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Green Technologies for Energy Transition

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

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 7326

Special Issue Editor

Dipartimento di Ingegneria Civile, Chimica e di Ambientale, Scuola Politecnica, Università degli Studi di Genova, via Opera Pia 15, 16145 Genova, Italy
Interests: green chemical products
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Sustainable development is significantly affected by the environmental impact of human activities and the progressive exhaustion of fossil fuel resources, both of which have been further aggravated by the recent worsening of the geopolitical situation in some oil- and gas-exporting countries. Without global political strategies and effective technological measures with which to face this situation, the future of the next generations could be put at risk. Significant portions of the huge amount of waste produced every year globally by industrial and human activities are often not treated or inadequately treated before disposal, even though waste is a valuable source of alternative energy. Therefore, technologies capable of combining environmental and energy aspects must be further developed.

This Special Issue of Energies (IF = 3.252) aims to provide an overview of the green technologies currently available for the energy transition, including the treatment of different types of waste and co-products (biomass, industrial, urban and agro-industrial wastes, etc.) as well as the possible recycling of resources and/or energy recovery. Special attention is also paid to innovative technologies for energy production and/or saving as well as new strategies for reducing impacts on the environment, such as a) gas-to-power technologies, i.e., highly efficient and environmentally friendly energy production through fuel cells; b) power-to-gas technologies, i.e., production of hydrogen or other fuels through electrolytic cells; c) microalgae or systems aiming to reduce carbon dioxide emissions via combining the two previously mentioned technological categories with traditional systems and/or renewable sources; d) traditional waste treatments, including biogas production, soil remediation, gasification and pyrolysis; and e) new biorefinery approaches.

Original papers, in the form of a scientific article, review or communication, are welcome. I look forward to receiving your contributions.

Prof. Dr. Attilio Converti
Guest Editor

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 submissions that pass pre-check are 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 2600 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

  • energy and environment
  • valorization of waste
  • Reduction of CO2 emissions
  • fuel and electrolytic cells
  • biogas production
  • waste recycling
  • microalgae growth
  • gasification and pyrolysis
  • alternative energy
  • soil remediation
  • biosurfactants
  • self-healing bioconcrete

Published Papers (7 papers)

