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This work evaluated the influence of superheated water steam injection in an autothermal 80 kWth pilot-scale bubbling fluidized bed during biomass direct (air) gasification, focusing on the effect of steam to biomass ratio in the producer gas composition and gasification efficiency parameters. The process was also evaluated in an externally heated 3 kWth bench-scale bubbling fluidized bed and simulated in a thermodynamic equilibrium model. For low-density biomass, the steam injection resulted in a producer gas with higher H2 concentration and H2/CO molar ratio, although with lower energy content, and in a decrease of the process efficiency. Thus, steam injection promoted a trade-off between parameters, that can be associated with a higher occurrence of the water-gas shift reaction. For high-density biomass, along with an increase of H2 concentration and H2/CO molar ratio, steam injection promoted an increase of the producer gas energy content and process efficiency, which can be justified by a higher char accumulation in the reactor bed and consequent higher occurrence of char-steam reforming reactions. Therefore, steam injection shows high potential to improve the producer gas quality from high-density biomass air gasification, however, for low-density biomass, it shows limited potential and should only be used to adjust H2/CO molar ratio.

Made available in DSpace on 2022-04-29T08:30:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Suomen Akatemia This work presents a technical analysis of an Integrated Biomass Direct Gasification/Gas Turbine (BIG-GT) technology within a sugarcane industry to produce electricity and thermal energy (process heat) using bagasse as fuel. Four possible configurations for the implementation of this technology were considered. A sensitivity analysis was made to assess the risks and the uncertainty level for each proposed solution. The results indicated that with the BIG-GT implementation the power generation efficiency increases for all the studied configurations as compared to the conventional system (η = 14.3%). For the configurations I, II, and III the efficiency increase was 9.1%, 11.0% and 12.6%, respectively. However, to support these configurations of the system, the fuel (bagasse) consumption is increased beyond the production capacity of the mill, and the additional amount of bagasse must be acquired to other mills. On the other hand, in configuration IV it is only considered the gasification of the bagasse produced in the mill, being the additional needs of thermal energy for the industrial process supplemented through the combustion of other biomass types (sugarcane straw produced in the mill plantations) in a Heat Recovery Steam Generator. In configuration IV, the electricity generation efficiency is only 5.9% higher than the conventional cycle, this efficiency is getting without the need for an external supply of bagasse. Ultimately, the sensitivity analysis showed that the plant's energy performance with the implementation of BIG-GT technology is particularly sensitive to variations related to the gasifier's efficiency. UNESP-Sao Paulo State University Faculty of Engineering Campus of Guaratinguetá Bioenergy Research Institute (IPBEN-UNESP) Laboratory of Energy Systems Optimization (LOSE), Av. Dr. Ariberto Pereirada Cunha, 333 Portal Das Colinas Guaratinguetá University of Oriente Efficiency Energy Study Center (Faculty of Mechanical Engineering) Julio Antonio Mella Headquarters, Ave de Las Américas y Casero Department of Environment and Planning - Centre for Environmental and Marine Studies (CESAM) University of Aveiro Campus Universitário de Santiago Polytechnic Institute of Portalegre Instituto Superior Técnico University of Lisbon UNESP-Sao Paulo State University Faculty of Engineering Campus of Guaratinguetá Bioenergy Research Institute (IPBEN-UNESP) Laboratory of Energy Systems Optimization (LOSE), Av. Dr. Ariberto Pereirada Cunha, 333 Portal Das Colinas Guaratinguetá Suomen Akatemia: 320229

In this work, the Taguchi method was used to optimize the dark fermentative H2 production from the organic fraction of municipal solid waste (OFMSW). The experiments were planned using the L16 orthogonal array design with each trial conducted at different levels of substrate concentration, inoculum-to-substrate ratio (ISR), and temperature. Based on the results, the optimal setting of the process parameters was the substrate concentration of 6 g-VS/L, ISR 0.5, and temperature of 55 °C. Furthermore, substrate concentration was the most important parameter affecting bio-H2 production among the three process parameters considered. Finally, a confirmation experiment under optimal conditions yielded 62.5 mL H2/g-VSadded, which was higher than all the bio-H2 yield values obtained in the other conditions tested in this study. The measured and predicted bio-H2 yields in the verification test were also very close to each other, confirming the reliability of the Taguchi method in optimizing the bio-H2 production process.

As thermochemical processes of converting biomass to energy have been increasing worldwide, finding economic and environmentally sound solutions to manage and valorize the huge amounts of ash produced is of most importance. To date, several applications have been proposed for biomass ash recycling, among which the biogas industry appears to offer many potential benefits in the context of a circular economy. This works aims to review the studies that have been conducted so far on the use of biomass ash in the processes of biogas production and purification while providing a summary of the historical background of biogas technology, main mechanisms involved in biogas generation, and information about biomass ash characteristics. It is also outlined the major obstacles to the industrial-scale application of biomass ash in biogas technology and discussed possible ways to tackle those barriers.

In anaerobic digestion processes, pH has a vital role due to the direct impacts on the microbial community. An eco-friendly approach has been applied to control pH in anaerobic bioreactors, using waste-containing fly ash geopolymer spheres (GS) instead of powdered chemical compounds, to promote continuous alkalis leaching. The influence of GS porosity and concentration on the behavior of anaerobic sequential batch reactor treating cheese whey was evaluated. Results showed that the use of GS with the highest concentration and porosity promoted an increase in methane yield up to 30%, compared to the assay with powdered chemical compounds addition. In addition, GS boosted butyric acid production to the detriment of propionic acid, which favored methane production by a factor up to 1.2. This innovative approach indicates that GS addition can regulate pH in anaerobic digesters treating challenging wastewaters and, simultaneously, improve not only its efficiency but also the sustainability of the entire process.

