Energies

2024

Jump to: 2023, 2022

18 pages, 2737 KiB

Open AccessArticle

Micro Photosynthetic Power Cell Array for Energy Harvesting: Bio-Inspired Modeling, Testing and Verification

by Kirankumar Kuruvinashetti, Shanmuga Sundaram Pakkiriswami, Dhilippan M. Panneerselvam and Muthukumaran Packirisamy

Energies 2024, 17(7), 1749; https://doi.org/10.3390/en17071749 - 5 Apr 2024

Viewed by 7377

Abstract

A micro-photosynthetic power cell (µPSC) generates electricity through the exploitation of living photosynthetic organisms through the principles of photosynthesis and respiration. Modeling such systems will enhance insights into the µPSC that can be employed to design real-time applications from µPSC. In this study, [...] Read more.

A micro-photosynthetic power cell (µPSC) generates electricity through the exploitation of living photosynthetic organisms through the principles of photosynthesis and respiration. Modeling such systems will enhance insights into the µPSC that can be employed to design real-time applications from µPSC. In this study, the bio-inspired electrical equivalent modeling of the array of µPSC is elucidated. The model is validated for array configurations of the micro-photosynthetic power cells. The developed arrayed model foresees the steady-state response at various electrical loadings. The polarization characteristics of the current-voltage (I-V) and current-power (I-P) characteristics of the array of µPSC in series and parallel, and their combinations in series and parallel connected µPSCs were validated with the experimental results. From this analysis, it is predicted that the arraying of the µPSC in the combination of series and parallel is the optimal array strategy to obtain the desired voltage and current from the µPSC such that it can be used to power real-time low and ultra-low power devices. Full article

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13 pages, 1454 KiB

Open AccessArticle

Real Options Volatility Surface for Valuing Renewable Energy Projects

by Rosa-Isabel González-Muñoz, Jesús Molina-Muñoz, Andrés Mora-Valencia and Javier Perote

Energies 2024, 17(5), 1225; https://doi.org/10.3390/en17051225 - 4 Mar 2024

Viewed by 1394

Abstract

Real options analysis is an adequate tool with which to value companies and projects under investment uncertainty. Nevertheless, the estimation of the volatility to be employed in the valuation procedure is a challenging task. The volatility parameter not only affects the investment value, [...] Read more.

Real options analysis is an adequate tool with which to value companies and projects under investment uncertainty. Nevertheless, the estimation of the volatility to be employed in the valuation procedure is a challenging task. The volatility parameter not only affects the investment value, but is also important in strategic decision-making. The aim of this paper is to provide a suitable methodology for the estimation of volatility in real option project valuation, with a focus on renewable energy projects. Our procedure is a straightforward extension of the implied volatility methodology employed for financial options; however, our proposal considers the debt-to-equity ratio instead of the moneyness or strike price. Thus, the volatility of the project is the implied volatility obtained from the volatility surface of comparable firms for a certain valuation date and the given debt-to-equity relation of a renewable project. Furthermore, the natural spline model is utilized to calibrate the volatility surface for real option valuation purposes. The empirical results demonstrate that the implied volatility ranges from 3.37% to 113.78%, with median values between 16.42% and 47.10%, in the period from January 2014 to December 2020, for our research study. Finally, we consider that our proposal is a natural and straightforward manner in which to estimate the implied volatility for projects under investment uncertainty, since real option valuation is based on the same idea and tools used in financial option pricing. Full article

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21 pages, 736 KiB

Open AccessReview

Effect of Emerging Micropollutants on the Anaerobic Digestion of Sewage Sludge

by Magdalena Zielińska and Agnieszka Cydzik-Kwiatkowska

Energies 2024, 17(5), 1033; https://doi.org/10.3390/en17051033 - 22 Feb 2024

Cited by 3 | Viewed by 1690

Abstract

The recovery of valuable resources from wastewater treatment plants (WWTPs) has received a great deal of attention as part of the concept of a circular economy. Anaerobic digestion for stabilizing sewage sludge in WWTPs, which produces biogas and stabilized biosolids, is a mature [...] Read more.

