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A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A4: Bio-Energy".

Deadline for manuscript submissions: closed (6 November 2023) | Viewed by 23666

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Prof. Dr. Małgorzata Wilk

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Department of Heat Engineering and Environment Protection, AGH University of Science and Technology, Mickiewicza 30 Av., 30-059 Kraków, Poland
Interests: thermal processes; hydrothermal carbonization; torrefaction; pyrolysis; combustion; thermal analysis; post-processing water analysis; fuel property evaluation; biomass; waste; sewage sludge
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Dear Colleagues,

Recently, the political situation has significantly influenced the demand for bioenergy production. The global energy market has been forced to reduce the consumption of natural gas. Additionally, global warming and the depletion of natural sources has imposed the implementation of many actions towards the development of renewable sources and the reduction in fossil fuel usage. Therefore, biomass, biofuels and waste are welcome as eco-friendly alternatives. In addition, new developing technologies should also be applied to sufficiently increase the production of biofuels and to utilize the potential of biomass or waste and the adequate disposal of by-products. Therefore, pre-treatment processes such as torrefaction, hydrothermal carbonization and slow pyrolysis processes are required to improve the properties of biomass or waste and turn them into successful biofuels. Thermal conversion methods, e.g., combustion, gasification or pyrolysis, must be undertaken to process biomass, biofuels or waste into energy or other applications including fuel cells, biofertilizers or absorbents, etc. Every aspect of these processes must be carefully studied. Therefore, a number of actions regarding waste management should also be introduced, including, among others: the reduction in waste generation, including food, mineral and plastic waste; the efficient segregation of municipal mixed solid waste; and the application of thermal processes in order to transform the combustible portion of waste into energy.

This Special Issue aims to present the most recent advancements related to experimental and numerical studies as well theory and design concerning biomass, biofuels and waste conversion technologies. In addition, the benefits and problems associated within their production will be highlighted. Research papers and reviews describing the state of the art are within the scope of this Special Issue.

Prof. Dr. Małgorzata Wilk
Guest Editor

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Keywords

biomass
biofuel
waste
sewage sludge
municipal solid waste
refuse-derived fuel
renewable fuels
waste management
liquid waste disposal
fuel characterization
circular economy
sustainability
thermal processing
hydrothermal carbonization
liquefaction
stream explosion
torrefaction
pyrolysis
gasification
combustion and incineration
anaerobic digestion and fermentation
wet oxidation
hydrogen
material recovery
energy recovery
energy balance
evaluation of fuel quality
life cycle and risk assessment
technoeconomic analysis
environmental consideration
biological processes
dark fermentation
biorefinery

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Related Special Issue

Biomass, Biofuels and Waste: 2nd Edition in Energies (8 articles)

Published Papers (12 papers)

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Research

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13 pages, 1827 KiB

Open AccessFeature PaperArticle

The Effect of Residence Time during the Hydrothermal Carbonization Process of Sewage Sludge on the Properties of Hydrochar

by Klaudia Czerwińska, Joanna Mikusińska, Aleksandra Błoniarz, Maciej Śliz and Małgorzata Wilk

Energies 2024, 17(14), 3380; https://doi.org/10.3390/en17143380 - 10 Jul 2024

Viewed by 805

Abstract

The optimal process conditions concerning the hydrothermal carbonization of digested sewage sludge are crucial to the economically effective technology needed to produce a solid product, hydrochar, for energy purposes. Accordingly, different residence times, 0.5 h, 1 h and 2 h, were investigated in order to understand the effect of residence time on the process. Furthermore, the physical and chemical properties of hydrochar were investigated and compared to the raw material. For these reasons, analyses describing fuel properties were performed, including ultimate and proximate analyses, HHV, and TGA analysis. The latter method was employed to study the combustion process of solid samples. In addition, the oxide content of different elements within the ash of solid samples was determined using the XRF method to calculate indices related to operational problems during the combustion process. The results confirmed that time did not matter significantly and the physical and chemical properties of hydrochar were very similar to each other. However, the contact angle for 2 h of residence time confirmed that a longer processing time resulted in a more hydrophobic character of hydrochar and enabled more effective dewaterability of hydrothermal slurry. It was also noted that the hydrothermal carbonization process affected the sewage sludge in a positive way. In brief, the results confirmed that the hydrochar was a brittle, moderately hydrophilic, solid carbon-containing product that provided a different combustion performance than the raw sewage sludge. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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12 pages, 2727 KiB

Open AccessArticle

Utilization of Sunflower Husk Ash in the Production of Polyurethane Materials

by Patrycja Zakrzewska, Monika Kuźnia, Beata Zygmunt-Kowalska, Anna Magiera and Aneta Magdziarz

