Research

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16 pages, 6078 KiB

Open AccessArticle

Technology Originality and Convergence Analysis in the Wind Power Field Using Patents

by Kyungwon Joo, Mina Lee and Gooyong Lee

Energies 2022, 15(9), 3316; https://doi.org/10.3390/en15093316 - 02 May 2022

Cited by 5 | Viewed by 2164

Currently, the world is moving rapidly toward carbon neutrality, and renewable energy technology is very important in carbon neutrality. Among various renewable energy technologies, wind power is attracting much attention due to its sustainability, resource abundance, and high applicability. This study analyzed wind [...] Read more.

Currently, the world is moving rapidly toward carbon neutrality, and renewable energy technology is very important in carbon neutrality. Among various renewable energy technologies, wind power is attracting much attention due to its sustainability, resource abundance, and high applicability. This study analyzed wind power patents from 2010 to 2021 to derive current global originality and convergence information. For IP5 countries, the growth stages of technology and the patent convergence networks were inferred by time series analysis and an association rule mining algorithm, respectively. The results showed that, during the analysis period, about 5000 patents were applied on annual average, and it was analyzed that China held the most patents at 48%, followed by the US, Europe, Korea, and Japan. According to the technology convergence network of patent codes from all the IP5 countries, patents related to ‘wind turbines with rotation axes in the wind direction’ occupied a very central position, and ‘power conversion electric or electronic aspects’ and ‘integration of patents related to renewable energy sources in buildings with wind power’ were found to show high connection strength. By country, it was analyzed that the US and China showed high patent competitiveness onshore and possessed many ‘independent power conversion cluster’ technologies. The research hypothesis was that technology development trends can be analyzed and the characteristics of each country can be understood through patent analysis in the wind power field. This hypothesis was analyzed through various patent analysis techniques, and this paper has novelty in that it presents the global megatrend in the wind power field through patent analysis and quantitatively presents the current status of technology development in five major countries. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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14 pages, 12675 KiB

Open AccessArticle

Effect of Rotational Control for Accelerating Water Discharge on the Performance of a Circular Polymer Electrolyte Membrane Fuel Cell

by Ji-Seong Kim, Keon-Soo Kim, Do-Young Kim, Min Heo and Kap-Seung Choi

Energies 2022, 15(8), 2843; https://doi.org/10.3390/en15082843 - 13 Apr 2022

Cited by 2 | Viewed by 1063

Abstract

Polymer electrolyte membrane fuel cells are emerging as an important research topic owing to increasingly intensified environmental pollution. The flow field pattern of the fuel cell controls the electrochemically uniform distribution and water flooding in the reaction area between the anode and cathode. [...] Read more.

Polymer electrolyte membrane fuel cells are emerging as an important research topic owing to increasingly intensified environmental pollution. The flow field pattern of the fuel cell controls the electrochemically uniform distribution and water flooding in the reaction area between the anode and cathode. Water discharge management in the channel is an important factor influencing the efficiency of the fuel cell. In this paper, we propose a polymer electrolyte fuel cell with a rotatable circular spiral channel set to a constant size. The mass transfer behavior was analyzed numerically according to the number of channel passes. Numerical analysis showed that the production and behavior of water are closely associated with the performance of fuel cells. The circular spiral-pattern fuel cell with the greatest membrane water content was rotated through the experimental device to confirm the performance change of the fuel cell for each rotation speed. The performance improved as the internal water was ejected by the rotational centrifugal force. However, when excessive rotation was applied, the performance decreased because the water was forcibly drained out by a strong centrifugal force. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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19 pages, 2622 KiB

Open AccessArticle

Technical Control and Optimal Dispatch Strategy for a Hybrid Energy System

by Laetitia Uwineza, Hyun-Goo Kim, Jan Kleissl and Chang Ki Kim

Energies 2022, 15(8), 2744; https://doi.org/10.3390/en15082744 - 08 Apr 2022

Cited by 7 | Viewed by 2176

Abstract

Optimal dispatch is a major concern in the optimization of hybrid energy systems (HESs). Efficient and effective dispatch models that satisfy the load demand at the minimum net present cost (NPC) are crucial because of the high capital costs of renewable energy technologies. [...] Read more.

