Managing energy-producing companies as well as managing the entire energy sector in the light of legal and environmental requirements requires a new vision, mission, and strategy. The paper analyses the strategies of energy enterprises. It is not enough now to produce energy and deliver it at appropriate, acceptable prices to consumers; it must be generated with the least negative impact on the environment. To achieve that plan, companies should cut the carbon intensity of their products by 20% by 2030, 45% by 2035, and 100% by 2050, using a baseline of 2016. To compared to 1990 levels, the greenhouse gas emission reduction target for 2030 should be increased to 55%. Bioenergy will represent 18% of total final energy consumption in 2050. Additionally, this requires the development of a long-term strategy that can force companies to completely reorganize their production or start a new operation and activities. A low-cost strategy or a competition strategy are insufficient, and it is ne... [more]

This study focused on the thermal degradation of peanut shells in the presence and absence of a termite hill as the catalyst. EDX, XRF, SEM, SAA and XRD were employed for the characterization of the termite hill. The bio-oil obtained from peanut shell pyrolysis was analyzed by GC-MS. To ascertain the kinetic parameters of the reaction, thermogravimetric analysis of peanut shells was carried out with and without a termite hill at heating rates of 3, 12, 20 and 30 °C·min−1. TG/DTG of peanut shells revealed four steps of weight loss from 30 to 800 °C. The weight loss was attributed to the evaporation of water and degradation of hemicellulose, cellulose and lignin. The Kissinger method was applied for the evaluation of kinetic parameters. The activation energy (E) for the non-catalyzed degradation reactions of hemicellulose, cellulose and lignin was evaluated as 108.082, 116.396 and 182.908 kJ/mol, with a pre-exponential factor (A) of 1.9 × 108, 2.42 × 109 and 2.98 × 1011 min−1, respective... [more]

The global need to transition to renewable and decentralized systems entails agricultural systems as producers of residual biomass. Avocado trees (Persea americana Mill.) are one of the main woody crops cultivated in Mexico, with over 150,000 hectares grown in the country. The aim of the present study is to evaluate the use of avocado pruning residues as an energy input, focusing on the revalorization of biomass and the generation of economic benefits for small producers in the region. For that purpose, we developed allometric equations to calculate biomass availability from pruning residues, evaluated their thermochemical properties, and proposed technological alternatives for their energy use. Two allometric equations for pruning residues as a function of tree height and crown diameter were obtained: one for light and minor maintenance pruning (R2 = 0.63) and one for rejuvenation pruning (R2 = 0.86). From these equations, we estimate the mean amount of biomass generated from light an... [more]

Hydrothermal carbonization (HTC) continues to gain recognition over other valorization techniques for organic and biomass residue in recent research. The hydrochar product of HTC can be effectively produced from various sustainable resources and has been shown to have impressive potential for a wide range of applications. As industries work to adapt the implementation of HTC over large processes, the need for reliable models that can be referred to for predictions and optimization studies are becoming imperative. Although much of the available research relating to HTC has worked on the modeling area, a large gap remains in developing advanced computational models that can better describe the complex mechanisms, heat transfer, and fluid dynamics that take place in the reactor of the process. This review aims to highlight the importance of expanding the research relating to computational modeling for HTC conversion of biomass. It identifies six research areas that are recommended to be f... [more]

Lignocellulosic biomass and waste, such as plastics, represent an abundant resource today, and they can be converted thermo-chemically into energy in a refinery. Existing research works on catalytic and non-catalytic pyrolysis performed in thermally-heated reactors have been reviewed in this text, along with those performed in microwave-heated ones. Thermally-heated reactors, albeit being the most commonly used, present various drawbacks such as superficial heating, high thermal inertia and slow response times. That is why microwave-assisted pyrolysis (MAP) appears to be a very promising technology, even if the process does present some technical drawbacks as well such as the formation of hot spots. The different types of catalysts used during the process and their impacts have also been examined in the text. More specifically, studies conducted in fluidised bed reactors (FBR) have been detailed and their advantages and drawbacks discussed. Finally, future prospects of MAP have been br... [more]