Energies 2023, 16(24), 8080; https://doi.org/10.3390/en16248080 - 15 Dec 2023

Viewed by 1015

Abstract

Energy produced from waste biomass is more environmentally friendly than that produced from fossil resources. However, the problem of managing waste from the thermal conversion of biomass arises. The overarching goal of this article was to propose a method of utilizing biomass ash (sunflower husk) as a filler that positively affects the properties of rigid polyurethane foams. The scope of the presented research is to obtain and characterize rigid polyurethane foams (RPUFs) with the addition of two types of fillers: sunflower husks (SHs) and sunflower husk ash (SHA). First, an analysis of the fillers was carried out. The carbon content of SHs (C~49%) was ten times higher in comparison to SHA’s carbon content (C~5%). The morphology of the fillers and the particle size distribution were determined, which showed that in the case of SHs, particles with a size of 500–1000 µm predominated, while in SHA, the particles were 1–20 µm. The content of inorganic compounds was also determined. Potassium and calcium compounds were the most abundant in both fillers. The second part of the research was the analysis of polyurethane materials with the addition of fillers. The obtained results indicate that filler addition had a positive effect on the dimensional stability of the foams by eliminating the risk of material shrinkage. The biodegradation process of polyurethane materials was also carried out. The reference foam weight loss after 8 weeks was ~10%, while the weight loss of the foam containing SHA was over 28%. Physical and mechanical properties, cell structure, and thermal stability tests were also carried out. The use of bio-waste fillers creates a possibility for the partial replacement of petrochemical products with environmentally friendly and recycled materials, which fits into the circular economy strategy. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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18 pages, 1823 KiB

Open AccessFeature PaperArticle

Evaluation of the Hemp Shive (Cannabis sativa L.) Energy Requirements Associated with the Biocomposite Compaction Process

by Jakub Nowakowski-Pałka and Kamil Roman

Energies 2023, 16(18), 6591; https://doi.org/10.3390/en16186591 - 13 Sep 2023

Cited by 2 | Viewed by 1014

Abstract

The main purpose of the present study was to develop an environmentally friendly and economical biocomposite that can be used to make hemp shive (Cannabis sativa L.) chipboard. The study involved the creation of a sample made of hemp shives and PLA (Polylactide) thermoplastic with varying amounts of concentrations of this plastic (25 and 50%) following a series of testing studies. The variabilities were differentiated fractions at four different levels (f₁, f₂, f₃, and f₄) ranging from 0–2 mm, 2–4 mm, 4–6 mm, and 6–8 mm. In this light, the purpose of this research was to optimize the parameters that will affect the compaction process and strength of the biocomposites the researchers tested, which were made from shredded hemp residues and PLA (polylactide). According to this hypothesis, the quality of the biocomposite produced depends on the variation of fractions that constitute the composite. This study aims to provide insight into the energy requirements associated with the production of a biocomposite from hemp scraps and PLA thermoplastic, in order to determine its feasibility. The study compared the densities of different hemp fraction mixtures. The conversion factor (χ) was used while calculating the specific density of the fractions, f₁, f₂, f₃, and f₄, which came to 1377.33 kg·m⁻³, 1122.27 kg·m⁻³, 1071.26 kg·m⁻³, and 1275.31 kg·m⁻³, respectively. The specific density of blends containing 50% PLA material was calculated to be 1326.32 kg·m⁻³. For blends containing 50% PLA, by taking into account the conversion factor, the density fractions were 1324.29 kg·m⁻³, 1428.34 kg·m⁻³, and 1479.36 kg·m⁻³. Using different types of mixtures and fractions to analyze the total compaction work values: Based on the addition of 50% PLA to fractions f₃ (4 ÷ 6) and f₄ (6 ÷ 8), bulk density ranged between 221.09 kg·m⁻³ and 305.31 kg·m⁻³. Based on the compaction process results, the density values for the various fractions ranged from 1101.28 kg·m⁻³ to 1292.40 kg·m⁻³. Depending on what density is desired, the amount of compaction work required, on average, ranges from 1.1 × 10⁻⁵ J to 4.5 × 10⁻⁵ J. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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12 pages, 2241 KiB

