Environmental protection, and in particular air protection against pollution, is an extremely important element of the global policy of many countries. The problem of air pollution is particularly important in Poland, where the heating market is one of the largest in Europe and is based in 74% on the use of fossil fuels, in particular hard coal. One of the technological solutions for the implementation of cleaner fuels is the co-combustion of coal and biomass. This process enables the reduction of harmful pollutants such as CO₂, SO₂, and can be implemented in existing boilers. Heating boilers achieve the highest design efficiency during optimal load at the level of 85–95% of nominal power. Under such conditions, heat production is most efficient. During operation, boilers are often started, extinguished or run below rated output, resulting in increased emissions. This publication presents the results of measurements of efficiency and concentrations of pollutants in the WR water boiler during operation below the technical minimum. Hard coal was cofired in the boiler with biomass of wood origin. It was noted that the amount of biomass had a significant impact on the boiler efficiency and pollutant emission. Based on the research, it was also noted that it was possible to make a qualitative prediction of these parameters. The obtained results are an introduction to a deeper analysis and further research on the correlation between the amount of biomass and boiler power and the efficiency and concentration of pollutants.

This article aims to analyze the energy efficiency of combining heat pumps with photovoltaic (PV) panels in energy-efficient homes. The research methodology involved a detailed energy balance analysis, assessment of the impact of mechanical ventilation, location, heat loss, and the choice and operation of heat sources, with a particular focus on heat pumps in synergy with PV installations. The results demonstrate that integrating heat pumps with PV panels can significantly reduce the demand for external energy sources and lower the operating costs of buildings, while contributing to their energy self-sufficiency. This study highlights that such a combination of technologies is key to promoting sustainable development and achieving energy efficiency goals in the residential sector. The results of this analysis expand knowledge about the effectiveness of such systems and provide practical recommendations for designers and engineers interested in implementing renewable energy technologies in modern energy-efficient buildings, taking into account the impact of these solutions on reducing CO₂ emissions as well.

The theme of the article is to determine the possibility of waste heat recovery and use it to prepare hot water. The scope includes a description of the existing sample of coal-fired boiler plant, the analysis of working condition and heat recovery proposals. For this purpose, a series of calculations necessary to identify the energy effect of exhaust temperature decreasing and transferring recovery heat to hot water processing. Heat recover solutions from the exhaust gases channel between boiler and chimney section were proposed. Estimation for the cost-effectiveness of such a solution was made. All calculations and analysis were performed for typical Polish conditions, for coal-fired boiler plant. Typicality of this solution is manifested by the volatility of the load during the year, due to distribution of heat for heating and hot water, determining the load variation during the day. Analysed system of three boilers in case of load variation allows to operational flexibility and adaptation of the boilers load to the current heat demand. This adaptation requires changes in the operating conditions of boilers and in particular assurance of properly conditions for the combustion of fuel. These conditions have an impact on the existing thermal loss and the overall efficiency of the boiler plant. On the boiler plant efficiency affects particularly exhaust gas temperature and the excess air factor. Increasing the efficiency of boilers plant is possible to reach by following actions: limiting the excess air factor in coal combustion process in boilers and using an additional heat exchanger in the exhaust gas channel outside of boilers (economizer) intended to preheat the hot water.

Ventilation systems consume more and more energy because of the often complex treatment of the air supplied to closed spaces. Looking for sources of energy allow for significant savings costs, which often translate into renewable energy sources. One of the more popular solutions is to use energy...

Straw is treated as agricultural waste, and it is available in almost every region of Poland. A total of 30 million tons of straw is produced per year, of which there is a surplus of approximately 13.5 million tons of undeveloped straw. For energy purposes, straw from cereals or rapeseed is most often used. When analyzing scientific publications, it was noticed that, in Poland, large amounts of oat straw are produced, and there is no alternative use for it. Hence, we conducted research to determine the energy value of oat straw. Raw material was obtained from an individual farm from 2018 to 2020. Selected energy parameters for straw burned alone (100%) or co-fired with coal were analyzed in the following weight proportions: 70/30, 80/20, and 90/10 coal/oat straw. It was shown that changing weather conditions, in particular years, had a modifying effect on some of the energy parameters of straw. The calorific value of straw was lower than that of coal, but its impact on environmental pollution turned out to be significantly lower. The difference in combustion heat between coal and straw was 11.74 MJ·kg⁻¹. Investigations into pollutant concentrations were performed for cubes of compressed straw and hard coal. Mixtures of these fuels were not studied in this part of the work. The combustion of straw resulted in a reduction of harmful NO, NO_X, and SO₂ pollutants and an increase in CO compared to coal combustion. As for hydrogen content—it was the highest in carbon and the lowest in straw. In the case of analytical moisture, an inverse relationship was observed. In the case of both coal and straw, the ash content varied throughout the years of research. As the boiler power increased from 5 to 25 kW, the consumption of burned raw material increased significantly. The results indicate that the surplus of oat straw can be rationally used to obtain thermal energy, including co-combustion with coal. This will allow one to avoid burning straw in the fields, which causes great harm to the natural environment.

One of the main environmental problems is the protection of atmospheric air from pollution, which is a result of increase the cover needs of the energy. This problem is particularly important in Poland, where the heat market is one of the largest in Europe and is based in 75% on the use of fossil fuels. The amount of fuel, its type and quality directly affect boiler operation, heat generation capacity, combustion process and thus emissions. The change of the pollutant emission factor also results in a variable load on the boiler room dependent on external conditions. Reduction of emissions pollutants in the energy production process is possible, for example, by increasing the share of renewable fuels in the overall energy balance. One of the possibilities to increase the share of these fuels in the energy sector is co-firing hard coal and biomass. The paper presents results of measurement of concentrations of selected air pollutants in the exhaust gases from co-firing of hard coal and biomassin the form woodchips coming from furniture companies. Based on experimental research, has been created statistical models on the influence of co-combustion of hard coal and biomass in WR water boilers during unstable conditions on the concentration of selected gaseous pollutants.