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Combustion Chemistry of Unsaturated Hydrocarbons Mixed with NOx: A Review with a Focus on Their Interactions
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Decarbonisation of Geographical Islands and the Feasibility of Green Hydrogen Production Using Excess Electricity
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Application of Biogas and Biomethane as Maritime Fuels: A Review of Research, Technology Development, Innovation Proposals, and Market Potentials
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Solar Hot Water Systems Using Latent Heat Thermal Energy Storage: Perspectives and Challenges
Journal Description
Energies
Energies
is a peer-reviewed, open access journal of related scientific research, technology development, engineering policy, and management studies related to the general field of energy, from technologies of energy supply, conversion, dispatch, and final use to the physical and chemical processes behind such technologies. Energies is published semimonthly online by MDPI. The European Biomass Industry Association (EUBIA), Association of European Renewable Energy Research Centres (EUREC), Institute for Chemical Processing of Coal (IChPW), International Society for Porous Media (InterPore), CYTED and others are affiliated with Energies and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Ei Compendex, RePEc, Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: CiteScore - Q1 (Engineering (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.7 days after submission; acceptance to publication is undertaken in 2.9 days (median values for papers published in this journal in the first half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Sections: published in 41 topical sections.
- Testimonials: See what our editors and authors say about Energies.
- Companion journals for Energies include: Fuels, Gases, Nanoenergy Advances and Solar.
Impact Factor:
3.2 (2022);
5-Year Impact Factor:
3.3 (2022)
Latest Articles
Potential Domestic Energy System Vulnerabilities from Major Exports of Green Hydrogen: A Case Study of Australia
Energies 2023, 16(16), 5881; https://doi.org/10.3390/en16165881 - 08 Aug 2023
Abstract
Australia has clear aspirations to become a major global exporter of hydrogen as a replacement for fossil fuels and as part of the drive to reduce CO2 emissions, as set out in the National Hydrogen Strategy released in 2019 jointly by the
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Australia has clear aspirations to become a major global exporter of hydrogen as a replacement for fossil fuels and as part of the drive to reduce CO2 emissions, as set out in the National Hydrogen Strategy released in 2019 jointly by the federal and state governments. In 2021, the Australian Energy Market Operator specified a grid forecast scenario for the first time entitled “hydrogen superpower”. Not only does Australia hope to capitalise on the emerging demand for zero-carbon hydrogen in places like Japan and South Korea by establishing a new export industry, but it also needs to mitigate the built-in carbon risk of its export revenue from coal and LNG as major customers, such as Japan and South Korea, move to decarbonise their energy systems. This places hydrogen at the nexus of energy, climate change mitigation and economic growth, with implications for energy security. Much of the published literature on this topic concentrates on the details of what being a major hydrogen exporter will look like and what steps will need to be taken to achieve it. However, there appears to be a gap in the study of the implications for Australia’s domestic energy system in terms of energy security and export economic vulnerability. The objective of this paper is to develop a conceptual framework for the implications of becoming a major hydrogen exporter on Australia’s energy system. Various green hydrogen export scenarios for Australia were compared, and the most recent and comprehensive was selected as the basis for further examination for domestic energy system impacts. In this scenario, 248.5 GW of new renewable electricity generation capacity was estimated to be required by 2050 to produce the additional 867 TWh required for an electrolyser output of 2088 PJ of green hydrogen for export, which will comprise 55.9% of Australia’s total electricity demand at that time. The characteristics of comparative export-oriented resources and their interactions with the domestic economy and energy system are then examined through the lens of the resource curse hypothesis, and the LNG and aluminium industries. These existing resource export frameworks are reviewed for applicability of specific factors to export-oriented green hydrogen production, with applicable factors then compiled into a novel conceptual framework for exporter domestic implications from large-scale exports of green hydrogen. The green hydrogen export superpower (2050) scenario is then quantitatively assessed using the established indicators for energy exporter vulnerability and domestic energy security, comparing it to Australia’s 2019 energy exports profile. This assessment finds that in almost all factors, exporter vulnerability is reduced, and domestic energy security is enhanced by the transition from fossil fuel exports to green hydrogen, with the exception of an increase in exposure of the domestic energy system to international market forces.