The aim of the present study was to evaluate the relationship between fuel certification and gaseous and PM10 emissions and their composition. Two pellets labelled as ENplus A1 (certified pellets R and P) and a non-certified brand of pellets were tested in a pellet stove. The impact of operating conditions on emissions was also evaluated. The highest carbon monoxide (CO, 2.7–6.1-fold) and total organic carbon (TOC, 1.9–11-fold) emissions were observed for certified pellets R. Nitrogen oxide (NO) emissions were higher for non-certified pellets (2.5–3.2-fold). The compliance of gaseous emissions with the Ecodesign thresholds was not ensured by certification. Certified pellets P generated significantly lower PM10 emissions than the other two types of pellets at medium and nominal loads. Water-soluble ions represented from 36 to 68 %wt. of the PM10 mass. The combustion of certified pellets P and non-certified pellets generated total carbon PM10 mass fractions ranging from 23 to 50 %wt., whereas pellets R resulted in lower mass fractions (7–14 %wt. PM10). The chromatographically resolved organic compounds were dominated by anhydrosugars and alkanols. Pyrene and retene were the most abundant among polyaromatic hydrocarbons.

In this study, granulated siderite/concrete-based catalysts are proposed for in-situ applications in biomass steam gasification, seeking H2-enrichement by the contribution of water gas shift and CO2 adsorption. A cost-effective procedure has been applied for the preparation of granulated catalysts. Water Gas Shift reaction was studied in a fixed bed reactor and Taguchi experimental design was used to elucidate the relevance of experimental parameters on catalyst performance. The results show that the impact of reaction temperature, concrete/siderite ratio and steam to carbon molar ratio on H2 promotion had the following order: reaction temperature (43.1 %), concrete/siderite ratio (30.2 %) and steam to carbon molar ratio (26.7 %). Additionally, the catalyst exhibited high activity when integrated into the freeboard zone of a bubbling fluidized bed gasifier. Compared to the reference condition, one observed significant impact at 700 ºC on the H2:CO ratio (1.9 to 3.3), H2 production (33.8 to 48.6 g_(H2)∙kg_(dry,fuel)^(-1)), carbon conversion efficiency (54.1 to 58.6 %) and cold gas efficiency (55.0 to 60.9 %). Though the catalyst exhibited resistance to sintering, post-mortem analysis suggests loss of active species after repeated cycles of regeneration due to thermal-induced stresses, which caused gradual decrease in activity. published

Biochars have been shown as promising materials for cadmium remediation. However, the different precursors and the pyrolysis process operating conditions can yield very different surface functional...

Despite the increasing global focus on replacing fossil fuels with biomass resources, handling the enormous quantity of ash from biomass thermochemical conversion processes into energy remains a serious challenge from both environmental and economic points of view. Therefore, in pursuit of the circular economy, the use of biomass-derived ash in beneficial applications can have a great contribution to address problems related to ash disposal, and at the same time to promote the valorization of wastes. This work attempts to provide a clear insight into the feasibility of the utilization of biomass ash in a valuable field, namely anaerobic digestion and biogas technology, along with a brief statement of possible opportunities and challenges. Keywords: Biogas technology, Biomass ash, Challenges, Opportunities

The main purpose of this work is to establish and analyzedistinct scenarios for the evolution of the energy system of the island of Santiago in Cabo Verde in the long term, that is, within the time horizon of 2040. The LEAP (Long-Rang Energy Alternatives Planning) simulation tool was used to simulate future projections of the evolution of energy system through insertion of demand data, transformation and resources. Three scenarios were established to project the energy matrix and to analyze the behavior of parameters such as the final energy demand of sectors as the domestic, commerce/industry/services, hoteliers, public institutions, desalination, thermoelectric power plant and total electric losses. It is observed that the current trend of the island’s is an increase in the total demand for energy and should reach an efficient scenario of approximately 670 GWh in 2040, which is more than three times that of 2017. Keywords: Energy consumption, Energy system, Santiago Island, Renewable energy resources

The Jatropha curcas fruit shells (JCFS) and Jatropha curcas seed cake (JCSC) have drawbacks when used as fuel, namely flame front instabilities and short combustion periods. In this work, a blend of 25 wt% Jatropha curcas pellets with 75 wt% of pruning residues (PR) resulted in a fuel mixture that promote a stable flame front and the combustion process could be sustained for periods larger than 60 min. The improvement in the combustion of the blend composed of Jatropha curcas pellets and PR, when compared to mono-combustion of Jatropha curcas pellets, can be explained in result of the better fuel properties given by PR to the fuel blend. It was observed that PR combustion is associated to higher temperatures in the flame gases and the CO concentration in the flue gas is less than 1500 mg/Nm3 (dry gases, 13% vol. O2), thus in accordance to the European standards for solid fuel stoves. Although the PR fraction in the biomass mixtures is high (75 wt%), the observed CO concentration in the flue gas during combustion of the fuel blends was higher than 1500 mg/Nm3 (dry gases, 13% vol. O2) especially in the fuel mixtures that incorporate JCFS in their composition.

In the worldwide more than 95% of biodiesel production feedstocks come from edible oils. The waste cooking oils (WCO) are an alternative feedstock for biodiesel production; its usage reduces significantly the cost of biodiesel production and has environmental benefits, e.g., a waste recovery instead of its elimination. This work aimed to optimize the process to produce fatty acid methyl esters (FAME) using the response surface methodology and a Box–Behnken experimental design from mixtures of refined palm oil (RPO) with WCO using a residual solid material as catalyst (biomass fly ashes). The influence on FAME yield of four operational variables (catalyst loading, methanol/oil molar ratio, RPO/WCO ratio and reaction temperature) was studied. The higher FAME yield achieved using the RMS method was 77.06% for: 14.63 wt% of catalyst loading, 5.42/1of methanol/oil molar ratio, 14.81 wt% of RPO in the oil mixture and 55 °C for the reaction temperature. Keywords: Biomass fly ash, FAME, Optimization, Refined palm oil, Response surface methodology, Solid catalyst, Waste cooking oil

