Clean and Low Carbon Energy

Topic Information

Dear Colleagues,

In recent years, the rapid development of the national economy has become inseparable from the contributions of traditional fossil energy such as coal, oil and natural gas. However, fossil energy has negative impacts such as environmental pollution, global warming and economic security. In this regard, it is important to break through the key bottlenecks of pollutants, carbon emissions and energy grade loss caused by the fossil energy utilization mode, and to build a clean and low-carbon energy utilization system based on solar energy, wind energy and geothermal energy, etc., to achieve the goal of environmental protection and energy technology revolution. Clean and low-carbon energy research has achieved major successes in the past decade and is expected to drive the development of other renewable energy sources. However, although significant progress has been made in clean and low-carbon energy in recent years, there are still major challenges in the implementation of new theories, new methods and new demands. From this perspective, this topic aims to contribute to the clean and low-carbon energy agenda by enhancing scientific and multidisciplinary work, aiming to improve knowledge and performance in harvesting clean and low-carbon energy. We strongly encourage papers providing innovative technological developments, reviews, case studies and analyses, as well as assessments and manuscripts targeting different disciplines, which are relevant to harvesting clean and low-carbon energy and its associated advances and challenges. The topic includes but is not limited to:

• Renewable energy resources and technologies;
• Renewable energy harvesting and conversion;
• Energy systems and efficiency improvement;
• Advanced energy technologies;
• Energy storage and applications;
• Energy and buildings;
• Energy use in industry;
• Energy and environment;
• Energy and nanotechnology;
• Energy mangement, policy and economics.

Prof. Dr. Dong Li
Prof. Dr. Fuqiang Wang
Prof. Dr. Zhonghao Rao
Prof. Dr. Chao Shen
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Batteries batteries	4.0	5.4	2015	17.7 Days	CHF 2700
Clean Technologies cleantechnol	3.8	4.5	2019	26.6 Days	CHF 1600
Energies energies	3.2	5.5	2008	16.1 Days	CHF 2600
Nanomaterials nanomaterials	5.3	7.4	2010	13.6 Days	CHF 2900
Sustainability sustainability	3.9	5.8	2009	18.8 Days	CHF 2400

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Published Papers (22 papers)

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All Batteries Clean Technol. Energies Nanomaterials Sustainability

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29 pages, 25122 KiB  

Open AccessArticle

Numerical Simulation Study on the Gas–Solid Flow Characteristics of a Large-Scale Dual Fluidized Bed Reactor: Verification and Extension

by Yubin Lin, Qinhui Wang, Guilin Xie, Mengxiang Fang and Zhongyang Luo

Energies 2024, 17(6), 1304; https://doi.org/10.3390/en17061304 - 08 Mar 2024

Viewed by 386

Abstract

Dual fluidized bed (DFB) reactor systems are widely used in gas–solid two-phase flow applications, whose gas–solid flow characteristics have a significant effect on the performance of many kinds of technologies. A numerical simulation model was established on the basis of a large-scale DFB [...] Read more.

Dual fluidized bed (DFB) reactor systems are widely used in gas–solid two-phase flow applications, whose gas–solid flow characteristics have a significant effect on the performance of many kinds of technologies. A numerical simulation model was established on the basis of a large-scale DFB reactor with a maximum height of 21.6 m, and numerical simulations focused on gas–solid flow characteristics were carried out. The effects of the superficial gas velocity of both beds and the static bed height and particle size on the distribution of the pressure and solid suspension density and the solid circulation rate were studied. The simulation results were in good agreement with the experimental data. With the strong support of the experimental data, the gas–solid flow characteristics of large-scale DFB reactors were innovatively evaluated in this numerical simulation study, which effectively makes up for the shortcomings of the current research. The results showed that the superficial gas velocity of both beds and the static bed height have different degrees of influence on the gas–solid flow characteristics. Specifically, for 282 μm particles, when the superficial gas velocity of both beds and the static bed height were 4.5 m/s, 2.5 m/s, and 0.65 m, respectively, under typical working conditions, the bottom pressure of the two furnaces was 3412.42 Pa and 2812.86 Pa, respectively, and the solid suspension density was 409.44 kg/m³ and 427.89 kg/m³, respectively. Based on the simulation results, the empirical formulas of the solid circulation rate were fitted according to different particle sizes. Under similar conditions, the solid circulation rates of particles with a particle size of 100 μm, 282 μm, 641 μm, and 1000 μm were 2.84–13.28, 0.73–4.91, 0.024–0.216, and 0.0026–0.0095 kg/(m²s), respectively. It can be found that the influence of the particle size on the solid circulation rate is the most significant among all parameters. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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21 pages, 4140 KiB  

Open AccessArticle

Analysis of the Influence Factors of the Crude Oil Temperature Maintenance System of Solar Sewage Heat Pumps in Cold Regions

by Shangwen Zhu, Xiaohua Gu, Mengyi Duan, Feiyang Yu, Danyi Zhao, Siwen Liu and Yan Liu

Energies 2023, 16(24), 8124; https://doi.org/10.3390/en16248124 - 18 Dec 2023

Viewed by 717

Abstract

Traditional crude oil heating methods that use fossil fuels or electricity have the disadvantages of high consumption of nonrenewable resources, low energy utilization, and high carbon emissions. Therefore, it is urgent to develop green and sustainable crude oil heating technologies. In this paper, [...] Read more.

