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Energy-Efficient Chemistry

A topical collection in Energies (ISSN 1996-1073). This collection belongs to the section "I3: Energy Chemistry".

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Editors


E-Mail Website
Collection Editor
Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Rome, Italy
Interests: life cycle assessment; environmental sustainability assessment; environmental chemistry; valorisation and sustainable use of resources; closing-the-loop approach; biorefineries and bio-based production

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Collection Editor
1. R2ES Lab, Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100 Siena, Italy
2. CSGI—Consortium for Colloid and Surface Science, via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
3. CNR-ICCOM, National Research Council—Institute for the Chemistry of OrganoMetallic Compounds, 50019 Sesto Fiorentino, Florence, Italy
Interests: physical chemistry; environmental chemistry; renewable energy systems; sustainable energy storage; environmental sustainability; life cycle assessment
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Collection Editor
Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
Interests: physical chemistry; environmental chemistry; renewable energy sources; life cycle assessment of energy processes; sustainable energy storage
Special Issues, Collections and Topics in MDPI journals

E-Mail Website1 Website2 Website3
Collection Editor
1. Department of Science and Technology, Parthenope University of Naples, Centro Direzionale, Isola C4, 80143 Napoli, Italy
2. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Beijing Normal University, No. 19 Xinjiekouwai Street, Beijing 100875, China
Interests: life cycle assessment; energy–exergy–emergy; environmental impact assessment; circular economy; urban metabolism and sustainability; food and water security; disparity in access to energy sources; large efforts invested in energy and resource efficiency, prosperous way down, and environmental integrity
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

The chemical industrial sector, due to its high energy requirements and related adverse environmental impacts, urgently needs to be innovated and made more efficient in view of the global sustainability targets for the coming decades. Although great efforts have been invested in green chemistry patterns, still more research and technology are needed in order to decrease the energy costs and environmental impacts of the fossil-based chemical industry.

According to the comprehensive circular economy approach, real efficiency can be achieved only if energy and material improvements are jointly addressed. Further, cumulative material and energy efficiency needs to be achieved by expanding the system boundaries and taking a life cycle perspective into account. The key points are the efficient use of resources as well as any possible energy savings which can be gained by reducing the requirements of electricity or fuels thanks to technological innovations or by replacing fossil fuels with renewable energy sources.

In this framework, the production of chemicals from renewable feedstocks is becoming an attractive topic of research. In particular, the use of biomass as feedstock for chemical production has been recommended as a potential game changer by the International Energy Agency (IEA, 2013 - Technology roadmap: energy and GHG reductions in the chemical industry via catalytic processes). The enhanced use of biomass would lead to a new manufacturing paradigm for sustainably providing valuable chemicals, in addition to liquid fuels, within the perspective of an implementation of energy efficiency.

The advantages of using biomass rather than fossil substrates include, among others, a lower pollution, no or greatly decreased net CO2 contribution to the atmosphere and more biodegradable and sustainable products. However, the transition from a fossil-based chemistry to one that exploits the potential of biomass requires the development of innovative, cost-effective, environment-friendly strategies and technologies. It is widely acknowledged that the best approach to maximize the valorisation of biomass is the processing of biological feedstocks in integrated biorefineries where both bio-based chemicals and energy carriers can be produced, similar to a traditional petroleum refinery.

The transition from theory to practice seems slower than expected, although large efforts are being made worldwide to make bio-based chemistry technically and economically feasible. Technological advancements are continuously being achieved, and although some challenges still remain unsolved, technology does not seem to be a constraint for the future market implementation of bio-based chemistry. On the other hand, the environmental benefit of producing chemicals from biomass, in terms of lower impacts over the entire production chain, needs to be thoroughly assessed.

This Special Issue will stress the current knowledge regarding the most recent innovations, emerging technologies, and strategies to be employed for energy-efficient chemical production. In line with the purpose of a more sustainable chemistry, biomass conversion processes should also conform to the principles of green chemistry to minimize waste and energy costs as well as related environmental impacts, by integrating green chemistry methods into biorefinery frameworks.