Open AccessFeature PaperArticle

Purified Glycerine from Biodiesel Production as Biomass or Waste-Based Green Raw Material for the Production of Biochemicals

by Grzegorz Borówka, Grzegorz Semerjak, Wojciech Krasodomski and Jan Lubowicz

Energies 2023, 16(13), 4889; https://doi.org/10.3390/en16134889 - 23 Jun 2023

Cited by 1 | Viewed by 2203

Abstract

Glycerine (glycerol) is a polyol consisting of three carbon atoms bonded to hydroxyl groups. It is a by-product of the transesterification of triglycerides, such as animal fats, vegetable oils, or used cooking oils during the biodiesel production process. Crude glycerine is subject to purification processes resulting in distilled glycerine containing at least 99.5% glycerol. Currently, produced high-quality distilled glycerine is used in the food, pharmaceutical, and cosmetic industries. Recently, technologies for converting glycerol to other chemicals through catalytic processes have been intensively developed, e.g., production of bio-based 1,2-propanediol. In the near future, glycerol will certainly become a promising renewable raw material in many modern biorefineries for the synthesis of biofuels, chemicals, and bioenergy production. This paper presents the possibility of using ion exchange resins to remove impurities with trace amounts of sulphur and nitrogen compounds from crude and distilled glycerine, produced during the biodiesel production process from used cooking oils. It was determined that using ion exchange resins at the preliminary purification stage (before distillation) was ineffective. Using cationite resins to purify distilled glycerine produced from waste materials enables the removal of impurities in the form of sulphur and nitrogen compounds. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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18 pages, 9641 KiB

Open AccessArticle

The Effect of Agricultural Biogas Plants on the Quality of Farm Energy Supply

by Magdalena Tymińska, Zbigniew Skibko and Andrzej Borusiewicz

Energies 2023, 16(12), 4600; https://doi.org/10.3390/en16124600 - 8 Jun 2023

Cited by 5 | Viewed by 1670

Abstract

Agricultural biogas plants are among the renewable energy sources. While they have many advantages, they are less common than photovoltaic or wind power plants. One of the reasons for the lack of support for the construction of new agricultural biogas plants is the belief that biogas plants will affect the operation of consumers connected in its immediate vicinity through interference introduced into the grid. This article presents the possibilities a biogas plant built on a farm offers. The impact of an on-farm biogas plant on the voltage parameters of a farm specializing in barnless cattle rearing is analyzed in detail. As demonstrated by the authors’ research in one of the agricultural biogas plants (with an electrical capacity of 40 kW), these plants do not introduce significant disturbances to the power quality into the grid. The most significant changes in the parameters of the voltage supplying the farm under study were caused by the operation of the digester mixer installed in the fermenter. Thanks to the research, it was also possible to identify a problem with the effect of the digester mixer on the energy parameters produced in the biogas plant. This problem has so far not been noticed or corrected by biogas plant manufacturers. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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13 pages, 977 KiB

Open AccessArticle

Biodiesel Production Catalyzed by Lipase Extract Powder of Leonotis nepetifolia (Christmas Candlestick) Seed

by Verónica Ávila Vázquez, Miguel Mauricio Aguilera Flores, Luis Felipe Hernández Casas, Nahum Andrés Medellín Castillo, Alejandro Rocha Uribe and Hans Christian Correa Aguado

Energies 2023, 16(6), 2848; https://doi.org/10.3390/en16062848 - 19 Mar 2023

Cited by 4 | Viewed by 1950

Abstract

This work aimed to evaluate the ability of lipase extract powder obtained from Leonotis nepetifolia seed for enzyme-catalyzed biodiesel production using Leonotis nepetifolia oil, commercial olive oil, and waste cooking oil as substrates. The lipase extract powder showed an enzymatic activity and hydrolysis percentage of 24.7 U/g and 21.31%, respectively, using commercial olive oil as a reference. Transesterification reaction conditions were 40 g of substrate, 34 °C, molar ratio oil: methanol of 1:3, lipase extract powder 20 wt%, phosphates buffer (pH 4.8) 20 wt%, and a reaction time of 8 h. Transesterification yields of 74.5%, 71.5%, and 69.3% for commercial olive oil, waste cooking oil, and Leonotis nepetifolia oil were obtained, respectively. Biodiesel physicochemical parameters were analyzed and compared with the international standards: EN 14214 (European Union) and ASTM D6751 (American Society for Testing and Materials). The biodiesel’s moisture and volatile matter percentages, iodine index, cooper strip corrosion, and methyl esters content conformed to the standards’ specifications. The fatty acid methyl ester content of the vegetable oils showed the presence of methyl oleate after enzyme-catalyzed transesterification. This study reveals that biodiesel production catalyzed by lipase extract powder from Leonotis nepetifolia could be a viable alternative, showing that transesterification yields competitive results. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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12 pages, 5430 KiB

Open AccessFeature PaperArticle

Biomass Origin Waste as Activators of the Polyurethane Foaming Process

by Patrycja Zakrzewska, Beata Zygmunt-Kowalska, Monika Kuźnia, Artur Szajding, Tadeusz Telejko and Małgorzata Wilk