The recovery of valuable resources from wastewater treatment plants (WWTPs) has received a great deal of attention as part of the concept of a circular economy. Anaerobic digestion for stabilizing sewage sludge in WWTPs, which produces biogas and stabilized biosolids, is a mature technology used worldwide. However, despite the necessity of achieving safe and reliable organic recycling, studies on the effect of some emerging micropollutants on this process are rare. This knowledge gap is of growing relevance because of the increasing use of some endocrine-disrupting compounds (EDCs), microplastics (MPs), and engineered nanoparticles (NPs) in industry and human life. These compounds are ubiquitous in wastewater streams and, therefore, may have serious effects on the course of the anaerobic digestion of sewage sludge, raising concerns about their effects on the environment. This article provides a comprehensive overview of the mechanisms by which selected EDCs, MPs, and NPs affect the valorization of sewage sludge, with a focus on the production of CH₄, H₂, and volatile fatty acids. This study takes into consideration the performance during all stages of anaerobic digestion, the shifts in microbial abundance and diversity, and the activity of key enzymes during the treatment process. Full article

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16 pages, 4805 KiB

Open AccessArticle

The Influence of Subsequent Harmonics of the Load Current on Errors of Electronic Energy Meters

by Marian Kampik, Artur Skórkowski, Michał Pecyna and Konrad Sowula

Energies 2024, 17(5), 1003; https://doi.org/10.3390/en17051003 - 21 Feb 2024

Cited by 1 | Viewed by 762

Abstract

In the electrical installations of buildings, there is an increasing number of non-linear energy receivers, which introduce strong distortions of the load current of electronic energy meters. Since the readings of these meters are the basis for financial settlements of electricity consumers, it [...] Read more.

In the electrical installations of buildings, there is an increasing number of non-linear energy receivers, which introduce strong distortions of the load current of electronic energy meters. Since the readings of these meters are the basis for financial settlements of electricity consumers, it is very important to determine how much the distortion of the receiver current affects the correct operation of commonly used electronic energy meters. The article will present exemplary results and analyses of research work on the impact of individual current harmonics on the readings and errors of selected energy meters. Full article

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22 pages, 445 KiB

Open AccessFeature PaperArticle

Diffusion of Solar PV Energy in Italy: Can Large-Scale PV Installations Trigger the Next Growth Phase?

by Alessandro Bessi, Mariangela Guidolin and Piero Manfredi

Energies 2024, 17(3), 726; https://doi.org/10.3390/en17030726 - 2 Feb 2024

Viewed by 1217

Abstract

The National Energy and Climate Plans (NECPs) of the EU Member States have established comprehensive goals for 2030 to speed up the process of energy transition. Though Italy was an innovator in the area of photovoltaics (PV) up until 2014, the subsequent collapse [...] Read more.

The National Energy and Climate Plans (NECPs) of the EU Member States have established comprehensive goals for 2030 to speed up the process of energy transition. Though Italy was an innovator in the area of photovoltaics (PV) up until 2014, the subsequent collapse and stagnation of its PV market have revealed an intrinsic fragility, which makes reaching international targets in the future unclear. This study used the Generalized Bass Model in a multi-phase extension to offer insights into and perspectives on the Italian PV market with the use of new data at finer temporal and market-size scales. Our model-based evidence suggests the possibility of a remarkable structural change corresponding to the “reboot” period after the pandemic crisis. In this period, small- and large-scale PV adoption, after years of parallel pathways, have taken largely different routes. On the one hand, small-scale adoption exhibited a fast decline with the end of the post-COVID-19 incentive programs, thus confirming the traditional “addiction to incentive” issue. On the other hand, during the “reboot” period, large-scale installations showed, for the first time, symptoms of exponential growth. This is consistent with the possibility that, finally, this sector is on an autonomous growth path. The latter evidence might represent a critically important novelty in the Italian PV landscape, where firms—rather than households—take the lead in the process. Nonetheless, future public monitoring and guidance are both urgent requirements to avoid a further catastrophic fall in the residential PV market and to make the sustained growth of the large-scale PV industry a robust phenomenon. Full article

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13 pages, 3216 KiB

Open AccessArticle

Influence of Environmental Conditions on the Electrical Parameters of Side Connectors in Glass–Glass Photovoltaic Modules

by Krzysztof Barbusiński, Paweł Kwaśnicki, Anna Gronba-Chyła, Agnieszka Generowicz, Józef Ciuła, Bartosz Szeląg, Francesco Fatone, Agnieszka Makara and Zygmunt Kowalski

Energies 2024, 17(3), 680; https://doi.org/10.3390/en17030680 - 31 Jan 2024

Cited by 4 | Viewed by 977

Abstract

This work focused on the verification of the electrical parameters and the durability of side connectors installed in glass–glass photovoltaic modules. Ensuring the safe use of photovoltaic modules is achieved, among others, by using electrical connectors connecting the PV cell circuit inside the [...] Read more.

