The use of organic solid waste for energy generation has become a promising and sustainable solution to address environmental issues, particularly those related to fossil fuel consumption. Producing energy from forest biomass offers a viable and eco-friendly alternative, aiming to reduce greenhouse gas (GHG) emissions. A key factor for the sustainable production and supply of bioenergy is the abundant availability of suitable raw materials. Among these, forestry pruning waste stands out as a significant resource, often poorly managed and improperly disposed of. An environmentally responsible way to utilize these residues is through incineration, using the resulting hot gases from combustion for energy generation. The primary goal of this study was to quantify the energy generation potential from the forestry pruning waste of UFPR. To achieve this, the organic waste from UFPR was chemically characterized through Proximate Analysis, along with determining the higher heating value and moisture content. A mathematical model was developed to quantify the generation of electrical energy, simulating the steady-state operation of the incineration system. Additionally, a mathematical model of the Rankine cycle plant was created to predict the necessary thermal exchange areas in the plant. The analyses of the collected samples showed heterogeneity, with low ash content at 0.76% and moisture content ranging from 10.67% to 16.80%, but an average high higher heating value of 19.39 MJ.kg-1. The mathematical model predicted that these residues could be sustainably used for electricity generation, with a power output of 54.28 kW. The chemical analysis results led to optimization in the thermal exchange areas of the Rankine cycle plant, facilitating the efficient utilization of hot gases produced from the incineration of these forestry residues.

A great technological advent is the use of renewable energies with the objective of promoting the migration of the world energy matrix. For this, alternatives to generate and store energy are sought. Among them, the use of hydrogen stands out - the most abundant chemical element in our universe - produced from various sources, such as natural gas, biomass and water electrolysis, making it a viable option as a renewable fuel, in addition to being considered a source of clean energy, as its burning does not emit gases such as carbon dioxide (CO2), one of the main responsible for global warming. In addition, hydrogen can be used in a range of applications, including transportation, power generation, heating and industry, making it versatile with fossil fuels. Its intrinsic properties such as its high energy density become advantageous from the perspective of the economy based on hydrogen. When used in fuel cells, it can generate electricity efficiently and without pollutants, after all, the only emission from the fuel cell system is water. The most common way to produce hydrogen is from natural gas, through a process called steam reforming, where methane from natural gas is combined with water vapor to produce hydrogen and carbon dioxide as a by-product. However, this approach still emits CO2, in a smaller amount, when compared to the direct burning of fossil fuels. Another option is the production of hydrogen from biomass, such as agricultural and forestry waste, through gasification processes or anaerobic fermentation, which can be neutral in terms of CO2 emissions, as the carbon released during production is offset by the carbon absorbed. by plants during their growth. In addition, water electrolysis, which uses electricity to split water into hydrogen and oxygen, is another option for producing hydrogen without CO2 emissions when the electricity used comes from renewable sources. With its vast production, hydrogen can be used as a form of renewable energy storage, after all, one of the main limitations of renewable energies, such as solar and wind, is their intermittency, that is, energy generation depends on climatic conditions. Hydrogen can be produced when there is a surplus of renewable energy available, being stored in liquid or gaseous form, in large spoons, facilitating its transport for later use, and also, meeting the growing world energy demand.

