Climate crisis and recent developments in bio-based restoration of ecosystems.

Over the years, due to the climate crisis, sustainable economic growth and biodiversity protection have been increasingly promoted. Scientists, researchers, and experts in the field of sustainable development highlighted that bio-based restoration of ecosystems and responsible management of existing resources are needed to meet the needs of future generations. This paper discusses some of the latest developments in three main areas of sustainability, i.e., energy, water and environment, that emerged from the "16th Sustainable Development of Energy, Water and Environment Systems Conference - SDEWES 2021". The purpose of this introduction article is to briefly review the articles included in this Virtual Special Issue. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES 2021 conference.

Sustainable development in period of climate crisis.

The ongoing process of climate change has shown that sustainable development of humankind is a necessity. Existing resources need to be used in a form of a circular economy, and no more in a linear economy as has been the case until now. Resources need to be better managed to meet the needs of future generations. Therefore, energy, water and environment systems need to be integrated in order to slow down their overexploitation. This paper discusses some of the latest developments in three main areas of sustainability, i.e., energy, water and environment, that emerged from the four "Sustainable Development of Energy, Water and Environment Systems" (SDEWES) Conferences that took place in 2020. The purpose of this review introduction article is to provide a brief introduction to the field and the articles included in this Virtual Special Issue. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES 2020 conferences.

Green development challenges within the environmental management framework.

Green development of energy, water and environment systems is essential as these three systems represent the basic life needs of humankind. Therefore, environmental problems arising from each of these three systems need to be carefully addressed to preserve the energy, water and environment resources for future generations. This paper discusses some of the latest developments in three main areas of sustainability themes, namely energy, water and environment, that emerged from the 14th Sustainable Development of Energy, Water and Environment Systems (SDEWES) Conference held in 2019. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES 2019 conference.

Environmental problems arising from the sustainable development of energy, water and environment system.

Integration of energy, water and environment systems is essential in the multidisciplinary concept of sustainable development, as they represent the basic life needs of mankind. Therefore, problems arising from the sustainable development concept need to be carefully addressed to preserve the energy, water and environment resources for future generations. This article discusses some of the latest developments in three main areas of sustainability themes, namely energy, water and environment, that emerged from three Sustainable Development of Energy, Water and Environment Systems (SDEWES) conferences held in 2018. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES2018 conferences.

Troubleshooting the problems arising from sustainable development.

Sustainable development as a concept of societal development encompasses some problems that need to be addressed carefully. They relate to overcoming the technical limits of individual systems, reducing environmental impact, social inclusion, green economic progress involving all stakeholders, limiting the impact of human activities, etc. Over the past few years, as a result of the increasingly pronounced climate change, more and more studies are addressing these problems and stress the importance of sustainable development. The key to sustainable development are, therefore, the solutions to the problems currently encountered by various stakeholders, that together contribute to the preservation of the environment for future generations. This is no longer based on the goodwill of individuals, but has become the responsibility of the entire generation. This article presents some examples of the solutions for the problems arising from sustainable development and is an overview of recent scientific achievements in the field of sustainable development that emerged from recent Sustainable Development of Energy, Water and Environment Systems (SDEWES) conferences. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, that is dedicated to the SDEWES2017 conference.

Experimental analysis of waste polyurethane from household appliances and its utilization possibilities.

Polyurethane has a good insulation characteristic, and it is widely used as an insulation and lining material for refrigerators. Nevertheless, at the end of a product's lifetime, serious problems arise related to waste management. Recently, energy recovery has been marked as a promising solution, especially, waste-to-energy applications. To find an appropriate application for such waste, a thermal analysis was performed. An experimental analysis of polyurethane (PU) waste material was performed by the method of pyrolysis gas chromatography with mass spectrometric detection (Py-GC/MS) at various pyrolytic temperatures, namely, at 500, 600 and 700 °C. Waste polyurethane foam was conducted to investigations in the form of a bulk sample and sorted grain-size samples with a goal to detect the chemical composition of the pyrolysate. The investigation revealed various groups of organic compounds such as heterocyclic compounds of nitrogen and simple and polycyclic aromatic hydrocarbons, while notable concentrations of compounds containing chlorine were detected as well. The experimental analysis found differences in the composition of amines and other compounds and in the dependence on grain size composition. Bulk samples produced the highest concentration of amines (˃ 40%) at a temperature of 500 °C. The sample homogenization led to a significant increase in amines production. Polyurethane waste of grain size from 0.125 to 0.25 mm contained approximately 80% amines. The pyrolysis of the bulk sample at 600 °C yielded only 24% nitrogen heterocyclic compounds, while from the sorted grain-size <0.045 mm and 0.045-0.063 mm, yields were increased to 47.4 and 45.7%, respectively.