Bioenergy is one of the most important renewable-energy sources worldwide, accounting for more than two-thirds of the renewable-energy mix. Biomass accounted for 13−14% of the primary energy consumption in 2018, and by 2050, it is expected to account for 50% of the global primary energy consumption. This article studies the biomass potential in Iraq. The potential of this country to be one of the leading producers of bioenergy is discussed, remarking on the importance of agricultural crop waste. Nowadays, Iraq generates a great quantity of biomass every year. Unfortunately, instead of contributing to the energy industry and economic progress, these wastes are burned directly, potentially causing a slew of environmental issues. Based on earlier studies, the theoretical energy potential of Iraq agricultural wastes is assessed. It is concluded that 10 million tons of dry agricultural leftovers can create 115 PJ of energy per year. According to the findings of this study, 10 million heads... [more]

The measurement of the higher heating value (HHV) of municipal solid wastes (MSWs) plays a key role in the disposal process, especially via thermochemical approaches. An optimized multi-variate grey model (OBGM (1, N)) is introduced to forecast the MSWs’ HHV to high accuracy with sparse data. A total of 15 cities and MSW from the respective city were considered to develop and verify the multi-variant models. Results show that the most accurate model was POBGM (1, 5) of which the least error measured 5.41% MAPE (mean absolute percentage error). Ash, being a major component in MSW, is the most important factor affecting HHV, followed by volatiles, fixed carbon and water contents. Most data can be included by using the prediction interval (PI) method with 95% confidence intervals. In addition, the estimations indicated that the MAPE from estimating the HHV for various MSW samples, collected from various cities, were in the range of 3.06−34.50%, depending on the MSW sample.

Crop byproducts are alternatives to nonrenewable energy resources. Burning biomass results in lower emission of undesirable nitrogen and sulfur oxides and contributes no significant greenhouse effect. There is a diverse range of energy-useful biomass, including in terms of calorific value. This article presents a new method of discriminating biomass, and of determining its calorific value. The method involves extracting the selected texture features on the surface of a briquette from a microscopic image and then classifying them using supervised classification methods. The fractal dimension, local binary pattern (LBP), and Haralick features are computed and then classified by linear discrimination analysis (LDA). The discrimination results are compared with the results obtained by random forest (RF) and deep neural network (DNN) type classifiers. This approach is superior in terms of complexity and operating time to other methods such as, for instance, the calorimetric method or analys... [more]

The adverse effect of the use of fossil fuels on the environment and public health has given rise to a sustained renewable energy research and development. An important component of global renewable energy mix is the use of loose biomass, including agricultural and forestry residues, to produce solid fuels in the form of briquettes. Briquettes play a significant role in bioenergy mix in developing and developed countries. The production of biomass briquettes often entails the collection, transportation, storage, processing, and compaction of loose biomass that meet specific quality parameters. The densification process often involves the addition of binders to improve the cohesive strength of the briquette material. This paper surveys recent literature from 2012 to 2021 to establish the current state of research on the use of binders in briquette production; and reviews current parameters used in assessing the quality of biomass briquettes with focus on mechanical and handling properti... [more]

The levelized cost of heat (LCOH) and the technical feasibility in the specific context of building construction or renovation are the major drivers of users’ choices for space heating and cooling solutions. In this work, the LCOH was assessed for the most diffused heating technologies in Piedmont (NW Italy): that is, fossil fuels (methane, heating oil and liquefied petroleum gas—LPG), wood biomass (wood logs and pellet) and heat pumps (air-source and ground-source), both in heating-only and in a heating and cooling configuration. A sensitivity analysis of the main LCOH drivers was performed to assess whether and how each technology is vulnerable to energy price and upfront cost changes. The results show that heat pumps are competitive against gas boilers, but they are heavily dependent on refurbishment incentives and penalized by the high electricity prices in Italy; on the other hand, wood biomasses are competitive even in the absence of incentives. The analysis confirmed that LPG an... [more]

