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Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency

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

Deadline for manuscript submissions: closed (5 May 2026) | Viewed by 15034

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Editors

Dr. Shujun Zhu

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Guest Editor

Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China
Interests: clean and efficient combustion of carbon-based fuels; thermal energy storage of solid particles
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Dr. Shuai Guo

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Guest Editor

School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China
Interests: waste to energy; co-combustion; pyrolysis and gasification; desulfurization and denitration
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Dr. Zhuozhi Wang

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Guest Editor

School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, China
Interests: high efficiency and clean utilization technology of solid fuels
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Dr. Lianfei Xu

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Guest Editor

School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, China
Interests: pyrolysis and gasification; denitration; electrochemical energy storage; utilization of organic solid waste
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The global pursuit of sustainable energy solutions has driven significant advancements in energy technologies and energy-saving strategies. As we face pressing environmental and energy challenges, the development of innovative systems with low emissions and high efficiency has become a top priority. Key areas of focus include renewable energy technologies such as wind, solar, biomass, and hydrogen energy, as well as improvements in traditional energy systems like coal-fired power plants. Advanced coal-fired power generation, incorporating high-efficiency and low-emission (HELE) technologies, continues to play a critical role in the global energy mix, offering pathways to cleaner and more efficient utilization of fossil fuels.

This Special Issue aims to provide a platform for showcasing the latest advancements and innovations across a broad spectrum of energy technologies, from renewable energy systems to traditional coal-fired power plants. Contributions highlighting strategies to optimize energy conversion, enhance energy efficiency, and minimize environmental impact are particularly encouraged.

Topics of interest for publication include, but are not limited to:

Advanced wind energy conversion systems and turbine technologies;
Innovations in solar photovoltaic and solar thermal energy systems;
Biomass and bioenergy technologies for clean energy production;
Hydrogen production, storage, and utilization in energy systems;
High-efficiency and low-emission coal-fired power generation (HELE) technologies;
Carbon capture, utilization, and storage (CCUS) for coal and other energy systems;
Renewable energy integration and optimization strategies;
Advanced energy storage technologies for grid stability and flexibility;
Smart grid technologies and energy management systems;
Energy-efficient materials and designs for renewable and conventional systems;
Policy, economic, and social analyses of energy-saving technologies.

We welcome contributions that explore the theoretical, experimental, and practical aspects of advanced energy systems, encompassing both renewable and traditional energy sources. This Special Issue seeks to foster innovative solutions and insights that support the transition to a low-carbon, energy-efficient future.

Dr. Shujun Zhu
Dr. Shuai Guo
Dr. Zhuozhi Wang
Dr. Lianfei Xu
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 250 words) can be sent to the Editorial Office for assessment.

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-anonymized peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

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Keywords

renewable energy
traditional energy
energy saving
high efficiency
low emissions

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Related Special Issue

Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency—2nd Edition in Energies

Published Papers (8 papers)

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Research

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24 pages, 20687 KB

Open AccessArticle

Fluid-Driven Opposed-Piston Pumps for Dense-Phase CO₂ Injection: Direct Force Coupling and Energy Efficiency Analysis

by Xiaoyu Wang, Hongtao Chen, Hongbao Liang, Yang Liu, Zhanheng Ma, Haibo Lin and Wanchun Sun

Energies 2026, 19(12), 2886; https://doi.org/10.3390/en19122886 - 18 Jun 2026

Viewed by 149

Abstract

Large-scale dense-phase carbon dioxide (CO₂) injection is an energy-intensive process in the carbon capture, utilization, and storage (CCUS) value chain. To address insufficient utilization of inlet pressure potential energy and sealing/friction losses of conventional reciprocating pumps under high-base-pressure dense-phase CO₂ transport conditions, this study develops a dense-phase CO₂-oriented structural optimization scheme for a hydraulically driven opposed-piston reciprocating pump based on force-coupling. A dynamic model was established to clarify the in situ recovery mechanism by which inlet pressure potential energy is converted into auxiliary thrust, enabling the drive load to shift from absolute pressure to net pressure difference. Simulation results show that under the rated 8 MPa inlet and 25 MPa discharge condition, the optimized opposed-piston configuration reduces peak driving oil pressure by 31.39% compared with the non-opposed reference configuration. Field reliability operation data show an average normalized specific energy consumption of 0.422 kWh/(MPa·m³) during the selected 24 h continuous operating period. The optimized configuration improves inlet-pressure utilization and reduces hydraulic power demand under high-base-pressure dense-phase CO₂ injection conditions, providing theoretical support and engineering reference for low-energy CCUS injection systems. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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25 pages, 881 KB

