Special Issue "Hydrothermal Technology in Biomass, Utilization & Conversion II"

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

Deadline for manuscript submissions: closed (30 April 2020).

Special Issue Editors

Prof. Dr. David Chiaramonti
Website1 Website2
Guest Editor
ReCord – Renewable Energy Consortium for Research and Demonstration and Department of Industrial Engineering of the University of Florence, Viale Morgagni 40, Florence, Italy
Interests: hydrothermal carbonization and liquefaction; pyrolysis; biocrude upgrading; biochar and biochar-derived products chararacterization and use; bio and thermochemical process integration; biofuels and biopoducts
Special Issues and Collections in MDPI journals
Prof. Dr. Andrea Kruse
Website
Guest Editor
Institute of Agricultural Engineering, Conversion Technologies of Biobased Resources, Universität Hohenheim / University of Hohenheim, Stuttgart, Germany
Interests: hydrothermal carbonization; carbon materials; platform-chemicals from biomass; nutrient recovery; hydrothermal conversion; hydrothermal liquefaction; hydrothermal gasification; hydrothermal pretreatment
Special Issues and Collections in MDPI journals
Dr. Ing. Marco Klemm
Website
Guest Editor
DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Germany
Interests: hydrothermal processes for solid and liquid products for different applications (e.g. solid fuel, carbon materials, liquid fuels, chemicals); balance, technical assessment and optimization of hydrothermal process; implementation of hydrothermal processes in provision chains; assessment of feedstock concerning application in hydrothermal processes

Special Issue Information

Dear Colleagues,

The possibility of converting biomass into fuels and products through wet processes is becoming more and more attractive, as new feedstock and applications are appearing on the scene of bioeconomy and bioenergy. Hydrothermal processing of various type of biomass, waste and residues thus rised the interest of many researchers and companies around the world, together with downstream upgrading processes and technologies: solid products as biochar, for instance, or liquid ones as crude bioliquids, are finding new market opportunities in circular economy schemes. The Special Issue aims at collecting recent innovative research works in the field, from basic to applied research, as well as pilot industrial applications/demo. The outcome will constitute a valuable set of references for those investing time and effort in research in the field.

Prof. Ing. David Chiaramonti
Prof. Dr. Andrea Kruse
Dr. Ing. Marco Klemm
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Hydrothermal Processing
  • Liquefaction
  • Carbonisation
  • Biochar
  • Biofuels
  • Bioproducts
  • Biochemicals

Published Papers (6 papers)

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Editorial

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Open AccessEditorial
Special Issue “Hydrothermal Technology in Biomass Utilization & Conversion II”
Energies 2021, 14(1), 103; https://doi.org/10.3390/en14010103 - 28 Dec 2020
Abstract
Hydrothermal processing (HTP) has gained a large amount of attention from the scientific community, the industrial stakeholders, and the economic operators given the significant technology and process developments that have occurred during the last decade [...] Full article
(This article belongs to the Special Issue Hydrothermal Technology in Biomass, Utilization & Conversion II)