Traditional crude oil heating methods that use fossil fuels or electricity have the disadvantages of high consumption of nonrenewable resources, low energy utilization, and high carbon emissions. Therefore, it is urgent to develop green and sustainable crude oil heating technologies. In this paper, a solar synergistic sewage heat pump (SSHS) dual heat source crude oil temperature maintenance system is proposed. The system utilizes clean and sustainable solar energy to heat crude oil while combining sensible heat storage technology and the waste heat utilization technology of a sewage source heat pump to solve the unstable fluctuation of the solar heating problem. A simulation and analysis model is established to analyze the influencing factors of the SSHS, and the optimal operation scheme is provided. The results show that the efficiency of the solar collector decreases and the proportion of crude oil heating increases with an increase in the solar energy guarantee rate, while the unit flow rate of the pump has a large impact on the performance of the sewage source heat pump. In order to avoid energy waste, it is more appropriate to adopt a 30% guarantee rate and an A3 pump unit flow rate, under which the solar collector efficiency is 50.18%, the proportion of solar heating of crude oil is 47.16%, the average temperature of crude oil is 42.59 °C, and the COP of the sewage source heat pump is 4.65. Further increases in the COP of the wastewater source heat pump can be realized by increasing the temperature of the wastewater supply. The results of this study provide a valuable reference for the optimization of crude oil storage heating systems. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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19 pages, 3707 KiB  

Open AccessArticle

Experimental Research on the Gas-Solid Flow Characteristics in Large-Scale Dual Fluidized Bed Reactor

by Yubin Lin, Qinhui Wang, Chao Ye, Yao Zhu and Haojie Fan

Energies 2023, 16(21), 7239; https://doi.org/10.3390/en16217239 - 25 Oct 2023

Cited by 1 | Viewed by 639

Abstract

A dual fluidized bed (DFB) reactor is the main operating system of various energy-efficient and clean utilization technologies. The gas-solid flow characteristics of the DFB reactor greatly affect the efficiency of various technologies. A large-scale DFB reactor with a maximum height of 21.6 [...] Read more.

A dual fluidized bed (DFB) reactor is the main operating system of various energy-efficient and clean utilization technologies. The gas-solid flow characteristics of the DFB reactor greatly affect the efficiency of various technologies. A large-scale DFB reactor with a maximum height of 21.6 m was built and relevant cold mode tests were carried out in this study. The effects of the superficial gas velocity of both beds, static bed height and particle size on the distribution of both pressure and solid suspension density, solid circulation rate, solid inventory distribution ratio and other characteristics were studied. For 282 μm-particles, the solid suspension density in the dense phase zone of the two beds was 100–400 and 400–800 kg/m³, respectively, when the static bed height was 0.65 m; the solid circulation rate was about 0.87–1.75, 1.04–3.04 and 1.13–3.69 kg/(m²s) when the static bed height was 0.65, 0.95 and 1.25 m, respectively. The solid circulation rate was positively correlated with the static bed height and the superficial gas velocity of both beds, yet negatively correlated with the particle size. Additionally, the empirical equation of solid circulation rate and the empirical equation of solid inventory distribution ratio were proposed, respectively. The material control method of the DFB reactor is put forward. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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19 pages, 3422 KiB  

Open AccessArticle

Performance Study of Booster-Driven Hybrid Cooling Units for Free Cooling in Data Centers

by Rong Zhuang, Feng Zhou, Xuwen Tian, Buqing Xu, Shaocong Li and Guoyuan Ma

Sustainability 2023, 15(19), 14558; https://doi.org/10.3390/su151914558 - 07 Oct 2023

Viewed by 734

Abstract

In the data center, using ambient energy cooling technology can effectively reduce the average power use efficiency, and the heat pipe as an effective use of ambient energy device has attracted much attention. For the dynamic heat pipe, reducing the power consumption of [...] Read more.

In the data center, using ambient energy cooling technology can effectively reduce the average power use efficiency, and the heat pipe as an effective use of ambient energy device has attracted much attention. For the dynamic heat pipe, reducing the power consumption of the pump effectively is the key to improving the efficiency. In this paper, the rotary booster is selected as the gas phase booster device of the heat pipe unit, the standard unit of the rotary booster is improved, and three types of boosters are obtained, including two improved boosters and one standard unit. Comparative test studies are conducted on three different types of boosters, and the power of the booster shows a downward trend with the increase in indoor and outdoor temperature differences (outdoor temperature decreases). With the increase in indoor and outdoor temperature differences, the cooling capacity increases first and then decreases. When the indoor and outdoor temperature difference is greater than 20 °C, the suction pressure of the booster is greater than the saturated condensing pressure force under outdoor ambient temperature, and the work of the booster decreases. Among the three types of boosters, the medium pressure ratio booster energy efficiency ratio (EER) is the largest. After throttling the standard unit, results show that its cooling capacity unit increases, but the booster power also increases, and the EER is still smaller than that of the improved unit. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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20 pages, 3549 KiB  

Open AccessArticle

Research on Provincial Carbon Emission Reduction Path Based on LMDI-SD-Tapio Decoupling Model: The Case of Guizhou, China

by Hongqiang Wang, Wenyi Xu and Yingjie Zhang

Sustainability 2023, 15(17), 13215; https://doi.org/10.3390/su151713215 - 03 Sep 2023

Cited by 1 | Viewed by 968

Abstract

The successful implementation of the national carbon emissions reduction work necessitates the collaboration of various regions. Carbon emission reduction strategies need to be adjusted according to local circumstances due to the differences in regional development levels. From 2005 to 2020, carbon emissions were [...] Read more.