Optimal dispatch is a major concern in the optimization of hybrid energy systems (HESs). Efficient and effective dispatch models that satisfy the load demand at the minimum net present cost (NPC) are crucial because of the high capital costs of renewable energy technologies. The dispatch algorithms native to hybrid optimization of multiple energy resources (HOMER) software, cycle-charging (CC) and load-following (LF), are powerful for modeling and optimizing HESs. In these control strategies, the decision to use fuel cell systems (FCs) or battery energy storage systems (BESs) at each time step is made based on the lowest cost choice. In addition, the simultaneous operation of a FC with a BES reduces the operating efficiency of the FC. These deficiencies can affect the optimal design of HESs. This study introduces a dispatch algorithm specifically designed to minimize the NPC by maximizing the usage of FCs over other components of HESs. The framework resolves the dispatch deficiencies of native HOMER dispatch algorithms. The MATLAB Version 2021a, Mathworks Inc., Natick, MA, USA Link feature in HOMER software was used to implement the proposed dispatch (PD) algorithm. The results show that the PD achieved cost savings of 4% compared to the CC and LF control dispatch strategies. Furthermore, FCs contributed approximately 23.7% of the total electricity production in the HES, which is more than that of CC (18.2%) and LF (18.6%). The developed model can be beneficial to engineers and stakeholders when optimizing HESs to achieve the minimum NPC and efficient energy management. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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23 pages, 8817 KiB

Open AccessFeature PaperArticle

Atmospheric Stability Effects on Offshore and Coastal Wind Resource Characteristics in South Korea for Developing Offshore Wind Farms

by Geon Hwa Ryu, Young-Gon Kim, Sung Jo Kwak, Man Soo Choi, Moon-Seon Jeong and Chae-Joo Moon

Energies 2022, 15(4), 1305; https://doi.org/10.3390/en15041305 - 11 Feb 2022

Cited by 9 | Viewed by 2454

Abstract

South Korea is surrounded by the sea on three sides. The characteristics of offshore wind resources vary from region to region due to the influence of the distribution of the coastline and differences in roughness length and atmospheric stability between the coast and [...] Read more.

South Korea is surrounded by the sea on three sides. The characteristics of offshore wind resources vary from region to region due to the influence of the distribution of the coastline and differences in roughness length and atmospheric stability between the coast and the sea. In particular, turbulent gusts and low-level wind shear occurring near the hub height of the wind turbine within the atmospheric boundary layer have a significant effect on the load of wind turbines. These severe weather phenomena are closely related to atmospheric stability. Therefore, the objective of this study is to determine differences in wind resource characteristics in the South Korean offshore and coast in relation to variations in atmospheric stability using observation data from the HeMOSU-1 meteorological tower in the West Sea and the Boseong meteorological observation tower on the southern coast. On the southern coast, changes in sea and land breezes are observed throughout diurnal and nocturnal periods, with an atmospheric stability distribution similar to that of land, which is unstable during the day and becomes more stable at night. On the other hand, the stable ratio continues to dominate in the west offshore. In the case of coastal areas, low-level wind shear occasionally occurs near the general wind turbine hub height approximately over 100 m due to the influence of winds from the sea. This study shows that when constructing an offshore wind farm, it is necessary to first analyze the characteristics of local coastal and offshore wind resources for more efficient and safe wind farm construction and operation. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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20 pages, 13948 KiB

Open AccessArticle

Cell-to-Module Simulation Analysis for Optimizing the Efficiency and Power of the Photovoltaic Module

by Hasnain Yousuf, Muhammad Aleem Zahid, Muhammad Quddamah Khokhar, Jinjoo Park, Minkyu Ju, Donggun Lim, Youngkuk Kim, Eun-Chel Cho and Junsin Yi

Energies 2022, 15(3), 1176; https://doi.org/10.3390/en15031176 - 05 Feb 2022

Cited by 5 | Viewed by 2499

Abstract

A 60-cell photovoltaic (PV) module was analyzed by optimizing the interconnection parameters of the solar cells to enhance the efficiency and increase the power of the PV module setup. The cell-to-module (CTM) losses and gains varied substantially during the various simulation iterations. Optimization [...] Read more.