Economic criteria have prevailed in studies on integration of renewable energies. Tons of dangerous emissions are emitted by a biomass fuel, causing negative impacts over atmosphere and health. Current research proposes Pinch Analysis of solar thermal energy and the joint use of biomass (sugarcane bagasse) to produce heat and power in a Caribbean sugar mill; measuring emissions like: carbon oxide CO, carbon dioxide CO2, dinitrogen monoxide N2O, nitrogen oxides NOx, sulfur oxides SOx, non-methane volatile organic compounds NMVOC, methane CH4, and particulate matters, to have a global and clear view of the impacts of biomass as a renewable fuel. Variables like kWh cost, the installation and device area of renewable energy, and greenhouse gas emissions, are analysed to assess the effect on the integration final design, the target of which is to control the use of biomass. It is possible to produce an economically competitive integration design of solar system LCOEth solar = 0.0636 US... [more]

The application of oxygen carriers as alternative bed material in fluidized bed combustion originates from chemical lopping processes. They serve as oxygen transport agents undergoing consecutive redox cycles. Thereby, oxygen carriers can provide surplus oxygen in oxygen-lean areas of fluidized bed combustion processes. In turn, re-oxidation takes place in oxygen-rich reactor parts. A more homogeneous combustion and reduced CO emissions follow during steady-state operation. However, especially regarding solid biomass conversion, inhomogeneous fuel qualities result in transient combustion conditions. Therefore, this research deals with the influence of the oxygen carrier ilmenite on solid biomass conversion. Separated batch experiments with methane (volatile), char and wood pellets took place in a laboratory bubbling fluidized bed reactor. They reveal that ilmenite enhances the in-bed CO2 yield by up to 63% during methane combustion. Batch char experiments confirm that solid−solid react... [more]

Biomass chemical looping gasification (BCLG) is a promising autothermic route for producing sustainable, N2-free, and carbon neutral syngas for producing liquid biofuels or high value hydrocarbons. However, different ash-related issues, such as high-temperature corrosion, fouling and slagging, bed agglomeration, or poisoning of the oxygen carrier might cause significant ecologic and economic challenges for reliable implementation of BCLG. In this work, lab-scale investigations under gasification-like conditions at 950 °C and thermodynamic modelling were combined for assessing the influence of composition, pre-treatment methods, such as torrefaction and water-leaching, and Ca-based additives on the release and fate of volatile inorganics, as well as on ash melting behavior. A deep characterization of both (non-)condensable gas species and ash composition behavior, joint with thermodynamic modelling has shown that different pre-treatment methods and/or Ca-additives can significantly coun... [more]

Tailpipe emissions from vehicles consist of CO2 and other greenhouse gases, which contribute immensely to the rise in global temperatures. Green hydrogen produced from the gasification of biomass can reduce the amount of CO2 emissions to zero. This study aims to provide a modelling framework to optimize the production of hydrogen from biomass waste obtained from different cities, for use in the road transport sector in Nigeria. A gasification model with post-treatment shift conversion and CO2 removal by adsorption is proposed. In this study, six cities are simulated based on technical and environmental considerations, using the Aspen Plus software package. The results revealed that Kaduna has the highest hydrogen generation potential of 0.148 million metric tons per year, which could reduce CO2 emissions to 1.60 and 1.524 million metric tons by the displacement of an equivalent volume of gasoline and diesel. This amounts to cost savings of NGN 116 and 161.8 billion for gasoline and die... [more]

This review article discusses the effects of inorganic content and mechanisms on raw biomass and char during gasification. The impacts of the inherent inorganics and externally added inorganic compounds are summarized based on a literature search from the most recent 40 years. The TGA and larger-scale studies involving K-, Ca-, and Si-related mechanisms are critically reviewed with the aim of understanding the reaction mechanisms and kinetics. Differences between the reaction pathways of inorganic matter, and subsequent effects on the reactivity during gasification, are discussed. The present results illustrate the complexity of ash transformation phenomena, which have a strong impact on the design of gasifiers as well as further operation and process control. The impregnation and mixing of catalytic compounds into raw biomass are emphasized as a potential solution to avoid reactivity-related operational challenges during steam and CO2 gasification. This review clearly identifies a gap... [more]