The successful implementation of the national carbon emissions reduction work necessitates the collaboration of various regions. Carbon emission reduction strategies need to be adjusted according to local circumstances due to the differences in regional development levels. From 2005 to 2020, carbon emissions were measured in Guizhou Province, and the contribution degree and action direction of various influencing factors were analyzed using the LMDI model. Using an SD model, we performed dynamic simulations of carbon emission trends under eight scenarios and calculated the Tapio decoupling relationship between economic growth and CO₂ emissions. According to the study, carbon emissions in Guizhou Province increased from 2005 to 2020, emphasizing the high pressure for carbon emission reduction. The industry sector ranked first in contribution, contributing 62.71% in 2020. Furthermore, this study found a weak decoupling relationship between economic growth and carbon emissions. The economic scale was the key driver driving the increase in carbon emissions, whereas the industrial fossil energy intensity was the main factor inhibiting the growth of carbon emissions. Additionally, it was predicted that carbon emissions would only peak at 277.71 million tons before 2030 if all three measures were implemented simultaneously, and a strong decoupling relationship with economic growth could be achieved as early as possible. These findings provided Guizhou Province with an effective path for reducing carbon emissions. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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16 pages, 860 KiB  

Open AccessArticle

Does Carbon Emissions Trading Policy Improve Inclusive Green Resilience in Cities? Evidence from China

by Bin Xiong and Qi Sui

Sustainability 2023, 15(17), 12989; https://doi.org/10.3390/su151712989 - 29 Aug 2023

Cited by 1 | Viewed by 801

Abstract

With the impact of external globalization uncertainties and the pressure of internal national environmental policies and markets, maintaining inclusive green resilience while coordinating economic, environmental, and social systems is critical for achieving green and sustainable urban development. We define inclusive green resilience for [...] Read more.

With the impact of external globalization uncertainties and the pressure of internal national environmental policies and markets, maintaining inclusive green resilience while coordinating economic, environmental, and social systems is critical for achieving green and sustainable urban development. We define inclusive green resilience for cities in this research and build a system of inclusive green resilience indicators. The DID model and entropy approach were used to examine the impact of carbon trading policies on inclusive green resilience in 184 representative Chinese cities from 2008 to 2018, and PSM-DID was utilized for further validation. According to the findings of the study, carbon emissions pricing policies can considerably increase inclusive green resilience in cities. Mechanism verification demonstrates that carbon trading programs improve inclusive green resilience in cities through industrial restructuring, technical innovation capability, and employment benefits. According to the city heterogeneity study, the implementation of the carbon emissions trading system has a scale effect and significant urban functional differences, and its impact on inclusive green resilience of cities is greater in large and medium-sized cities and non- resource-based cities. This research offers a new way of thinking about inclusive green resilience as well as empirical data for future sustainable policy development. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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13 pages, 4491 KiB  

Open AccessArticle

An Investigation of the Effect of Propylene Gas Flame on Emissions and Temperature Distribution of a Preheated Metal Plate

by Y. Nhu Quach and Ocktaeck Lim

Sustainability 2023, 15(16), 12306; https://doi.org/10.3390/su151612306 - 12 Aug 2023

Viewed by 826

Abstract

This study investigates the effect of the propylene gas flame on the emissions and temperature distribution of the metal plate during the preheating process. Experimental tests were carried out using a preheating system with a cylindrical chamber for emissions measurement and a metal [...] Read more.

This study investigates the effect of the propylene gas flame on the emissions and temperature distribution of the metal plate during the preheating process. Experimental tests were carried out using a preheating system with a cylindrical chamber for emissions measurement and a metal plate placed near the torch head. Emissions were measured using a gas analyzer, while the temperature distribution of the metal plate was measured using an infrared thermal camera and thermocouples. The findings reveal that the emissions decrease as the equivalence ratio is increased as it approaches a ratio of 1. However, when the appropriate equivalence ratio is reached, NO_x emissions will rise and then gradually fall. The peak temperature of propane fuel is higher than that of other fuels because of the concentrated flame. Propane fuel can achieve a peak temperature of 347.65 °C, surpassing both propylene fuel (275.45 °C) and acetylene fuel (335.45 °C). Using a propylene gas flame results in a reduction in emissions of carbon monoxide and nitrogen oxides compared to a propane flame. But, acetylene fuel produces the most NO_x emissions, reaching 450.79 ppm for the experimental conditions. Additionally, the temperature distribution of the preheated metal plate was more uniform with the propylene gas flame, indicating improved heat transfer. However, the peak temperature of the metal plate was slightly lower when using the propylene gas flame. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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16 pages, 5504 KiB  