Full article
(This article belongs to the Special Issue Hydrogen in the Energy-X-Nexus)
Open AccessArticle
Passive Island Detection Method Based on Sequence Impedance Component and Load-Shedding Implementation
Energies 2023, 16(16), 5880; https://doi.org/10.3390/en16165880 - 08 Aug 2023
Abstract
Active islanding detection techniques majorly affect power quality due to injected harmonic signals, whereas passive methods have a large non-detection zone (NDZ). This article presents a new method based on the resultant sequential impedance component (RSIC) as a new approach to island detection
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Active islanding detection techniques majorly affect power quality due to injected harmonic signals, whereas passive methods have a large non-detection zone (NDZ). This article presents a new method based on the resultant sequential impedance component (RSIC) as a new approach to island detection with zero NDZs. The abrupt variable in the conventional impedance approach was replaced by the RSIC of the inverter in this method. When the measured value exceeds the threshold range, islanding is detected by monitoring the variations in the RSIC at the point of common coupling (PCC). For proper power utilization in the identified islands, a priority-based load-shedding strategy is also recommended and implemented in this article. Its efficacy was verified in a wide range of real-world settings. It offers superior stability in various non-islanding (NIS) scenarios to prevent accidental tripping. The proposed method advantages include a cheap cost, the simplicity of implementation, independence from the number and type of distributed generation (DG) units connected, and no power quality effects. Compared to other methods reported in the literature, the obtained detection times illustrate that the proposed method is superior.
Full article
(This article belongs to the Special Issue Modern Challenges in Renewable Energy Sources Integrated Power System Industrial Applications)
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Open AccessBrief Report
Impact of Bypass Diode Fault Resistance Values on Burnout in Bypass Diode Failures in Simulated Photovoltaic Modules with Various Output Parameters
Energies 2023, 16(16), 5879; https://doi.org/10.3390/en16165879 - 08 Aug 2023
Abstract
The bypass diode (BPD), a protective element in a photovoltaic system (PVS), occasionally fails as a result of lightning damage. In this study, using various resistance values, we investigated the burnout risk of PV modules experiencing BPD failures through experiments that replicated conditions
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The bypass diode (BPD), a protective element in a photovoltaic system (PVS), occasionally fails as a result of lightning damage. In this study, using various resistance values, we investigated the burnout risk of PV modules experiencing BPD failures through experiments that replicated conditions in which a BPD fails. Specifically, we evaluated the electric power generated by the failed BPD as we varied the faulty resistance value. Furthermore, we examined the impact of the failure resistance value of the BPD on PV module burnout. The results indicated that the power consumption of a BPD is particularly high, ranging from approximately 2 to 10 Ω when the PV module operates at its maximum power point. In addition, when the load is disconnected, the risk of heat generation is significantly higher, at BPD fault resistance values of approximately 0.1–10 Ω. Moreover, a faulty BPD with a resistance of approximately 0.1–10 Ω poses a high risk of burnout, particularly during load disconnection, owing to the increased heat generated by a BPD failure.
Full article
(This article belongs to the Special Issue Photovoltaic Solar Cells and Systems: Fundamentals and Applications)
Open AccessArticle
Engineering-Scale Integrated Energy System Data Projection Demonstration via the Dynamic Energy Transport and Integration Laboratory
Energies 2023, 16(16), 5878; https://doi.org/10.3390/en16165878 - 08 Aug 2023
Abstract
The objective of this study is to demonstrate and validate the Dynamic Energy Transport and Integration Laboratory (DETAIL) preliminary scaling analysis using Modelica language system-code Dymola. The DETAIL preliminary scaling analysis includes a multisystem integral scaling package between thermal-storage and hydrogen-electrolysis systems. To
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The objective of this study is to demonstrate and validate the Dynamic Energy Transport and Integration Laboratory (DETAIL) preliminary scaling analysis using Modelica language system-code Dymola. The DETAIL preliminary scaling analysis includes a multisystem integral scaling package between thermal-storage and hydrogen-electrolysis systems. To construct the system of scaled equations, dynamical system scaling (DSS) was applied to all governing laws and closure relations associated with the selected integral system. The existing Dymola thermal-energy distribution system (TEDS) facility and high-temperature steam electrolysis (HTSE) facility models in the Idaho National Laboratory HYBRID repository were used to simulate a test case and a corresponding scaled case for integrated system HYBRID demonstration and validation. The DSS projected data based on the test-case simulations and determined scaling ratios were generated and compared with scaled case simulations. The preliminary scaling analysis performance was evaluated, and scaling distortions were investigated based on data magnitude, sequence, and similarity. The results indicated a necessity to change the normalization method for thermal storage generating optimal operating conditions of 261 kW power and mass flow rate of 6.42 kg/s and the possibility of reselecting governing laws for hydrogen electrolysis to improve scaling predictive properties. To enhance system-scaling similarity for TEDS and HTSE, the requirement for scaling validation via physical-facility demonstration was identified.
