations governing the permissible emission of harmful substance components into the environment. These include substances emitted by combustion engines, the use of which remains high in many industries. Consequently, research is being conducted to reduce the emissions of harmful exhaust components from existing and newly manufactured internal combustion engines. This research presents a used semi-truck engine, in which an innovative Compressed Natural Gas (CNG) supply system was applied. Using this fuel supply installation allows a mass exchange of the base diesel fuel to natural gas of up to 90%. The study evaluated the effect of the diesel/CNG exchange ratio for different engine operating conditions (engine load, speed) on the concentration of toxic components, such as CO, NO, NO₂, NO_X, as a sum of NO, NO₂, CH₄, C₂H₄, C₂H₆, C₃H₈, NH₃, and CH₂O. The use of a dual-fuel system had a positive effect on the emissions of some harmful exhaust components, even in an engine from a vehicle that had been running for many years on diesel and at high mileage, but, simultaneously, the emissions of some harmful exhaust gas components increased.

Displacing internal combustion engines (ICE) from the passenger car sector does not mean displacing it from all industries and specific applications. Thanks to the analysis of data on compression ignition (CI) engines used in the world, it is possible to prepare ready-made solutions for the most common engines in selected industries or for those whose greenhouse gas emissions will be the largest and most expensive for their owners in the coming years. The basic solution presented in this article gives the possibility of powering the engines with the most ecological currently known alternative motor fuels and using the already existing methane transmission infrastructure around the world. Their greatest advantage is their availability and low carbon content, which allows to minimize carbon dioxide emissions, both by burning hydrogen-enriched fuels and by increasing the efficiency of the engines modified by dual fuel supply system. Properly made external dual-fuel installation allows to improve the thermal efficiency of the CI engine. Work on this issue may help in the development of, for example, high-efficiency flex fuel power generators, which, as the current situation in Ukraine shows, are worthy. Thanks to the diversification of power sources for power generators, the countriesy is able to increase the reliability and security of energy supplies even in difficult conditions, such as armed conflict or natural disasters.