Editorial

4 pages, 177 KiB

Open AccessEditorial

Green Energy Technology

by Wei-Hsin Chen, Hwai Chyuan Ong, Shih-Hsin Ho and Pau Loke Show

Energies 2021, 14(20), 6842; https://doi.org/10.3390/en14206842 - 19 Oct 2021

Cited by 4 | Viewed by 1826

Our environment is facing several serious challenges from energy utilization, such as fossil fuel exhaustion, air pollution, deteriorated atmospheric greenhouse effect, global warming, climate change, etc [...] Full article

(This article belongs to the Special Issue Green Energy Technology)

Research

Jump to: Editorial

17 pages, 5250 KiB

Open AccessArticle

Performance Analysis of a Printed Circuit Heat Exchanger with a Novel Mirror-Symmetric Channel Design

by Cheng-Yen Chang, Wei-Hsin Chen, Lip Huat Saw, Arjay Avilla Arpia and Manuel Carrera Uribe

Energies 2021, 14(14), 4252; https://doi.org/10.3390/en14144252 - 14 Jul 2021

Cited by 7 | Viewed by 4201

Abstract

The printed circuit heat exchanger (PCHE) is a promising waste heat recovery technology to improve energy efficiency. The current investigation presents the experimental results on the thermal performance of a novel PCHE for low-temperature waste heat recovery. The novel PCHE was manufactured using [...] Read more.

The printed circuit heat exchanger (PCHE) is a promising waste heat recovery technology to improve energy efficiency. The current investigation presents the experimental results on the thermal performance of a novel PCHE for low-temperature waste heat recovery. The novel PCHE was manufactured using precision machining and diffusion bonding. The thermal performances, such as effectiveness and NTU values at different temperatures, are evaluated, and water is used as a working fluid. The experimental results indicate that the PCHE’s effectiveness is around 0.979 for an inlet flow temperature of 95 °C. The predominant factors affecting the thermal performance of the PCHE are the inlet flow temperature and the flow rate of the working fluid. In addition, a comparison of the experimental results and the literature shows that the effectiveness of the PCHE is better than the others, which have fewer layers of PCHE fins. Full article

(This article belongs to the Special Issue Green Energy Technology)

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12 pages, 1832 KiB

Open AccessArticle

Success Factors for the Implementation of Community Renewable Energy in Thailand

by Nilubon Luangchosiri, Takaya Ogawa, Hideyuki Okumura and Keiichi N. Ishihara

Energies 2021, 14(14), 4203; https://doi.org/10.3390/en14144203 - 12 Jul 2021

Cited by 4 | Viewed by 2076

Abstract

Community renewable energy (CRE) has recently been proposed as one of the effective policy tools to make a community sustainable and to strengthen this association. CRE is, however, not widespread yet in Thailand, and evidence-based research on CRE in the country is rather [...] Read more.

Community renewable energy (CRE) has recently been proposed as one of the effective policy tools to make a community sustainable and to strengthen this association. CRE is, however, not widespread yet in Thailand, and evidence-based research on CRE in the country is rather scarce. This paper aims to investigate the characteristics of CRE in Thailand to identify the key factors affecting its implementation. Data were collected through semi-structured interviews and document analysis for 26 active CRE projects in Thailand. Results show that the characteristics of CRE in Thailand are rooted in the geographical location of a community. A legal structure was created from a pre-existing group to implement a CRE project. The primary motivation for implementing CRE is sustainable development of a community. We examined essential factors separated into two groups—internal and external factors—in reference to CRE in developed nations. We highlight several issues concerning the further development of CRE in Thailand. First, a strong group leader and a formal structure are essential to drive and manage a project. Second, networks of CRE projects and long-term revolving funds are crucial external support to implement CRE. Full article

(This article belongs to the Special Issue Green Energy Technology)

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17 pages, 7010 KiB

Open AccessArticle

Experimental Investigation of Illumination Performance of Hollow Light Pipe for Energy Consumption Reduction in Buildings

by Jiraphorn Mahawan and Atthakorn Thongtha

Energies 2021, 14(2), 260; https://doi.org/10.3390/en14020260 - 06 Jan 2021

Cited by 7 | Viewed by 2142

Abstract

This work investigates the light illumination intensity, light transmission performance, light distribution on the floor, and daylight factor of vertical light hollow tubes at various incident elevation angles of a light source. The light tubes were made from commercial aluminum alloy sheets and [...] Read more.