Original research/review/opinion/perspective articles are welcome, to broadly address the following topics:

  • Technical improvements and innovations within the green chemistry framework, to achieve further energy savings and decreased impacts;
  • Innovations and novel procedures to manufacture chemicals from renewable feedstocks as well as by means of renewable energy;
  • “Green” extraction of bioactive compounds and/or platform chemicals from agro-industrial residues and the organic fraction of urban waste;
  • Production pathways based on the biorefinery concept, with a special focus on material and energy diversity and efficiency;
  • Environmental and sustainability assessment methodologies, including life cycle assessment, energy, exergy and emergy analysis, carbon footprint, social LCA and life cycle costing among others, and their integration/application to bio-based production systems;
  • Energy and environmental implications of bio-based production chains at global scale;
  • Relation of bio-based economy, cumulative energy demand and environmental integrity.

Dr. Gabriella Fiorentino
Prof. Dr. Maria Laura Parisi
Prof. Dr. Riccardo Basosi
Prof. Dr. Sergio Ulgiati
Collection Editors

Manuscript Submission Information

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Keywords

  • energy-efficient chemistry
  • environmental chemistry
  • chemical industry
  • circular chemistry
  • biorefinery

Published Papers (9 papers)

2024

Jump to: 2023, 2022

16 pages, 5993 KiB  
Article
Investigating the Applicability of the Tafel Equation in Polymer Electrolyte Membrane Electrolyzers via Statistical Analysis
by Fabian Scheepers and Werner Lehnert
Energies 2024, 17(13), 3298; https://doi.org/10.3390/en17133298 - 5 Jul 2024
Viewed by 334
Abstract
Analyzing PEM electrolyzer polarization curves via voltage breakdown analysis involves decomposing contributions from underlying processes, typically based on the assumption of reaction kinetics that may be expressed by means of the Tafel equation. When extrapolating the corresponding straight line to high current densities, [...] Read more.
Analyzing PEM electrolyzer polarization curves via voltage breakdown analysis involves decomposing contributions from underlying processes, typically based on the assumption of reaction kinetics that may be expressed by means of the Tafel equation. When extrapolating the corresponding straight line to high current densities, there is a discrepancy between the measurement and model, which is often attributed to mass transport resistance. In addition to the qualitative description of this mass transport resistance, a consistent quantification is difficult to obtain from the measurement results. Accordingly, the approach to the breakdown analysis of the polarization curves is strongly based on assumptions that evade experimental verification. In this study, an alternative statistical method is introduced that permits the falsifiability of the standard approach. By means of experiments at different hydrogen partial pressures and a subsequent data fit, it is possible to extract the kinetic behavior without prior specification. The results indicate that behavior corresponding to the Tafel equation cannot be proven wrong. In addition, transport coefficients can be evaluated that fall between those of membranes and porous transport layers, indicating that the catalyst layer predominantly contributes to the mass transport resistance. Full article
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18 pages, 5428 KiB  
Article
Polyolefin Pyrolysis in Multilayer Fluidized Beds: An Innovative Approach to Obtain Valuable Alternative Fuels
by Witold Żukowski, Krystian Leski, Gabriela Berkowicz-Płatek and Jan Wrona
Energies 2024, 17(5), 1034; https://doi.org/10.3390/en17051034 - 22 Feb 2024
Viewed by 764
Abstract
This paper presents the application of two versions of the multilayer fluidized bed made out of two materials with significantly different densities. The first type of fluidized bed was composed of raw cenospheres and quartz sand. The second type of fluidized bed was [...] Read more.
This paper presents the application of two versions of the multilayer fluidized bed made out of two materials with significantly different densities. The first type of fluidized bed was composed of raw cenospheres and quartz sand. The second type of fluidized bed was composed of cenospheres coated with iron oxides and quartz sand. A variable vertical density profiles in the prepared fluidized beds were confirmed, making them suitable for processing polymeric materials, specifically, polyolefins with a density below 1 g/cm3. The polyolefin pyrolysis process was investigated in both versions of the fluidized bed at temperatures of 520, 540, 560, and 590 °C. The products of the pyrolysis were monitored using high-resolution infrared spectroscopy (with a resolution of 1 cm−1). While the process is organized in these fluidized beds, the absence of the accumulation of solid residues is notable. The results show that the pyrolytic gaseous mixture is composed of numerous compounds, namely, unsaturated and saturated aliphatic hydrocarbons and benzene. The possibility of producing a gas rich in ethylene, propylene, and 1-butene during the pyrolysis was demonstrated. Additionally, during the pyrolysis of both polymers, the production of benzene was shown with yields, ranging from 5%wt. in the fluidized bed made out of raw cenospheres to 11 %wt. in the fluidized bed made out of cenospheres modified by iron oxides. Due to the complex nature of the resulting pyrolytic gas, it is suggested that we process the created gaseous mixtures entirely in a steam conversion process, making them a potential source of hydrogen. Full article
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2023