Open AccessArticle

Detection Stability Improvement of Near-Infrared Laser Telemetry for Methane Emission from Oil/Gas Station Using a Catadioptric Optical Receiver

by Dai Geng, Di Wang, Yushuang Li, Wei Zhou and Hanbing Qi

Energies 2023, 16(9), 3854; https://doi.org/10.3390/en16093854 - 30 Apr 2023

Viewed by 1011

Abstract

Open-path laser telemetry of methane leakage yields security guarantees of energy storage and transportation for oil/gas station production operation. In order to further improve the long-term detection stability under the condition of long-distance non-cooperative targets, a catadioptric optical receiver (COR) consisting of a [...] Read more.

Open-path laser telemetry of methane leakage yields security guarantees of energy storage and transportation for oil/gas station production operation. In order to further improve the long-term detection stability under the condition of long-distance non-cooperative targets, a catadioptric optical receiver (COR) consisting of a Fresnel lens, cone reflector and parabolic reflector is proposed to focus the laser echo light that deviates gradually with the increase in atmospheric turbulence. The geometric configuration parameters of COR are optimized by the ray-tracing method, and the condensing performance of COR is further verified. The self-developed methane laser telemetry system coupled with COR is calibrated in the laboratory and then moved to the field for a signal receiving stability experiment under turbulence interference. The results show that the receiving angle of COR increases 3.8 times compared with the Fresnel lens optical receiver (FOR). The RMSE and IS of the COR system are 0.00173 V and 84.79%, respectively. For comparison, these two evaluating indicators of the FOR system are 0.00288 V and 76.23%. This self-developed methane laser telemetry system coupled with COR is feasible for improving the long-term detection stability of remote leakage monitoring in oil/gas stations. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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18 pages, 4623 KiB  

Open AccessArticle

Power Output Optimisation via Arranging Gas Flow Channels for Low-Temperature Polymer Electrolyte Membrane Fuel Cell (PEMFC) for Hydrogen-Powered Vehicles

by James Chilver-Stainer, Anas F. A. Elbarghthi, Chuang Wen and Mi Tian

Energies 2023, 16(9), 3722; https://doi.org/10.3390/en16093722 - 26 Apr 2023

Cited by 2 | Viewed by 1351

Abstract

As we move away from internal combustion engines to tackle climate change, the importance of hydrogen-powered vehicles and polymer electrolyte membrane fuel cell (PEMFC) technology has dramatically increased. In the present study, we aimed to determine the optimal configuration for the power output [...] Read more.

As we move away from internal combustion engines to tackle climate change, the importance of hydrogen-powered vehicles and polymer electrolyte membrane fuel cell (PEMFC) technology has dramatically increased. In the present study, we aimed to determine the optimal configuration for the power output of a PEMFC system using computational fluid dynamics (CFD) modelling to analyse variations of the primary serpentine design of gas flow channels. This helps improve efficiency and save on valuable materials used, reducing potential carbon emissions from the production of hydrogen vehicles. Different numbers of serpentine gas channels were represented with various spacing between them, within the defined CFD model, to optimise the gas channel geometry. The results show that the optimum configuration was found to have 11 serpentine channels with a spacing of 3.25 mm. In this optimum configuration, the ratio between the channel width, channel spacing, and serpentine channel length was found to be 1:2.6:38 for PEMFCs. Furthermore, the inclusion of fillets to the bends of the serpentine gas channels was found to have a negative effect on the overall power output of the fuel cell. Moreover, the optimisation procedures with respect to the number of gas channels and the spacing revealed an optimal power density exceeding 0.65 W/cm². Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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15 pages, 4799 KiB  

Open AccessArticle

Simulation of the Temperature of a Shielding Induction Motor of the Nuclear Main Pump under Different Turbulence Models

by Likun Ai, Yiping Lu, Jiade Han and Wenxu Suo

Energies 2023, 16(6), 2792; https://doi.org/10.3390/en16062792 - 17 Mar 2023

Cited by 1 | Viewed by 1066

Abstract

Thermal design and the choice of turbulence models are crucial for motors. In this project, the geometrical model of the vertical shielding induction motor for a small nuclear main pump was established by SolidWorks software and the finite volume method was adopted to [...] Read more.

Thermal design and the choice of turbulence models are crucial for motors. In this project, the geometrical model of the vertical shielding induction motor for a small nuclear main pump was established by SolidWorks software and the finite volume method was adopted to investigate the temperature of the motor, especially the temperatures of bearings lubricated water. To make the numerical simulation of flow and heat transfer in the rotating clearance of the shielding induction motor more accurate, the effects of four types of different two equation turbulence models on the temperature field of the shielding induction motor were studied. The results showed that different choices of turbulence models had little effect on the temperature of the winding insulation but influenced the temperature of the lower guide bearing lubricating water and the secondary cooling water outlet. The SST k-ω model showed the lowest relative error result of the temperature of the winding insulation and the bearing lubricating water in the primary loop system of the shielding induction motor. The temperature of the clearance water, the spiral tube water and the spiral groove water increased approximately linearly along the axial direction. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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20 pages, 4337 KiB  

Open AccessArticle

Facilitating Investment in Photovoltaic Systems in Iran Considering Time-of-Use Feed-in-Tariff and Carbon Market

by Asrin Seyedzahedi and Salah Bahramara

Energies 2023, 16(3), 1067; https://doi.org/10.3390/en16031067 - 18 Jan 2023

Cited by 1 | Viewed by 1099

Abstract

Photovoltaic (PV) systems are the leading solutions for reducing carbon dioxide (CO₂) emissions in Iran’s energy system. However, there are some challenges to investing in PV systems in Iran, such as the low energy market price and the high investment cost [...] Read more.

