The use of organic residues and waste for production of biogas as an energy source is a viable option for waste management and reduction of greenhouse gas emissions. However, before any eventual utilization of biogas, hydrogen sulfide (H₂S) and carbon dioxide (CO₂) must be removed since those contaminants are highly undesirable in combustion systems. This work deals with the construction and examination of a laboratoryscale, low-cost test stand for quick evaluation of the existing and new methods for H₂S and CO₂ removal from biogas. The test stand consists of two sections: one based on absorption in liquid phase (barbotage process) and the other adsorption in a bed of solid reagent. Seven different reagents of various concentrations were used in the experiment: sodium hydroxide (NaOH), ethylene glycol (EG), ethanoloamine (EA), diethanoloamine (DEA), and distilled water (H₂O) in the barbotage section of the test stand, and bog iron ore (BIO) and activated carbon (AC) in the adsorption column. In the absorption tests, treating biogas with 1M NaOH solution and 100% EA resulted in complete removal of H₂S and CO₂. For 100% DEA, high H₂S and moderate CO₂ absorption efficiency were achieved. EG and H₂O allowed the removal of H₂S only to a very limited extent. Both reagents used in the tests with adsorption in a bed, BIO and AC, were able to eliminate H₂S from biogas, but practically did not change the concentration of CO₂.

Ammonia is regarded as an attractive alternative fuel for combustion engines with a great potential to replace currently used petroleum-based energy carriers. Its direct combustion does not result in emission of carbon dioxide and it can be produced from renewable sources. The energy density of ammonia is reasonable, it is relatively easy to store and has well established infrastructure for production, storage, handling and distribution. However, ammonia is corrosive to some materials, difficult to ignite due to high octane number and high autoignition temperature, and has low heating value. Therefore theoretical and experimental studies are needed to enhance the performance and expand the operating range of ammonia-fuelled engines. This study investigates the feasibility of introducing ammonia to dual-fuel compression-ignition engine, where a pilot dose of diesel oil initiates the ignition of ammonia-air mixture. Numerical simulations of the combustion process were carried out using a one-dimensional model, parametrized according to the specifications of a four-cylinder, turbocharged compression-ignition engine with conventional direct injection supply system, modified slightly for ammonia induction. The model was validated by comparison with empirically determined data. The simulations were performed for different combinations of ammonia-diesel oil ratios at various engine load. Ammonia was treated as an energy replacement for diesel oil. Engine performance and emissions of selected pollutants in dual-fuel operation mode were compared to that with diesel oil only. The results showed that different ammonia-diesel oil ratios can be used to achieve the same engine torque. A higher than rated power, depending on engine load conditions, can be obtained with the addition of an extra dose of ammonia. The influence of ammonia on the emissions of particular pollutants varied and was discussed in detail. Acquired combustion characteristics and engine performance parameters allow for a positive verification of the proposed model. The drawn conclusions may be useful for the development of dual-fuel engine control algorithms.

In this paper, energy consumption of two light-duty vehicles, battery electric and conventional with an internal combustion engine, was investigated on the basis of chassis dynamometer test results. The sensitivity of energy consumption to various zero-dimensional characteristics of the driving pattern was discussed. The results demonstrated that under dynamic driving conditions, the electric vehicle used on average 64% less energy than the conventional one, even with battery charging efficiency taken into account. Among selected zero-dimensional characteristics, the average velocity and the average absolute value of the product of velocity and acceleration proved to be the best characteristics to describe the energy consumption of vehicles.