This work focused on the verification of the electrical parameters and the durability of side connectors installed in glass–glass photovoltaic modules. Ensuring the safe use of photovoltaic modules is achieved, among others, by using electrical connectors connecting the PV cell circuit inside the laminate with an external electric cable. In most of the cases for standard PV modules, the electrical connector in the form of a junction box is attached from the back side of the PV module. The junction box is glued to the module surface with silicone where the busbars were previously brought out of the laminate through specially prepared holes. An alternative method is to place connectors on the edge of the module, laminating part of it. In such a case, the specially prepared “wings” of the connector are tightly and permanently connected using laminating foil, between two glass panes protecting against an electrical breakdown. Additionally, this approach eliminates the process of preparing holes on the back side of the module, which is especially complicated and time-consuming in the case of glass–glass modules. Moreover, side connectors are desirable in BIPV applications because they allow for a more flexible design of installations on façades and walls of buildings. A series of samples were prepared in the form of PV G-G modules with side connectors, which were then subjected to testing the connectors for the influence of environmental conditions. All samples were characterized before and after the effect of environmental conditions according to PN-EN-61215-2 standards. Insulation resistance tests were performed in dry and wet conditions, ensuring full contact of the tested sample with water. For all modules, before being placed in the climatic chamber, the resistance values were far above the minimum value required by the standards, allowing the module to be safely used. For the dry tests, the resistance values were in the range of GΩ, while for the wet tests, the obtained values were in the range of MΩ. In further work, the modules were subjected to environmental influences in accordance with MQT-11, MQT-12, and MQT-13 and then subjected to electrical measurements again. A simulation of the impact of changing climatic conditions on the module test showed that the insulation resistance value is reduced by an order of magnitude for both the dry and wet tests. Additionally, one can observe visual changes where the lamination foil is in contact with the connector. The measurements carried out in this work show the potential of side connectors and their advantage over rear junction boxes, but also the technological challenges that need to be overcome. Full article

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19 pages, 4346 KiB

Open AccessReview

Exploring Biomass Linkages in the Food and Energy Market—A Systematic Review

by Christian Barika Igbeghe, Adrián Nagy, Zoltán Gabnai and Attila Bai

Energies 2024, 17(3), 563; https://doi.org/10.3390/en17030563 - 24 Jan 2024

Cited by 1 | Viewed by 1521

Abstract

This study delves into the intricate landscape of biomass utilization within the food and energy markets. It entails a systematic review of the existing literature with the aim of unraveling the complexities of the food and energy discourse, especially in the context of [...] Read more.

This study delves into the intricate landscape of biomass utilization within the food and energy markets. It entails a systematic review of the existing literature with the aim of unraveling the complexities of the food and energy discourse, especially in the context of significant market factors influencing biomass use for food and energy. We leveraged the Scopus database to examine 73 pertinent scientific articles carefully selected following the PRISMA framework. The articles were analyzed using the advanced qualitative data analytics tool NVivo 12 Plus. Furthermore, we employed the Biblioshiny R-package tool to extract valuable insights from the metadata, unveiling pivotal trends and providing descriptive statistical details. The findings offer comprehensive insights into the debate on biomass utilization from 2010 to 2023, tracing the influence of the COVID-19 pandemic. We identify regions that have made notable contributions and highlight those that require increased attention. The analysis underscores the collaborative nature of this field, with 281 authors contributing to 39 different sources. Surprisingly, the observed annual growth rate of −10.93% indicates a potential decline in research output in this field. Nevertheless, the sources identified in our research provide a valuable roadmap for further research exploration of the biomass–food–energy nexus. Full article

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15 pages, 1615 KiB

Open AccessFeature PaperArticle

Energy Production in Microbial Fuel Cells (MFCs) during the Biological Treatment of Wastewater from Soilless Plant Cultivation

by Artur Mielcarek, Kamil Łukasz Bryszewski, Karolina Kłobukowska, Joanna Rodziewicz and Wojciech Janczukowicz

Energies 2024, 17(3), 548; https://doi.org/10.3390/en17030548 - 23 Jan 2024

Viewed by 1368

Abstract

The management of drainage water (DW), which is produced during the soilless cultivation of plants, requires a high energy input. At the same time, DW is characterized by a high electrolytic conductivity, a high redox potential, and is also stable and putrefaction-free. In [...] Read more.