Photovoltaic (PV) systems are the leading solutions for reducing carbon dioxide (CO₂) emissions in Iran’s energy system. However, there are some challenges to investing in PV systems in Iran, such as the low energy market price and the high investment cost of PV systems. Although the flat feed-in tariff (FiT) is defined to help purchase energy from the PV systems, it is not attractive to investors. In this paper, a mathematical formulation is developed for the planning problem of the PV systems with battery energy storages (BESs) considering two incentive policies: (1) Designing time-of-use FiT to encourage the PV systems to sell energy to the grid at peak hours (2) Participating in the carbon trading energy market. The insolation in Iran is calculated regarding mathematical formulations which divide Iran into eight zones. The results of the base case show high payback periods for all zones. In the presence of the incentive policies, the payback period decreases considerably from 5.46 yrs. to 3.75 yrs. for the best zone. Also, the net present value increases more than 170 percent in some zones compared to the base case. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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11 pages, 1259 KiB  

Open AccessArticle

Impacts of Government Policies on the Adoption of Biomass Power: A System Dynamic Perspective

by Zhao Xin-gang, Wang Wei, Hu Shuran and Liu Xuan

Sustainability 2023, 15(2), 1723; https://doi.org/10.3390/su15021723 - 16 Jan 2023

Cited by 3 | Viewed by 1616

Abstract

As a kind of renewable energy, biomass power has great development potential in mitigating greenhouse gas emissions. Therefore, under the background of carbon peak and carbon neutrality, the diffusion of biomass power generation technology has practical significance. To address these issues, this paper [...] Read more.

As a kind of renewable energy, biomass power has great development potential in mitigating greenhouse gas emissions. Therefore, under the background of carbon peak and carbon neutrality, the diffusion of biomass power generation technology has practical significance. To address these issues, this paper constructs a system dynamics model to study the impact of different policy effects on the diffusion of biomass power generation technologies. The results show that the feed-in tariff policy can significantly promote the installed capacity growth of biomass power generation projects; on the other hand, carbon emission trading increases the investment value of projects and promotes the growth of the installed capacity of biomass power generation projects, to a certain extent, so relevant policies need to be improved to achieve the promotion of biomass power generation technology in the future. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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11 pages, 1463 KiB  

Open AccessArticle

Liquid–Liquid Extraction of Volatile Fatty Acids from Anaerobic Acidification Broth Using Ionic Liquids and Cosolvent

by Tao Xing, Shutai Yu, Jingliang Tang, Huiliang Liu, Feng Zhen, Yongming Sun and Xiaoying Kong

Energies 2023, 16(2), 785; https://doi.org/10.3390/en16020785 - 10 Jan 2023

Cited by 2 | Viewed by 1549

Abstract

Promoting efficiency of liquid–liquid extraction at a high pH is a main challenge for the recovery of volatile fatty acids (VFAs) from organic wastes. In this study, the extraction efficiency of VFAs from artificial solution and acidification fermentation broth of kitchen wastes using [...] Read more.

Promoting efficiency of liquid–liquid extraction at a high pH is a main challenge for the recovery of volatile fatty acids (VFAs) from organic wastes. In this study, the extraction efficiency of VFAs from artificial solution and acidification fermentation broth of kitchen wastes using ionic liquids (ILs) was assessed at high pH. The effect of ILs addition ratio in diluent, volumetric solvent to feed ratio (S/F) on extraction efficiency were investigated. The solvent consists of [P666,14][Cl] (IL101) and dodecane was found to be the promising solvent for VFA extraction at pH 6.0, especially for butyric acid. The IL-101 ratio in dodecane and S/F was significant factors for the liquid–liquid extraction of VFAs. In general, a higher IL-101 ratio and S/F can promote the extraction efficiency of single VFAs. As a result, the maximum extraction rate of acetic acid (38.4–49.9%) and butyric acid (66.0–92.1%) from different VFA concentration solutions was observed at 10% IL-101 in dodecane and S/F = 2/1. The solvent was also effective in different types of real fermentation broth of kitchen wastes. The maximum extraction rate and selectivity of butyric acid was 60.2%/70.5% in butyric acid type broth and 74.6%/62.7% in mixture acid type broth. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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22 pages, 1831 KiB  

Open AccessReview

Diesel Spray: Development of Spray in Diesel Engine

by Djati Wibowo Djamari, Muhammad Idris, Permana Andi Paristiawan, Muhammad Mujtaba Abbas, Olusegun David Samuel, Manzoore Elahi M. Soudagar, Safarudin Gazali Herawan, Davannendran Chandran, Abdulfatah Abdu Yusuf, Hitesh Panchal and Ibham Veza

Sustainability 2022, 14(23), 15902; https://doi.org/10.3390/su142315902 - 29 Nov 2022

Cited by 5 | Viewed by 3802

Abstract

Research and development in the internal combustion engine (ICE) has been growing progressively. Issues such as air pollution, fuel cost, and market competitiveness have driven the automotive industry to develop and manufacture automobiles that meet new regulation and customers’ needs. The diesel engine [...] Read more.