Full article
(This article belongs to the Special Issue Advances in Thermal Energy Storage and Applications)
Open AccessArticle
The Statistical Fingerprint of Fluid-Injection Operations on Microseismic Activity at the Val d’Agri Oil Field (Southern Italy)
Energies 2023, 16(16), 5877; https://doi.org/10.3390/en16165877 - 08 Aug 2023
Abstract
In this paper, we examined the dynamical properties of the fluid-injection microseismicity at the Val d’Agri oil field (southern Italy) by applying different statistical methods to find correlations and common periodicities with injection parameters, such as injected volumes and injection pressure. Two periods
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In this paper, we examined the dynamical properties of the fluid-injection microseismicity at the Val d’Agri oil field (southern Italy) by applying different statistical methods to find correlations and common periodicities with injection parameters, such as injected volumes and injection pressure. Two periods of observation were analyzed: (1) from 2006 to 2015 (the first 10 years after the beginning of injection operations), the seismicity was recorded by the seismic network of the ENI company that manages the exploitation of the oilfield; (2) from 2016 to 2018, the seismicity was recorded by a denser seismic network capable of significantly reducing the completeness magnitude. If a significant correlation between seismicity and fluid-injection variables was found in the first period, in the second period, the seismic activity and injection variables were characterized by common periodicities after the reservoir acidification and for injection rates above 1900 m3/day. Finally, we applied and compared two different approaches proposed in the literature to forecast the maximum expected magnitude. The results showed that one of the approaches yielded an estimated maximum magnitude of Mmax = 1.7 ± 0.4, which is consistent with the maximum observed magnitude.
Full article
(This article belongs to the Special Issue Seismic Monitoring of the Subsoil for the Exploitation of Energy Sources)
Open AccessArticle
Carbon Sequestration in Remediated Post-Mining Soils: A New Indicator for the Vertical Soil Organic Carbon Variability Evaluation in Remediated Post-Mining Soils
Energies 2023, 16(16), 5876; https://doi.org/10.3390/en16165876 - 08 Aug 2023
Abstract
The present study experimentally investigated two different open-cast post-mining areas with different remediation methods for the vertical distribution of sequestered soil organic carbon (SOC). The study has been performed for two soil layers (0–15 cm, and 15–30 cm) for the four areas with
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The present study experimentally investigated two different open-cast post-mining areas with different remediation methods for the vertical distribution of sequestered soil organic carbon (SOC). The study has been performed for two soil layers (0–15 cm, and 15–30 cm) for the four areas with different remediation advancement (up to 20 years) at both studied post-mining soils: the limestone post-mining soil remediated with embankment and lignite post-mining soil remediated with sewage sludge. The study revealed that SOC is more stable within soil depths for lignite post-mining soil remediated with sewage sludge in comparison to the limestone post-mining soil remediated with embankment. The lignite post-mining soil remediated with sewage sludge showed a better hydrophobicity, humidity, aromaticity, and C/N ratio according to the 13C NMR. Therefore, in that soil, an increased microbial community has been observed. The study observed a positive correlation between GRSP content with a fungi community within soil depths. For lignite post-mining soil remediated with sewage sludge, the activity of ureases and dehydrogenases was generally lower compared to the post-mining soil remediation with embankment. The investigation found good parameters of Ce and NCER which for both studied areas were negative which indicate for the privilege of the higher capturing of CO2 over its release from the soil into the atmosphere. The study finds no relevant changes in SOC, POXC, TC, and LOI content within soil depth and remediation age. Due to the lack of a possible well-describing indicator of the vertical distribution of SOC stability in post-mining remediation soil, we proposed two different indicators for differentially managed post-mining soil remediations. The model of calculation of vertical SOC variability index can be universally used for different post-mining soils under remediation, however, both proposed calculated indexes are unique for studied soils. The proposed model of an index may be helpful for remediation management, C sequestration prediction, and lowering the carbon footprint of mining activity.