Energies 2023, 16(3), 1354; https://doi.org/10.3390/en16031354 - 27 Jan 2023

Cited by 7 | Viewed by 2265

Abstract

Rigid polyurethane foams (RPUFs) are characterized by their excellent viable properties; thus, these materials can be successfully used as thermal insulation materials. The main problem, the solution of which is partly indicated in this paper, is that the products for the synthesis of RPUFs are produced from petrochemicals. Due to this, the use of natural fillers in the form of waste biomass is introduced for the synthesis of RPUFs. The biodegradable biomass waste used in the RPUF production process plays multiple roles: it becomes an activator of the RPUF foaming process, improves selected properties of RPUF materials and reduces the production costs of insulating materials. The paper presents the results of the foaming process with the use of six different fillers: sunflower husk (SH), rice husk (RH), buckwheat husk (BH), sunflower husk ash (SHA), rice husk ash (RHA) and buckwheat husk ash (BHA). In all cases, composites of rigid polyurethane foam with 10 wt.% of filler were produced. New foams were compared with polyurethane materials without the addition of a modifier. Moreover, the paper presents the results of the fillers’ analysis used in the tests and the effects of the fillers’ addition as activators of the RPUF foaming process. Promising results were obtained for two of the fillers, BHA and SHA, as activators of the foaming process and confirmed by the volumetric results, where the named samples reached their maximum value in half the time compared to the remaining samples. In addition, the expansion rate for PU_10BHA was a maximum of approximately 11 cm³/s and PU_10SHA was a maximum of approximately 9 cm³/s, whereas the remaining samples showed this parameter at about 3 cm³/s. During the research, the scanning electron microscopy method and infrared camera technique were used. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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15 pages, 6194 KiB

Open AccessArticle

Solvothermal Liquefaction of Blackcurrant Pomace in the Water-Monohydroxy Alcohol Solvent System

by Mariusz Wądrzyk, Łukasz Korzeniowski, Marek Plata, Rafał Janus, Marek Lewandowski, Grzegorz Borówka and Przemysław Maziarka

Energies 2023, 16(3), 1127; https://doi.org/10.3390/en16031127 - 19 Jan 2023

Cited by 5 | Viewed by 1459

Abstract

Wet organic wastes are especially troublesome in valorization. Therefore, innovative solutions are still in demand to make valorization feasible. In this study, we tested a new transformation route of a blackcurrant pomace as a high-moisture industrial waste through a series of high-temperature and pressure solvothermal liquefaction experiments. The feedstock was directly converted under near-critical conditions of the binary solvent system (water/2-propanol). The goal was to examine the effect of conversion parameters (temperature, biomass-to-solvent ratio) on the change in the yield of resultant bioproducts, as well as the quality thereof. The experiments were conducted in a batch autoclave at a temperature between 250 and 300 °C. The main product of the transformation was liquid biocrude, which was obtained with the highest yield (ca. 52 wt.%) at 275 °C. The quality of biocrude was examined by ATR-FTIR, GC-MS, and elemental analysis. The ultimate biocrude was a viscous heterogeneous mixture containing various groups of components and exhibiting evident energy densification (ca. 145–153%) compared to the value of the feedstock. The proposed processing method is suitable for further development toward efficient valorization technology. More specifically, the co-solvent additive for liquefaction is beneficial not only for the enhancement of the yield of the desired product, i.e., biocrude, but also in terms of technological aspects (reduction of operational pressure and temperature). Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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14 pages, 1651 KiB

Open AccessArticle

Developing a Proximate Component Prediction Model of Biomass Based on Element Analysis

by Sunyong Park, Seok Jun Kim, Kwang Cheol Oh, La Hoon Cho and DaeHyun Kim

Energies 2023, 16(1), 509; https://doi.org/10.3390/en16010509 - 2 Jan 2023

Cited by 7 | Viewed by 2066

Abstract

Interest in biomass has increased due to current environmental issues, and biomass analysis is usually performed using element and proximate analyses to ascertain its fuel characteristics. Mainly, element component prediction models have been developed based on proximate analysis, yet few studies have predicted proximate components based on element analysis. Hence, this study developed a proximate component prediction model following the calorific value calculation. Analysis of Pearson’s correlation coefficient showed that volatile matter (VM) and fixed carbon (FC) were positively correlated with hydrogen and oxygen, and with carbon, respectively. Thus, the model correlation was developed using a combination of the “stepwise” and “enter” methods along with linear or nonlinear regressions. The optimal models were developed for VM and ash content (Ash). The VM optimal model values were: R² = 0.9402, root-mean-square error (RMSE) = 7.0063, average absolute error (AAE) = 14.8170%, and average bias error (ABE) = −11.7862%. For Ash, the values were: R² = 0.9249, RMSE = 2.9614, AAE = 168.9028%, and ABE = 167.2849%, and for FC, the values were: R² = 9505, RMSE = 6.3214, AAE = 18.3199%, and ABE = 15.0094%. This study provides a model to predict the proximate component by element analysis. Contrary to existing method, proximate analysis can be predicted based on elemental analysis, and shows that consume samples can be performed at once. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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10 pages, 1412 KiB