The objective of this work is the experimental investigation and characterization of the influence of biomass feeding on combustion efficiency of an industrial biomass boiler. The collected experimental data relate the biomass feeding control with the operating conditions and boiler performance parameters. Two different methods to control of the biomass feeding are considered. One consists on the manually controlled biomass feeding through the boiler control system. The other consists on an automatic control, with the screw-feeder controlled by the boiler control system. Boiler control system governs the introduction of the biomass material into the furnace based on the O2content of the combustion flue gas stream. Results show that the biomass feeding into the furnace significantly affects the combustion process and the pollutant emissions (e.g., CO and NO). Keywords: Biomass, Feeding system, Fixed grate industrial boiler, O2content, CO, NO

In this work, in-situ application of natural occurring ilmenite (FeTiO3) for upgrading the producer gas from a pilot-scale bubbling fluidized bed gasifier was performed and its influence on the gas characteristics and gasifier performance was analyzed. Without using ilmenite, the producer gas average composition (volumetric basis, dry gas) was 15.2% CO, 7.6% H 2 , 3.8% CH4 and 15.6% CO2, with 0.50 H 2 :CO molar ratio and 5.0 MJ/Nm3 lower heating value. For this condition, 1.6 Nm3 gas/kg biomass (dry basis) specific dry gas production, 44.5% cold gas efficiency and 68.4% carbon conversion efficiency were attained. Using ilmenite as catalyst, the producer gas average composition (volumetric basis, dry gas) was 13.9% CO, 11.7% H 2 , 4.0% CH4 and 17.9% CO2, with 0.84 H 2 :CO molar ratio and 5.1 MJ/Nm3 lower heating value. For this condition, 1.7 Nm3 gas/kg biomass (dry basis) specific dry gas production, 49.8% cold gas efficiency and 75.5% carbon conversion efficiency were attained. Thus, in-situ application of ilmenite generally improved the gasifier performance and induced an increase of H 2 concentration and H 2 :CO molar ratio in the producer gas of 35.1% and 40.7%, respectively, improving its suitability for advanced gas applications that require high H 2 :CO ratios, such as liquid fuels and chemicals synthesis.

Densification of the biomass residues as an efficient method to produce a renewable and CO2 neutral energy resource has been in consideration in recent years. However, according to a recent boost in the European wood pellet demand, the importance of R&D studies for substitution and enhancement of current raw materials for pelleting purposes has been increased. A large amount of annual garden waste and agricultural residues in Portugal causes that so-called Mixed Biomass Pelleting (MBP) method becomes a promising approach of the future that by closing the cycles in the agro-economic environments of Portugal, enhances the socio-economic conditions in the rural areas. This itself will have one more important consequence of wildfire prevention in the Portuguese forests. This work as a subset of a broader study that aims to develop an evaluation tool for circular economies will cover the information required for a techno-economic analysis of mixed biomass pelleting by a review on potential assessment methods, a rough-cut assessment of agro-residues potential for Portugal and gathering the required information about pellets origin, characteristics and legislative frames. Keywords: Biomass residues, Circular economy, Mixed biomass pelleting, Portugal, Potential assessment

Municipal solid waste (MSW) management in dense urban areas is a challenge for municipalities, especially in developing countries, which commonly have deficient waste management. For example, the metropolitan region of Goias State, Brazil, has 19 municipalities that dispose of about 72.5% of total MSW in unlicensed MSW final disposal facilities. Therefore, this study analysed the investment and operating costs, and revenues of a municipal solid waste management facility, projected for 20 years, shared among these 19 municipalities. The economic viability analysis, has shown that, regardless of the management facility type, MSW collection and transport are the most expensive cost components, accounting for about 60% of MSW management operating costs. For an Internal Rate of Return of 0%, anaerobic digestion is 11% more expensive (in total) than using community composting. For 2040 (last year), the monthly MSW management tariffs will vary between 3.5 and 10.8 R$·inhabitant−1·month−1, depending on the municipality. So, as the unit price of biowaste treatments lowers with waste quantities, for the municipalities with large biowaste quantities, anaerobic digestion becomes recommended for its economic attractiveness. This study can serve as a model for other municipalities in Brazil and elsewhere, helping public decision makers to establish a strategy for MSW management.

The increasing use of forest biomass as a fuel for power plants due to environmental concerns will certainly increase the amount of woody biomass ash produced. Because of the environmental problems derived from woody biomass ash disposal, an important aspect for the sustainable development of the energy sector is the implementation of effective ash management strategies. The purpose of this study is to assess the environmental impacts of woody biomass ash landfarming for soil amelioration through a Life Cycle Assessment. The baseline scenario corresponds to the current most common practice of woody biomass ash management (landfilling), and two different landfarming alternatives were assessed: liming and fertilisation. Credits were given to the system due to the substitution of three traditional liming products and five traditional fertilisers. Woody biomass ash landfarming presented satisfactory performance in five impact categories under study in comparison to landfilling. When woody biomass ash was used for liming, the environmental savings were more pronounced when substituting hydrated lime. For potassium supply, the substitution of potassium nitrate by woody biomass ash presented the best environmental performance, while for phosphorus supply, the environmental savings were more pronounced substituting single superphosphate. However, in four impact categories, the environmental impacts of ash landfarming exceeded the impacts of ash landfilling, due to the emission to soil of nutrients and trace elements to soil. But this does not necessarily imply increased risks for the environment, as the potential pollutants leaching depends on their bioavailability in the soil.