Research

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Open AccessArticle
Combustion Characteristics of Hydrochar and Pyrochar Derived from Digested Sewage Sludge
Energies 2020, 13(16), 4164; https://doi.org/10.3390/en13164164 - 12 Aug 2020
Cited by 1
Abstract
In this paper, hydrochars and pyrochars were produced at 260 °C under different residence times (2 and 4 h) using anaerobic digested sewage sludge (SSL) as initial feedstock. The effect of reaction time on the fuel properties of hydrochars and pyrochars was evaluated. [...] Read more.
In this paper, hydrochars and pyrochars were produced at 260 °C under different residence times (2 and 4 h) using anaerobic digested sewage sludge (SSL) as initial feedstock. The effect of reaction time on the fuel properties of hydrochars and pyrochars was evaluated. Moreover, the combustion kinetics of raw SSL and the derived pyrochars and hydrochars without coal blending were determined at two different air flows (20 and 90 mL/min) and compared. In the same conditions, the yield of hydrochar was significantly lower than that of pyrochar, confirming the different reaction pathways followed in each process. The results showed hydrochars have lower carbon recovery and energy yield than pyrochars, making the latter more suitable for energy purposes. The thermogravimetric combustion study showed that both thermochemical treatments increased the ignition temperature but decreased the burnout temperature, which results in higher stability during handling and storage. However, raw SSL is better for combustion than hydrochar according to the combustibility index. In addition, the kinetic study showed that the activation energy of the combustion of biochars, especially pyrochar, is lower than that of raw SSL, which is advantageous for their combustion. Full article
(This article belongs to the Special Issue Hydrothermal Technology in Biomass, Utilization & Conversion II)
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Open AccessArticle
Experimental Evaluation of a New Approach for a Two-Stage Hydrothermal Biomass Liquefaction Process
Energies 2020, 13(14), 3692; https://doi.org/10.3390/en13143692 - 17 Jul 2020
Cited by 2
Abstract
A new approach for biomass liquefaction was developed and evaluated in a joint research project. Focus of the project, called [email protected]2O, lies on a two-step hydrothermal conversion. Within step 1, the input biomass is converted employing a hydrothermal degradation without added [...] Read more.
A new approach for biomass liquefaction was developed and evaluated in a joint research project. Focus of the project, called [email protected]2O, lies on a two-step hydrothermal conversion. Within step 1, the input biomass is converted employing a hydrothermal degradation without added catalyst or by homogeneous catalysis. Within step 2, the hydrogen accepting products of step 1, e.g., levulinic acid (LA) are upgraded by a heterogeneously catalyzed hydrogenation with hydrogen donor substances, e.g., formic acid (FA). As a result, components with an even lower oxygen content in comparison to step 1 products are formed; as an example, γ-valerolactone (GVL) can be named. Therefore, the products are more stable and contained less oxygen as requested for a possible application as liquid fuel. As a hydrothermal process, [email protected]2O is especially suitable for highly water-containing feedstock. The evaluation involves hydrothermal conversion tests with model substances, degradation of real biomasses, transfer hydrogenation or hydrogenation with hydrogen donor of model substances and real products of step 1, catalyst selection and further development, investigation of the influence of reactor design, the experimental test of the whole process chain, and process assessment. Full article
(This article belongs to the Special Issue Hydrothermal Technology in Biomass, Utilization & Conversion II)
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Open AccessArticle
Bio-Based Carbon Materials from Potato Waste as Electrode Materials in Supercapacitors
Energies 2020, 13(9), 2406; https://doi.org/10.3390/en13092406 - 11 May 2020
Cited by 3
Abstract
This study investigates the production of biobased carbon materials from potato waste and its application in energy storage systems such as supercapacitors. Three different categories of carbons were produced: hydrochar (HC) from hydrothermal carbonization (HTC) at three different temperatures (200 °C, 220 °C, [...] Read more.
This study investigates the production of biobased carbon materials from potato waste and its application in energy storage systems such as supercapacitors. Three different categories of carbons were produced: hydrochar (HC) from hydrothermal carbonization (HTC) at three different temperatures (200 °C, 220 °C, 240 °C) and two different duration times (two hours and five hours), pyrolyzed hydrochar (PHC) obtained via pyrolysis of the HTC chars at 600 °C and 900 °C for two hours and pyrochar from the pyrolysis of biomass at 600 °C and 900 °C for two hours. The carbon samples were analysed regarding their physico-chemical properties such as elemental composition, specific surface area, bulk density and surface functionalities as well as their electrochemical characteristics such as electric conductivity and specific capacity via cyclic voltammetry. N- and O-enriched carbon materials with promising specific surface areas of up to 330 m2 g−1 containing high shares of microporosity were produced. Electric conductivities of up to 203 S m−1 and specific capacities of up to 134 F g−1 were obtained. The presence of high contents of oxygen (4.9–13.5 wt.%) and nitrogen (3.4–4.0 wt.%) of PHCs is assumed to lead to considerable pseudocapacitive effects and favor the high specific capacities measured. These results lead to the conclusion that the potential of agricultural biomass can be exploited by using hydrothermal and thermochemical conversion technologies to create N- and O-rich carbon materials with tailored properties for the application in supercapacitors. Full article
(This article belongs to the Special Issue Hydrothermal Technology in Biomass, Utilization & Conversion II)
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Open AccessFeature PaperArticle
Hydrothermal Depolymerization of Biorefinery Lignin-Rich Streams: Influence of Reaction Conditions and Catalytic Additives on the Organic Monomers Yields in Biocrude and Aqueous Phase
Energies 2020, 13(5), 1241; https://doi.org/10.3390/en13051241 - 07 Mar 2020
Cited by 3
Abstract
Hydrothermal depolymerization of lignin-rich streams (LRS) from lignocellulosic ethanol was successfully carried out in a lab-scale batch reactors unit. A partial depolymerization into oligomers and monomers was achieved using subcritical water as reaction medium. The influence of temperature (300–350–370 °C) and time (5–10 [...] Read more.
Hydrothermal depolymerization of lignin-rich streams (LRS) from lignocellulosic ethanol was successfully carried out in a lab-scale batch reactors unit. A partial depolymerization into oligomers and monomers was achieved using subcritical water as reaction medium. The influence of temperature (300–350–370 °C) and time (5–10 minutes) was investigated to identify the optimal condition on the monomers yields in the lighter biocrude (BC1) and aqueous phase (AP) fractions, focusing on specific phenolic classes as well as carboxylic acids and alcohols. The effect of base catalyzed reactions (2–4 wt. % of KOH) was compared to the control tests as well as to acid-catalyzed reactions obtained with a biphasic medium of supercritical carbon dioxide (sCO2) and subcritical water. KOH addition resulted in enhanced overall depolymerization without showing a strong influence on the phenolic generation, whereas sCO2 demonstrated higher phenolic selectivity even though no effect was observed on the overall products mass yields. In conclusion, a comparison between two different biocrude collection procedures was carried out in order to understand how the selected chemical extraction mode influences the distribution of compounds between BC1 and AP. Full article
(This article belongs to the Special Issue Hydrothermal Technology in Biomass, Utilization & Conversion II)
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Review