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Research

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25 pages, 10467 KiB  
Article
Experimental Evaluation of a 2 kW/100 kHz DC–DC Bidirectional Converter Based on a Cuk Converter Using a Voltage-Doubler Concept
by Wanderson Francisco Lopes, Mário Lúcio da Silva Martins, Attilio Converti, Hugo Valadares Siqueira and Carlos Henrique Illa Font
Energies 2024, 17(2), 362; https://doi.org/10.3390/en17020362 - 11 Jan 2024
Viewed by 477
Abstract
This paper presents a theoretical analysis of steady-state operation, control-oriented modeling for voltage control, and the experimental results of a DC–DC bidirectional converter based on a Cuk converter using a voltage-doubler concept. Due to the voltage-doubler concept, the voltage stress across semiconductors is [...] Read more.
This paper presents a theoretical analysis of steady-state operation, control-oriented modeling for voltage control, and the experimental results of a DC–DC bidirectional converter based on a Cuk converter using a voltage-doubler concept. Due to the voltage-doubler concept, the voltage stress across semiconductors is reduced when compared with the conventional Cuk converter; this allows for the use of semiconductors with reduced drain–source on-resistance. Moreover, due to the input and output current source characteristics, the converter presents advantages, such as draining/injecting currents on both sides with low-ripple currents. Furthermore, the theoretical analysis is verified by experimental results obtained from a proof-of-concept prototype designed with a 250 V input voltage, a 360 V output voltage, 2 kW rated power, and 100 kHz switching frequency. Full article
(This article belongs to the Special Issue Green Technologies for Energy Transition)
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25 pages, 1929 KiB  
Article
A Review of On-Board Carbon Capture and Storage Techniques: Solutions to the 2030 IMO Regulations
by Riccardo Risso, Lucia Cardona, Maurizio Archetti, Filippo Lossani, Barbara Bosio and Dario Bove
Energies 2023, 16(18), 6748; https://doi.org/10.3390/en16186748 - 21 Sep 2023
Cited by 3 | Viewed by 1756
Abstract
The maritime sector is among the most polluting industrial sectors in the world. To oppose this and following the global trend towards carbon neutrality, the International Maritime Organization (IMO) introduced the objective to reduce the CO2 emission of vessels by the year [...] Read more.
The maritime sector is among the most polluting industrial sectors in the world. To oppose this and following the global trend towards carbon neutrality, the International Maritime Organization (IMO) introduced the objective to reduce the CO2 emission of vessels by the year 2030 of 40% and at the same time the European Union will introduce the maritime sector into the ETS system. Therefore, there is a need to reduce the emissions of the working vessels, and this can be accomplished through the Carbon Capture and Storage (CCS). There are many possible CCS technologies that can be applied to vessels: the one that has already been studied the most is the ammine scrubbing of the exhaust gasses. In parallel, other technologies have been proposed to reduce volume and energy needs, which are the Molten Carbonate Fuel Cells (MCFCs), membrane technologies, fixed bed absorption processes and limestone. The review shows how, depending on the used vessel type, the technology to be used may vary, and proposes some preferential options for different applications. The obtained results can be of relevant importance in the present context of energy transition promoting immediate retrofitting to respond to the urgent request for intervention. Full article
(This article belongs to the Special Issue Green Technologies for Energy Transition)
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18 pages, 5889 KiB  
Article
A Three-Phase Phase-Modular Single-Ended Primary-Inductance Converter Rectifier Operating in Discontinuous Conduction Mode for Small-Scale Wind Turbine Applications
by Guilherme Ferreira de Lima, William de Jesus Kremes, Hugo Valadares Siqueira, Bahar Aliakbarian, Attilio Converti and Carlos Henrique Illa Font
Energies 2023, 16(13), 5220; https://doi.org/10.3390/en16135220 - 07 Jul 2023
Viewed by 720
Abstract
Small-scale wind turbines play an important role in distributed generation since customers can use their houses, farms, and business to produce electric energy. The development of the power electronics system that processes the electric energy from small-scale wind turbines is a concern due [...] Read more.
Small-scale wind turbines play an important role in distributed generation since customers can use their houses, farms, and business to produce electric energy. The development of the power electronics system that processes the electric energy from small-scale wind turbines is a concern due to cost, simplicity, efficiency, and performance trade-offs. This paper presents the results of applying a three-phase phase-modular single-ended primary-inductance converter rectifier to processing the energy of a small-scale wind turbine system. The rectifier was designed according to the specifications of a commercial small-scale wind turbine system and tested in an emulator workbench, providing experimental data on the operation of the rectifier in this application. The rectifier can process the energy of a non-sinusoidal three-phase system since the permanent magnet synchronous generator has trapezoidal waveforms. The results show that the rectifier has the advantages of (i) using the inductance of the generator as the input filter inductor of the rectifier, (ii) providing input currents with the same shape as the voltages and in phase without the use of a current control system, (iii) simplicity of control of the DC output voltage and PWM modulation, and (iv) phase-modular characteristics that allow operating with phase fault without any additional control techniques. Due to the operation in discontinuous conduction mode, low efficiency in high power and/or low input voltage specifications are disadvantages. Full article
(This article belongs to the Special Issue Green Technologies for Energy Transition)
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23 pages, 3391 KiB  
Article
Treatment of Effluent Containing p-Cresol through an Advanced Oxidation Process in a Batch Reactor: Kinetic Optimization
by Julierme G. C. Oliveira, Yana B. Brandão, Dinaldo C. Oliveira, Jailson R. Teodosio, Cristiane M. Moraes, Attilio Converti, Alessandro Alberto Casazza, Leonie Asfora Sarubbo and Mohand Benachour
Energies 2023, 16(13), 5027; https://doi.org/10.3390/en16135027 - 28 Jun 2023
Viewed by 710
Abstract
The present research is related to the study of p-cresol oxidation reaction in aqueous phase. Firstly, the conventional advanced oxidation process (AOP) in a lab-scale batch reactor was used, seeking to identify the most impacting process variables and then to propose an optimization [...] Read more.
The present research is related to the study of p-cresol oxidation reaction in aqueous phase. Firstly, the conventional advanced oxidation process (AOP) in a lab-scale batch reactor was used, seeking to identify the most impacting process variables and then to propose an optimization approach for ensuring the complete p-cresol degradation and the highest total organic carbon (TOC) conversion. In the AOP with the use of hydrogen peroxide as the oxidizing agent, the oxidation reaction was optimized with the aid of a factorial design, and a maximum TOC conversion of 63% was obtained. The Lumped Kinetic Model (LKM) was used to describe the profile of residual TOC concentration due to chemical species, which were categorized into two groups (refractory and non-refractory compounds). The model was able to satisfactorily describe the profile of the residual fractions of these two classes of organic compounds and allowed estimating the related kinetic constants (k) at two different temperatures, namely (a) 3.19 × 10−1 and 2.82 × 10−3 min−1 for non-refractory and refractory compounds at 80 °C and (b) 4.73 × 10−1 and 5.09 × 10−3 min−1 for the same compound classes at 90 °C, while the activation energy (Ea) of the process was 42.02 and 62.09 kJ mol−1, respectively. The kinetic modeling of organic pollutants oxidation in liquid effluents would allow to perform in situ seawater treatment on vertical reactors installed in offshore platforms and to properly release treated water into the oceans. In this way, ocean contamination caused by the exploration on offshore platforms of oil and natural gas, the main energy sources and vectors in the current world, may be remarkably reduced, thus favoring a more eco-friendly energy production. Full article
(This article belongs to the Special Issue Green Technologies for Energy Transition)
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15 pages, 2080 KiB  
Article
Valorization of Corn Cobs for Xylitol and Bioethanol Production through Column Reactor Process
by Felipe A. F. Antunes, Jade B. F. Freitas, Carina A. Prado, Maria J. Castro-Alonso, Erick Diaz-Ruiz, Alain E. Mera, Júlio C. Santos and Silvio S. da Silva
Energies 2023, 16(13), 4841; https://doi.org/10.3390/en16134841 - 21 Jun 2023
Cited by 3 | Viewed by 1217
Abstract
Corncobs are a plentiful lignocellulosic material that can be utilized for energy production as well as the generation of other high-value products. Within the modern concept of biorefineries, we present processes conducted in a column reactor for the valorization of corncobs as a [...] Read more.
Corncobs are a plentiful lignocellulosic material that can be utilized for energy production as well as the generation of other high-value products. Within the modern concept of biorefineries, we present processes conducted in a column reactor for the valorization of corncobs as a substrate for ethanol and xylitol production. In the first step, corncobs were subjected to acid hydrolysis, resulting in a hemicellulosic hydrolysate rich in xylose sugars intended for xylitol production by Candida tropicalis UFMGBX12-a. The YP/S (yield coefficient of product to substrate) and QP (productivity) values were approximately 0.2 g/g and 0.15 g/L·h, respectively, for the assays conducted in the column reactor. Next, the remaining solid portion of cellulignin was used for ethanol production through semi-simultaneous saccharification and fermentation process by Scheffersomyces parashehatae UFMG-HM 52.2. This approach involved an intensified successive process consisting of alkaline pretreatment of cellulignin, followed by enzymatic hydrolysis and fermentative processes conducted in the same reactor without biomass transfer. After obtaining the enzymatic hydrolysate, a QP value of 0.4 g/L·h for ethanol production was observed in the fermentation process conducted in the column reactor. The results demonstrate the potential of corncobs as a carbon source for biomolecules production, utilizing a process conducive to scale-up. Full article
(This article belongs to the Special Issue Green Technologies for Energy Transition)
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15 pages, 3150 KiB  
Article
Induced Pre-Saturation Tower: A Technological Innovation for Oily Water Treatment in Semi-Industrial Scale
by Leonardo Bandeira dos Santos, Rita de Cássia Freire Soares da Silva, Leonildo Pereira Pedrosa, Jr., Rodrigo Dias Baldo, Mohand Benachour, Attilio Converti, Leonie Asfora Sarubbo and Valdemir Alexandre dos Santos
Energies 2023, 16(5), 2278; https://doi.org/10.3390/en16052278 - 27 Feb 2023
Viewed by 911
Abstract
In this work, an induced pre-saturation tower (IPST) for oil–water separation was built on a semi-industrial scale, based on experimental results obtained on a laboratory scale prototype. The main strategy for generating these criteria was to increase the efficiency of the bench scale [...] Read more.
In this work, an induced pre-saturation tower (IPST) for oil–water separation was built on a semi-industrial scale, based on experimental results obtained on a laboratory scale prototype. The main strategy for generating these criteria was to increase the efficiency of the bench scale prototype, which is limited by conditions of low levels of automation and control, with the use of a biosurfactant as an auxiliary collector. The validation of the developed criteria allowed the construction of an IPST with three stages, all fed with previously saturated effluents. The IPST was built in stainless steel, with multistage centrifugal pumps and adapted to generate microbubbles without the use of saturation tanks or compressors. The most relevant operational parameters were selected using a fractional factorial design, while a central composite rotatable design (CCRD) followed by the application of the desirability function allowed to optimize the conditions for partial and global variables, the latter with desirability of 95%. A nominal flow rate of approximately 1000 L·h−1, a recycle flow rate of 450 L·h−1, a scraper rotation speed of 80 rpm, an average pressure of the microbubble pumps of 11 bar, and an effluent temperature from IPST of about 38 °C ensured optimized operation for the proposed technological development. Full article
(This article belongs to the Special Issue Green Technologies for Energy Transition)
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Review

