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A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: closed (25 November 2021) | Viewed by 43684

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Special Issue Editors

Prof. Dr. Ambra Giovannelli

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Guest Editor

Department of Engineering, University of Roma Tre, Via della Vasca Navale, 79, 00146 Rome, Italy
Interests: turbomachinery for unconventional fluids; power production from renewable energy; supercritical CO₂ power plants; organic rankine cycle (ORC) plants; high-temperature solar receivers; medium- and high-temperature thermal storage systems; compressed air storage systems (CAES); thermochemical hydrogen production
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Dr. Muhammad Anser Bashir

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Guest Editor

Department of Engineering, Roma Tre University, Via della Vasca Navale 79, 00146 Rome, Italy
Interests: solar thermal systems, CFD analysis, phase-change materials; concentrated solar thermal systems; thermal energy storage; CFD simulations; high temperature solar receivers; phase change materials; photovoltaic systems
Special Issues, Collections and Topics in MDPI journals

Dr. Giuseppina Di Lorenzo

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Guest Editor

Department of Engineering, Università degli studi Roma Tre, 00146 Rome, Italy
Interests: low-emission power generation processes; sustainable energy systems; process modelling and simulaton; techno-economic evaluation; stochastic modelling and analysis

Special Issue Information

Dear Colleagues,

It has been widely recognized that one of the biggest challenges facing the energy sector today is to ensure a reliable supply of affordable electricity with minimized environmental impact. Population growth, high-income earnings, and rural-urban migration are significant factors stressing the current energy sector in most countries; such factors are the driving force leading globally to an increase in energy needs and to a diversification in the energy mix. Although most countries still rely on fossil fuels, some are now diverting to renewable energy production. In this context, the role traditional sources can play in a low-carbon scenario is also changing dramatically. Different strategies such as increasing efficiency of fossil-fuel-based energy conversion systems, implementation of carbon capture and storage technologies, massive use of renewable energy sources have to be simultaneously used. The share of renewables in the power generation mix adds important operational constraints to existing power plants and influences choice and integration of new supplies. It is predicted that in the future all fossil fuel power generation must run more flexibly, according to the prevailing grid requirements and without penalties in performance and emissions. Energy storage has been advocated as a viable solution to eliminate intermittancy of supply.

This Special Issue on “Clean Energy Conversion Processes” aims to curate novel advances in energy conversion applications. Also, review papers providing critical overviews on state-of-the-art developments and supplementary guidelines of energy research are welcomed. Topics include, but are not limited to:

Optimization of energy conversion systems
Techno-economic analysis of novel systems
Renewable energy sources electricity production
Waste heat recovery/pollution prevention
Energy storage and harvesting

Dr. Ambra Giovannelli
Dr. Muhammad Anser Bashir
Dr. Giuseppina Di Lorenzo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All 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. Processes is an international peer-reviewed open access monthly 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 2400 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

Environment-friendly power generation
Renewable energy technologies
Waste heat recovery
Process modelling
Engineering-economic analysis
Feasibility study
Storage systems

Published Papers (10 papers)

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Research

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24 pages, 9845 KiB

Open AccessArticle

Piece-Wise Droop Controller for Enhanced Stability in DC-Microgrid-Based Electric Vehicle Fast Charging Station

by Mallareddy Mounica, Bhooshan A. Rajpathak, Mohan Lal Kolhe, K. Raghavendra Naik, Janardhan Rao Moparthi and Sravan Kumar Kotha

Processes 2024, 12(5), 892; https://doi.org/10.3390/pr12050892 - 28 Apr 2024

Viewed by 341

Abstract

The need for public fast electric vehicle charging station (FEVCS) infrastructure is growing to meet the zero-emission goals of the transportation sector. However, the large charging demand of the EV fleet may adversely impact the grid’s stability and reliability. To improve grid stability and reliability, the development of a DC microgrid (MG) leveraging renewable energy sources to supply the energy demands of FEVCSs is the sustainable solution. Balancing the intermittent EV charging demand and fluctuating renewable energy generation with the stable DC bus voltage of a DC MG is a challenging objective. To address this objective, a piece-wise droop control strategy is proposed in this work. The proposed scheme regulates DC bus voltage and power sharing with droop value updating in a region-based load current distribution. Voltage compensation in individual regions is carried out to further improve the degree of freedom. In this paper, the performance of the proposed strategy is evaluated with the consideration of real-time solar PV dynamics and EV load dynamics. Further, to showcase the effectiveness of the proposed strategy, a comparative analysis with a maximum power point tracking (MPPT) controller against various dynamic EV load scenarios is carried out, and the results are validated through a hardware-in-loop experimental setup. Despite the intermittent source and EV load dynamics, the proposed piece-wise droop control can maintain voltage regulation with less than 1% deviation. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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15 pages, 825 KiB