Full article
(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse Volume 2)
Open AccessArticle
TERA of Gas Turbine Propulsion Systems for RORO Ships
Energies 2023, 16(16), 5875; https://doi.org/10.3390/en16165875 - 08 Aug 2023
Abstract
Recently, regulations on emissions produced by vessels from international maritime organizations, along with the instability of fuel prices, have encouraged researchers to explore fuels and technology that are cleaner than heavy fuel oil and diesel engines. In this study, we employed the TERA
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Recently, regulations on emissions produced by vessels from international maritime organizations, along with the instability of fuel prices, have encouraged researchers to explore fuels and technology that are cleaner than heavy fuel oil and diesel engines. In this study, we employed the TERA method to evaluate the feasibility of using gas turbine engines with cleaner fuels as a replacement for diesel engines as a propulsion system for RORO ships. A sensitivity evaluation and risk assessment were also conducted to investigate the impact of applied emission taxes on the economic results. The findings indicated that the diesel engine emitted higher nitrogen oxide emissions than the gas turbine fuelled by natural gas and hydrogen. The gas turbine with hydrogen had zero carbon dioxide emissions, making it a sustainable energy production option. The economic aspects were evaluated based on an international route, and they revealed that economic profitability significantly depended on fuel costs and consumption. The diesel engine fuelled by marine diesel oil and the gas turbine fuelled by natural gas were economically attractive, whereas the gas turbine fuelled by hydrogen was less viable due to its high operating cost. However, in a scenario where a carbon dioxide tax was introduced, the gas turbine fuelled by hydrogen showed high potential as a low-risk investment compared to the other technologies. In summary, this study demonstrated the usefulness of the TERA method in the maritime sector for selecting and comparing various propulsion systems.
Full article
(This article belongs to the Special Issue Reliability Evaluation of Integrated Electricity and Natural Gas Systems)
Open AccessReview
A Review of the Evaluation of Building Energy Code Compliance in the United States
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, , , , , , and
Energies 2023, 16(16), 5874; https://doi.org/10.3390/en16165874 - 08 Aug 2023
Abstract
Building energy codes are essential tools for achieving energy efficiency in buildings. However, the full energy savings potential of these codes can only be realized if buildings are constructed in compliance with them. Therefore, evaluating building energy code compliance is crucial in bridging
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Building energy codes are essential tools for achieving energy efficiency in buildings. However, the full energy savings potential of these codes can only be realized if buildings are constructed in compliance with them. Therefore, evaluating building energy code compliance is crucial in bridging the gap between the energy efficiency requirements set by energy codes and the actualized energy savings achieved. An energy code compliance evaluation serves as a mechanism to assess construction practices, evaluate the effectiveness of code enforcement, identify gaps in compliance, and guide strategies for improvement through training and education. Conducting code compliance evaluation activities involves field studies that require careful design and significant resources. Historically, more emphasis has been placed on developing and adopting building energy codes, while efforts to evaluate compliance have been relatively limited and lacking consistent approaches. The passage of the 2009 American Recovery and Reinvestment Act (ARRA), which mandated that states create plans for achieving 90% compliance within eight years, stimulated the need for an energy code compliance evaluation. As a result, federal, state, and local governments, and utilities have invested in the development of methodologies and tools for code compliance evaluation studies. This paper reviews the code compliance evaluation studies conducted in the United States over the past three decades. It describes and compares the methodologies and metrics used to assess building energy code compliance, summarizes the general elements and steps involved in the evaluation process, and discusses common issues in these studies. Over time, code compliance evaluation methodologies have evolved from isolated development within individual states, regions, and utilities, to widely accepted protocols applicable across different states and local jurisdictions. There has been a transition in compliance metrics, shifting from historical compliance rates to energy-consumption-oriented approaches.
Full article
(This article belongs to the Special Issue Building Energy Audits-Diagnosis and Retrofitting towards Decarbonization and Sustainable Cities)
Open AccessArticle
The Condensation Characteristics of Propane in Binary and Ternary Mixtures on a Vertical Plate
Energies 2023, 16(16), 5873; https://doi.org/10.3390/en16165873 - 08 Aug 2023
Abstract
Natural gas is one of the most common forms of energy in our daily life, and it is composed of multicomponent hydrocarbon gas mixtures (mainly of methane, ethane and propane). It is of great significant to reveal the condensation mechanism of multicomponent mixtures
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Natural gas is one of the most common forms of energy in our daily life, and it is composed of multicomponent hydrocarbon gas mixtures (mainly of methane, ethane and propane). It is of great significant to reveal the condensation mechanism of multicomponent mixtures for the development and utilization of natural gas. A numerical model was adopted to analyze the heat and mass transfer characteristics of propane condensation in binary and ternary gas mixtures on a vertical cold plate. Multicomponent diffusion equations and the volume of fluid method (VOF) are used to describe the in-phase and inter-phase transportation. The conditions of different wall sub-cooled temperatures (temperature difference between the wall and saturated gas mixture) and the inlet molar fraction of methane/ethane are discussed. The numerical results show that ethane gas is more likely to accumulate near the wall compared with the lighter methane gas. The thermal resistance in the gas boundary layer is one hundred times higher than that of the liquid film, revealing the importance of diffusion resistance. The heat transfer coefficients increased about 11% (at ΔT = 10 K) and 7% (at ΔT = 40 K), as the molar fraction of ethane increased from 0 to 40%. Meanwhile, the condensation heat transfer coefficient decreased by 53~56% as the wall sub-cooled temperature increased from 10 K to 40 K.