Jump to: 2024, 2022

55 pages, 13244 KiB  
Review
Investigation of Underground Coal Gasification in Laboratory Conditions: A Review of Recent Research
by Ján Kačur, Marek Laciak, Milan Durdán and Patrik Flegner
Energies 2023, 16(17), 6250; https://doi.org/10.3390/en16176250 - 28 Aug 2023
Cited by 3 | Viewed by 1217
Abstract
The underground coal gasification (UCG) technology converts coal into product gas and provides the option of environmentally and economically attractive coal mining. Obtained syngas can be used for heating, electricity, or chemical production. Numerous laboratory coal gasification trials have been performed in the [...] Read more.
The underground coal gasification (UCG) technology converts coal into product gas and provides the option of environmentally and economically attractive coal mining. Obtained syngas can be used for heating, electricity, or chemical production. Numerous laboratory coal gasification trials have been performed in the academic and industrial fields. Lab-scale tests can provide insight into the processes involved with UCG. Many tests with UCG have been performed on ex situ reactors, where different UCG techniques, the effect of gasification agents, their flow rates, pressures, and various control mechanisms to improve gasification efficiency and syngas production have been investigated. This paper provides an overview of recent research on UCG performed on a lab scale. The study focuses on UCG control variables and their optimization, the effect of gasification agents and operating pressure, and it discusses results from the gasification of various lignites and hard coals, the possibilities of steam gasification, hydrogen, and methane-oriented coal gasification, approaches in temperature modeling, changes in coal properties during gasification, and environmental risks of UCG. The review focuses on laboratory tests of UCG on ex situ reactors, results, and the possibility of knowledge transfer to in situ operation. Full article
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9 pages, 1136 KiB  
Article
B20 Fuel Compatibility with Steels in Case of Fuel Contamination
by Katriina Sirviö, Jonna Kaivosoja, Carolin Nuortila, Huaying Wang-Alho, Seppo Niemi and Teemu Ovaska
Energies 2023, 16(16), 5933; https://doi.org/10.3390/en16165933 - 11 Aug 2023
Cited by 1 | Viewed by 971
Abstract
This study evaluated the compatibility with steels for three B20 fuel samples blended from fossil diesel and used cooking oil methyl ester. One sample was untreated and its concentration of copper was analyzed as <1 ppm. Another sample was doped by adding Cu [...] Read more.
This study evaluated the compatibility with steels for three B20 fuel samples blended from fossil diesel and used cooking oil methyl ester. One sample was untreated and its concentration of copper was analyzed as <1 ppm. Another sample was doped by adding Cu at a concentration of ≤2 ppm and the third sample by adding Cu at a concentration of ≤4 ppm. Steel samples (carbon steel, stainless steel and a special alloy) were then put into the fuel blends and stored at 50 °C for 692 h. After storing, the metal concentrations of the fuel blends were again analyzed, and signs of corrosion were evaluated visually. The aim of this study was to find out if the fuel already contaminated by copper will affect the corrosion of the chosen steel qualities. Additionally, fuel properties were measured for all three blend samples before the immersion of steels. Visual evaluation of the steels indicated that signs of corrosion were seen in all studied samples, but Cu doping did not increase the signs of corrosion notably. The results also showed that the copper content from 1 to 2 and 4 ppm reduced the oxidation stability and increased the acid number of the fuel samples. Full article
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23 pages, 3852 KiB  
Review
Pyrolysis and Extraction of Bark in a Biorefineries Context: A Critical Review
by Umut Şen, Bruno Esteves and Helena Pereira
Energies 2023, 16(13), 4848; https://doi.org/10.3390/en16134848 - 21 Jun 2023
Cited by 6 | Viewed by 1301
Abstract
Bark-based biorefineries are estimated to become a trending topic in the coming years, particularly with their adsorbent applications and antioxidant production. While the potential benefits of bark-based biorefineries are well-recognized, it is not known how to develop a bark-based biorefinery considering different unit [...] Read more.