Open AccessArticle

Voltage Stability Index Using New Single-Port Equivalent Based on Component Peculiarity and Sensitivity Persistence

by Muhammad Shoaib Bhutta, Muddassar Sarfraz, Larisa Ivascu, Hui Li, Ghulam Rasool, Zain ul Abidin Jaffri, Umer Farooq, Jamshed Ali Shaikh and Muhammad Shahzad Nazir

Processes 2021, 9(10), 1849; https://doi.org/10.3390/pr9101849 - 18 Oct 2021

Cited by 9 | Viewed by 1791

Abstract

A voltage stability index is proposed using a new single-port equivalent depending on component peculiarity representation and sensitivity persistence to locate and determine long-term voltage instability in transmission and distribution power networks. The suggested single-port equivalent effectively represents the equivalence of various component types and assures the consistency of sensitivity information before and after the equivalence which is compulsory for the equivalent accuracy in estimating the voltage stability analysis. The stability index is derived from the new single-port equivalent to determine the system voltage instability. The proposed stability index is compared with indices based on virtual impedance and Thevenin impedance models. This new stability index shows more accuracy and effectiveness as compared to the indices based on virtual and Thevenin equivalent models. The index also determines the weak buses, where an improvement or functional measure can be used to reduce the system voltage instability. The validity of the proposed equivalent approach and stability index is presented by utilizing two radial systems, four IEEE systems and an actual system having bus size from five to 1010 buses. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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11 pages, 3389 KiB

Open AccessFeature PaperArticle

Experimental Evaluation of Hydrotreated Vegetable Oils as Novel Feedstocks for Steam-Cracking Process

by Adam Karaba, Jan Patera, Petra Dvorakova Ruskayova, Héctor de Paz Carmona and Petr Zamostny

Processes 2021, 9(9), 1504; https://doi.org/10.3390/pr9091504 - 26 Aug 2021

Cited by 6 | Viewed by 2869

Abstract

Hydrotreated vegetable oils (HVOs) are currently a popular renewable energy source, frequently blended into a Diesel-fuel. In the paper, HVO potential as feedstock for the steam-cracking process was investigated, since HVOs promise high yields of monomers for producing green polymers and other chemicals. Prepared HVO samples of different oil sources were studied experimentally, using pyrolysis gas chromatography to estimate their product yields in the steam-cracking process and compare them to traditional feedstocks. At 800 °C, HVOs provided significantly elevated ethylene yield, higher yield of propylene and C4 olefins, and lower oil yield than both atmospheric gas oil and hydrocracked vacuum distillate used as reference traditional feedstocks. The HVO preparation process was found to influence the distribution of steam-cracking products more than the vegetable oil used for the HVO preparation. Furthermore, pyrolysis of HVO/traditional feedstock blends was performed at different blending ratios. It provided information about the product yield dependence on blending ratio for future process design considerations. It revealed that some product yields exhibit non-linear dependence on the blending ratio, and therefore, their yields cannot be predicted by the simple principle of additivity. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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22 pages, 2189 KiB

Open AccessArticle

Renewable Portfolio Standard Development Assessment in the Kingdom of Saudi Arabia from the Perspective of Policy Networks Theory

by Amjad Ali, Fahad A. Al-Sulaiman, Ibrahim N. A. Al-Duais, Kashif Irshad, Muhammad Zeeshan Malik, Md Shafiullah, Md. Hasan Zahir, Hafiz Muhammad Ali and Sheraz Alam Malik

Processes 2021, 9(7), 1123; https://doi.org/10.3390/pr9071123 - 28 Jun 2021

Cited by 26 | Viewed by 2994

Abstract

Electricity generation from renewable energy (RE) sources has not been well utilized in the Kingdom of Saudi Arabia (KSA). KSA has publicized its Vision 2030 renewable energy target to deploy 58.7 gigawatts of RE, paving the way for a low-carbon economy in the country. Renewable portfolio standard (RPS) may play an influential role as a policy instrument to stimulate the RE development and consumption on a large scale and pursue the Vision 2030 objectives. In this study, the renewable portfolio standards policy assessment was carried out to investigate the issues impelling the employment of or plan to adopt RPS. To elucidate the collaborating interaction amongst the multiple stakeholders at different levels in the formulation of renewable portfolio standard, in this assessment study, we used a multi-theoretical approach for examining the policy networks theory (PNT) to inspect the communication links and strategies of different actors who are responsible and involved in KSA policy formulation and enactment. It will help overcome the interaction limitations amongst the actors, contribute to understanding various actors’ behaviors and facilitate RPS development and implementation. In this paper, PNT’s four strategy phases (interaction, agenda-setting, action plan and legislative) are used for RPS development assessment. In this paper, we presented KSA’s overall systematic picture for RPS formulation to adopt and implement it practically for a collaborative relationship between five actors—policy and regulatory bodies, professional bodies, inter-governmental bodies, power producers and social networks—at different levels by using PNT to analyze the interactive relationship amongst actors. This detailed analysis will help KSA overcome the institutional relationship and interaction limitations of the actors in RPS formulation and thereby offer significant success for RE deployment in KSA, while providing viable ideas, procedures and bases for government departments to formulate applicable policies for the renewable energy system efficiently. The evaluation of the communications among major partakers in the policy network field helps to efficiently explicate the hindrances in policy formulation and enactment to make the RPS more effective. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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12 pages, 2345 KiB