This work investigates the light illumination intensity, light transmission performance, light distribution on the floor, and daylight factor of vertical light hollow tubes at various incident elevation angles of a light source. The light tubes were made from commercial aluminum alloy sheets and commercial zinc alloy sheets to investigate internal illuminance for buildings and reducing the demand of electrical energy from artificial lighting. The vertical light tubes with a constant length of 0.5 m and diameters of 0.20, 0.25, and 0.30 m were designed in a testing room model, with dimensions of 1 m × 1 m × 1 m. A 20-W light-emitting diode (LED) lamp was used as the light source for the lighting simulations, which was placed away from the top of the light tube. The incident elevation angle of the light source was changed between 0° and 80° with 5° increments. It was found that the elevation angle of the incidence light had an influence on the light intensity distribution on both ends of light tube. The average illuminance performance of both material types increased with an increase of the incidence angle from 0° to 80° and an increase of the tube diameter from 0.20 m to 0.30 m. The commercial aluminum alloy tube promotes greater light transmission and daylight factor when compared with the commercial zinc alloy tube in each condition. This illuminance measurement demonstrates that the light tube could be included in the lighting systems of some deeper or windowless areas of buildings to decrease the demand of energy consumption in the lighting of buildings. Full article

(This article belongs to the Special Issue Green Energy Technology)

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26 pages, 4197 KiB

Open AccessArticle

An Estimation of Hydraulic Power Take-off Unit Parameters for Wave Energy Converter Device Using Non-Evolutionary NLPQL and Evolutionary GA Approaches

by Mohd Afifi Jusoh, Mohd Zamri Ibrahim, Muhamad Zalani Daud, Zulkifli Mohd Yusop and Aliashim Albani

Energies 2021, 14(1), 79; https://doi.org/10.3390/en14010079 - 25 Dec 2020

Cited by 11 | Viewed by 2509

Abstract

This study is concerned with the application of two major kinds of optimisation algorithms on the hydraulic power take-off (HPTO) model for the wave energy converters (WECs). In general, the HPTO unit’s performance depends on the configuration of its parameters such as hydraulic [...] Read more.

This study is concerned with the application of two major kinds of optimisation algorithms on the hydraulic power take-off (HPTO) model for the wave energy converters (WECs). In general, the HPTO unit’s performance depends on the configuration of its parameters such as hydraulic cylinder size, hydraulic accumulator capacity and pre-charge pressure and hydraulic motor displacement. Conventionally, the optimal parameters of the HPTO unit need to be manually estimated by repeating setting the parameters’ values during the simulation process. However, such an estimation method can easily be exposed to human error and would subsequently result in an inaccurate selection of HPTO parameters for WECs. Therefore, an effective approach of using the non-evolutionary Non-Linear Programming by Quadratic Lagrangian (NLPQL) and evolutionary Genetic Algorithm (GA) algorithms for determining the optimal HPTO parameters was explored in the present study. A simulation–optimisation of the HPTO model was performed in the MATLAB/Simulink environment. A complete WECs model was built using Simscape Fluids toolbox in MATLAB/Simulink. The actual specifications of hydraulic components from the manufacturer were used during the simulation study. The simulation results showed that the performance of optimal HPTO units optimised by NLPQL and GA approaches have significantly improved up to 96% and 97%, respectively, in regular wave conditions. The results also showed that both optimal HPTO units were capable of generating electricity up to 62% and 77%, respectively, of their rated capacity in irregular wave circumstances. Full article

(This article belongs to the Special Issue Green Energy Technology)

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24 pages, 7221 KiB

Open AccessArticle

Water Conservation Potential of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics

by Koami Soulemane Hayibo, Pierce Mayville, Ravneet Kaur Kailey and Joshua M. Pearce

Energies 2020, 13(23), 6285; https://doi.org/10.3390/en13236285 - 28 Nov 2020

Cited by 14 | Viewed by 5591

Abstract

A potential solution to the coupled water–energy–food challenges in land use is the concept of floating photovoltaics or floatovoltaics (FPV). In this study, a new approach to FPV is investigated using a flexible crystalline silicon-based photovoltaic (PV) module backed with foam, which is [...] Read more.