Forest management operations adequately integrated in the forestry value-chain are the gold standard in wildfire prevention. However, these operations generate considerable amounts of residual forest biomass (RFB) that cannot be legally disposed in land and further require suitable management. Residual biomass also includes highly flammable plants existing in the Portuguese forest such as gorse, broom, giant reed and acacia. Quite often wildfires in Portugal are linked with spreading of this residual biomass that promotes fuel accumulation. Besides deleterious impacts on rural and forestry economy, wildfires are also a driver for desertification and soil degradation. Alternative uses for this residual biomass to promote its valorisation and enable proper models of management of forest areas are needed, thus providing economic and environmental benefits towards decreasing of the fuel load. Though this biomass has reasonable carbon content and heating value, they also present inorganic composition (e.g. Na, K, Cl) that promotes operating problems in thermochemical conversion processes as combustion and gasification for useful energy production because of ash related problems (e.g., sintering/fouling), thus restricting their use in such applications. As such, biochar production by pyrolysis is a potential alternative to generate added-value. During pyrolysis the volatile matter of biomass is released to the gaseous phase, resulting a solid product, biochar, which is carbon-rich and contains most of the inorganics (nutrients) of the raw biomass. Exposure of biomass inorganics as free ashes is prevented in this process, and hence pyrolysis mitigates their negative effects. Nonetheless, the efficient pyrolysis of these types of biomass requires development of novel solutions optimized for energy and environmental performance. Enhancing of the energetic sustainability of the process and minimizing of the environmental impacts associated to the emission of gaseous pollutants are aspects of major relevance. Additionally, the biochar quality depends on biomass type, technology and operating conditions used. The BioValChar project (https://biovalchar.web.ua.pt/en/) seeks to answer these challenges related to valorisation of low-quality residual biomass through production of biochar by pyrolysis, which can return back to forest and rural soils. This approach will provide both carbon/nutrient cycling and synergies within forestry management, wildfire prevention, improvement of soil quality and rural development, under the circular economy principle. The research focus valorisation of residual forest biomass in full-control pyrolytic batch and continuous (auger-type reactor) processes, and testing of the resulting biochar performance as soil amendment. Moreover, a prototype of an integrated mobile unit for auto-thermal and continuous biochar production by pyrolysis of biomass is also being developed, by using the pyrolysis gases to provide the energetic needs of the process. Here we present the project overview, as well as some preliminary results on pyrolytic valorisation of one selected biomass (acacia) into biochar through distinct operating modes and conditions.

Concrete was evaluated as low-cost catalyst for in-situ application in an autothermal 80 kWth pilot-scale bubbling fluidized bed direct (air) biomass gasifier. To improve the understanding of the observed phenomena, the process was also evaluated in smaller-scale reactive system, namely an externally heated 3 kWth bench-scale bubbling fluidized bed. Concrete application showed promising results regarding the relative increase of H2 concentration and H2/CO molar ratio in the producer gas (up to 99.2 and 77.4%, respectively), indicating that this material can promote the water-gas shift reaction. However, this effect was dependent on the gas-solid contact time and catalyst temperature, being that it was only relevant when these parameters were at least 5.2 s and 746 °C, respectively. A maximum lower heating value of 7.5 MJ/Nm3 of the producer gas was found with concrete application (23.8% relative increase), which is higher than commonly found in the literature. Relative increases of up to 25.1, 55.3 and 47.0% for the specific dry gas production, cold gas efficiency and carbon conversion efficiency, respectively, were also found, consequently suggesting that, in addition to the promotion of the water-gas shift reaction, this material has potential to promote tar reforming/cracking and carbon gasification reactions.

Nowadays, much attention is being paid to so-called Negative Emissions Technologies (NETs), designed to remove carbon dioxide from the atmosphere and keep global temperature rise below 1.5 °C. The deployment of NETs can trigger environmental impacts, which can be addressed through the lens of Life Cycle Assessment (LCA). According to the literature, there are several drawbacks when NETs are assessed under the life cycle framework. In this sense, this study aims at contributing to the literature by assessing a NET in a manner that the existing drawbacks are overcome. For such purpose, dynamic LCA and land-water-energy nexus were applied to a Bioenergy with Carbon Capture and Storage system (BECCS). The results show that harnessing residual forest biomass for electricity generation and carbon storage accomplished a great positive climate performance. In line with European climate goals, climate change impact resulted in −2.49E+04 kg CO2eq/MWhe and −3.40E+04 kg CO2eq/t Cstored at year 20. However, the BECCS system analyzed comes at the expense of impacting land, water and energy that cannot be overlooked. The land impact was 3.57E+05Pt/t Cstored and 2.61 E+05Pt/MWhe, green water impact was 11.1 m3/t Cstored and 8.16 m3/MWhe, and the Energy Return on Energy Investment (EROI) was 3.34. The sensitive analysis indicates that special attention should be paid to the efficiency of the system since it directly impacts on land, water and energy (EROI). Finally, this study contributes to increasing the knowledge on NETs, thus supporting climate-energy policymaking.

Millions of tons of forest residues, agricultural residues, and municipal solid waste are generated in Latin America (LATAM) each year. Regularly, municipal solid waste is diverted to landfills or dumpsites. Meanwhile, forest and agricultural residues end up decomposing in the open air or burnt, releasing greenhouse gases. Those residues can be transformed into a set of energy vectors and organic/chemical products through thermochemical conversion processes, such as pyrolysis and gasification. This book chapter provides information on current examples of gasification on large scale in the world, which typically operate at 700°C, atmospheric pressure, and in a fluidized bed reactor. The produced gas is used for heat and energy generation. Whereas pyrolysis at a large scale operates around 500°C, atmospheric pressure, and in an inert atmosphere, using a fluidized bed reactor. The produced combustible liquid is used for heat and energy generation. The decision of using any of these technologies will depend on the nature and availability of residues, energy carries, techno-socio-economic aspects, and the local interest. In this regard, the particular situation of Brazil and Mexico is analyzed to implement these technologies. Its implementation could reduce the utilization of fossil fuels, generate extra income for small farmers or regions, and reduce the problem derived from the accumulation of residues. However, it is concluded that it is more convenient to use decentralized gasification and pyrolysis stations than full-scale processes, which could be an intermediate step to a large-scale process. The capabilities of numerical models to describe these processes are also provided to assess the potential composition of a gas produced from some biomass species available in these countries.