Numerical modelling of emissions of nitrogen oxides in solid fuel combustion.

Among the combustion products, nitrogen oxides are one of the main contributors to a negative impact on the environment, participating in harmful processes such as tropospheric ozone and acid rains production. The main source of emissions of nitrogen oxides is the human combustion of fossil fuels. Their formation models are investigated and implemented with the goal of obtaining a tool for studying the nitrogen-containing pollutant production. In this work, numerical simulation of solid fuel combustion was carried out on a three-dimensional model of a drop tube furnace by using the commercial software FIRE. It was used for simulating turbulent fluid flow and temperature field, concentrations of the reactants and products, as well as the fluid-particles interaction by numerically solving the integro-differential equations describing these processes. Chemical reactions mechanisms for the formation of nitrogen oxides were implemented by the user functions. To achieve reasonable calculation times for running the simulations, as well as efficient coupling with the turbulent mixing process, the nitrogen scheme is limited to sufficiently few homogeneous reactions and species. Turbulent fluctuations that affect the reaction rates of nitrogen oxides' concentration are modelled by probability density function approach. Results of the implemented model for nitrogen oxides' formation from coal and biomass are compared to the experimental data. Temperature, burnout and nitrogen oxides' concentration profiles are compared, showing satisfactory agreement. The new model allows the simulation of pollutant formation in the real-world applications.

Low NOx combustion and SCR flow field optimization in a low volatile coal fired boiler.

Low NOx burner redesign and deep air staging have been carried out to optimize the poor ignition and reduce the NOx emissions in a low volatile coal fired 330 MWe boiler. Residual swirling flow in the tangentially-fired furnace caused flue gas velocity deviations at furnace exit, leading to flow field unevenness in the SCR (selective catalytic reduction) system and poor denitrification efficiency. Numerical simulations on the velocity field in the SCR system were carried out to determine the optimal flow deflector arrangement to improve flow field uniformity of SCR system. Full-scale experiment was performed to investigate the effect of low NOx combustion and SCR flow field optimization. Compared with the results before the optimization, the NOx emissions at furnace exit decreased from 550 to 650 mg/Nm³ to 330-430 mg/Nm³. The sample standard deviation of the NOx emissions at the outlet section of SCR decreased from 34.8 mg/Nm³ to 7.8 mg/Nm³. The consumption of liquid ammonia reduced from 150 to 200 kg/h to 100-150 kg/h after optimization.

A kinetic study on the catalysis of KCl, K2SO4, and K2CO3 during oxy-biomass combustion.

Biomass combustion under the oxy-fuel conditions (Oxy-biomass combustion) is one of the approaches achieving negative CO2 emissions. KCl, K2CO3 and K2SO4, as the major potassium species in biomass ash, can catalytically affect biomass combustion. In this paper, the catalysis of the representative potassium salts on oxy-biomass combustion was studied using a thermogravimetric analyzer (TGA). Effects of potassium salt types (KCl, K2CO3 and K2SO4), loading concentrations (0, 1, 3, 5, 8 wt%), replacing N2 by CO2, and O2 concentrations (5, 20, 30 vol%) on the catalysis degree were discussed. The comparison between TG-DTG curves of biomass combustion before and after water washing in both the 20%O2/80%N2 and 20%O2/80%CO2 atmospheres indicates that the water-soluble minerals in biomass play a role in promoting the devolatilization and accelerating the char-oxidation; and the replacement of N2 by CO2 inhibits the devolatilization and char-oxidation processes during oxy-biomass combustion. In the devolatilization stage, the catalysis degree of potassium monotonously increases with the increase of potassium salt loaded concentration. The catalysis degree order of the studied potassium salts is K2CO3 > KCl > K2SO4. In the char-oxidation stage, with the increase of loading concentration the three kinds of potassium salts present inconsistent change tendencies of the catalysis degree. In the studied loading concentrations from 0 to 8 wt%, there is an optimal loading concentration for KCl and K2CO3, at 3 and 5 wt%, respectively; while for K2SO4, the catalysis degree on char-oxidation monotonically increases with the loading potassium concentration. For most studied conditions, regardless of the potassium salt types or the loading concentrations or the combustion stages, the catalysis degree in the O2/CO2 atmosphere is stronger than that in the O2/N2 atmosphere. The catalysis degree is also affected by the O2 concentrations, and the lowest catalysis degree is generally around 20 vol% O2 concentration. The kinetic parameters under the different studied conditions are finally obtained.