Bark-based biorefineries are estimated to become a trending topic in the coming years, particularly with their adsorbent applications and antioxidant production. While the potential benefits of bark-based biorefineries are well-recognized, it is not known how to develop a bark-based biorefinery considering different unit operations and the potential end products. The characterization and screening of different barks for chemical composition is the initial step in biorefinery development, along with the selection of the relevant conversion processes. This state-of-the-art review provides background knowledge on the pyrolysis and extraction studies of bark as the key conversion operations. The results of recent (2010–2022) bark pyrolysis and extraction studies were critically analyzed for process conditions, product properties, and product yields, as well as a discussion of energy-saving possibilities. A biorefinery scheme was proposed based on these data. The current knowledge gaps were identified and future directions were evaluated, which include the production of charcoals, platform chemicals, and extract profiling for specific applications. The results indicate that barks are particularly rich in hydrophilic extractives with potential antioxidant properties and pyrolysis operations, resulting in functional chars that may be used in value-added applications as adsorbent materials. A biorefinery scheme allows for the production of platform chemicals, antioxidant extracts and biochars from barks while contributing to the reduction of waste and environmental pollution. Full article
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21 pages, 699 KiB  
Perspective
Circular Economy and Green Chemistry: The Need for Radical Innovative Approaches in the Design for New Products
by Amos Ncube, Sandile Mtetwa, Mahak Bukhari, Gabriella Fiorentino and Renato Passaro
Energies 2023, 16(4), 1752; https://doi.org/10.3390/en16041752 - 9 Feb 2023
Cited by 46 | Viewed by 8937
Abstract
The idea of a circular economy (CE) has gained ground over the past ten years as a means of addressing sustainable development and getting around the limitations of the current and linear dominant production and consumption patterns. The primary goal of a CE [...] Read more.
The idea of a circular economy (CE) has gained ground over the past ten years as a means of addressing sustainable development and getting around the limitations of the current and linear dominant production and consumption patterns. The primary goal of a CE is to encourage the adoption of closing-the-loop production methods to improve resource use efficiency, modify chemical processes, and increase product and material lifespan. According to the 2030 Agenda for Sustainable Development, which focuses on 17 Sustainable Development Goals, 14 of which call for the appropriate application of green chemistry (GC) concepts and patterns, the role that chemistry may play in the shift toward more sustainable models is critical. By serving as the foundation for novel products made from renewable feedstocks and designed to be reused, recycled, or recovered with the associated minimum energy requirements, green and sustainable chemistry could be the key to unlocking the economic potential of the CE toward new product design and ultimately solving waste management problems. The aim of this perspective paper, while using a variety of literature sources, is to essentially capture the main issues associated with the CE and GC paradigms and how these two approaches can merge toward sustainable business models and the production of new materials. This integration focuses on reducing waste, conserving resources, and minimizing negative environmental impacts, while also considering economic viability. However, the obstacles to achieving implementation of the CE and GC principles are investment, environmental education, and legislation. To advance toward the circular economy and green chemistry, international agreements should be reconsidered to provide an appropriate framework, including the creation of incentives for businesses and individuals to adopt circular practices, the establishment of education programs to promote the benefits of circular practices, and the development of regulations to support the transition to sustainable production and consumption patterns. Full article
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2022