This work aimed to investigate the effects of supplementing two distinct types of ash, namely fly ash (FA) and bottom ash (BA) on the dark fermentation (DF) process of food waste (FW) for H2 production. Both types of biomass combustion ash (BCA) were collected in an industrial bubbling fluidized bed combustor, using residual forest biomass as fuel. Results indicated that adding BCA at different doses of 1, 2 and 4 g/L could effectively enhance H2 generation when compared to the control test without BCA addition. This stimulatory effect was attributed to the crucial role of metal elements released from BCA such as sodium, potassium, calcium, magnesium, and iron in the provision of buffering capacity and inorganic nutrients for the functioning of hydrogen-forming bacteria. The highest H2 yield of 169 mL per g of volatile solids (VS) were obtained by adding only a small amount of BA (1 g/L) to the reactive system, representing a significant increment of 1070% compared to the control reactor. Furthermore, a significant decrease in the bacterial lag phase time from 26 h to 2.7 h, as well as about a 12-fold increase in the energy recovery as H2 gas was observed at BA dosage of 1 g/L in comparison with the control reactor. Overall, this study suggested that a proper addition of BCA could promote the DF process of FW and enhance biohydrogen production.

Ash generated during the combustion of woody biomass for energy production is an industrial waste that should be properly managed in order to minimise the respective environmental impacts. Woody biomass ash valorisation in construction materials to replace conventional materials is an alternative that has proven to be technically feasible. On the other hand, it can present potential environmental impacts that should be evaluated to support the choice of more sustainable alternatives. Thus, the purpose of this work is to assess the potential impacts of woody biomass ash valorisation of through incorporation in construction materials using life cycle assessment. The valorisation alternatives consider the incorporation of woody biomass ash in cement mortars, adhesive mortars, concrete blocks, and bituminous asphalts. In addition, a base scenario consisting of ash landfilling is also assessed. Four types of woody biomass ashes were considered, namely fly and bottom ashes generated in a vibrating grate and fly and bottom ashes generated in a fluidised bed. The impact assessment method used is that suggested in the International Reference Life Cycle Data System for selected impact categories. The results showed that the impacts of ash transport and pre-processing and the impacts of producing the avoided materials are factors that affect the net impact of the valorisation scenarios and should be considered in the end-of-life management of biomass ash. Nevertheless, all valorisation scenarios had a lower impact than landfilling in all the impact categories under study, resulting in a significant decrease of the environmental impacts in some scenarios.

Currently, different types of raw materials are under investigation to fulfil the demand for pellet-based renewable energy. The aim of this study was to experimentally quantify and characterise the gaseous and particulate matter (PM10) emissions from the combustion of a pelletised invasive species growing in the Portuguese coastal areas. The combustion of acacia pellets in a stove used for domestic heating led to a noticeable production of environmentally relevant contaminants, such as carbon monoxide (CO, 2468 ± 485 mg MJ−1), sulphur dioxide (SO2, 222 ± 115 mg MJ−1) and nitrogen oxides (NOx, 478 ± 87 mg MJ−1). Besides gaseous pollutant emissions, substantial particle emissions (118 ± 14 mg MJ−1) were also generated. Particles consisted mostly of inorganic matter, mainly alkaline metals, sulphur and chlorine. About 25%wt. of the PM10 emitted had carbonaceous nature. The chromatographically resolved organic compounds were dominated by anhydrosugars, especially levoglucosan (284 μg g−1 PM10), and several types of phenolic compounds. Retene (8.77 μg g−1 PM10) was the chief compound among polyaromatic hydrocarbons.

Most Brazilian municipalities are small, i.e., with less than 50,000 inhabitants. In the State of Goiás, for example, 91% of the municipalities are small. Of these, only 4% have their municipal solid waste (MSW) disposed in authorized landfills. Thus, the present study aimed to propose a municipal solid waste management facility (MSWMF) shared between two small municipalities of the microregion of Chapada dos Veadeiros, in Northeast Goiás. The reason for selecting this microregion is that it is composed only of small municipalities that use waste dumps for the disposal of their MSW. For this purpose, the areas subject to approval or restricted for the installation of a MSWMF were identified with the aid of a geographic information system (GIS). Also, the host municipality (HM) of the MSWMF proposed for Campos Belos and Monte Alegre de Goiás was defined with the use of mass geometry methodology. According to the results obtained, 59% of the territories of these two municipalities that will integrate the proposed MSWMF are restricted for the installation of landfills, and Monte Alegre de Goiás was selected to host the landfill.

Only 16 of the 246 municipalities of Goiás State, Brazil, dispose their municipal solid waste (MSW) in licensed landfills. Therefore, this study proposes the host municipality (HM) of the future shared MSW management facility (MSWMF), serving the Metropolitana de Goiânia (MGyn) microregion. First, the potential areas to construct MSW final disposal facilities (landfills) were identified. Subsequently, using mass point geometry, the HM of the proposed MSWMF for MGyn was defined. The results show that only 19.4% of the area of the studied municipalities is available or subject to approval for landfill construction. The HM will be Aparecida de Goiânia, which will process most of the MSW and send the rejects of treated MSW to the landfill that will be established in the neighboring municipality of Hidrolândia. Additionally, this MSWMF will serve 19 municipalities and will have nine waste transfer stations that will receive waste from 17 municipalities, to minimize MSW transport costs.

Growing quantities of biomass ashes are currently produced worldwide due to the increasing consumption of biomass in energy applications. The disposal of biomass ash in landfills is costly and leads to the loss of valuable resources. Biomass ash has important macro-nutrient contents and relevant soil liming capacity, and can be recycled to soils, thus contributing to biomass-to-energy process integration and a sustainable energy production. Although the EU Thematic Strategy for Soil Protection has highlighted the importance of promoting soil amelioration through nutrient recycling and some Member States have already recognised biomass-ash value in a context of circular economy, recycling of this material at the EU level and the potential use of ash-based material in fertilisers is still not properly framed by the EU regulatory framework. Adequate regulation for biomass ash from the energy sector is recognised of most importance as a driving force towards implementation of correct management and valorisation of ash as a raw material. This review provides a discussion on biomass ash properties and related EU regulations, notably the Waste Framework Directive and the Fertilisers Regulation, which are relevant for implementing a strategy for valorisation of biomass ash for soil amelioration purposes. Steps needed to provide the biomass ash with an appropriate end-of-waste and/or by-product status were identified. Key product and process aspects to enable the inclusion of biomass ash in the list of materials that can be used as fertilisers or as ingredients of soil fertilisers in the scope of the revised Fertilisers Regulation were discussed. Quality and safety standards to be harmonised at the EU level, as well as necessary revisions of the risk assessment framework were also discussed here.