The giant miscanthus (Miscanthus × giganteus) is one of the most essential energy plants. It also finds various alternative uses, including installing belts to prevent soil erosion. Biomass from such belts should be removed and rationally managed every year. The parameters of miscanthus biomass were investigated in terms of its suitability for combustion and anaerobic fermentation. Under the conditions of the experiment, miscanthus achieved a stable yield already in the second year of vegetation, mainly due to the high planting density. Energy parameters turned out to be typical for straw biomass (calorific value 18.06 MJ/kg). Relatively low ash melting temperatures (<1400 °C) and their chemical composition meant a high risk of contamination depositing on heating devices, which is often indicated as a shortcoming of biomass compared to hard coal. Miscanthus silage can be a valuable substrate for anaerobic digestion, but it requires a sufficiently early harvest, which affects the yie... [more]

The paper investigates the optimization of ecosystem services of podzolized heavy loamy chernozem (black soil) as a result of the cultivation of the perennial energy culture of Miscanthus x giganteus. The research was conducted on an experimental land plot during 2016−2021. No fertilization was applied to the soil during the experiments, and over the years of research, the growing seasons were accompanied by abnormal droughts, but even under such conditions, the plants of Miscanthus x giganteus gradually increased their yield. At the initial stage of research, in the third year of cultivation, dry biomass of Miscanthus x giganteus was obtained at 14.3 t/ha, in the fourth year−18.6 t/ha, and already in the fifth and sixth years, 21.7 and 24.5 t/ha, respectively. That is, energy-wise, the harvest for the last year was equivalent to 15.9 tons of coal or 12,618 m3 of natural gas. Cultivation of Miscanthus x giganteus on black soil for six years has improved the provision of its ecosystem s... [more]

Residential biomass combustion has been pointed out as one of the largest sources of atmospheric pollutants. Rising awareness of the environmental effects of residential biomass combustion emissions boosted the development of different emission reduction devices that are currently available on the market for small-scale appliances. However, detailed studies on the efficiency of these devices in different combustion systems available in Southern European countries are lacking. In this study, two pollution control devices (catalytic converter and electrostatic precipitator) were tested in two different combustion systems (batch mode operated woodstove and automatically fed pellet stove) in order to assess the emission reduction potential of the devices. Pine firewood was used to fuel the woodstove. One commercial brand of pellets and an agricultural fuel (olive pit) were taken for the experiments in the pellet stove. While the efficiency of the electrostatic precipitator in reducing PM10... [more]

Rapid climate change and forecasted damage from fossil fuel combustion, forced researchers to investigate renewable and clean energy sources for the sustainable development of societies throughout the world. Biomass-based energy is one of the most important renewable energy sources for meeting daily energy needs, which are gaining in popularity daily. Gasification-based bioenergy production is an effective way to replace fossil fuels and reduce CO2 emissions. Even though biomass gasification has been studied extensively, there is still much opportunity for improvement in terms of high-quality syngas generation (high H2/CO ratio) and reduced tar formation. Furthermore, the presence of tar has a considerable impact on syngas quality. Downdraft gasifiers have recently shown a significant potential for producing high-quality syngas with lower tar concentrations. This article presents a comprehensive review on the advancement in biomass downdraft gasification technologies for high-quality s... [more]

This work presents new data on the life cycle impact assessment of various lignocellulosic biomass types in Mexico. A comparative life cycle assessment model of biomass densification systems was conducted. An integrated approach that incorporated various process variables, such as technology and variations in feed properties, within the analysis was employed to evaluate the environmental impact of producing 1 MJ of energy-containing densified fuel. The results show that the densification unit and curing (fuel drying) have the highest impact on the life cycle’s operational energy and the total life cycle energy, respectively. Of all the 33 biomass types from the 17 species sources considered in this study, sweet sorghum and sandbur grass have the highest global warming potential, 0.26 and 0.24 (kg CO2-eq), and human toxicity 0.58 and 0.53 (kg 1,4-dichlorobenzene-eq), respectively, while coffee pulp and cooperi pine wood have the least impact in both categories, with values of 0.08 and 0... [more]