The increase of wastewater follows the expansion of the world population generating a deficit in basic sanitation and in the sewage collection provided. It is widely known that the United Nations (UN) instituted the 2030 Agenda, a plan for the sustainability of the planet, improvement of people's lives and world prosperity. There are 17 Sustainable Development Goals (SDGs) in the 2030 Agenda. We highlight the SDG 6: “Clean water and sanitation”, which is aimed at basic sanitation and access to drinking water. Currently, the treatment system is divided into three stages: primary, secondary and tertiary. In the secondary stage, one makes use of microorganisms to remove organic matter from the medium, such as microalgae or bacteria. Preference has been given to the use of microalgae, classified as microorganisms of rapid cell growth with photoautotrophic capacity. However, the free state physical dimension of a microalgae makes the treatment process more expensive and potentially, impacts the treatment time, thus burdening the treatment. With that in mind, a method of immobilization of microalgae and the elaboration of a photobioreactor for the treatment of effluents was developed. Immobilization is a practice that consists of fixing algae within small spheres, which simplifies the separation methodology of microorganisms from the treated effluent. The immobilizing medium provides mechanical resistance and protects the culture from possible contamination. In order to demonstrate the functionality of the system, as a means of effluent treatment, a mathematical modeling of the effluent treatment was conceived. Fortran was the programming language used to solve nonlinear differential equations through temporal discretization. Runge-Kutta was the numerical method chosen to solve the equations of the model that are based on Monod’s model. Monod’s model predicts the growth parameters during the life cycle determining the amount of substrates and the number of microalgae along the lag phase, log phase and stabilization level. It also expresses the consumption of the substrates. Thus, the model allows the visualization of the biomass growth, consumption of inorganic substances and the treatment time under study.

In face of the current high energy consumption and demand worldwide, a change to a sustainable energy matrix became one of the pillars for global sustainability. The use of renewable energy has been one of the most attractive subjects in recent years. Several public policies in this matter have been suggested and there are ongoing efforts toward their implementation. The United Nations (UN) proposed what is called the 2030 Agenda, which considers 17 Sustainable Development Goals (SDG) to be achieved by the year 2030. In support of the 2030 Agenda, research on the production of fuels from clean and sustainable sources is being conducted by the scientific community around the world. Fossil fuels are finite and also a major source of environmental pollutants, therefore the choice of using renewable sources of energy tends to be an increasingly growing and attractive alternative. Hydrogen is a fuel with a high heating value and is known as the most abundant gaseous element and simplest in chemical structure. The scientific community researching fuel cells has given much attention to the generation and storage of hydrogen. Besides the electrolytic hydrogen production and the reforming of fossil fuels (e.g., natural gas), hydrogen can be generated by metallic means, for example, by oxidation of aluminum in an alkaline solution. The use of recyclable metals, such as aluminum in this study, is an option for sustainable hydrogen generation processes. Nevertheless, like any chemical reaction, part of the products generated are waste, and some are even harmful to the environment, which makes the production of sustainable fuels unfeasible in case of not finding an appropriate technological industrial destination for such waste. The herein study comprises the investigation of the industrial and technological applications of the products of the hydrogen generation reaction from aluminum. Mastering the chemical reaction parameters of that reaction is paramount for the optimal design of a hydrogen generation system. The disposal of the waste is relevant since it makes the energy supply chain complete and sustainable.

In order to reduce oil dependency and reduce CO2 emissions stabilizing the greenhouse effect on the planet, the search for new renewable energy sources has been intensified, with a particular interest in hydrogen based solutions. Hydrogen can be used in fuel cells, which have several applications. Fuel Cells are among the environmentally friendly energy conversion systems for the 21st century with simple components such as membrane, catalyst, rearrangeable configurations that allow them to accommodate space limitations, and their use of hydrogen and oxygen. There are many types of fuel cells that are distinguished by the electrolyte type and their operating temperature. Alkaline Membrane Fuel Cells (AMFCs) and Proton-Exchange Membrane Fuel Cells (PEMFCs) are major types that work in low temperatures and produce only H2O and electricity as part of the electrochemical reaction. AMFC is a fuel cell that has more affordable membranes, when compared to the PEMFC that uses a polymeric membrane with high cost, making applications more expensive. In AMFCs, the alkaline membrane used, is a simple filter paper saturated with KOH solution that allows ions to pass through the membrane, however, suffers CO2 poisoning when it gets in contact to the carbon dioxide present in the air, reacting in the KOH and capturing hydroxyl ions. The poisoning will generate chemical compounds that will interfere with the energy generation and efficiency of the fuel cell. The main cause of the decreasing performance of carbonate formation is the precipitation of large metal carbonate crystals such as K2CO3 and the formation of H2O in the membrane, decreasing KOH concentration. If not addressed, this issue will limit the use of AMFC to pure oxygen applications only, instead of the air itself, which restricts the applicability of the technology. This study presents a mathematical model of a purifier that reduces the concentration of CO2 present in the air, improving conditions to be used in AMFC for mobile applications as automotive vehicles and without the need to use pure oxygen.