In this work, the concept of biomass direct (air) gasification was demonstrated in a pilot-scale bubbling fluidized bed and the influence of in-situ application of low-cost catalytic materials on the produced gas characteristics and gasifier performance was analyzed. Three different low-cost catalysts were tested: bottom bed ashes resulting from combustion of residual forest biomass derived from eucalyptus, char particles resulting from wood pellets direct (air) gasification, and synthetic fayalite (Fe2SiO4). Without using catalysts, the produced gas composition was 7.7–16.9%v CO, 3.2–8.3%v H2, 0.5–3.4%v CH4 and 9.5–14.6%v CO2, with 2.4–4.3 MJ/Nm3 lower heating value, specific dry gas production between 1.0 and 1.8 Nm3 dry gas/kg biomass (dry basis), cold gas efficiency between 13.7 and 30.5% and carbon conversion efficiency between 30.7 and 50.9%. With the use of catalysts, the produced gas composition was 14.2–37.6%v CO, 9.5–14.7%v H2, 2.6–3.5%v CH4 and 3.6–14.8%v CO2, with 3.9–6.3 MJ/Nm3 lower heating value, specific dry gas production between 1.4 and 2.0 Nm3 dry gas/kg biomass (dry basis), cold gas efficiency between 38.1 and 66.3% and carbon conversion efficiency between 56.8 and 86.6%. The highest increase in H2 concentration (352% increase) was observed on experiments using wood pellets char as catalyst while the highest increase in CO (305% increase), lower heating value (123% increase), specific dry gas production (62% increase), cold gas efficiency (262% increase) and carbon conversion efficiency (174% increase), was observed on experiments using synthetic Fe2SiO4 as catalyst.

The pulp and paper industry has been researching different treatments for the degradation of adsorbable organohalogens (AOX). In this work, two agitation processes (mechanical and ultrasound) were analyzed in the AOX degradation of the bleaching wastewater using nano zero valent iron (nZVI). The work used different variables for the AOX removal process, such as pH, time, nZVI, and hydrogen peroxide (H 2 O2) concentration. Results show an increase in AOX degradation when a higher nZVI concentration is used. The optimal combination of variables for the treatment with mechanical agitation was found in the ratio 2:5 (nZVI : H 2 O2), degrading 85% of AOX in 60 min, with acid pH. Ultrasound treatment consisted of half process time and less degradation than mechanical agitation treatment. The 2:5 ratio in ultrasound agitation degraded 55% of AOX within 30 min at the end of the process. Both methods of the homogenization process of zero valent iron nanoparticles in the bleaching wastewater of the paper and cellulose industry are efficient. However, the mechanical stirring process has a more significant potential for AOX degradation. The variables (pH, concentration of nZVI and H 2 O2 and duration of the process) used in the bleaching wastewater treatment process must be considered for future implementation in the pulp and paper industry.

Charcoal production in Portugal is mostly based on the valorization of woody residues from cork oak and holm oak, the latter being considered a reference feedstock in the market. Nevertheless, since wildfire prevention became a priority in Portugal, after the recent dramatic wildfires, urgent actions are being conducted to reduce the fuel load in the forests, which is increasing the amount of biomass that is available for valorization. Additionally, biomass residues from agriculture, forest management, control of invasive species, partially burnt wood from post-fire recovery actions, and waste wood from storm devastated forests need also to be considered within the national biomass valorization policies. This has motivated the present work on whether the carbonization process can be used to valorize alternative woody biomasses not currently used on a large scale. For this purpose, slow pyrolysis experiments were carried out with ten types of wood, using a fixed bed reactor allowing the controlled heating of large fuel particles at 0.1 to 5 °C/min and final temperatures within 300–450 °C. Apart from an evaluation of the mass balance of the process, emphasis was given to the properties of the resulting charcoals considering its major market in Portugal—barbecue charcoal for both recreational and professional purposes.