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(This article belongs to the Special Issue Fluid, Energy and Thermal Comfort in Buildings)
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Drivers, Motivations, and Barriers in the Creation of Energy Communities: Insights from the City of Segrate, Italy
Energies 2023, 16(16), 5872; https://doi.org/10.3390/en16165872 - 08 Aug 2023
Abstract
Energy communities (ECs) are considered significant instruments in the energy transition toward a low-carbon world. Important elements for the creation of ECs are the individual drivers, motivations, and barriers that could stimulate their creation. In this article, we focus on developing
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Energy communities (ECs) are considered significant instruments in the energy transition toward a low-carbon world. Important elements for the creation of ECs are the individual drivers, motivations, and barriers that could stimulate their creation. In this article, we focus on developing an understanding of which aspects favor or slow down the establishment of ECs in the community of Segrate (Italy). From a methodological point of view, the authors present a study based on (i) a preliminary desk analysis, consisting of an extensive and multidisciplinary literature review; (ii) an empirical investigation into the case study of Segrate (a municipality in the Lombardy region, Italy), including energy-related data and geospatial information (i.e., from the census and geographic information system); and (iii) data analysis and the collection of original materials incorporating quantitative and qualitative information (based on online surveys and on-the-spot participatory events) relating to the context. As emerges from the survey, in Segrate (considered a typical European middle-sized city), it is difficult to identify the best physical dimension for ECs: the scale of Segrate’s neighborhoods do not correspond to the EC dimension usually referred to in the literature. In Segrate, the neighborhoods encompass between 4000 and 8000 inhabitants, while existing ECs (with heating systems) cover between 20 and 1200 apartments. Multi-vector ECs are forecastable with 10–20 apartments.
Full article
(This article belongs to the Section G1: Smart Cities and Urban Management)
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Open AccessArticle
Three-Dimensional Geological Modeling and Resource Estimation of Hot Dry Rock in the Gonghe Basin, Qinghai Province
Energies 2023, 16(16), 5871; https://doi.org/10.3390/en16165871 - 08 Aug 2023
Abstract
The Gonghe Basin, situated on the northeastern margin of the Qinghai–Tibet Plateau, is a strike-slip pull-apart basin that has garnered considerable attention for its abundant high-temperature geothermal resources. However, as it is located far from the Himalayan geothermal belt, research on the geothermal
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The Gonghe Basin, situated on the northeastern margin of the Qinghai–Tibet Plateau, is a strike-slip pull-apart basin that has garnered considerable attention for its abundant high-temperature geothermal resources. However, as it is located far from the Himalayan geothermal belt, research on the geothermal resources in the Gonghe Basin has mainly focused on the heat source mechanism, with less attention given to the distribution and resource potential of hot dry rock. In this project, a comprehensive approach combining geological surveys, geophysical exploration, geochemical investigations, and deep drilling was employed to analyze the stratigraphic structure and lithological composition of the Gonghe Basin, establish a basin-scale three-dimensional geological model, and identify the lithological composition and geological structures within the basin. The model revealed that the target reservoirs of hot dry rock in the Gonghe Basin exhibit a half-graben undulation pattern, with burial depths decreasing from west to east and reaching a maximum depth of around 7000 m. Furthermore, the distribution of the temperature field in the area was determined, and the influence of temperature on rock density and specific heat was investigated to infer the thermal properties of the deep reservoirs. The Qiabuqia region, situated in the central-eastern part of the basin, was identified as a highly favorable target area for hot dry rock exploration and development. The volume method was used to evaluate the potential of hot dry rock resources in the Gonghe Basin, which was estimated to be approximately 4.90 × 1022 J, equivalent to 1.67 × 1012 t of standard coal, at depths of up to 10 km.