The management of drainage water (DW), which is produced during the soilless cultivation of plants, requires a high energy input. At the same time, DW is characterized by a high electrolytic conductivity, a high redox potential, and is also stable and putrefaction-free. In the present study, the natural properties of drainage water and a biotreatment method employing an external organic substrate in the form of citric acid (C/N 1.0, 1.5, 2.0) were utilized for energy recovery by a microbial fuel cell (MFC). The cathode chamber served as a retention tank for DW with a carbon felt electrode fixed inside. In turn, a biological reactor with biomass attached to the filling in the form of carbon felt served as the anode chamber. The filling also played the role of an electrode. The chambers were combined by an ion exchange membrane, forming an H letter-shaped system. They were then connected in an external electrical circuit with a resistance of 1k Ω. The use of a flow-through system eliminated steps involving aeration and mixing of the chambers’ contents. Citric acid was found to be an efficient organic substrate. The voltage of the electric current increased from 44.34 ± 60.92 mV to 566.06 ± 2.47 mV for the organic substrate dose expressed by the C/N ratio ranging from 1.0 to 2.0. At the same time, the denitrification efficiency ranged from 51.47 ± 9.84 to 95.60 ± 1.99% and that of dephosphatation from 88.97 ± 2.41 to 90.48 ± 1.99% at C/N from 1.0 to 2.0. The conducted studies confirmed the possibility of recovering energy during the biological purification of drainage water in a biofilm reactor. The adopted solution only required the connection of electrodes and tanks with an ion-selective membrane. Further research should aim to biologically treat DW followed by identification of the feasibility of energy recovery by means of MFC. Full article

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13 pages, 2276 KiB

Open AccessArticle

Energy Recovery from Municipal Solid Waste through Co-Gasification Using Steam or Carbon Dioxide with Olive By-Products

by Despina Vamvuka and Petros Tsilivakos

Energies 2024, 17(2), 304; https://doi.org/10.3390/en17020304 - 8 Jan 2024

Cited by 1 | Viewed by 1379

Abstract

The valorization of untreated municipal waste (MSW) biochar for energetic uses, through its co-gasification with olive stone (OST) biochar under a steam or carbon dioxide atmosphere, was investigated. The experiments were conducted in a fixed bed unit and a thermal analysis–mass spectrometer system. [...] Read more.

The valorization of untreated municipal waste (MSW) biochar for energetic uses, through its co-gasification with olive stone (OST) biochar under a steam or carbon dioxide atmosphere, was investigated. The experiments were conducted in a fixed bed unit and a thermal analysis–mass spectrometer system. The thermal behavior, reactivity, conversion, product gas composition, syngas yield and energy potential were determined, while the influence of the fuel’s internal structure, chemical functional groups and operating conditions were examined. The concentrations of H₂ and CO₂ in the product gas mixture under a steam atmosphere were increased with steam/biochar ratio, while that of CO was reduced. At a steam/biochar = 3 H₂ yield, the higher heating value and conversion for the OST were 52.8%, 10.8 MJ/m³ and 87.5%; for the MSW, they were 44.4%, 9.9 MJ/m³ and 51.5%, whereas for their blend, they were 50%, 10.6 MJ/m³ and 76.6%, respectively. Under a carbon dioxide atmosphere, the reactivity and conversion of the OST biochar (84%) were significantly higher as compared with the MSW biochar (50%). The higher heating value of the product gas was 12.4–12.9 MJ/m³. Co-gasification of the MSW with OST (in proportions 30:70) resulted in the enhanced reactivity, conversion, syngas yield and heating value of product gas compared with gasification of solely MSW material. Full article

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21 pages, 6107 KiB

Open AccessArticle

Wildfire-Induced Risk Assessment to Enable Resilient and Sustainable Electric Power Grid

by Srikar Kovvuri, Paroma Chatterjee, Sagnik Basumallik and Anurag Srivastava

Energies 2024, 17(2), 297; https://doi.org/10.3390/en17020297 - 7 Jan 2024

Cited by 1 | Viewed by 1626

Abstract

To ensure the sustainability of the future power grid, the rate of expansion of distributed energy resources (DERs) has introduced operational challenges. These include managing transmission constraints with DER power injection, dispatching DERs efficiently, managing system frequency, and ensuring sufficient reactive power for [...] Read more.