Environmental management as a pillar for sustainable development.

There is a growing concern about how to minimize the impact of human activities on the environment. Already nowadays, in some places adaptation efforts are needed in order to avoid the irreversibility of negative human activities. Due to climate changes, and corresponding environmental and social changes, there is a great need for a more sustainable development of mankind. Over the years, research studies that analyzed the sustainable development of different communities with a multi-disciplinary approach, stressed the necessity of preserving the environment for next generations. Therefore, responsible and conscientious management of the environment is a pillar of the sustainable development concept. This review introduction article provides an overview of the recent top scientific publications related to sustainable development that mostly originated from previous SDEWES conferences.

Modelling pollutant emissions in diesel engines, influence of biofuel on pollutant formation.

In order to reduce the harmful effect on the environment, European Union allowed using the biofuel blends as fuel for the internal combustion engines. Experimental studies have been carried on, dealing with the biodiesel influence on the emission concentrations, showing inconclusive results. In this paper numerical model for pollutant prediction in internal combustion engines is presented. It describes the processes leading towards the pollutant emissions, such as spray particles model, fuel disintegration and evaporation model, combustion and the chemical model for pollutant formation. Presented numerical model, implemented in proprietary software FIRE®, is able to capture chemical phenomena and to predict pollutant emission concentration trends. Using the presented model, numerical simulations of the diesel fuelled internal combustion engine have been performed, with the results validated against the experimental data. Additionally, biodiesel has been used as fuel and the levels of pollutant emissions have been compared to the diesel case. Results have shown that the biodiesel blends release lower nitrogen oxide emissions than the engines powered with the regular diesel.

Numerical analysis of ammonia homogenization for selective catalytic reduction application.

Selective catalytic reduction based on urea water solution as ammonia precursor is a promising method for the NOx abatement form exhaust gasses of mobile diesel engine units. It consists of injecting the urea-water solution in the hot flue gas stream and reaction of its products with the NOx over the catalyst surface. During this process flue gas enthalpy is used for the urea-water droplet heating and for the evaporation of water content. After water evaporates, thermolysis of urea occurs, during which ammonia, a known NOx reductant, and isocyanic acid are generated. The uniformity of the ammonia before the catalyst as well as ammonia slip to the environment are important counteracting design requirements, optimization of which is crucial for development of efficient deNOx systems. The aim of this paper is to show capabilities of the developed mathematical framework implemented in the commercial CFD code AVL FIRE®, to simulate physical processes of all relevant phenomena occurring during the SCR process including chemical reactions taking part in the catalyst. First, mathematical models for description of SCR process are presented and afterwards, models are used on the 3D geometry of a real SCR reactor in order to predict ammonia generation, NOx reduction and resulting ammonia slip. Influence of the injection direction and droplet sizes was also investigated on the same geometry. The performed study indicates importance of droplet sizes on the SCR process and shows that counterflow injection is beneficial, especially in terms of minimizing harmful ammonia slip to environment.

Numerical study of co-firing pulverized coal and biomass inside a cement calciner.

The use of waste wood biomass as fuel is increasingly gaining significance in the cement industry. The combustion of biomass and particularly co-firing of biomass and coal in existing pulverized-fuel burners still faces significant challenges. One possibility for the ex ante control and investigation of the co-firing process are computational fluid dynamics (CFD) simulations. The purpose of this paper is to present a numerical analysis of co-firing pulverized coal and biomass in a cement calciner. Numerical models of pulverized coal and biomass combustion were developed and implemented into a commercial CFD code FIRE, which was then used for the analysis. Three-dimensional geometry of a real industrial cement calciner was used for the analysis. Three different co-firing cases were analysed. The results obtained from this study can be used for assessing different co-firing cases, and for improving the understanding of the co-firing process inside the calculated calciner.