Full article
(This article belongs to the Special Issue The Status and Development Trend of Geothermal Resources)
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Open AccessArticle
Research on the Design of Carbon-Neutralized Building in Rural China: A Case Study of “Impression of Yucun”
Energies 2023, 16(16), 5870; https://doi.org/10.3390/en16165870 - 08 Aug 2023
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Energy conservation and emission reduction in rural buildings is essential to China’s response to climate change. Within the context of China’s ‘dual carbon’ initiative and the overarching goal of a ‘zero carbon countryside’, the first rural carbon-neutral building in China—‘Impression of Yucun’ was
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Energy conservation and emission reduction in rural buildings is essential to China’s response to climate change. Within the context of China’s ‘dual carbon’ initiative and the overarching goal of a ‘zero carbon countryside’, the first rural carbon-neutral building in China—‘Impression of Yucun’ was established in Anji County, Zhejiang Province. Accordingly, this study investigates building carbon-neutral design, calculating and analyzing the carbon emissions and offsets facilitated by carbon neutrality technology throughout the buildings’ life cycle. In addition, the comprehensive benefits of the buildings are evaluated from both technical and economic perspectives. The implementation pathway for rural carbon-neutral buildings is also explored. The results demonstrate that through the judicious application of carbon neutrality technology design, the inherent carbon emissions of the buildings amount to 120.91 t and the energy consumption during the operational phase of the building is 64,284.4 kWh/a, correlating to carbon emissions of 33.72 t. The case can theoretically reduce carbon emissions by 65.64 tCO2 annually by implementing carbon offset measures. Considering photovoltaic cell decay, the building can achieve a carbon-neutral state for the first time in the fifth year of operation, with a net carbon emission of −5.58 tCO2. Simultaneously, the investment in photovoltaic systems can be recouped between the seventh and ninth years of operation. This study can offer methodological reference and data support for designing and evaluating carbon-neutral buildings.
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Open AccessArticle
Performance Analysis of Solar Tracking Systems by Five-Position Angles with a Single Axis and Dual Axis
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, , , , , , , , , , , and
Energies 2023, 16(16), 5869; https://doi.org/10.3390/en16165869 - 08 Aug 2023
Abstract
This research presents an analysis of the five-position angle in both single-axis (one-axis tracking) and dual-axis (two-axis tracking) solar tracking systems. The study compares these tracking systems, where four solar panels move simultaneously, with a fixed solar panel system. The findings revealed that
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This research presents an analysis of the five-position angle in both single-axis (one-axis tracking) and dual-axis (two-axis tracking) solar tracking systems. The study compares these tracking systems, where four solar panels move simultaneously, with a fixed solar panel system. The findings revealed that the five-position angle Sun-tracking technique resulted in lower energy consumption by the tracking mechanism than in the case of an all-time solar tracking system. The key component of the implemented system is a light-dependent resistor (LDR) sensor for controlling the motion of the motor for five positions on the vertical axis and horizontal axis, processed by a microcontroller to ensure the necessary solar tracking always moves in a perpendicular direction. According to the results, the voltage, current, and power increased with both one-axis and two-axis tracking compared to those of the fixed solar panel system under the same conditions. However, when evaluating the total energy with numerical integration methods, one-axis and two-axis provided 183.12 Wh and 199.79 Wh, respectively. Consequently, the energy production of the one-axis tracking system and the one-axis tracking system was found to be 16.71% and 24.97%, respectively, when compared to the fixed-axis system. Thus, the five-position angles of the sun-tracking technique resulted in lower energy consumption than is the case of an all-time solar tracking system.
Full article
(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)
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Open AccessReview
Current Progress of Efficient Active Layers for Organic, Chalcogenide and Perovskite-Based Solar Cells: A Perspective
by
, , , , , and
Energies 2023, 16(16), 5868; https://doi.org/10.3390/en16165868 - 08 Aug 2023
Abstract
Photovoltaics has become one of the emerging alternatives to progressively supply/replace conventional energy sources, considering the potential exploitation of solar energy. Depending on the nature of the light harvester to influence on its light-absorption capability and the facility to produce electricity, different generations
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Photovoltaics has become one of the emerging alternatives to progressively supply/replace conventional energy sources, considering the potential exploitation of solar energy. Depending on the nature of the light harvester to influence on its light-absorption capability and the facility to produce electricity, different generations of solar devices have been fabricated. Early studies of organic molecules (dye sensitizers) with good absorption coefficients, going through metal chalcogenides and, lastly, the timely emergence of halide perovskites, have promoted the development of novel and low-cost solar cells with promising photoconversion efficiency (PCE), close to the well-established Si-based devices. However, main drawbacks such as the degradation/photocorrosion of the active layer, the existence of intrinsic defect sites, and the inherent toxicity of the material due to the presence of some harmful elements have blocked the future commercialization of the above kind of solar cells. In this review, we highlight the current progress in achieving efficient photomaterials for organic, chalcogenides and halide perovskites-based solar cells with the purpose of achieving high PCE values, some of which are breakthroughs in this research topic, and the diverse approaches used to extend the stability of the active layer and improve the performance of the solar devices.