A potential solution to the coupled water–energy–food challenges in land use is the concept of floating photovoltaics or floatovoltaics (FPV). In this study, a new approach to FPV is investigated using a flexible crystalline silicon-based photovoltaic (PV) module backed with foam, which is less expensive than conventional pontoon-based FPV. This novel form of FPV is tested experimentally for operating temperature and performance and is analyzed for water-savings using an evaporation calculation adapted from the Penman–Monteith model. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based FPV, and thus a 3.5% higher energy output per unit power. Therefore, foam-based FPV provides a potentially profitable means of reducing water evaporation in the world’s at-risk bodies of fresh water. The case study of Lake Mead found that if 10% of the lake was covered with foam-backed FPV, there would be enough water conserved and electricity generated to service Las Vegas and Reno combined. At 50% coverage, the foam-backed FPV would provide over 127 TWh of clean solar electricity and 633.22 million m³ of water savings, which would provide enough electricity to retire 11% of the polluting coal-fired plants in the U.S. and provide water for over five million Americans, annually. Full article

(This article belongs to the Special Issue Green Energy Technology)

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22 pages, 1683 KiB

Open AccessFeature PaperArticle

A Preliminary Assessment of the Potential of Low Percentage Green Hydrogen Blending in the Italian Natural Gas Network

by Marco Pellegrini, Alessandro Guzzini and Cesare Saccani

Energies 2020, 13(21), 5570; https://doi.org/10.3390/en13215570 - 23 Oct 2020

Cited by 41 | Viewed by 5647

Abstract

The growing rate of electricity generation from renewables is leading to new operational and management issues on the power grid because the electricity generated exceeds local requirements and the transportation or storage capacities are inadequate. An interesting option that is under investigation by [...] Read more.

The growing rate of electricity generation from renewables is leading to new operational and management issues on the power grid because the electricity generated exceeds local requirements and the transportation or storage capacities are inadequate. An interesting option that is under investigation by several years is the opportunity to use the renewable electricity surplus to power electrolyzers that split water into its component parts, with the hydrogen being directly injected into natural gas pipelines for both storage and transportation. This innovative approach merges together the concepts of (i) renewable power-to-hydrogen (P2H) and of (ii) hydrogen blending into natural gas networks. The combination of renewable P2H and hydrogen blending into natural gas networks has a huge potential in terms of environmental and social benefits, but it is still facing several barriers that are technological, economic, legislative. In the framework of the new hydrogen strategy for a climate-neutral Europe, Member States should design a roadmap moving towards a hydrogen ecosystem by 2050. The blending of “green hydrogen”, that is hydrogen produced by renewable sources, in the natural gas network at a limited percentage is a key element to enable hydrogen production in a preliminary and transitional phase. Therefore, it is urgent to evaluate at the same time (i) the potential of green hydrogen blending at low percentage (up to 10%) and (ii) the maximum P2H capacity compatible with low percentage blending. The paper aims to preliminary assess the green hydrogen blending potential into the Italian natural gas network as a tool for policy makers, grid and networks managers and energy planners. Full article

(This article belongs to the Special Issue Green Energy Technology)

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19 pages, 11794 KiB

Open AccessArticle

Design of Kinetic-Energy Harvesting Floors

by Thitima Jintanawan, Gridsada Phanomchoeng, Surapong Suwankawin, Phatsakorn Kreepoke, Pimsalisa Chetchatree and Chanut U-viengchai

Energies 2020, 13(20), 5419; https://doi.org/10.3390/en13205419 - 16 Oct 2020

Cited by 25 | Viewed by 11775

Abstract

Alternative energy generated from people’s footsteps in a crowded area is sufficient to power smart electronic devices with low consumption. This paper aims to present the development of an energy harvesting floor—called Genpath—using a rotational electromagnetic (EM) technique to generate electricity from human [...] Read more.