Open AccessArticle

Design Requirements for a Common-Shaft Switch-Mode Power Transformer for Ocean Wave-Powered Reverse Osmosis

by Sayak Pradhan, Jeremy W. Simmons and James D. Van de Ven

Energies 2026, 19(11), 2692; https://doi.org/10.3390/en19112692 - 3 Jun 2026

Viewed by 229

Abstract

Wave-powered reverse osmosis (RO) desalination with cogeneration of electricity is promising for freshwater production. The design performance of the default architecture seen in literature and commercialization suffers on metrics of power density, cost, and productivity. The design choices constraining this performance is the choice to drive a seawater pump with the WEC that operates at the same pressure as the reverse osmosis process. There have been studies comparing this default, baseline architecture with architectures operating at higher pressure, either by introducing a series of processes or by including a power transformer. This work contributes three studies that expand on the work on one such architectural choice, the inclusion of a switch-mode power transformer (SMPT). This study expands on the SMPT architecture and introduces a common-shaft power distribution approach, in which the rotary machines are mechanically coupled on a shared shaft. Three studies are performed: a static power-flow study comparing the baseline architecture with two SMPT-based architectures, a shaft-dynamics study quantifying the trade-off between switching frequency, flywheel inertia, and shaft-speed variation, and a pressure-dynamics study evaluating the effects of switch valve area, transition ratio, switching volume, and switching frequency on throttling losses. The baseline architecture delivers 34.97% of the input power to permeate production, whereas the SMPT and SMPT with common-shaft architectures deliver 32.47% and 34.02%, respectively. The shaft dynamics study found that switching frequencies above 15 Hz kept the shaft speed variations below 5%, while lower frequencies require added shaft inertia. A pressure dynamics study shows that switching losses are dominated by valve-opening transients, favoring a large effective flow area and short transition time. The overall findings are that (i) the SMPT enables significant pump downsizing at a small cost in efficiency, (ii) most of the efficiency loss is recovered with the common shaft approach, and (iii) the shaft inertia and valve requirements for the SMPT are reasonable. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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21 pages, 4088 KB

Open AccessArticle

Implementing Overfire Air Technology in Coal-Fired Power Plants to Promote Environmentally Friendly Energy Generation

by Saltanat Bolegenova, Aliya Askarova, Aizhan Nugymanova, Valeriy Maximov, Symbat Bolegenova, Nariman Askarov, Shynar Ospanova and Zhanar Shortanbayeva

Energies 2026, 19(2), 347; https://doi.org/10.3390/en19020347 - 10 Jan 2026

Viewed by 671

Abstract

This paper presents a numerical study on the deployment of Overfire Air (OFA) technology in coal-fired thermal power plants in Kazakhstan to reduce harmful emissions. The simulation utilized a digital model of the combustion chamber of the BKZ-75 boiler at Shakhtinsk thermal power plant, which utilizes high-ash Karaganda coal containing 35.10% ash. During the development of two-stage combustion technology, different methods of supplying extra air via OFA injectors were examined. Various positions within the combustion chamber were evaluated for their placement: at heights of h = 0.165 m; 0.75 m; 1.375 m; 2.25 m; 2.5 m; 8 m; 9.4 m; 10 m; 11 m; and 12 m. The baseline combustion mode (OFA = 0%) and several additional air injector settings were analyzed, including OFA levels of 5%, 10%, 15%, 18%, 20%, 25%, and 30% of the total air volume. Numerical simulations generated temperature distributions along with carbon monoxide (CO) and nitrogen (NO) concentration fields, both inside and outside the combustion chamber outlet. Research indicates that the most effective reduction in pollutant emissions happens when OFA injectors are positioned at 9.4 m and supply supplementary air at an OFA rate of 18%. Under these settings, the carbon monoxide concentration at the combustion chamber outlet decreases by approximately 36%, while nitrogen oxide levels drop by 25%, compared to the baseline condition (OFA = 0%). These insights can be utilized to upgrade boiler units, promoting cleaner fuel combustion in coal-fired thermal power plants. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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26 pages, 5274 KB

Open AccessArticle

Hybrid Artificial Neural Network and Perturb & Observe Strategy for Adaptive Maximum Power Point Tracking in Partially Shaded Photovoltaic Systems

by Braulio Cruz, Luis Ricalde, Roberto Quintal-Palomo, Ali Bassam and Roberto I. Rico-Camacho