Biochar e o material carbonaceo, produzido a partir de biomassa de origem biogenica, por meio de pirolise, e que tem como caracteristicas sua producao ambientalmente sustentavel, qualidade e usos inovadores. Os agrorresiduos constituem uma fonte importante de biomassa vegetal; e a pirolise vem sendo reconhecida como uma tecnologia eficiente de conversao desta tipologia de residuos na obtencao de produtos de maior valor. Este trabalho investigou a influencia das condicoes de operacao da pirolise nas caracteristicas dos produtos. Tres tipos de agrorresiduos obtidos em agroindustrias (bagaco de cana-de-acucar-BCA, casca de arroz-CA e casca de coco verde-CCV) foram pirolisados num reator horizontal, em escala de bancada, do tipo leito fixo e com aquecimento eletrico. As condicoes de operacao foram: temperaturas de pirolise (350, 450 e 550 °C), taxas de aquecimento (2, 10 e 30 °C.min -1 ), 30 min de tempo de imersao na temperatura de pirolise e, vazao de 250 cm 3 .min -1 de N 2 como gas de arraste. As amostras de biomassa e os produtos da pirolise foram avaliados por meio da analise gravimetrica, bem como analises termicas, quimicas e fisicas. Os resultados mostraram que, em geral, a temperatura de pirolise foi o parâmetro que teve maior influencia sobre o rendimento dos produtos. Quando a temperatura de pirolise foi aumentada de 350 para 550 °C, na taxa de aquecimento de 10 °C.min -1 , o rendimento do biochar do BCA diminuiu de 33,9 para 25,1 %wt, da CA diminuiu de 45,7 para 38,1 %wt, e da CCV diminuiu de 42,2 para 33,4 %wt, em base seca. A curva TG mostrou que a desvolatilizacao esta praticamente concluida aos 350 °C, no entanto, de acordo com os padroes do IBI, a estrutura do biochar passou de termicamente alterada a termicamente convertida em temperaturas mais altas. Isso foi observado por meio das razoes molares H:C que foram 0,73 a 450 °C, 0,61 a 550 °C e 0,67 a 450 °C para as amostras de biochar do BCA, CA e CCV, respectivamente. Os resultados da analise de FTIR mostraram que as amostras de biochar dos tres tipos de biomassa produzidas na temperatura de 450 °C apresentaram maior aromaticidade em comparacao com aquelas produzidas a 350 °C, e indica aumento da recalcitrância com o aumento da temperatura de pirolise. Alem disso, o aumento da temperatura de pirolise causou o aumento do pH e a diminuicao da CTC. A analise MEV mostrou que as amostras de biochar possuem uma estrutura complexa de poros de diferentes dimensoes que consiste em multiplas redes interconectadas com diferentes formas e arranjos. A energia disponivel nos produtos foi avaliada e foi realizado o balanco de energia por meio de uma simulacao, em termos especificos, da producao de biochar em um reator continuo. A simulacao sugere que a combustao dos gases de pirolise pode gerar a energia termica necessaria para a pirolise nos tres tipos de biomassa avaliados, restando entre 2,5 a 3,4 de energia termica, que e energia util para, p. ex., secagem da biomassa. A pesquisa mostrou a relevância em se conhecer a influencia das condicoes de operacao nas propriedades dos produtos. O balanco de energia pode orientar o desenvolvimento de tecnologias para escalonar o processo.

One of the problems associated with biomass combustion is the amount of fly ashes generated and its subsequent management. The search for ways of valorizing these ashes has been a challenge for the academic and industrial community. On the other hand, used cooking oils are wastes which management is quite difficult, by they have a very important energetic potential. The goal of this work was to optimize the Fatty Acid Methyl Esters (FAME) process, recovering two residual materials (waste cooking oils (WCO), and biomass fly flash (BFA)). The optimization of the process was achieved using the response surface methodology and a Box-Benhken experimental design applied to mixtures of WCO and refined palm oil (RPO), using BFA as catalyst. The influence on FAME yield of four variables (catalyst loading, methanol/oil molar ratio, RPO/WCO ratio and reaction temperature) was studied. The higher FAME yield achieved was 73.8% for the following operating conditions: 13.57 wt% of catalyst loading, 6.7 of methanol/oil molar ratio, 28.04 wt% of RPO in the oil mixture with WCO and 55 °C for the reaction temperature. The reusability of the BFA catalyst in the process was also studied through three successive usage cycles finding no loss of catalytic activity.

Pollutants resulting from domestic combustion would have harmful effects on public health, causing disturbances in the atmosphere chemistry and the climate. In this work, the emissions from the combustion of pellets made of 80% poplar (organically fertilized) and 20% cereal straw (Triticum aestivum) have been analysed. Poplar wood from I-214 and AF-8 clones was obtained from fertilized and non-fertilized plots (CONTROL). Dairy wastewater treatment (MUD) and dehydrated sewage sludge (BIOSOLIDS) were the fertilizers employed. BIOSOLIDS-I214 pellets had lower quality standards, so its combustion was omitted. A flue gas sample was sampled together with the particles emitted. The I-214 MUD sample had the highest emitted CO value (1505 mg/MJ). Regarding HCl emission factors, there was a homogeneity in the results linked with the Cl content present in the raw material. A higher particle emission was associated with pellets with higher ash content. Particles were composed mainly for elemental carbon (26&ndash, 80 mg/MJ), except I-214 MUD. I-214 pellets had the indicators of incomplete combustion and, therefore, major contaminants emission and major environmental impact. Thus, both the poplar clone and the organic fertilizer influenced the parameters and emissions analysed. Therefore, special attention must be paid to both characteristics.

This manuscript presents a scientometric analysis on the studies performed on the application of biochar for soil amendment in order to investigate the research and developments in this field and to identify the existing gaps to provide recommendations for future studies. A total of 2982 bibliographic records were retrieved from the Web of Science (WoS) database using appropriate sets of keywords, and these were analyzed based on the criteria of authors, publishing journals, citations received, contributing countries, institution, and categories in research and development. Based on these data, progress of research was mapped to identify the scientific status, such as current scientific and technological trends as well as the knowledge gaps. The majority of scientific developments started in the early 2000′s and accelerated considerably after 2014. China and USA are the leading countries in the application of biochar for the treatment of soils. Among the active journals, “Plant and Soil” has received the highest number of citations. This study attempts for a comprehensive discussion and understanding on scientific advances as well as the progress made, especially in recent years.

In this work, two approaches to predict the producer gas composition obtained by direct (air) biomass gasification in bubbling fluidized beds were developed and compared, namely empirical modelling based on reported experimental results in the literature and non-stoichiometric chemical equilibrium modelling. For this purpose, an extensive database containing a set of 19 published experimental results from the literature was compiled and a non-stoichiometric chemical equilibrium model developed. The prediction capability of the empirical and chemical equilibrium model was evaluated by comparison with experimental data obtained in an 80 kWth bubbling fluidized bed direct (air) biomass gasifier. The empirical model shows moderate accuracy in the determination of the producer gas composition (CO, H2 and CH4), whereas the chemical equilibrium clearly overestimates the concentration of H2 and CO, and underestimates the concentration of CH4, leading to subpar accuracy in the determination of typical gasification efficiency parameters. Thus, the empirical model is suited for preliminary estimates of gasification products, while black-box chemical equilibrium modelling, without experimental knowledge integration, is considered as unreliable for these gasification conditions.