Alternative energy generated from people’s footsteps in a crowded area is sufficient to power smart electronic devices with low consumption. This paper aims to present the development of an energy harvesting floor—called Genpath—using a rotational electromagnetic (EM) technique to generate electricity from human footsteps. The dynamic models of the electro-mechanical systems were developed using MATLAB^®/Simulink to predict the energy performances of Genpath and help fine-tune the design parameters. The system in Genpath comprises two main parts: the EM generator and the Power Management and Storage (PMS) circuit. For the EM generator, the conversion mechanism for linear translation to rotation was designed by using the rack-pinion and lead-screw mechanism. Based on the simulation analysis, the averaged energy of the lead-screw model is greater than that of the rack-pinion model. Thus, prototype-II of Genpath with 12-V-DC generator, lead-screw mechanism was recently built. It shows better performance when compared to the previous prototype-I of Genpath with 24-V-DC-generator, rack-pinion mechanism. Both prototypes have an allowable displacement of 15 mm. The Genpath prototype-II produces an average energy of up to 702 mJ (or average power of 520 mW) per footstep. The energy provided by Genpath prototype-II is increased by approximately 184% when compared to that of the prototype-I. The efficiency of the EM-generator system is ~26% based on the 2-W power generation from the heel strike of a human’s walk in one step. Then, the PMS circuit was developed to harvest energy into the batteries and to supply the other part to specific loads. The experiment showed that the designed PMS circuit has the overall efficiency of 74.72%. The benefit of the design system is for a lot of applications, such as a wireless sensor and Internet of Thing applications. Full article

(This article belongs to the Special Issue Green Energy Technology)

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18 pages, 5611 KiB

Open AccessArticle

100% Renewable Energy Grid for Rural Electrification of Remote Areas: A Case Study in Jordan

by Loiy Al-Ghussain, Mohammad Abujubbeh, Adnan Darwish Ahmad, Ahmad M. Abubaker, Onur Taylan, Murat Fahrioglu and Nelson K. Akafuah

Energies 2020, 13(18), 4908; https://doi.org/10.3390/en13184908 - 18 Sep 2020

Cited by 21 | Viewed by 4669

Abstract

Many developing countries suffer from high energy-import dependency and inadequate electrification of rural areas, which aggravates the poverty problem. In this work, Al-Tafilah in Jordan was considered as a case study, where the technical, economic, and environmental benefits of a decentralized hybrid renewable [...] Read more.

Many developing countries suffer from high energy-import dependency and inadequate electrification of rural areas, which aggravates the poverty problem. In this work, Al-Tafilah in Jordan was considered as a case study, where the technical, economic, and environmental benefits of a decentralized hybrid renewable energy system that can match 100% of the city demand were investigated. A tri-hybrid system of wind, solar, and hydropower was integrated with an energy storage system and optimized to maximize the match between the energy demand and production profiles. The optimization aimed at maximizing the renewable energy system (RES) fraction while keeping the levelized cost of electricity (LCOE) equal to the electricity purchase tariff. The techno-economic analysis showed that the optimal system in Al-Tafilah comprises a 28 MW wind system, 75.4 MW PV, and 1 MW hydropower, with a 259 MWh energy storage system, for which a RES fraction of 99% can be achieved, and 47,160 MtCO₂ are avoided yearly. This study can be easily extended to other rural cities in Jordan, as they have higher renewable energy system (RES) potential. The presented findings are essential not only for Jordan’s planning and economy-boosting but also for contributing to the ongoing force against climate change. Full article

(This article belongs to the Special Issue Green Energy Technology)

