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The presented case study evaluates the environmental and economic effects of carbon bio pellet production from orchard grass by Farmutil HS Inc. through the hydrothermal carbonisation method, using obtained biofuel as a substitute for natural gas for heat production. Hydrothermal carbonisation is a zero-waste technology that produces renewable bioenergy by substituting fossil fuels for non-renewable resources. Processing 60,000 t/y of orchard grass with this method resulted in a total amount of heat production of 456,780 GJ/y. This means that over 60% of the energy produced from natural gas could be substituted by renewable bioenergy. It is also very important that the estimated cost of heat produced from carbon bio pellets is 29% lower in comparison to the cost of heat produced from natural gas

In the dynamic field of photovoltaic technology, the pursuit of efficiency and sustainability has led to continuous novelty, shaping the landscape of solar energy solutions. One of the key elements affecting the efficiency of photovoltaic cells of IInd and IIIrd generation is the presence of transparent conductive oxide (TCO) layers, which are key elements impacting the efficiency and durability of solar panels, especially for DSSC, CdTe, CIGS (copper indium gallium diselenide) or organic, perovskite and quantum dots. TCO with low electrical resistance, high mobility, and high transmittance in the VIS–NIR region is particularly important in DSSC, CIGS, and CdTe solar cells, working as a window and electron transporting layer. This layer must form an ohmic contact with the adjacent layers, typically the buffer layer (such as CdS or ZnS), to ensure efficient charge collection Furthermore it ensures protection against oxidation and moisture, which is especially important when transporting the active cell structure to further process steps such as lamination, which ensures the final seal. Transparent conductive oxide layers, which typically consist of materials such as indium tin oxide (ITO) or alternatives such as fluorine-doped tin oxide (FTO), serve dual purposes in photovoltaic applications. Primarily located as the topmost layer of solar cells, TCOs play a key role in transmitting sunlight while facilitating the efficient collection and transport of generated electrical charges. This complex balance between transparency and conductivity highlights the strategic importance of TCO layers in maximizing the performance and durability of photovoltaic systems. As the global demand for clean energy increases and the photovoltaic industry rapidly develops, understanding the differential contribution of TCO layers becomes particularly important in the context of using PV modules as building-integrated elements (BIPV). The use of transparent or semi-transparent modules allows the use of building glazing, including windows and skylights. In addition, considering the dominant position of the Asian market in the production of cells and modules based on silicon, the European market is intensifying work aimed at finding a competitive PV technology. In this context, thin-film, organic modules may prove competitive. For this purpose, in this work, we focused on the electrical parameters of two different thicknesses of a transparent FTO layer. First, the influence of the FTO layer thickness on the transmittance over a wide range was verified. Next, the chemical composition was determined, and key electrical parameters, including carrier mobility, resistivity, and the Hall coefficient, were determined.

The valorisation of sewage sludge for sustainable agricultural use and biofuel production proposes an effective and beneficial management of sewage sludge in a closed-loop cycle. The management of sewage sludge biowaste is a rising problem due to increasing waste storage expenses. In this sense, the use of circular economy principles in sewage sludge management creates opportunities to develop new technologies for processing. The biorefinery model allows the application of wasteless technologies via sewage sludge valorisation in terms of agricultural use and biofuel production, especially with the hydrothermal carbonisation method. Applying hydrothermal carbonisation in the treatment of biosolid sewage sludge has numerous benefits due to processing highly hydrated organic waste into carbon hydro char, a high-quality solid biofuel. The direct use of sewage sludge in the soil does not allow for full use of its functional properties. However, the hydrothermal carbonisation of sewage sludge results in biocarbon pellets, making it a viable approach. This work also discusses the barriers (legal, chemical, biological, and technical) and possibilities related to sewage sludge biorefining processes.

This work focused on the verification of the electrical parameters and the durability of side connectors installed in glass–glass photovoltaic modules. Ensuring the safe use of photovoltaic modules is achieved, among others, by using electrical connectors connecting the PV cell circuit inside the laminate with an external electric cable. In most of the cases for standard PV modules, the electrical connector in the form of a junction box is attached from the back side of the PV module. The junction box is glued to the module surface with silicone where the busbars were previously brought out of the laminate through specially prepared holes. An alternative method is to place connectors on the edge of the module, laminating part of it. In such a case, the specially prepared “wings” of the connector are tightly and permanently connected using laminating foil, between two glass panes protecting against an electrical breakdown. Additionally, this approach eliminates the process of preparing holes on the back side of the module, which is especially complicated and time-consuming in the case of glass–glass modules. Moreover, side connectors are desirable in BIPV applications because they allow for a more flexible design of installations on façades and walls of buildings. A series of samples were prepared in the form of PV G-G modules with side connectors, which were then subjected to testing the connectors for the influence of environmental conditions. All samples were characterized before and after the effect of environmental conditions according to PN-EN-61215-2 standards. Insulation resistance tests were performed in dry and wet conditions, ensuring full contact of the tested sample with water. For all modules, before being placed in the climatic chamber, the resistance values were far above the minimum value required by the standards, allowing the module to be safely used. For the dry tests, the resistance values were in the range of GΩ, while for the wet tests, the obtained values were in the range of MΩ. In further work, the modules were subjected to environmental influences in accordance with MQT-11, MQT-12, and MQT-13 and then subjected to electrical measurements again. A simulation of the impact of changing climatic conditions on the module test showed that the insulation resistance value is reduced by an order of magnitude for both the dry and wet tests. Additionally, one can observe visual changes where the lamination foil is in contact with the connector. The measurements carried out in this work show the potential of side connectors and their advantage over rear junction boxes, but also the technological challenges that need to be overcome.