To ensure the sustainability of the future power grid, the rate of expansion of distributed energy resources (DERs) has introduced operational challenges. These include managing transmission constraints with DER power injection, dispatching DERs efficiently, managing system frequency, and ensuring sufficient reactive power for voltage support. Coupled with the intensification of wildfires, power infrastructures across the United States face challenges to minimize the impact of these factors and maintain system reliability and resiliency. This research embarked on a comprehensive evaluation, beginning with an in-depth historical analysis to delineate regions most susceptible to wildfires. Utilizing a multidimensional approach, the study assessed wildfire-induced risks to power grids by integrating historical wildfire occurrences, real-time wildfire proximities, Moderate-Resolution Imaging Spectroradiometer (MODIS)-derived vegetation metrics, and system parameters. Principal component analysis (PCA)-based optimal weights were then used, leading to the formulation of a novel risk factor model. This risk factor model has the potential to be the key to ensuring the resilience of a renewable-rich smart grid when faced with a severe weather event. Our model’s applicability was further verified through an empirical assessment, selecting representative networks from diverse regions, providing insights into the geographical variability of risk factors. Ultimately, this study offers stakeholders and policymakers a comprehensive toolset, empowering decisions regarding infrastructure investments, grid reinforcements, and strategic power rerouting to ensure consistent energy delivery during wildfires. Full article

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2023

Jump to: 2024, 2022

24 pages, 4161 KiB

Open AccessReview

The Energy Storage Technology Revolution to Achieve Climate Neutrality

by Ioana-Cristina Badea, Beatrice-Adriana Șerban, Ioana Anasiei, Dumitru Mitrică, Mihai Tudor Olaru, Andrey Rabin and Mariana Ciurdaș

Energies 2024, 17(1), 140; https://doi.org/10.3390/en17010140 - 27 Dec 2023

Cited by 3 | Viewed by 2463 | Correction

Abstract

The intensive exploitation and usage of fossil fuels has led to serious environmental consequences, including soil, water, and air pollution and climate changes, and it has compromised the natural resources available for future generations. In this context, identifying new energy storage technologies can [...] Read more.

The intensive exploitation and usage of fossil fuels has led to serious environmental consequences, including soil, water, and air pollution and climate changes, and it has compromised the natural resources available for future generations. In this context, identifying new energy storage technologies can be considered a sustainable solution to these problems, with potential long-term effects. In this work, were analyzed different alternatives that can be suitable for replacing non-renewable sources, where hydrogen, wave, wind, or solar energies were considered. Although they have numerous advantages in terms of usage and substantially reducing the environmental impact, this paper is focused on lithium-ion batteries, whose high performance and safety during operation have made them attractive for a wide range of applications. The study of potential replacement technologies and the technical requirements for the main materials used is the starting point in reducing the environmental footprint, without affecting the technical capabilities, followed by the transition toward economic circularity and climate neutrality. Full article

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23 pages, 2459 KiB

Open AccessArticle

Radiation Force Modeling for a Wave Energy Converter Array

by Salman Husain, Gordon G. Parker, David Forehand and Enrico Anderlini

Energies 2024, 17(1), 6; https://doi.org/10.3390/en17010006 - 19 Dec 2023

Viewed by 1942

Abstract

The motivation and focus of this work is to generate passive transfer function matrices that model the radiation forces for an array of WECs. Multivariable control design is often based on linear time-invariant (LTI) systems such as state-space or transfer function matrix models. [...] Read more.