Energies 2025, 18(19), 5053; https://doi.org/10.3390/en18195053 - 23 Sep 2025

Viewed by 1063

Abstract

Partial shading in photovoltaic (PV) systems causes multiple local maximum power points (LMPPs), complicating tracking and reducing energy efficiency. Conventional maximum power point tracking (MPPT) methods, such as Perturb and Observe (P&O), often fail because of oscillations and entrapment at local maxima. To address these shortcomings, this study proposes a hybrid MPPT strategy combining artificial neural networks (ANNs) and the P&O algorithm to enhance tracking accuracy under partial shading while maintaining implementation simplicity. The research employs a detailed PV cell model in MATLAB/Simulink (2019b) that incorporates dynamic shading to simulate non-uniform irradiance. Within this framework, an ANN trained with the Levenberg–Marquardt algorithm predicts global maximum power points (GMPPs) from voltage and irradiance data, guiding and accelerating subsequent P&O operation. In the hybrid system, the ANN predicts the maximum power points (MPPs) to provide initial estimates, after which the P&O fine-tunes the duty cycle optimization in a DC-DC converter. The proposed hybrid ANN–P&O MPPT method achieved relative improvements of 15.6–49% in tracking efficiency, 16–20% in stability, and 14–54% in convergence speed compared with standalone P&O, depending on the irradiance scenario. This research highlights the potential of ANN-enhanced MPPT systems to maximize energy harvest in PV systems facing shading variability. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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19 pages, 5877 KB

Open AccessArticle

Numerical Investigation of Combustion Characteristics in a 330 MW Coal-Fired Boiler with Preheating Combustion Devices at Half Load Operation

by Siyuan Wang, Hong Tang, Zuodong Liu, Lingfang Sun and Zhiming Xu

Energies 2025, 18(18), 5042; https://doi.org/10.3390/en18185042 - 22 Sep 2025

Viewed by 1273

Abstract

To reduce the impact of renewable energy generation on power grid stability, preheating combustion technology is introduced to maintain coal-fired boiler efficiency at low loads. A 330 MW coal-fired boiler is retrofitted with preheating combustion devices to improve combustion performance and lower NO_x emissions. The device is installed in the reduction zone between the furnace burnout zone and the burner zone. The combustion characteristics of the boiler with and without these devices are examined at 50% rated load. Numerical simulations are conducted to analyze the effects of preheating coal input and burner arrangement on temperature and species distribution within the boiler. Results show that increasing preheating coal input from 0 to 30 t/h enhances NO_x reduction due to a higher flow rate of preheated products. At a preheating coal input of 20 t/h, the combustion efficiency reaches 96.9%. The NO_x concentration at the furnace exit rises from 122.4 to 171.3 mg/Nm³ as the height of the burner arrangement increases. The middle three-layer burner arrangement achieves a uniform temperature distribution and a peak combustion efficiency of 97.6%. The bottom and middle three-layer burner arrangements are recommended for efficient and clean combustion. Compared to the original boiler, the retrofitted boiler’s combustion efficiency increases from 96.3% to a maximum of 97.6%, while the NO_x concentration at the furnace outlet drops from 168.1 to 93.2 mg/Nm³, showing that installing preheating combustion devices promotes efficient and clean combustion. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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13 pages, 1125 KB

Open AccessFeature PaperArticle

Oxidative Pyrolysis of Typical Volatile Model Compounds Under Low Oxygen Equivalence Ratios During Oxidative Pyrolysis of Biomass