Open AccessArticle

Cross-Comparison of the Impact of Grass Silage Pulsed Electric Field and Microwave-Induced Disintegration on Biogas Production Efficiency

by Dawid Szwarc, Anna Nowicka and Katarzyna Głowacka

Energies 2022, 15(14), 5122; https://doi.org/10.3390/en15145122 - 14 Jul 2022

Cited by 4 | Viewed by 1234

Abstract

Lignocellulosic biomass is included in the group of renewable energy sources. Its calorific value is high, owing to which it can be successfully used in the production of second-generation fuels, e.g., biogas. However, its complex structure makes it necessary to apply a pretreatment in order to increase the biogas output. This study presents the usability of a pulsed electric field in grass silage pretreatment in methane fermentation and compares it with microwave-induced disintegration. The experiment shows that substrate disintegration with a pulsed electric field (PEF) results in an increase in methane output. The productivity of methane from PEF pretreatment silage increased by 20.1% compared to the untreated control. The application of microwave disintegration, with the assumption that the same energy is used for the pretreatment, resulted in a methane output increase of 6% compared to the control. The highest biogas production output in PEF-pretreated samples was 535.57 NL/kg VS, while the highest biogas output from substrates pretreated with microwaves was 487.18 NL/kg VS. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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Review

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18 pages, 2190 KiB

Open AccessFeature PaperReview

Hydrothermal Carbonization of Digestate Produced in the Biogas Production Process

by Joanna Mikusińska, Monika Kuźnia, Klaudia Czerwińska and Małgorzata Wilk

Energies 2023, 16(14), 5458; https://doi.org/10.3390/en16145458 - 18 Jul 2023

Cited by 9 | Viewed by 2154

Abstract

In agricultural biogas plants, besides biogas, the by-product digestate is also produced. Due to its high moisture content and organic origin, it can successfully be applied in the hydrothermal carbonization process to avoid the fate of landfilling. This paper reviews the properties of agricultural digestate and its hydrothermal conversion (HTC) into hydrochar and process water. The type of feedstock and the parameters of the HTC process, such as temperature, pressure and residence time, affects the physical and chemical characteristics of hydrochar. Therefore, its possible application might be as a biofuel, fertilizer, soil improver, adsorber, or catalyst. In this paper, the properties of hydrochar derived from agricultural digestate are widely discussed. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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34 pages, 2432 KiB

Open AccessEditor’s ChoiceReview

Biological Aspects, Advancements and Techno-Economical Evaluation of Biological Methanation for the Recycling and Valorization of CO₂

by Ruggero Bellini, Ilaria Bassani, Arianna Vizzarro, Annalisa Abdel Azim, Nicolò Santi Vasile, Candido Fabrizio Pirri, Francesca Verga and Barbara Menin

Energies 2022, 15(11), 4064; https://doi.org/10.3390/en15114064 - 1 Jun 2022

Cited by 25 | Viewed by 4978

Abstract

Nowadays, sustainable and renewable energy production is a global priority. Over the past decade, several Power-to-X (PtX) technologies have been proposed to store and convert the surplus of renewable energies into chemical bonds of chemicals produced by different processes. CO₂ is a major contributor to climate change, yet it is also an undervalued source of carbon that could be recycled and represents an opportunity to generate renewable energy. In this context, PtX technologies would allow for CO₂ valorization into renewable fuels while reducing greenhouse gas (GHG) emissions. With this work we want to provide an up-to-date overview of biomethanation as a PtX technology by considering the biological aspects and the main parameters affecting its application and scalability at an industrial level. Particular attention will be paid to the concept of CO₂-streams valorization and to the integration of the process with renewable energies. Aspects related to new promising technologies such as in situ, ex situ, hybrid biomethanation and the concept of underground methanation will be discussed, also in connection with recent application cases. Furthermore, the technical and economic feasibility will be critically analyzed to highlight current options and limitations for implementing a sustainable process. Full article

(This article belongs to the Special Issue Biomass, Biofuels and Waste)

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