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15 pages, 2213 KiB

Open AccessArticle

Experimental Study on the Performance of an SI Engine Fueled by Waste Plastic Pyrolysis Oil–Gasoline Blends

by Khairil, Teuku Meurah Indra Riayatsyah, Samsul Bahri, Sarwo Edhy Sofyan, Jalaluddin Jalaluddin, Fitranto Kusumo, Arridina Susan Silitonga, Yanti Padli, Muhammad Jihad and Abd Halim Shamsuddin

Energies 2020, 13(16), 4196; https://doi.org/10.3390/en13164196 - 14 Aug 2020

Cited by 12 | Viewed by 3731

Abstract

Pyrolyzed waste plastic-based green fuel has been reported to be used as an alternate fuel for diesel engines. Some of the main challenges for implementing this in current automotive technology include evaluating engine performance, emission, noise vibration harshness (NVH), and knock characteristics of [...] Read more.

Pyrolyzed waste plastic-based green fuel has been reported to be used as an alternate fuel for diesel engines. Some of the main challenges for implementing this in current automotive technology include evaluating engine performance, emission, noise vibration harshness (NVH), and knock characteristics of this fuel. This study focuses on the engine performance of poly-ethylene terephthalate (PET)-based waste plastic oil (WPO) at varying engine speed conditions. The pyrolysis of mixed-waste plastic was carried out at 300 °C in a fixed-bed reactor. Physicochemical properties such as viscosity, density, calorific value, sulfur, and research octane number (RON) of the plastic fuel and its blends with gasoline were analyzed using ASTM standard test methods. The WPO was blended with two different types of gasoline (RON88 and RON90) at 10, 20, and 30%, and was tested in a spark-ignition (SI) engine. The experimental results showed that different WPO–gasoline blends can be used in an SI engine without any engine modifications, and the performance indicators for different blends were found to be close to that of pure gasoline. The brake power and brake specific fuel consumption (BSFC) were found to be 4.1 kW and 0.309 kg/kW h, respectively. The 10% WPO and 90% RON90 blend produced optimal engine performance at 3500 rpm. Full article

(This article belongs to the Special Issue Green Energy Technology)

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26 pages, 506 KiB

Open AccessArticle

Value Co-Creation Behavior in Green Supply Chains: An Empirical Study

by Xianliang Shi, Genzhu Li, Ciwei Dong and Yefei Yang

Energies 2020, 13(15), 3902; https://doi.org/10.3390/en13153902 - 30 Jul 2020

Cited by 11 | Viewed by 3542

Abstract

As an important supply chain development strategy, green investment and sustainability are concerns of the government and enterprises. However, due to the high cost and low profit of green investment, a large number of small and medium-sized firms can be deterred from their [...] Read more.

As an important supply chain development strategy, green investment and sustainability are concerns of the government and enterprises. However, due to the high cost and low profit of green investment, a large number of small and medium-sized firms can be deterred from their implementation. Value co-creation has become a key measure to solve this problem. This article explores the relationship between the green supply chain (GSC) strategy, value co-creation, and corporate performance in the manufacturing environment, and considers the regulatory effects of internal environmental factors and external environmental pressures on this relationship. Based on data from 115 manufacturers in China, we tested the hypotheses, explained the statistical results, and identified key concerns for implementing GSC through value co-creation. The findings reveal that the GSC strategy can promote a high level of firms’ value co-creation with their supply chain partners, and different value co-creation modes have different effects on firm performance (i.e., operational performance, innovation performance, and financial performance). In addition, the findings indicate that macro-level external pressure and micro-level internal support could enhance such effects. This study enriches the literature with value co-creation modes and GSC management by integrating GSC strategies and value co-creation strategies, providing confidence to the firms and their supply chain partners in value co-creation, thus helping them to better implement a GSC strategy. Full article

(This article belongs to the Special Issue Green Energy Technology)

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18 pages, 4640 KiB

Open AccessArticle

Continuous Phenol Removal Using a Liquid–Solid Circulating Fluidized Bed

by Nandhini Sureshkumar, Samiha Bhat, Shwetha Srinivasan, Nirmala Gnanasundaram, Murugesan Thanapalan, Rambabu Krishnamoorthy, Hatem Abuhimd, Faheem Ahmed and Pau Loke Show

Energies 2020, 13(15), 3839; https://doi.org/10.3390/en13153839 - 27 Jul 2020

Cited by 18 | Viewed by 2214

Abstract

A liquid-solid circulating fluidized bed (LSCFB) helps to overcome the shortcomings of conventional fluidized beds by using a particle separation and return system as an integral part of the overall reactor configuration. Batch adsorption experiments were carried out for the removal of phenol [...] Read more.