Research and development in the internal combustion engine (ICE) has been growing progressively. Issues such as air pollution, fuel cost, and market competitiveness have driven the automotive industry to develop and manufacture automobiles that meet new regulation and customers’ needs. The diesel engine has some advantages over the gasoline or spark ignition engine, including higher engine efficiency, greater power output, as well as reliability. Since the early stage of the diesel engine’s development phase, the quest to obtain better atomization, proper fuel supply, and accurate timing control, have triggered numerous innovations. In the last two decades, owing to the development of optical technology, the visualization of spray atomization has been made possible using visual diagnostics techniques. This advancement has greatly improved research in spray evolution. Yet, a more comprehensive understanding related to these aspects has not yet been agreed upon. Diesel spray, in particular, is considered a complicated phenomenon to observe because of its high-speed, high pressure, as well as its high temperature working condition. Nevertheless, several mechanisms have been successfully explained using fundamental studies, providing several suggestions in the area, such as liquid atomization and two-phase spray flow. There are still many aspects that have not yet been agreed upon. This paper comprehensively reviews the current status of theoretical diesel spray and modelling, including some important numerical and experimental aspects. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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17 pages, 4553 KiB  

Open AccessArticle

Study on Properties of Regenerated Fluorinated Polyurethane Rigid Foam Prepared by Degrading Waste Polyurethane

by Da-Sheng Zhang, Xiao-Hua Gu, Si-Wen Liu, Yan Liu, Qing-Yun Zhou, Shang-Wen Zhu and Yan-Wei Zhu

Sustainability 2022, 14(23), 15685; https://doi.org/10.3390/su142315685 - 25 Nov 2022

Cited by 2 | Viewed by 1264

Abstract

Polyurethane (PU) has become one of the most widely used materials in the industrial field due to its excellent performance and wide range of applications. The increasing consumption of polyurethane materials has resulted in significant polyurethane waste. We can recycle waste polyurethane to [...] Read more.

Polyurethane (PU) has become one of the most widely used materials in the industrial field due to its excellent performance and wide range of applications. The increasing consumption of polyurethane materials has resulted in significant polyurethane waste. We can recycle waste polyurethane to obtain recycled polyurethane, but to make the recycled polyurethane meet different performance requirements in terms of utility and cost and enable the recycled polyether polyol to be further applied to high-end applications, it is necessary to improve the use value of recycled polyether polyol. In this paper, self-made Fluorodiol was added to the degradation process of waste polyurethane to obtain fluorinated regenerated polyether polyol. Recycled fluorinated polyurethane with excellent performance was prepared using fluorine-containing recycled polyether polyol. The regenerated fluorinated polyether polyols were characterized by infrared spectroscopy, viscosity, hydroxyl value, and GPC molecular weight distribution. The density, apparent morphology, water absorption, mechanical strength, thermal conductivity, and thermal stability of RFPU rigid foams with different fluorine contents were studied by scanning electron microscopy. The results show that when the addition of Fluorodiol was 8% of the mass of waste polyurethane, the density was 41.2 kg/m³, the immersion loss rate was 2.125%, the compressive strength was 0.315 Mpa, and the thermal conductivity was 0.0227 W/m·K. The RFPU prepared by Fluorodiol has low surface energy, good compressive strength, hydrolysis resistance, and is expected to be widely used in special insulation materials. Thus, the sustainable recycling of polyurethane is achieved. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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16 pages, 4014 KiB  

Open AccessArticle

PV-CrackNet Architecture for Filter Induced Augmentation and Micro-Cracks Detection within a Photovoltaic Manufacturing Facility

by Muhammad Hussain, Hussain Al-Aqrabi and Richard Hill

Energies 2022, 15(22), 8667; https://doi.org/10.3390/en15228667 - 18 Nov 2022

Cited by 14 | Viewed by 1361

Abstract

Photovoltaic cell manufacturing is a rigorous process involving many stages where the cell surface is exposed to external pressure and temperature differentials. This provides fertile ground for micro-cracks to develop on the cell surface. At present, domain experts carry out a manual inspection [...] Read more.