Algae are ubiquitous organisms whose capabilities have drawn much attention as of late in the bioengineering field due to their potential to enable a wide range of bioproducts. Microalgae are ideal organisms for the application of the biorefinery concept since they can be grown in wastewater and, at the same time, produce many products of commercial interest. These microorganisms are also known for their resilience to extreme environmental conditions and suitable cell growth rates. Beyond the known potential for biofuel production, these microorganisms can still produce other compounds, being lipids, pigments, vitamins, proteins, and polysaccharides, whose applications go from pharmaceutical to agricultural industries. Recently, the research focus has been directed to the biopolymer-producing ability of both micro- and macroalgae, as they can be rather varied and useful to many applications. However, this is still an ongoing research field, and new data are frequently added in the literature, notably on biomass processing, which can be done with the intent of use into dyes, bioplastics, paints, and even as biochar in solid fuel cells. Microalgae-based biopolymers can be used in a wide range of products, nevertheless, the resulting process efficiency and yields depend on the extraction process utilized, as well as on the microalgae species used and the culture conditions. Furthermore, the polymer extraction can be done directly with common solvents at atmospheric pressure or with other fluids, such as supercritical CO2 or subcritical solvents, and assisted by specific treatments, e.g., ultrasound and microwave. The residual biomass can still be used to produce other less valuable products, such as feedstock, and energy via combustion. In this sense, the present work aims to provide a state-of-the-art review on microalgae biopolymers. Issues related to the efficiency of current treatment methods, industrial applications, and environmental performance are presented and discussed. Besides, the perspectives in this area of knowledge are also a contribution of the present work, the extent to which scientific research is still under development.

The objective of this paper is to determine if it is possible to refrigerate an area by means of a heat source. Theory determines that an absorption refrigerator can work as a possible solution through a refrigeration fluid. According to it, the system works by the evaporation or condensation of the working fluid. The traditional process consists of using engine fuel to run an electric compressor and by its means achieve refrigeration. That process has its toll on fuel economy and engine efficiency and the refrigeration fluid damages the ozone layer or is based on the transportation of ice previously bought on shore. The technological improvement will be equipped on fishing boats, in order to make the trip last longer due to the possibility of not needing to buy and transport ice and for the purpose of lowering the fishing industry cost. Absorption refrigeration can augment engine efficiency by using heat energy that is normally wasted and the system could reach temperatures of freezing water, meaning that it could be possible to follow Brazilian and international standards. The methodology of this work consists of an energy analysis of an absorption refrigerator, which is the determination of the heat transfer equations on the ammonia evaporator, condenser and exhaust/ammonia. Furthermore, it should be analyzed if it’s possible to determine to which working parameters the system will have an optimum operation. From the mathematical analysis, the system shows that with the equations it is possible to operate an absorption refrigeration based on the exhaust gases of fishing boats. Furthermore, the process can be operated on a wide range of temperatures, being possible to determine according to a few dimensionless parameters to which temperature levels the process of refrigeration shows the best removal of heat.

O aquecimento global é uma questão considerável que vem sendo discutida recentemente e, devido às altas taxas de emissão de gases de efeito estufa (GEE), tem sido um dos principais fatores que pode comprometer a segurança hídrica, alimentar e energética mundial.Dessa maneira, é imprescindível atuar por meio de estratégias e aplicações sustentáveis a fim de minimizar esses impactos negativos.Este capítulo compila informações a respeito de análise de ciclo de vida (ACV) aplicada à processos e produtos a partir do cultivo de microalgas.O trabalho salienta que são necessárias investigações para compreender melhor os prejuízos causados pelas