Open AccessArticle

Research on the Optimal Configuration of Regional Integrated Energy System Based on Production Simulation

by Tao Shi, Ruan-Ming Huang and Cang-Bi Ding

Processes 2020, 8(8), 892; https://doi.org/10.3390/pr8080892 - 25 Jul 2020

Cited by 3 | Viewed by 2178

Abstract

This paper is focused mainly on the production simulation method of a regional integrated energy system under random scenarios for optimal configuration. First, the cooling, heating, and electric load demand of the regional integrated energy system is described quantitatively in the form of time series, as well as the power characteristics of renewable energy, such as wind power and photovoltaic power generation. Then, a typical scenario set of regional integrated energy system configurations considering the random probability characteristics is established through scene clustering. Second, considering the power output characteristics and cost factors of different types of distributed energy, the corresponding technical and economic quantitative model is established. Third, a multi-objective production simulation model of a regional integrated energy system considering configuration constraints and operation constraints is proposed with economic and environmental protection as the main objectives. Finally, the accuracy and effectiveness of the above methods are verified based on a case study of actual engineering. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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22 pages, 5133 KiB

Open AccessArticle

Short-Term Load Forecasting Using Smart Meter Data: A Generalization Analysis

by Aida Mehdipour Pirbazari, Mina Farmanbar, Antorweep Chakravorty and Chunming Rong

Processes 2020, 8(4), 484; https://doi.org/10.3390/pr8040484 - 21 Apr 2020

Cited by 42 | Viewed by 5212

Abstract

Short-term load forecasting ensures the efficient operation of power systems besides affording continuous power supply for energy consumers. Smart meters that are capable of providing detailed information on buildings energy consumption, open several doors of opportunity to short-term load forecasting at the individual building level. In the current paper, four machine learning methods have been employed to forecast the daily peak and hourly energy consumption of domestic buildings. The utilized models depend merely on buildings historical energy consumption and are evaluated on the profiles that were not previously trained on. It is evident that developing data-driven models lacking external information such as weather and building data are of great importance under the situations that the access to such information is limited or the computational procedures are costly. Moreover, the performance evaluation of the models on separated house profiles determines their generalization ability for unseen consumption profiles. The conducted experiments on the smart meter data of several UK houses demonstrated that if the models are fed with sufficient historical data, they can be generalized to a satisfactory level and produce quite accurate results even if they only use past consumption values as the predictor variables. Furthermore, among the four applied models, the ones based on deep learning and ensemble techniques, display better performance in predicting daily peak load consumption than those of others. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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11 pages, 1941 KiB

Open AccessArticle

Selecting the Optimal Configuration for a Solar Air Heater Using the Grey–Taguchi Method

by Raheleh Nowzari, Nima Mirzaei and Kiyan Parham

Processes 2020, 8(3), 317; https://doi.org/10.3390/pr8030317 - 9 Mar 2020

Cited by 4 | Viewed by 3031

Abstract

In this study, a typical Grey–Taguchi method has been applied in order to select the optimal configuration of a solar air heater to achieve optimum performance. The analysis is performed for different system configurations in terms of collector type, mass flow rate, and cover type. The Grey–Taguchi method, which requires the minimum possible numbers of the demanded experiments for accomplishing a robust statistical decision for a given experimental problem, has been employed, and temperature difference and thermal performance have been used as the two main criteria. It is found that by considering the temperature difference criterion, at a mass flow rate of 0.011 kg/s, the best configuration is the double-pass solar collector owning a one-fourth pierced Plexiglas cover with a distance of 60 mm between the centers of the holes. On the other hand, by considering the thermal performance as the criterion, the best configuration at a mass flow rate of 0.032 kg/s is found to be the double-pass solar collector holding a half-pierced Plexiglas cover and a distance of 60 mm distance between the centers of the holes. Finally, once both factors are taken into consideration, the optimal configuration suggested by the method is the double-pass collector with a one-quarter pierced Plexiglas cover. The method also suggests keeping a 30 mm distance between the centers of the holes and applying 0.032 kg/s of the mass flow rate to achieve the highest performance. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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22 pages, 5468 KiB