Sustainability of energy, water, and environmental systems: a view of recent advances: Special issue dedicated to 2021 conference on sustainable development of energy, water, and environment systems.

This paper presents an overview for the Special Issue (SI) of Clean Technology and Environmental Policy journal (CTEP), and it includes accepted papers from 16th Conferences on Sustainable Development of Energy, Water and Environment Systems (SDEWES) held from October 10-15, 2021, in Dubrovnik, Croatia. Considering CTEPs policy of high-quality research papers, guest editors have invited 35 research articles, presented at the SDEWES 2021 conference. After a vigorous review process, 12 papers have been accepted for publication in this special issue. All 12 accepted papers are briefly presented in this overview together with a wider view that presents research efforts within the SDEWES community published through previous SDEWES special issues.

A preface to the special issue of optimization and engineering dedicated to SDEWES 2020 conferences.

Global warming and climate change call for urgent minimization of the impact of human activities on the environment. There is a great need for the improvement of resource efficiencies by integrating various life-supporting systems. The challenge is on the energy, water and environment systems to integrate and become more sustainable. This research field has received increased attention over the past years with studies across the energy, water and environment systems that optimized different engineering problems. The present Special Issue stems from four Conferences on Sustainable Development of Energy, Water and Environment Systems held in 2020, in four countries of three continents. This review introduction article intends to introduce the topical field and the articles included in this Special Issue of Optimization and Engineering.

Technical potential and geographic distribution of agricultural residues, co-products and by-products in the European Union.

Value waste chain generates a significant amount of different agricultural wastes, co-products and by-products (AWCB) that occur during three major stages of a complex path, from farm to fork. This paper presents stages where and how waste occurs along the path from the ground to the table for a period of 7 years, from 2010 to 2016 in the 28 member countries of the European Union (EU28). Considering the specific conditions of the EU28 community, four different sectors with 26 commodities and waste types that occur in those sectors were analysed: 5 commodities in the Fruit sector, 10 commodities in the Vegetable sector, 7 commodities in the Cereal sector and 4 commodities in the Animal sector. The analysis consists of three stages of waste appearance: production (harvesting, farming), processing and consumption (raw, uncooked food). Production data were taken from Eurostat, import and export data were taken from FAOSTAT. Methodology and calculations consist of relations between specific values. Those specific values for every commodity are the production data, import and export data, and consumption of raw food by the inhabitants of a country. Total consumption of raw food by inhabitant is calculated from the specific consumption per capita and population. The results of the study showed that from 2010 to 2016 in the EU28 the estimated quantity of the AWCB appeared to be around 18.4 billion tonnes, with the sector percentages as follows: Animal ~31%, Vegetable ~44%, Cereal ~22% and Fruit ~2%. In the Animal sector, the most dominant were developed countries, with high population density and high level of industrialisation. The Cereal, Fruit and Vegetable sectors have shown to generate higher AWCB quantities in the countries with more available land area and appropriate climate conditions.

A kinetic study of roadside grass pyrolysis and digestate from anaerobic mono-digestion.

The aim of this research is to evaluate the thermogravimetric behaviour of roadside grass and its digestate obtained from mesophilic anaerobic mono-digestion by quantifying its impacts on biomass composition and properties. Thermogravimetric measurements were conducted in a laboratory furnace under nitrogen flowrate of 100 mL/min in the temperature range from 35 to 800 °C at five different heating rates of 2.5, 5, 10, 15 and 20 °C/min. Friedman and Kissinger-Akahira-Sunose differential and integral isoconversional models were applied to determine the distributions of activation energies and modified pre-exponential factors per reacted mass (degree of conversion). The investigation demonstrated that anaerobic digestion of roadside grass can be used to generate biochar-richer material (with significantly greater yield of final residues after pyrolysis) with less energy required for subsequent pyrolysis in comparison with raw roadside grass.