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19 pages, 1989 KiB  
Review
Looking for an Optimal Composition of Nickel-Based Catalysts for CO2 Methanation
by Guido Busca, Elena Spennati, Paola Riani and Gabriella Garbarino
Energies 2023, 16(14), 5304; https://doi.org/10.3390/en16145304 - 11 Jul 2023
Cited by 3 | Viewed by 984
Abstract
A detailed critical analysis of the scientific literature data concerning catalysts for CO2 methanation based on nickel supported over oxides was performed. According to the obtained information, it seems that an ionic support is necessary to allow a good nickel dispersion to [...] Read more.
A detailed critical analysis of the scientific literature data concerning catalysts for CO2 methanation based on nickel supported over oxides was performed. According to the obtained information, it seems that an ionic support is necessary to allow a good nickel dispersion to produce very small nickel metal particles. Such small metal particles result in being very active toward methanation, limiting the production of carbonaceous materials. The use of support and/or surface additives gives rise to medium surface basicity, allowing medium-strong adsorption of CO2, and it is also advisable to increase the reaction rate. A medium nickel loading would allow the free support geometric surface to be covered densely by small nickel metal particles without the production of larger Ni crystals. It is also advisable to work at temperatures where Ni(CO)4 formation is not possible (e.g., >573 K). The promising properties of systems based on doped Ni/Al2O3, doped with basic and re-active oxides such as MnOx or/and CeO2, and those based on Ni/CeO2 were underlined. Full article
(This article belongs to the Special Issue Green Technologies for Energy Transition)
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