A liquid-solid circulating fluidized bed (LSCFB) helps to overcome the shortcomings of conventional fluidized beds by using a particle separation and return system as an integral part of the overall reactor configuration. Batch adsorption experiments were carried out for the removal of phenol from a synthetically prepared solution using fresh activated-carbon-coated glass beads. The morphological features and surface chemistry of the adsorbent were analyzed via SEM and FTIR techniques. The adsorbent dosage, contact time and temperature were varied along with solution pH to assess their effects on the adsorbent performance for phenol removal. Isotherm modeling showed that the phenol removal using the activated-carbon glass beads followed the Langmuir model. Effectively, it was observed at an adsorbent loading of 2.5 g/150 mL of feed volume and a contact time of 3 h produced an 80% efficiency in the batch study. Furthermore, on scaling it up to the column, the desired 98% phenol-removal efficiency was obtained with an adsorbent dosage of 250 g and contact time of 25 min. Adsorbent regeneration using 5% (v/v) ethanol showed a 64% desorption of phenol from the sorbent within 20 min in the LSCFB. Full article

(This article belongs to the Special Issue Green Energy Technology)

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13 pages, 6282 KiB

Open AccessArticle

Influence of Two-Phase Crossflow for Void Prediction in Bundles Using Thermal-Hydraulic System Codes

by Yunseok Lee and Taewan Kim

Energies 2020, 13(14), 3686; https://doi.org/10.3390/en13143686 - 17 Jul 2020

Cited by 3 | Viewed by 1873

Abstract

The previous study, where the void fraction predictability of three different thermal-hydraulic system codes was assessed against PSBT (PWR Subchannel and Bundle Test) benchmark data, indicated a general overprediction tendency of all system codes, especially in bundles. Because all codes have been utilized [...] Read more.

The previous study, where the void fraction predictability of three different thermal-hydraulic system codes was assessed against PSBT (PWR Subchannel and Bundle Test) benchmark data, indicated a general overprediction tendency of all system codes, especially in bundles. Because all codes have been utilized for best-estimate analyses, it is necessary to conduct further assessments in order to find the root cause of the overprediction. A further assessment has been performed using two thermal-hydraulic system codes, TRACE V5.0 patch 5 and MARS-KS 1.4, and the assessment has been carried out for both one- and multi-dimensional components. The results indicate that there is no significant difference in the predictability of the void fraction between one- and multi-dimensional components. In addition, it is found that the turbulent mixing model implemented for the multi-dimensional component of MARS-KS does not play an important role in the prediction of void distribution. Meanwhile, TRACE reveals a significant overprediction due to much less crossflow calculation compared to MARS-KS. By conducting an additional analysis with the modified one-dimensional models, it is clearly confirmed that crossflow significantly affects the void distribution. Therefore, it is concluded that the model for the thermal hydraulic mixing by crossflow in each system code should be improved in order to predict the void distribution in bundles appropriately. Full article

(This article belongs to the Special Issue Green Energy Technology)

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22 pages, 1486 KiB

Open AccessFeature PaperArticle

The Philippines’ and Singapore’s Journeys towards Liberalised Electricity Supply Industries—Takeaways for Malaysia

by Hazleen Aris, Iskandar Shah Mohd Zawawi and Bo Nørregaard Jørgensen

Energies 2020, 13(14), 3514; https://doi.org/10.3390/en13143514 - 08 Jul 2020

Cited by 5 | Viewed by 4428

Abstract

Malaysia is in the process of liberalising its electricity supply industry (ESI) further, with the second reform series announced in September 2018. If everything goes as planned, Malaysia would be the third country in the Association of Southeast Asia Nations (ASEAN) to have [...] Read more.