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(This article belongs to the Special Issue Advanced Technologies of Solar Cells)
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Open AccessArticle
Technique for Reactive Loss Reduction and Loading Margin Enhancement Using the Curves of Losses versus Voltage Magnitude
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, , , , and
Energies 2023, 16(16), 5867; https://doi.org/10.3390/en16165867 - 08 Aug 2023
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This paper presents an alternative methodology to obtain the precise amount of shunt reactive power compensation in order to simultaneously reduce the total reactive power losses, improve the voltage profile and increase the loading margin of power systems. The amount of shunt reactive
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This paper presents an alternative methodology to obtain the precise amount of shunt reactive power compensation in order to simultaneously reduce the total reactive power losses, improve the voltage profile and increase the loading margin of power systems. The amount of shunt reactive power compensation to be allocated is determined based on the curve of the total reactive power losses versus the voltage magnitude of a chosen bus. The best places for shunt reactive compensation are defined by the load bus participation factors of the critical mode provided by the static modal analysis. Simulation results employing shunt capacitors obtained with the new approach for the IEEE test systems (14, 57 and 300 buses) show that the procedure leads to a reduction in total reactive and active power losses and simultaneously improves the voltage profile and loading margin.
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Open AccessArticle
Series FACTS Devices for Increasing Resiliency in Severe Weather Conditions
by
and
Energies 2023, 16(16), 5866; https://doi.org/10.3390/en16165866 - 08 Aug 2023
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Severe weather conditions are low-probability, high-impact events that affect grid operations. The majority of power outages are caused by severe weather conditions. Grid resiliency to weather events can be enhanced by decreasing the reliance on its affected sections. One way to do this
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Severe weather conditions are low-probability, high-impact events that affect grid operations. The majority of power outages are caused by severe weather conditions. Grid resiliency to weather events can be enhanced by decreasing the reliance on its affected sections. One way to do this is to reduce the power flow through lines vulnerable to severe weather. If a line is disconnected, its initial power flow is distributed through the neighbor lines, which may cause congestion in the grid. FACTS devices can be used to control the power flow of lines that have a higher chance of power outages. Most previous works do not consider weather events in power flow control. In this work, a linearized optimal power flow (OPF)–based algorithm is developed to minimize the real power flow of vulnerable lines considering the thermal limits of lines to prevent infeasible solutions; the simulation is fast, making it suitable for large-scale systems. The proposed optimization problem is presented as a mixed-integer linear program (MILP), making it capable of using short-term load forecasting due to its high solution speed. The proposed optimization problem considers multiple lines with different outage probabilities and the uncertainties of the weather forecast. Moreover, it estimates the power reduction in vulnerable lines due to changes in the series FACTS devices. The performance of the proposed optimization problem is tested on IEEE 14-, 30-, and 118-bus systems for several scenarios. The results are validated with the AC power flow results from MATPOWER.
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Open AccessArticle
Experimental Study on Wind Turbine Airfoil Trailing Edge Noise Reduction Using Wavy Leading Edges
Energies 2023, 16(16), 5865; https://doi.org/10.3390/en16165865 - 08 Aug 2023
Abstract
Aerodynamic noise produced by the rotating blade is an important hindrance for the rapid development of modern wind turbines. Among the various noise sources, the airfoil trailing edge noise contributes a lot to the wind turbine noise. The control of wind turbine airfoil
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Aerodynamic noise produced by the rotating blade is an important hindrance for the rapid development of modern wind turbines. Among the various noise sources, the airfoil trailing edge noise contributes a lot to the wind turbine noise. The control of wind turbine airfoil trailing edge self-noise by bio-inspired sinusoidal wavy leading edges is experimentally studied in a semi-anechoic chamber. The noise radiated by the baseline NACA 0012 airfoil and various wavy airfoils is measured using a planar microphone array consisting of fifty-two microphones. The noise source identifications are achieved by using the CLEAN-SC method. The effects of velocity and angle of attack on noise radiation of the baseline airfoil are analyzed in detail. The noise control law of the wavy amplitude and wavelength on airfoil trailing edge noise is explored. Based on the acoustic beamforming results, the noise control effects of the wavy leading edges are intuitively demonstrated. In general, the wavy leading edge with a larger amplitude and smaller wavelength has a better effect on the airfoil trailing edge noise reduction. The maximum sound pressure level reduction can be up to 33.9 dB. The results of this study are expected to provide important information for wind turbine aerodynamic noise control.