Photovoltaic cell manufacturing is a rigorous process involving many stages where the cell surface is exposed to external pressure and temperature differentials. This provides fertile ground for micro-cracks to develop on the cell surface. At present, domain experts carry out a manual inspection of the cell surface to judge if any micro-cracks are present. This research looks to overcome the issue of cell data scarcity through the proposed filter-induced augmentations, thus providing developers with an effective, cost-free mechanism for generating representative data samples. Due to the abstract nature of the cell surfaces, the proposed augmentation strategy is effective in generating representative samples for better generalization. Furthermore, a custom architecture is developed that is computationally lightweight compared to state-of-the-art architectures, containing only 7.01 million learnable parameters while achieving an F1-score of 97%. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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20 pages, 6068 KiB  

Open AccessArticle

Computational Tool to Support the Decision in the Selection of Alternative and/or Sustainable Refrigerants

by Guilherme Jesus, Martim L. Aguiar and Pedro D. Gaspar

Energies 2022, 15(22), 8497; https://doi.org/10.3390/en15228497 - 14 Nov 2022

Cited by 1 | Viewed by 1424

Abstract

There have been consequences regarding the increment of the greenhouse effect, such as the rise in the planet’s global temperature, and climate change. Refrigerants have an important contribution to the aforementioned environmental impact. In particular, hydrofluorocarbons (HFCs) contribute to the destruction of the [...] Read more.

There have been consequences regarding the increment of the greenhouse effect, such as the rise in the planet’s global temperature, and climate change. Refrigerants have an important contribution to the aforementioned environmental impact. In particular, hydrofluorocarbons (HFCs) contribute to the destruction of the ozone layer and the increase of the greenhouse effect. Protocols, international agreements, and legislation were developed to slow down the emission of greenhouse gases. Prohibition and definition of deadlines for the gradual elimination of various refrigerants have been proposed to replace them with others that are environmentally sustainable. Soon, the refrigeration sector will have to replace some refrigerants with others that are alternative and/or sustainable with minimal or zero environmental impact. A computational tool to support decision-making regarding the selection of alternative and/or sustainable refrigerant to replace the old one is developed to be used by refrigeration companies, manufacturers, and installers. A suggestion of refrigerants with reduced environmental impact is provided, ensuring similar thermal performance and energy efficiency, considering the safety level and renovation cost of the installation and refrigerant itself. This decision support system (DSS) uses an objective function that includes the technical specifications and properties of alternative and sustainable refrigerants. The computational tool is applied in the agri-food sector in three case studies. The results show not only the consistency of the computational tool, but also its flexibility, objectivity, and simplicity. Its use allows companies to choose refrigerants with reduced environmental impact, reduced or zero ozone depletion potential and global warming impact, thus contributing to environmental sustainability. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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23 pages, 1256 KiB  

Open AccessArticle

Study on the Impact of Clean Power Investment on Regional High-Quality Economic Development in China

by Xianrong Zhuang and Lingying Pan

Energies 2022, 15(22), 8364; https://doi.org/10.3390/en15228364 - 09 Nov 2022

Cited by 1 | Viewed by 1227

Abstract

In 2017, the 19th CPC National Congress proposed to “establish a sound economic system of green, low-carbon and circular development”, which indicates the direction of high-quality economic development in the new era of China. Clean power investment is a powerful way to promote [...] Read more.

In 2017, the 19th CPC National Congress proposed to “establish a sound economic system of green, low-carbon and circular development”, which indicates the direction of high-quality economic development in the new era of China. Clean power investment is a powerful way to promote high-quality economic development by adopting non-fossil-energy utilization and low-emission technologies, as well as creating new jobs. Meanwhile, large-scale investment and a long investment return period result in negative effects on local economies. To better understand the effect of clean power investment, this paper selects panel data of thirty provinces in China from 2010 to 2019 to establish a spatial Durbin model to explore the impact of clean power investment on regional high-quality economic development. The results show that inter-regional high-quality economic development shows significant spatial auto-correlation characteristics. Clean power investment has not only a positive direct effect on high-quality economic development but also generates positive spatial spillover effects. Human capital, degree of government intervention, and urbanization rate have positive effects on regional high-quality economic development, while they play a suppressed role on neighboring regions. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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15 pages, 11081 KiB  

Open AccessArticle

Impact of Battery Energy System Integration in Frequency Control of an Electrical Grid with Wind Power

by Anukriti Pokhriyal, José Luis Domínguez-García and Pedro Gómez-Romero

Clean Technol. 2022, 4(4), 972-986; https://doi.org/10.3390/cleantechnol4040060 - 09 Oct 2022

Cited by 4 | Viewed by 2546

Abstract

The rapid increase in the integration of renewable energy sources into the electrical grid is posing new challenges for the dynamic responses due to the global inertia reduction. In this regard, the impact on frequency stability of such reduction and the potential support [...] Read more.

The rapid increase in the integration of renewable energy sources into the electrical grid is posing new challenges for the dynamic responses due to the global inertia reduction. In this regard, the impact on frequency stability of such reduction and the potential support from wind power have been investigated lately. However, it is well-known that the variability of wind power and its reduced inertia may not be enough to handle the power unbalance. Energy storage systems (e.g., batteries) may provide the required additional flexibility to ensure proper response. In this paper, an analysis of how the different control loops for frequency support on wind power and batteries interact and perform is presented. To gain insights from the different impacts, a sensitivity analysis comparison for frequency regulation through (i) inertia and droop control of a variable speed wind turbine and (ii) battery is performed. The analysis was carried out through simulations using the well-known 4 generator 2-area model adapted to include a wind farm. From a battery perspective, its ramping capabilities were varied to provide frequency regulation. The paper shows how, depending on the control parameters and battery size, the frequency response may even become unstable due to interactions of the various pieces of technology. Thus, it shows that coordinated actions, control optimization and grid status among different actors on the grid (as battery and wind) is required for stable operation. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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18 pages, 3906 KiB  