A 60-cell photovoltaic (PV) module was analyzed by optimizing the interconnection parameters of the solar cells to enhance the efficiency and increase the power of the PV module setup. The cell-to-module (CTM) losses and gains varied substantially during the various simulation iterations. Optimization was performed to inspect and augment the gain and loss parameters for the 60-cell PV module. The power and efficiency of the module were improved by refining several parameters, such as number of busbars, size of the contact pads, interconnected ribbon width, thickness of the core, and distance between the solar cells and strings, to obtain the maximum efficiency of 21.09%; the CTM efficiency achieved was 94.19% for the proposed strategy related to the common interconnection setup of the ribbon-based system. The CTM efficiency was improved by optimizing the geometrical, optical, and electrical parameters precisely, the power enhancement was up to 325.3 W, and a CTM power of 99.1% was achieved from a standard PV module with rectangular ribbon interconnections. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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16 pages, 42221 KiB

Open AccessArticle

Development of an Optimized Curtailment Scheme through Real-Time Simulation

by Jeong-Hwan Kim, Iseul Nam, Sungwoo Kang and Seungmin Jung

Energies 2022, 15(3), 1074; https://doi.org/10.3390/en15031074 - 31 Jan 2022

Cited by 2 | Viewed by 1782

Abstract

When a lot of surplus power occurs in wind power system, an output limit is implemented to directly or indirectly curtail the output to maintain a balance between the supply and demand of the power system. The curtailment process of a large-scale wind [...] Read more.

When a lot of surplus power occurs in wind power system, an output limit is implemented to directly or indirectly curtail the output to maintain a balance between the supply and demand of the power system. The curtailment process of a large-scale wind farm causes loss of power and mechanical loads. Resultantly, imbalanced curtailments often occur, resulting in unilateral burdens for the owners of wind farms. Considering the curtailment issue, the study for minimizing system loss of power plants is required in terms of operational efficiency. This paper proposes an algorithm to achieve flexible control during the actual power curtailment process in a wind farm, considering the wake effect. Here, the Monte Carlo method was adopted to calculate the curtailment weight in wind farms by using power loss terms. In addition, an equivalent model of a real wind farm was implemented and simulated through real simulation computer-aided design (RSCAD) software. This paper verified the effectiveness of the proposed method by applying the curtailment communication signal to a real-time digital simulator (RTDS). The results showed a reduction in the computational loading of individual wind turbine curtailment values with the decline of the total effective power loss. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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11 pages, 1039 KiB

Open AccessArticle

Modulation of Antioxidant Activity Enhances Photoautotrophic Cell Growth of Rhodobacter sphaeroides in Microbial Electrosynthesis

by Yu Rim Lee, Soo Youn Lee, Jiye Lee, Hui Su Kim, Jin-Suk Lee, Won-Heong Lee and Sangmin Lee

Energies 2022, 15(3), 935; https://doi.org/10.3390/en15030935 - 27 Jan 2022

Cited by 2 | Viewed by 2124

Abstract

Global warming is currently accelerating due to an increase in greenhouse gas emissions by industrialization. Microbial electrosynthesis (MES) using electroactive autotrophic microorganisms has recently been reported as a method to reduce carbon dioxide, the main culprit of greenhouse gas. However, there are still [...] Read more.