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(This article belongs to the Special Issue Advanced Research and Methods of Noise Control for Wind Turbine)
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Open AccessArticle
Dynamic Analysis of a Supercapacitor DC-Link in Photovoltaic Conversion Applications
by
, , , , , and
Energies 2023, 16(16), 5864; https://doi.org/10.3390/en16165864 - 08 Aug 2023
Abstract
In this work, a dynamic analysis describing the charge and discharge process of a supercapacitor for the DC-link between a photovoltaic source and a constant power load is presented. The analysis results in a complete nonlinear and dynamic model that can be used
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In this work, a dynamic analysis describing the charge and discharge process of a supercapacitor for the DC-link between a photovoltaic source and a constant power load is presented. The analysis results in a complete nonlinear and dynamic model that can be used for simulation and control for DC–DC converters, achieving fast recharge times and accurate steady-state voltages in the DC link to avoid overcharging the supercapacitor during low power absorption scenarios. The proposed approach includes parasitic elements for the supercapacitor and efficiency effects on the conversion stage, proposing equations useful for design and control. Stability is also discussed for the charge process of the supercapacitor. Validation of the analytical model is performed by comparison with LTSpice simulation, confirming a good agreement between theory and simulation.
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(This article belongs to the Special Issue Advanced DC-DC Power Converters and Switching Converters II)
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Open AccessArticle
Renewable Energy Management in European Union Member States
Energies 2023, 16(16), 5863; https://doi.org/10.3390/en16165863 - 08 Aug 2023
Abstract
This article presents information on energy carriers from renewable sources and their share in the energy balance of the European Union Member States. The subject is extremely dynamic, and this field is still developing. The European Union is constantly implementing new programs to
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This article presents information on energy carriers from renewable sources and their share in the energy balance of the European Union Member States. The subject is extremely dynamic, and this field is still developing. The European Union is constantly implementing new programs to help Europe go green. Based on the analysis of statistical data, the scale and manner of using energy from renewable sources in each of the EU Member States have been presented and compared. The article also presents indicators of the share of total and sectoral energy from renewable sources in gross final energy consumption, monitoring the implementation of EU commitments.
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(This article belongs to the Section B2: Clean Energy)
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Open AccessArticle
Mass Transfer Analysis of CO2-Water-Rock Geochemical Reactions in Reservoirs
Energies 2023, 16(16), 5862; https://doi.org/10.3390/en16165862 - 08 Aug 2023
Abstract
It is difficult to exploit low-permeability reservoirs, and CO2 flooding is an effective method to improve oil recovery from low permeability reservoirs. However, in the process of CO2 flooding, acidic fluids dissolved in formation water will react with rock to cause
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It is difficult to exploit low-permeability reservoirs, and CO2 flooding is an effective method to improve oil recovery from low permeability reservoirs. However, in the process of CO2 flooding, acidic fluids dissolved in formation water will react with rock to cause dissolution and precipitation, resulting in pores and precipitates, changing the evolution law of seepage channels, destroying formation integrity, and affecting the effect of CO2 oil displacement. The change in rock’s physical properties and the mass transfer law between CO2-water-rock are unclear. This paper considers the coupling effects of seepage, mechanics, and chemistry when CO2 is injected into the formation. The mass transfer model of CO2-water-rock in the geochemical reaction process is established on this basis. The physical properties of the reservoir after CO2 injection are quantitatively studied based on the microscopic mechanism of chemical reaction, and the migration law of solute in the reservoir rock during CO2 flooding under the coupling effects of multiple fields is clarified. The experimental results show that with the increase in reaction time, the initial dissolution reaction of formation rocks will be transformed into a precipitation reaction of calcite, magnesite, and clay minerals. The porosity and permeability of the rocks near the well first increase and then decrease. The far well end is still dominated by dissolution reactions, and the average values of formation porosity and permeability show an upward trend. Although the dissolution reaction of CO2-water-rock can improve the physical properties of reservoir rocks to a certain extent, the mutual transformation of the dissolution reaction and precipitation reaction further exacerbates the heterogeneity of formation pore structure, leading to the instability of CO2 migration, uneven displacement, and destruction of formation stability. The research results of this paper solve the problem of quantitative calculation of physical parameters under the coupling effect of multiple fields after CO2 injection into reservoirs and can predict the changes in formation physical properties, which can provide a certain theoretical basis for evaluating formation integrity and adjusting CO2 injection under the condition of CO2 flooding.
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(This article belongs to the Special Issue CO2 Enhanced Oil Recovery and Carbon Sequestration)
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