Electricity production from biomass has the potential to significantly contribute to the share of renewable energy in the global power mix with lesser environmental impact than non-renewable resources. The production of bioenergy from forest biomass residues is currently increasing in Portugal, mainly as a consequence of concerns related to climate change and forest fires. In Portugal, the annual production of residual biomass from forest logging is estimated at 0.8-1.2 million dry tons per year, and about 47-58% of these residues come from eucalypt. This study evaluates the environmental impacts resulting from electricity production in Portugal using eucalypt logging residues (composed of branches, foliage and tops) and considering two types of technologies: grate furnaces and fluidised bed furnaces. This assessment was performed using life cycle assessment (LCA) methodology, a methodology that evaluates the environmental impacts entire life cycle of a product or process (from the extraction of the raw materials until its end-of-life), allowing to identify the most significant stages and processes along the life cycle, and supporting by this way the decision and policy-making.Two alternative scenarios for biomass-to-energy conversion technologies were simulated: grate furnace and fluidised bed furnace. The functional unit is the production of electricity from the combustion of eucalypt logging residues equivalent to 1 kWh delivered by the power plant to the Portuguese grid. System boundaries include the following stages: (1) forest management (including site preparation, planting, stand tending and logging); (2) residues collection; and (3) energy conversion (including forest biomass combustion as well as treatment and final destination of wastes). Seven impact categories from the International Reference Life Cycle Data System (ILCD) are considered: climate change, particulate matter, photochemical ozone formation, acidification, freshwater eutrophication, marine eutrophication and mineral and fossil resource depletion.The results show that the forest management stage had a low contribution to the total impact in all impact categories for both technologies under analysis. The only exception is the impact category of mineral and fossil depletion, in which forest management is mainly responsible and which accounts for 92-94% of the total impact for both technologies analysed. The energy conversion is the hotspot in most of the impacts studied (climate change —49-63%, particulate matter —94-95%, photochemical ozone formation —85-88% of, acidification —76-79%, freshwater eutrophication —56-58% and marine eutrophication —70-71% of the total impact) and therefore, this is the stage for which improvements should be primarily establishedestablished for both technologies analysed. In addition, for all impact categories analysed, the fluidised bed presented the smallest environmental impact. Even when the grate furnace efficiency increases and the fluidised bed efficiency decreases in a sensitivity analysis, the fluidised bed has lower impacts than the grate furnace and is a good alternative for implementing new power plants. Further research is needed to analyse the effects of converting the grate technology in Portugal to fluidised bed technology.

Energy plays a key role for humanity, so the best way to absorb the huge increase in energy demand is perhaps through energy diversification and decentralization [...]

It was studied the production of biochar by pyrolysis of biological sludge from wastewater treatment in the pulp and paper industry. The pyrolysis process was conducted in bench-scale fixed-bed reactor using distinct operating conditions of heating rate (2, 10, 20 and 30 ºC/min) and peak temperature (300, 375, 450, 525, and 600 ºC). The biochar yield is in the range 0.40 to 0.73 kg/kg dry sludge, and decreases with increasing peak temperature and heating rate. The organic matter content of the biochar is in the range 55.9 to 75.3%wt. (dry basis). Both the temperature increase and the heating rate increase promote the decrease of biochar volatile matter content within values between 14.4 and 48.4%wt. (dry basis). The biochar ash content increases with peak temperature and heating rate, and it has values in the range 24.7 to 44.1%wt. (dry basis). The corresponding fixed carbon content is between 26.2 and 42.4%wt. (dry basis), and increases with an increase in the peak temperature. The carbon concentration in the biochar is in the range 42.8 to 47.0%wt. (dry basis). The biochar pH is in the range 6.9 to 11.2, and the electrical conductivity (EC) is in the range 2.2 to 5.0 mS/cm. Keywords: Biological sludge, Pyrolysis, Heating rate, Peak temperature, Biochar

Recently, wood pellets have become a reliable and clean renewable fuel for residential heating, replacing fossil fuels and reducing greenhouse gas emissions. Wood pellets are normally produced in industrial pellet plants (centralised production), but decentralised small-scale local production also occurs. This study applies Life Cycle Assessment (LCA) to quantify and compare the environmental profile of one centralised and two decentralised alternatives for wood pellet production for residential heating in Portugal: (1) industrial wood pellets production (centralised), (2) wood pellets production at sawmills (decentralised) and (3) wood pellets production at households (decentralised). System boundaries include the stages of forest management, wood pellet production, wood pellet distribution and wood pellet energetic conversion. The impact results show that industrial pellet production ranks as the worst alternative, while pellet production at households has the best environmental profile for all the impact categories under study. However, the environmental impacts of pellet production at the sawmill do not differ greatly from those of the pellet production at households; they are 14 to 16% higher for global warming and fossil resources scarcity and 0.3 to 3% higher for the remaining impact categories. The worst environmental performance of the industrial pellet production alternative is mainly due to high electricity and diesel consumption during wood pellet production and the use of logging residues to generate heat for drying biomass feedstock. A sensitivity analysis was performed to evaluate the influence of changing the distance travelled during the transport of packed pellets to stores and sawdust to households. The results show changes in the environmental performance ranking, highlighting that for short distances, both decentralised alternatives can be more sustainable from an environmental perspective than the centralised alternative, but for larger distances, the pellet production at households should be avoided.

Refuse-derived fuel (RDF) is generated by selected Municipal Solid Waste (MSW) fractions. Due to MSW composition changes by location, it is challenging to sell RDF as a product in the market. This article compiles the significant standards and rules governing RDF manufacture and usage. Additionally, it emphasizes the key actors that have already made a business of its commercialization and energy production through thermochemical processes. Combustion is the most often utilized thermochemical process, and this paper gathers information from several works on the combustion of RDF and RDF blends. Pyrolysis and gasification are also discussed, along with the primary benefits and drawbacks of RDF usage. Finally, the market's potential and significant constraints are examined. The primary constraint is the RDF price due to commercialization fees. However, RDF is aligned with the circular economy, sustainable development goals, and CO2 reductions by avoiding the extraction of new fossil fuels.