Global warming is currently accelerating due to an increase in greenhouse gas emissions by industrialization. Microbial electrosynthesis (MES) using electroactive autotrophic microorganisms has recently been reported as a method to reduce carbon dioxide, the main culprit of greenhouse gas. However, there are still few cases of application of MES, and the molecular mechanisms are largely unknown. To investigate the growth characteristics in MES, we carried out growth tests according to reducing power sources in Rhodobacter sphaeroides. The growth rate was significantly lower when electrons were directly supplied to cells, compared to when hydrogen was supplied. Through a transcriptome analysis, we found that the expression of reactive oxygen species (ROS)-related genes was meaningfully higher in MES than in normal photoautotrophic conditions. Similarly, endogenous contents of H₂O₂ were higher and peroxidase activities were lower in MES. The exogenous application of ascorbic acid, a representative biological antioxidant, promotes cell growth by decreasing ROS levels, confirming the inhibitory effects of ROS on MES. Taken together, our observations suggest that reduction of ROS by increasing antioxidant activities is important for enhancing the cell growth and production of CO₂-converting substances such as carotenoids in MES in R. sphaeroides Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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22 pages, 10449 KiB

Open AccessArticle

Seismic Fragility Assessment of a Novel Suction Bucket Foundation for Offshore Wind Turbine under Scour Condition

by Duc-Vu Ngo, Young-Jin Kim and Dong-Hyawn Kim

Energies 2022, 15(2), 499; https://doi.org/10.3390/en15020499 - 11 Jan 2022

Cited by 6 | Viewed by 2150

Abstract

This study proposed a new suction bucket (SB) foundation model for offshore wind turbines (OWT) suitable for a shallow muddy seabed, using more than three single buckets through kinetic derivation. The performance of new optimal foundation was evaluated by its horizontal displacement capacity [...] Read more.

This study proposed a new suction bucket (SB) foundation model for offshore wind turbines (OWT) suitable for a shallow muddy seabed, using more than three single buckets through kinetic derivation. The performance of new optimal foundation was evaluated by its horizontal displacement capacity and compared with a conventional SB composed of three buckets. Under external loads such as earthquakes, wind, and the combination of the both, the stability of this novel SB foundation was verified. The seismic fragility curve was also evaluated at some scour depths. These results were compared with the response of a tripod suction bucket (TSB) foundation, which was also designed for a shallow muddy seabed. The results indicated that scour significantly changed the dynamic response of this novel SB foundation but it had a better bearing capacity than the TSB foundation, despite its smaller size and weight. The fragility of TSB is always higher than the developed foundation in the same environmental condition. With reasonable volume and size, this novel SB foundation has great potential for future industrialization and commercialization. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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Review

Jump to: Research

13 pages, 3433 KiB

Open AccessReview

Review of the Liquid Hydrogen Storage Tank and Insulation System for the High-Power Locomotive

by Daehoon Kang, Sungho Yun and Bo-kyong Kim

Energies 2022, 15(12), 4357; https://doi.org/10.3390/en15124357 - 15 Jun 2022

Cited by 15 | Viewed by 7951

Abstract

Hydrogen has been attracting attention as a fuel in the transportation sector to achieve carbon neutrality. Hydrogen storage in liquid form is preferred in locomotives, ships, drones, and aircraft, because these require high power but have limited space. However, liquid hydrogen must be [...] Read more.

Hydrogen has been attracting attention as a fuel in the transportation sector to achieve carbon neutrality. Hydrogen storage in liquid form is preferred in locomotives, ships, drones, and aircraft, because these require high power but have limited space. However, liquid hydrogen must be in a cryogenic state, wherein thermal insulation is a core problem. Inner materials, including glass bubbles, multi-layer insulation (MLI), high vacuum, and vapor-cooled shields, are used for thermal insulation. An analytic study is preferred and proceeds liquid hydrogen tanks due to safety regulations in each country. This study reviewed the relevant literature for thermodynamic modeling. The literature was divided into static, dynamic, and systematic studies. In summary, the authors summarized the following future research needs: The optimal design of the structure, including suspension, baffle, and insulation system, can be studied to minimize the boil-off gas (BOG). A dynamic study of the pressure, mass flow, and vaporizer can be completed. The change of the components arrangement from the conventional diesel–electric locomotive is necessary. Full article

(This article belongs to the Special Issue Selected Papers from the 10th Asia-Pacific Forum on Renewable Energy (AFORE 2021))

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