Malaysia is in the process of liberalising its electricity supply industry (ESI) further, with the second reform series announced in September 2018. If everything goes as planned, Malaysia would be the third country in the Association of Southeast Asia Nations (ASEAN) to have a fully liberalised ESI after the Philippines and Singapore. A number of initiatives have been in the pipeline to be executed and a lot more will be planned. At this juncture, it is important for Malaysia to look for the best practices and lessons that can be learnt from the experience of other countries that have successfully liberalised their ESIs. Being in the same region, it is believed that there is a lot that Malaysia can learn from the Philippines and Singapore. This paper therefore presents and deliberates on the chronological development of the countries’ progressive journeys in liberalising their ESIs. The aim is to discern the good practices, the challenges as well as the lessons learnt from these transformations. Analysis is being made and discussed from the following four perspectives; legislative framework, implementation phases, market components and impact on renewable energy penetration. Findings from this study would provide useful insight for Malaysia in determining the course of actions to be taken to reform its ESI. Beyond Malaysia, the findings can also serve as the reference for the other ASEAN countries in moving towards liberalising their ESIs. Full article

(This article belongs to the Special Issue Green Energy Technology)

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15 pages, 428 KiB

Open AccessArticle

Policy Implications for the Clean Energy Transition: The Case of the Boston Area

by Almona Tani and Piergiuseppe Morone

Energies 2020, 13(10), 2615; https://doi.org/10.3390/en13102615 - 21 May 2020

Cited by 9 | Viewed by 2257

Abstract

In this paper, we investigate the transition to clean energy technologies in the Boston area, as perceived through the lens of strategic niche management. The main goal of the study was to assess the role of policy in fostering/hindering the development of the [...] Read more.

In this paper, we investigate the transition to clean energy technologies in the Boston area, as perceived through the lens of strategic niche management. The main goal of the study was to assess the role of policy in fostering/hindering the development of the clean energy niche and the complete deployment of clean energy technologies in this area. Using argumentative discourse analysis, our research showed that the clean energy niche in the Boston area is generally perceived as strong and dynamic. However, the public de-legitimizing narrative identified gaps at the policy level that include, among others, the limited engagement of the local and federal government in breaking through well-established practices and regulatory frameworks, funding, and infrastructure. These gaps are likely to delay the market uptake of clean energies in this area. Full article

(This article belongs to the Special Issue Green Energy Technology)

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13 pages, 4957 KiB

Open AccessArticle

Effect of Single-Row and Double-Row Passive Vortex Generators on the Deep Dynamic Stall of a Wind Turbine Airfoil

by Chengyong Zhu, Tongguang Wang, Jie Chen and Wei Zhong

Energies 2020, 13(10), 2535; https://doi.org/10.3390/en13102535 - 16 May 2020

Cited by 14 | Viewed by 2541

Abstract

Passive vortex generators (VGs) have been widely applied on wind turbines to boost the aerodynamic performance. Although VGs can delay the onset of static stall, the effect of VGs on dynamic stall is still incompletely understood. Therefore, this paper aims at investigating the [...] Read more.

Passive vortex generators (VGs) have been widely applied on wind turbines to boost the aerodynamic performance. Although VGs can delay the onset of static stall, the effect of VGs on dynamic stall is still incompletely understood. Therefore, this paper aims at investigating the deep dynamic stall of NREL S809 airfoil controlled by single-row and double-row VGs. The URANS method with VGs fully resolved is used to simulate the unsteady airfoil flow. Firstly, both single-row and double-row VGs effectively suppress the flow separation and reduce the fluctuations in aerodynamic forces when the airfoil pitches up. The maximum lift coefficient is therefore increased beyond 40%, and the onset of deep dynamic stall is also delayed. This suggests that deep dynamic-stall behaviors can be properly controlled by VGs. Secondly, there is a great difference in aerodynamic performance between single-row and double-row VGs when the airfoil pitches down. Single-row VGs severely reduce the aerodynamic pitch damping by 64%, thereby undermining the torsional aeroelastic stability of airfoil. Double-row VGs quickly restore the decreased aerodynamic efficiency near the maximum angle of attack, and also significantly accelerate the flow reattachment. The second-row VGs can help the near-wall flow to withstand the adverse pressure gradient and then suppress the trailing-edge flow separation, particularly during the downstroke process. Generally, double-row VGs are better than single-row VGs concerning controlling deep dynamic stall. This work also gives a performance assessment of VGs in controlling the highly unsteady aerodynamic forces of a wind turbine airfoil. Full article