by Liying Wang, Dan Lin, Dongjing Liu, Xing Xie, Shihong Zhang and Bin Li

Energies 2025, 18(11), 2996; https://doi.org/10.3390/en18112996 - 5 Jun 2025

Cited by 6 | Viewed by 1306

Abstract

This study aims to investigate the oxidative pyrolysis of biomass volatiles with a particular focus on the formation of liquid products. Furfural, hydroxyacetone, and 3,4-dimethoxybenzaldehyde were chosen as volatile model compounds. The impacts of the oxygen equivalence ratio (ER, 0–15%) and temperature (400–500 °C) on the product composition and distribution were examined using a two-stage quartz-tube reactor. The results showed that volatile pyrolysis was limited at the lower temperature of 400 °C even with oxygen introduction, while it could be significantly promoted at 500 °C as illustrated by the observed great decrease in the GC-MS peak areas of the volatile compounds especially under an oxidative atmosphere. For instance, the peak area of 3,4-dimethoxybenzaldehyde at 500 °C under an ER of 4% was only ~9% of that at 400 °C. Oxygen introduction enhanced the volatile decomposition with the formation of mainly permanent gases (although not given in the study) rather than liquid products, but distinct impacts were obtained for varied volatile compounds possibly due to their different chemical structures and autoignition temperatures. From the perspective of liquid product formation, furfural would undergo the cleavage of C-C/C-O bonds to form linear intermediates and subsequent aromatization to generate aromatics (benzene and benzofuran). The presence of oxygen could enhance the oxidative destruction of the C-C/C-O bonds and the removal of O from the molecules to form simple aromatics such as benzene, phenol, and toluene. Hydroxyacetone mainly underwent C-C/C-O cleavage that was further enhanced in the presence of oxygen; the resultant intermediates would recombine to generate acetoin and 2,3-pentanedione. A higher ER would directly oxidize the alcoholic hydroxyl group (-OH) into an aldehyde group (-CHO) to form methyl glyoxal, while 3,4-dimethoxybenzaldehyde mainly underwent cleavage and recombination of bonds connected with the benzene ring including aldehyde group (-CHO), C_Ar-O, C_Methoxy-O bonds, thus forming 1,2-dimethoxybenzene, toluene, and 3-hydroxybenzadehyde. This study provides more fundamental insights into the homogeneous oxidation of volatiles during the oxidative fast pyrolysis of biomass, facilitating the deployment of this technology. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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29 pages, 5334 KB

Open AccessEditor’s ChoiceArticle

Optimal Multi-Area Demand–Thermal Coordination Dispatch

by Yu-Shan Cheng, Yi-Yan Chen, Cheng-Ta Tsai and Chun-Lung Chen

Energies 2025, 18(11), 2690; https://doi.org/10.3390/en18112690 - 22 May 2025

Viewed by 1063

Abstract

With the soaring demand for electric power and the limited spinning reserve in the power system in Taiwan, the comprehensive management of both thermal power generation and load demand turns out to be a key to achieving the robustness and sustainability of the power system. This paper aims to design a demand bidding (DB) mechanism to collaborate between customers and suppliers on demand response (DR) to prevent the risks of energy shortage and realize energy conservation. The concurrent integration of the energy, transmission, and reserve capacity markets necessitates a new formulation for determining schedules and marginal prices, which is expected to enhance economic efficiency and reduce transaction costs. To dispatch energy and reserve markets concurrently, a hybrid approach of combining dynamic queuing dispatch (DQD) with direct search method (DSM) is developed to solve the extended economic dispatch (ED) problem. The effectiveness of the proposed approach is validated through three case studies of varying system scales. The impacts of tie-line congestion and area spinning reserve are fully reflected in the area marginal price, thereby facilitating the determination of optimal load reduction and spinning reserve allocation for demand-side management units. The results demonstrated that the multi-area bidding platform proposed in this paper can be used to address issues of congestion between areas, thus improving the economic efficiency and reliability of the day-ahead market system operation. Consequently, this research can serve as a valuable reference for the design of the demand bidding mechanism. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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Review

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39 pages, 17694 KB

Open AccessReview

Coal Gangue Utilization: Applications, Challenges, and Sustainable Development Strategies

by Yinghui Sun, Bohao Bai, Xu Yang, Shujun Zhu, Jilin Tian, Zhuozhi Wang, Li Xu, Lianfei Xu and Boxiong Shen

Energies 2025, 18(2), 444; https://doi.org/10.3390/en18020444 - 20 Jan 2025

Cited by 31 | Viewed by 8009

Abstract

Coal gangue is a kind of typical by-product emitted during the coal mining and washing process. With the increase in coal resource utilization, a large amount of coal gangue was not reasonably utilized, causing environmental pollution and resource waste. The main purpose of this article is to introduce the surface structural features and compositional characteristics of coal gangue and to summarize the utilization of coal gangue in the fields of building materials, energy production, agricultural utilization, and high-value-added areas such as catalysts and adsorbents. Secondly, this review discussed the environmental challenges and technical difficulties derived from the process of coal gangue utilization and how to solve these problems through innovative methods and technological improvements. Finally, the article proposed the development direction and strategies for the future resource utilization of coal gangue, emphasizing the importance of coal gangue as a sustainable resource and its significant role in achieving a circular economy for reducing environmental pollution. By analyzing the potentiality of coal gangue for resource utilization systematically, this article aims to provide valuable references and insights for researchers and decision-makers in related fields. Full article

(This article belongs to the Special Issue Advanced Energy Technologies and Energy Savings: Low Emissions and High Efficiency)

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