Open AccessArticle

Real-Driving Emissions of an Aging Biogas-Fueled City Bus

by Kirsi Spoof-Tuomi, Hans Arvidsson, Olav Nilsson and Seppo Niemi

Clean Technol. 2022, 4(4), 954-971; https://doi.org/10.3390/cleantechnol4040059 - 02 Oct 2022

Cited by 2 | Viewed by 2215

Abstract

Transition to low emission transportation and cleaner cities requires a broad introduction of low- and zero-carbon alternatives to conventional petrol- and diesel-powered vehicles. New-generation gas buses are a cost-effective way to reduce local air pollutants from urban transportation. Moreover, major greenhouse gas (GHG) [...] Read more.

Transition to low emission transportation and cleaner cities requires a broad introduction of low- and zero-carbon alternatives to conventional petrol- and diesel-powered vehicles. New-generation gas buses are a cost-effective way to reduce local air pollutants from urban transportation. Moreover, major greenhouse gas (GHG) savings may be achieved using biogas as the power source. The main objective of this research was to investigate CH₄ and other gaseous emissions of a biogas-fueled urban bus equipped with a three-way catalyst (TWC) in real-world conditions. The study focused on emissions from a six-year-old gas-powered city bus, supplementing emission data from aging bus fleets. Impaired CH₄ oxidation and NO_x reduction were observed in the catalyst after its service life of 375,000 km–400,000 km. The main reason for low CH₄ and NO_x conversion over the TWC was concluded to be the partial deactivation of the catalyst. Another critical issue was the fluctuating air-to-fuel ratio. The results show that the efficiency of exhaust after-treatment systems should be closely monitored over time, as they are exposed to various aging processes under transient driving conditions, leading to increased real-world emissions. However, the well-to-wheels (WTW) analysis showed that an 80% GHG emission benefit could be achieved by switching from diesel to biomethane, giving a strong environmental argument for biogas use. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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17 pages, 3409 KiB  

Open AccessSystematic Review

A Review of Stimulation Technologies for Weakly-Consolidated Natural Gas Hydrate Reservoirs

by Bo Ning, Yanjiang Yu, Jing Zeng and Qiuping Lu

Energies 2022, 15(19), 7195; https://doi.org/10.3390/en15197195 - 30 Sep 2022

Cited by 3 | Viewed by 1441

Abstract

As an unconventional clean resource with huge reserves and a wide distribution, natural gas hydrates (NGHs) have good application prospects. However, due to limited understanding and available production technology for NGHs, there is still a large gap between current production tests and commercial [...] Read more.

As an unconventional clean resource with huge reserves and a wide distribution, natural gas hydrates (NGHs) have good application prospects. However, due to limited understanding and available production technology for NGHs, there is still a large gap between current production tests and commercial exploitation. A breakthrough in reservoir stimulation technologies is key to realizing the industrialization of NGHs in the future. Through a comprehensive summary of hydrate production test cases in Japan and China, this paper highlights the difficulties in the transformation of weakly-consolidated reservoirs. By systematically reviewing the theory and technology of hydrate reservoir transformation and engineering applications, this paper elucidates in detail the technical principles and mechanisms of several available stimulation technologies for weakly-consolidated reservoirs, and assesses the feasibility of their application to increase the production of NGHs. Existing problems and challenges are summarized and future prospects are discussed. Finally, suggestions are put forward for research and development of transformation technology for weakly-consolidated NGHs reservoirs in the future. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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13 pages, 3289 KiB  

Open AccessArticle

Lattice Boltzmann Simulation of Coupling Heat Transfer between Solid and Gas Phases of Nanoporous Materials

by Yafen Han, Shuai Li, Haidong Liu and Yucong Li

Nanomaterials 2022, 12(19), 3424; https://doi.org/10.3390/nano12193424 - 29 Sep 2022

Cited by 1 | Viewed by 1270

Abstract

In order to deeply study the heat conduction of nanoporous aerogel, a model of gas-solid heat conduction was established based on the microstructure of aerogel. The model was divided into two subdomains with uniform mesh because of the different gas-solid characteristics, and simulation [...] Read more.

In order to deeply study the heat conduction of nanoporous aerogel, a model of gas-solid heat conduction was established based on the microstructure of aerogel. The model was divided into two subdomains with uniform mesh because of the different gas-solid characteristics, and simulation was performed on each domain using the lattice Boltzmann method. The value of temperature on the boundaries of subdomains was determined by interpolation. Finally, the temperature distribution and the thermal conductivity were maintained. It can be concluded that when the gas-phase scale was fixed, the temperature distribution of the solid phase became more uniform when the scale increased; when the solid-phase scale was fixed, the temperature jump on the gas-solid interface decreased with the increase in the gas-phase scale; and the thermal conductivity of gas-solid coupling varied with the scale of the gas phase or solid phase, showing a scale effect in varying degrees. Full article

(This article belongs to the Topic Clean and Low Carbon Energy)

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