Open AccessArticle

Triangulum City Dashboard: An Interactive Data Analytic Platform for Visualizing Smart City Performance

by Mina Farmanbar and Chunming Rong

Processes 2020, 8(2), 250; https://doi.org/10.3390/pr8020250 - 24 Feb 2020

Cited by 21 | Viewed by 7603

Abstract

Cities are becoming smarter by incorporating hardware technology, software systems, and network infrastructure that provide Information Technology (IT) systems with real-time awareness of the real world. What makes a “smart city” functional is the combined use of advanced infrastructure technologies to deliver its core services to the public in a remarkably efficient manner. City dashboards have drawn increasing interest from both city operators and citizens. Dashboards can gather, visualize, analyze, and inform regional performance to support the sustainable development of smart cities. They provide useful tools for evaluating and facilitating urban infrastructure components and services. This work proposes an interactive web-based data visualization and data analytics toolkit supported by big data aggregation tools. The system proposed is a cloud-based prototype that supports visualization and real-time monitoring of city trends while processing and displaying large data sets on a standard web browser. However, it is capable of supporting online analysis processing by answering analytical queries and producing graphics from multiple resources. The aim of this platform is to improve communication between users and urban service providers and to give citizens an overall view of the city’s state. The conceptual framework and architecture of the proposed platform are explored, highlighting design challenges and providing insight into the development of smart cities. Moreover, results and the potential statistical analysis of important city services offered by the system are introduced. Finally, we present some challenges and opportunities identified through the development of the city data platform. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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Review

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37 pages, 4107 KiB

Open AccessFeature PaperReview

Thermal Analysis Technologies for Biomass Feedstocks: A State-of-the-Art Review

by Jun Sheng Teh, Yew Heng Teoh, Heoy Geok How and Farooq Sher

Processes 2021, 9(9), 1610; https://doi.org/10.3390/pr9091610 - 8 Sep 2021

Cited by 29 | Viewed by 4649

Abstract

An effective analytical technique for biomass characterisation is inevitable for biomass utilisation in energy production. To improve biomass processing, various thermal conversion methods such as torrefaction, pyrolysis, combustion, hydrothermal liquefaction, and gasification have been widely used to improve biomass processing. Thermogravimetric analysers (TG) and gas chromatography (GC) are among the most fundamental analytical techniques utilised in biomass thermal analysis. Thus, GC and TG, in combination with MS, FTIR, or two-dimensional analysis, were used to examine the key parameters of biomass feedstock and increase the productivity of energy crops. We can also determine the optimal ratio for combining two separate biomass or coals during co-pyrolysis and co-gasification to achieve the best synergetic relationship. This review discusses thermochemical conversion processes such as torrefaction, combustion, hydrothermal liquefaction, pyrolysis, and gasification. Then, the thermochemical conversion of biomass using TG and GC is discussed in detail. The usual emphasis on the various applications of biomass or bacteria is also discussed in the comparison of the TG and GC. Finally, this study investigates the application of technologies for analysing the composition and developed gas from the thermochemical processing of biomass feedstocks. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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22 pages, 4659 KiB

Open AccessFeature PaperReview

Review of Sulfuric Acid Decomposition Processes for Sulfur-Based Thermochemical Hydrogen Production Cycles

by Claudio Corgnale, Maximilian B. Gorensek and William A. Summers

Processes 2020, 8(11), 1383; https://doi.org/10.3390/pr8111383 - 30 Oct 2020

Cited by 21 | Viewed by 11485

Abstract

Thermochemical processes based on sulfur compounds are among the most developed systems to produce hydrogen through water splitting. Due to their operating conditions, sulfur cycles are suited to be coupled with either nuclear or solar plants for renewable hydrogen production. A critical review of the most promising sulfur cycles, namely the Hybrid Sulfur, the Sulfur Iodine, the Sulfur Bromine and the Sulfur Ammonia processes, is given, including the work being performed for each cycle and discussing their maturity and performance for nuclear and solar applications. Each sulfur-based process is comprised of a sulfuric acid thermal section, where sulfuric acid is concentrated and decomposed to sulfur dioxide, water and oxygen, which is then separated from the other products and extracted. A critical review of the main solutions adopted for the H₂SO₄ thermal section, including reactor configurations, catalytic formulations, constitutive materials and chemical process configurations, is presented. Full article

(This article belongs to the Special Issue Clean Energy Conversion Processes)

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