(This article belongs to the Special Issue Green Energy Technology)

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12 pages, 5414 KiB

Open AccessArticle

Experimental Investigation of Natural Lighting Systems Using Cylindrical Glass for Energy Saving in Buildings

by Atthakorn Thongtha and Piromporn Boontham

Energies 2020, 13(10), 2528; https://doi.org/10.3390/en13102528 - 16 May 2020

Cited by 10 | Viewed by 1940

Abstract

This research focuses on the use of natural lighting integrated into buildings. Cylindrical glass was fitted into the top of our test model, which was 1 m × 1 m × 1 m, which enhanced the light inside it. The glass fitted comprised [...] Read more.

This research focuses on the use of natural lighting integrated into buildings. Cylindrical glass was fitted into the top of our test model, which was 1 m × 1 m × 1 m, which enhanced the light inside it. The glass fitted comprised a single layer (G), two layers (2G), or two layers of glass filled with distilled water (2GW). Each combination of glass increased the number of glass cylinders from two to six. The nine formats were tested indoors using a light intensity of 1000 W/m² and the temperature was controlled at 25 °C. The lowest temperature averaged 34.4 °C, which was recorded using only two glass cylinders that had two layers of glass filled with distilled water. The average internal illumination was 549 lux, which agreed with the CIE standard. Then, the two layers of glass filled with water were examined under natural conditions. It was found that the highest average inside temperature was 40.4 °C at 1:30 p.m. The average illuminant values for three days were in the range of 300–500–750 lux, which concurred with the CIE standard. Additionally, the use of the 2S-2GW resulted in the conservation of electrical energy consumed by the cooling load and the illumination of the building between 9:00 a.m. and 3:00 p.m. Full article

(This article belongs to the Special Issue Green Energy Technology)

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15 pages, 2871 KiB

Open AccessArticle

Microwave-Assisted Noncatalytic Esterification of Fatty Acid for Biodiesel Production: A Kinetic Study

by Hoang Chinh Nguyen, Fu-Ming Wang, Kim Khue Dinh, Thanh Truc Pham, Horng-Yi Juan, Nguyen Phuong Nguyen, Hwai Chyuan Ong and Chia-Hung Su

Energies 2020, 13(9), 2167; https://doi.org/10.3390/en13092167 - 01 May 2020

Cited by 10 | Viewed by 2873

Abstract

This study developed a microwave-mediated noncatalytic esterification of oleic acid for producing ethyl biodiesel. The microwave irradiation process outperformed conventional heating methods for the reaction. A highest reaction conversion, 97.62%, was achieved by performing esterification with microwave irradiation at a microwave power of [...] Read more.

This study developed a microwave-mediated noncatalytic esterification of oleic acid for producing ethyl biodiesel. The microwave irradiation process outperformed conventional heating methods for the reaction. A highest reaction conversion, 97.62%, was achieved by performing esterification with microwave irradiation at a microwave power of 150 W, 2:1 ethanol:oleic acid molar ratio, reaction time of 6 h, and temperature of 473 K. A second-order reaction model (R² of up to 0.997) was established to describe esterification. The reaction rate constants were promoted with increasing microwave power and temperature. A strong linear relation of microwave power to pre-exponential factors was also established, and microwave power greatly influenced the reaction due to nonthermal effects. This study suggested that microwave-assisted noncatalytic esterification is an efficient approach for biodiesel synthesis. Full article

(This article belongs to the Special Issue Green Energy Technology)

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