Research on the properties of hydroxyapatite ashes from an industrial unit burning meat and bone meal in an industrial rotary kiln is presented. High carbon content (10%), relatively low phosphorus (34%), and sulfides were found. The ash obtained was unsuitable for producing superphosphate fertilizer due to the emission of hydrogen sulfide in the reaction of the raw material with sulfuric acid. The research showed that decreasing the meat-bone meal calcining temperature below 950 °C and recycling the ashes, reusing them after mixing in a 1:1 ratio with dosed meat and bone meal, allows reducing the carbon content in the hydroxyapatite ash to the level of 2O5 content in the ash to 39%, and eliminates hydrogen sulfide emissions. The improved parameters allow the production of hydroxyapatite ash that could be a substitute for phosphorites used in the production of fertilizers. Incineration of the meat-bone meal allowed the production of bioenergy and hydroxyapatite. This is an example of implementing a very profitable circular economy solution.

A complex method developed to assess quality within a proposed framework and at a certain scope of measurement for circular economy (CE) quality indicators is presented. This was used to compare three different scenarios for municipal waste management systems: 1—incineration; 2—recycling and reuse of separated municipal waste and the transformation of the organic fraction into biodiesel and bio-coal; and 3—an upgraded Scenario 2 including decreased recycling of waste streams and the bioprocessing of paper/cardboard and processing the non-recycled fraction into bio-diesel, bio-coal, and second-generation biofuel. For the evaluation of the CE quality indicator, a set of technical, environmental, economic, and social elements was selected by a panel of experts, who also assigned them a qualitative assessment and weighting on the basis of the factors identified. The calculated Relative Increase in the CE indicator for the scenarios analyzed showed that Scenarios 3 and 2 are much more beneficial than Scenario 1 in technical, environmental, economic and social terms.

The developed production of heat (steam) by Farmutil Company enables use of renewable energy from biofuel meat-bone meal which is incinerated in rotary kilns utilising vapours and odours from its production, instead of natural gas, to ensure Farmutil’s own needs for heat. The transformation of existing district heating in Piła city (currently using coal) into a fourth generation district heating system was proposed, predicting the use of heat (hot water) after combustion of biofuel meat-bone meal as district heating in the city of Piła. The maximum possible surplus amount of heat that can be produced at Farmutil exceeds the needs for the district heating demands of the city of Piła (860,200 GJ/y) by 53.2% at a meat-bone meal burning scale of 150,000 t/y. The use of 52,000 t/y of meat-bone meal for district heating production also results in an increase in incomes through the sale of hydroxyapatite ash from its combustion, amounting 1.638 million EUR/y. The closure of the coal-fired heating plant eliminates the consumption of 44,000 t/y of coal and the need to pay CO2 emission permits amount to over 5.588 million EUR/y.

LCA analysis with 16 impact categories was used for the comparison of two developed combustion technologies: Scenario I—the combustion of meat bone meal produced from all types of meat waste; Scenario II—the combustion of meat bones from the production of meat products. The key hotspots determined were electricity and natural gas consumption, covering as much as 98.2% of the total influence on the environment in Scenario I and 99.3% in Scenario II. Without taking into account the environmental burdens avoided, the LCA analysis showed that Scenario I was assessed to have 71.2% less environmental impact. The avoided burdens approach changed the relationship between the two scenarios. The absolute value score for the overall environmental impact shows that Scenario II can be more environmentally beneficial than Scenario I; however, Scenario I allowed the elimination of all types of Polish meat waste, and Scenario II could only be carried out in meat production units for the elimination of meat bone waste and by-products from meat processing (i.e., 23% of the total meat waste produced in Poland).

Oily brine from the gas and oil industries remains the most difficult wastewater to treat due to its complex chemical composition, which includes aromatic hydrocarbons. Even at low concentrations, the presence of BTX (benzene, toluene, xylenes) can be extremely harmful to aquatic ecosystems. Fixed-bed adsorption columns are recommended for oily water treatment due to their flexibility and easy operation. In this research, pine sawdust modified with polydimethysiloxane (PDMS) and hydrophobic nanosilica was applied as a sorbent in a filtration system. The surface modification of raw fiber allowed to change its morphology and increase the roughness of it. The Yoon−Nelson, Bohart−Adams, Clark, and Belter models were applied to simulate continuous biosorption. The Bohart−Adams model strongly correlated with the experimental data and described the whole dynamic behavior of the column. The effect of feed flow rate (10−50 mL/min) on breakthrough characteristics was determined. Both the breakthrough and saturation time decreased as the flow rate increased. This study indicated that hydrophobized pine sawdust is an effective low-cost potential biosorbent for the removal of BTX fraction from produced water in continuous column mode.