This paper investigates possibilities for the diversification and decentralization of heat energy sources in the district heating system of Tuzla, with the aim of increasing energy security, reducing CO₂ emissions and improving overall system efficiency. The existing model, which relies almost exclusively on the Tuzla Thermal Power Plant (TE Tuzla), is characterized by high dependence on fossil fuels, limited operational flexibility and hydraulic challenges in peripheral parts of the network. The study analyses potentials for integrating alternative heat sources, biomass cogeneration, waste-to-energy (RDF) and solar thermal systems, and assesses the role of thermal energy storage in optimizing operation and mitigating seasonal variability. Comparative scenario analysis demonstrates feasible transition pathways towards a sustainable heating model that reduces emissions and increases local control over energy supplies while accounting for Tuzla's specific technical and institutional context.

Fully halogenated chlorofluorocarbons (CFCs) are, despite their good thermodynamic properties, stability and non-toxicity, eliminated from use. Due to the content of one chlorine atom in the molecule, the use of hydrochlorofluorocarbons (HCFCs) has been reduced in many European countries. The use of partially halogenated hydrofluorocarbons (HFCs) in which the molecules have no chlorine atoms, due to increased inflammability, is also to a large extent limited. This paper presents a methodology for selecting working fluids or mixtures for use in cogeneration ORCs on biomass, which will, in addition to thermodynamics, also take into account the safety and environmental requirements of working fluid acceptability. The effects of thermodynamic properties of preselected working fluids on the performance of the cogeneration ORC plant have been analyzed and the thermodynamic properties of the working fluid are optimized by the exergy efficiency of the ORC as a function of the target, using a genetic algorithm. Optimal values of the exergy efficiency, component size and exergy losses of the cogeneration ORC for the use of biomass energy are compared and analyzed under the same heat source conditions and pre-defined boundary conditions. The experimental analysis of the cogeneration ORC shows that the most preferred working fluid is p-xylene because in comparison to undekan, MDM (OMTS) and D4 (OMCTS) it has the highest value of exergy efficiency but also requires the least dimension of ORC components (turbines and capacitors).

Installation of plants for wet Hue gas desulphurization has a significant impact on energy consumption, and thus the overall level of utilization of the power plant units. The aim of this paper is to use mathematical models in analysis of the influence of wet Hue gas desulphurization plants which are additionally installed on existing units and finds the optimal operating range regarding the specific heat consumption. The proven mathematical model can be further used in the analysis of wet Hue gas desulphurization that is planned for used in units that use similar coals.