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Open AccessReview
Sub- and Supercritical Water Liquefaction of Kraft Lignin and Black Liquor Derived Lignin
Energies 2020, 13(13), 3309; https://doi.org/10.3390/en13133309 - 28 Jun 2020
Cited by 3
Abstract
To mitigate global warming, humankind has been forced to develop new efficient energy solutions based on renewable energy sources. Hydrothermal liquefaction (HTL) is a promising technology that can efficiently produce bio-oil from several biomass sources. The HTL process uses sub- or supercritical water [...] Read more.
To mitigate global warming, humankind has been forced to develop new efficient energy solutions based on renewable energy sources. Hydrothermal liquefaction (HTL) is a promising technology that can efficiently produce bio-oil from several biomass sources. The HTL process uses sub- or supercritical water for producing bio-oil, water-soluble organics, gaseous products and char. Black liquor mainly contains cooking chemicals (mainly alkali salts) lignin and the hemicellulose parts of the wood chips used for cellulose digestion. This review explores the effects of different process parameters, solvents and catalysts for the HTL of black liquor or black liquor-derived lignin. Using short residence times under near- or supercritical water conditions may improve both the quality and the quantity of the bio-oil yield. The quality and yield of bio-oil can be further improved by using solvents (e.g., phenol) and catalysts (e.g., alkali salts, zirconia). However, the solubility of alkali salts present in black liquor can lead to clogging problem in the HTL reactor and process tubes when approaching supercritical water conditions. Full article
(This article belongs to the Special Issue Hydrothermal Technology in Biomass, Utilization & Conversion II)
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