Currently, hydrogen energy is the most promising energy vector, while gasification is one of the major routes for its production. However, gasification suffers from various issues, including slower carbon conversion, poor syngas quality, lower heating value and higher emissions. Multiple factors affect gasification performance, such as the selection of gasifiers, feedstock’s physicochemical properties and operating conditions. In this review, the status of gasification, key gasifier technologies and the effect of solid-fuel (i.e., coal, biomass and MSW) properties on gasification performance are reviewed critically. Based on the current review, the co-gasification of coal, biomass and solid waste, along with a partial utilisation of CO2 as a reactant, are suggested. Furthermore, a technological breakthrough in carbon capture and sequestration is needed to make it industrially viable.

The combustion of waste biomass is becoming a key challenge for the energy sector, especially in times of growing energy demand and increasing environmental awareness of society. Processing such fuels is usually demanding. Mathematical modeling makes it possible to adapt the course of the process. The best option is to use appropriate fuel mixtures. The aim of this work was to develop a simple model that would allow the pre-selection of the mixture of two types of digestate. Residues from methane fermentation of maize and apple pomace were used in the study. The paper presents both a mathematical model and laboratory tests. The practical part was to check the validity of the model estimates. The model works on the basic data from physicochemical analysis. Laboratory tests included combustion of the samples of different mixtures. We used image analysis of thermograms to determine changes during combustion, which allowed us to determine when and where the main combustion occurs. Results... [more]

This paper presents results that show the effect of hydrothermal carbonization and subsequent cold plasma jet treatment with helium and argon on the structure and sorption properties of a material—spent brewery grain. Treatment of activated carbon, with a cold atmospheric plasma jet, was used comparatively. The effect of activation on the pore structure of the materials was carried out by the volumetric method at low pressure (N2, 77 K). The specific surface area as well as the total pore volume, average pore size, and pore size distribution were determined using different theoretical models. A high improvement in the sorption capacity parameter was obtained for hydrochars after cold atmospheric plasma jet treatment with an increase of 7.5 times (using He) and 11.6 times (using Ar) compared with hydrochars before cold atmospheric plasma jet treatment. The increase in specific surface area was five-fold (He) and fifteen-fold (Ar). For activated carbon, such a large change was not obtain... [more]

Alkali metal compounds are released during the thermal conversion of biofuels and fossil fuels and have a major impact on the efficiency of conversion processes. Herein, we describe a novel method for the simultaneous characterization of alkali release and mass loss from materials used in combustion and gasification processes including solid fuels, fluidized bed materials, and catalysts for gas reforming. The method combines the thermogravimetric analysis of selected samples with the on-line measurement of alkali release using a surface ionization detector. The technique builds on the careful treatment of alkali processes during transport from a sample to the downstream alkali monitor including the losses of alkali in the molecular form to hot walls, the formation of nanometer-sized alkali-containing particles during the cooling of exhaust gases, aerosol particle growth, and diffusion losses in sampling tubes. The performance of the setup was demonstrated using biomass samples and flui... [more]

TG/FT-IR techniques, UV-spectroscopy, microwave extraction, XRD and SEM were used to study how densification of the three types of agricultural biomass wastes (wheat straw, soft wood, and sunflower husk) changes the composition and structure of their pyrolysis products. It was determined that densification changes the composition of volatile products of pyrolysis at the temperature of 420 °C: sunflower husk emits 4.9 times less saturated and unsaturated hydrocarbons and 1.9 times less compounds with carbonyl group; soft wood emits 1.8 times more saturated and unsaturated hydrocarbons and compounds with carbonyl groups and 1.3 times more alcohols and phenols; and wheat straw emits 2 times more compounds with carbonyl groups. These changes are probably caused by the differences in interaction of formed volatiles with the surface of chars. These differences can be caused by distinct places of cumulation of inorganic components in the densified samples. In the densified char, the inorganic... [more]