Jump to: 2024, 2023

35 pages, 10587 KiB  
Review
Gel Fuels: Preparing, Rheology, Atomization, Combustion
by Dmitrii Glushkov, Kristina Paushkina and Andrei Pleshko
Energies 2023, 16(1), 298; https://doi.org/10.3390/en16010298 - 27 Dec 2022
Cited by 9 | Viewed by 3084
Abstract
The review presents the results of experimental and theoretical studies obtained in recent years within the framework of the main areas of research of gel fuels: choice of component composition and substantiation of fuel preparation technologies and their rheological characteristics; fuel transportation and [...] Read more.
The review presents the results of experimental and theoretical studies obtained in recent years within the framework of the main areas of research of gel fuels: choice of component composition and substantiation of fuel preparation technologies and their rheological characteristics; fuel transportation and atomization processes; and the processes of their ignition and combustion. The main advantages of gel fuels in comparison with widely used liquid and solid fuels are considered. The advantages and disadvantages of known experimental approaches to the study of the combustion processes of gel fuels are analyzed. The well-known physical and mathematical models of gel fuels ignition are given, including those under conditions of melt droplets dispersion. The tendencies of further development of gel fuels within the framework of the combustion theory are formulated. Full article
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13 pages, 2312 KiB  
Review
Stannous Tungstate Semiconductor for Photocatalytic Degradation and Photoelectrochemical Water Splitting: A Review
by Weixin Qiu and Yang Liu
Energies 2022, 15(23), 9194; https://doi.org/10.3390/en15239194 - 4 Dec 2022
Cited by 3 | Viewed by 1401
Abstract
The use of photocatalysis and photoelectrocatalysis is expected to achieve the efficient utilization of solar energy to alleviate and even solve the problems of energy depletion and environmental pfollution. At present, stannous tungstate materials have attracted extensive attention in the fields of photocatalysis [...] Read more.
The use of photocatalysis and photoelectrocatalysis is expected to achieve the efficient utilization of solar energy to alleviate and even solve the problems of energy depletion and environmental pfollution. At present, stannous tungstate materials have attracted extensive attention in the fields of photocatalysis and photoelectrocatalysis as favorable candidates for such utilization because of their narrow band gap energy (which is ~1.7 eV for the α phase and ~2.7 eV for the β phase, respectively) and unique band structure (which covers the oxidation and reduction potential of water). However, their practical application is still limited by excessive electron–hole recombination and poor stability. In this review, basic information (crystal and electronic structures) related to photocatalysis and photoelectrocatalysis is presented. Additionally, various strategies to enhance the photocatalytic and photoelectrochemical properties of stannous tungstate materials, such as morphological modification, crystal facet engineering, doping modification, and multicomponent compositing, are summarized. Furthermore, the achievements and difficulties of the relevant studies are discussed. The information presented in this review can provide a reference for subsequent research on the photocatalytic and photoelectrochemical performance of tungstate-based materials. Full article
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20 pages, 11562 KiB  
Article
Influence of Densification on the Pyrolytic Behavior of Agricultural Biomass Waste and the Characteristics of Pyrolysis Products
by Marcin Bielecki, Valentina Zubkova and Andrzej Strojwas
Energies 2022, 15(12), 4257; https://doi.org/10.3390/en15124257 - 9 Jun 2022
Cited by 6 | Viewed by 2109
Abstract
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 [...] Read 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 inorganics cumulate on the surface of sunflower husk whereas for wheat straw they cumulate inside the sample. In the case of soft wood, the inorganics cumulate both inside and on the surface. The decreased contribution of hydrocarbons in volatiles can be connected with the morphology of nano-particles formed in inorganics. Full article
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