The motivation and focus of this work is to generate passive transfer function matrices that model the radiation forces for an array of WECs. Multivariable control design is often based on linear time-invariant (LTI) systems such as state-space or transfer function matrix models. The intended use is for designing real-time control strategies where knowledge of the model’s poles and zeros is helpful. This work presents a passivity-based approach to estimate radiation force transfer functions that accurately replace the convolution operation in the Cummins equation while preserving the physical properties of the radiation function. A two-stage numerical optimization approach is used, the first stage uses readily available algorithms for fitting a radiation damping transfer function matrix to the system’s radiation frequency response. The second stage enforces additional constraints on the form of the transfer function matrix to increase its passivity index. After introducing the passivity-based algorithm to estimate radiation force transfer functions for a single WEC, the algorithm was extended to a WEC array. The proposed approach ensures a high degree of match with the radiation function without degrading its passivity characteristics. The figures of merit that will be assessed are (i) the accuracy of the LTI systems in approximating the radiation function, as measured by the normalized root mean squared error (NRMSE), and (ii) the stability of the overall system, quantified by the input passivity index,

ν

, of the radiation force transfer function matrix. Full article

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21 pages, 3298 KiB

Open AccessArticle

An Analysis of Energy Consumption in Railway Signal Boxes

by Marian Kampik, Krzysztof Bodzek, Anna Piaskowy, Adam Pilśniak and Marcin Fice

Energies 2023, 16(24), 7985; https://doi.org/10.3390/en16247985 - 9 Dec 2023

Cited by 2 | Viewed by 1180

Abstract

This study assessed hourly electricity consumption profiles in railway signal boxes located in Poland. The analyses carried out consisted of assessing the correlation among the hourly demand profile, weather indicators, and calendar indicators, e.g., temperature, cloud cover, day of the week, and month. [...] Read more.

This study assessed hourly electricity consumption profiles in railway signal boxes located in Poland. The analyses carried out consisted of assessing the correlation among the hourly demand profile, weather indicators, and calendar indicators, e.g., temperature, cloud cover, day of the week, and month. The analysis allowed us to assess which indicator impacts the energy consumption profile and would be useful when forecasting energy demand. In total, 15 railway signal boxes were selected for analysis and grouped according to three characteristic repeatability profiles. On this basis, six of the signal boxes and one that did not fit into any of the groups were selected for further analysis. Four correlation research methods were selected for analysis: Pearson’s method, Spearman’s method, scatter plots, and distance covariance. The possibility of forecasting electricity consumption based on previously aggregated profiles and determining correlations with indicators was presented. The given indicators vary depending on the facility. Analyses showed different dependencies of the electricity demand profile. The ambient temperature and time of day have the greatest impact on the profile. Regarding the correlation with temperature, the results of the Pearson’s and Spearman’s coefficients ranged from approximately −0.4 to more than −0.8. The highest correlation coefficients were obtained when comparing the demand profile with the previous day. In this case, the Pearson’s and Spearman’s coefficients for all analysed objects range from approximately 0.7 to over 0.9. Full article

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22 pages, 1006 KiB

Open AccessReview

Solid Biofuel Production from Biomass: Technologies, Challenges, and Opportunities for Its Commercial Production in Nigeria

by Okey Francis Obi, Temitope Olumide Olugbade, Joseph Ifeolu Orisaleye and Ralf Pecenka

Energies 2023, 16(24), 7966; https://doi.org/10.3390/en16247966 - 8 Dec 2023

Cited by 5 | Viewed by 2242

Abstract

Producing durable and efficient solid biofuels should be an important consideration in Nigeria’s present economy due to the numerous advantages associated with it. It offers the benefit of energy generation, particularly in rural areas, and could potentially replace fossil fuels. However, the adoption [...] Read more.

Producing durable and efficient solid biofuels should be an important consideration in Nigeria’s present economy due to the numerous advantages associated with it. It offers the benefit of energy generation, particularly in rural areas, and could potentially replace fossil fuels. However, the adoption and production of solid biofuels at commercial scale in Nigeria is limited by some challenges, including the lack of a developed supply chain structure, inadequate facilities, and air pollution. The present study summarizes the types of solid biofuel production technologies deployed in Nigeria as well as the biomass feedstock utilized in the production of fuel briquettes and pellets. While opportunities exist in the gasification of biomass in Nigeria, direct combustion is a readily applicable fuel conversion process that can be utilized to generate electricity from solid biofuel. The major challenges surrounding the full adoption of solid biofuel production and utilization in Nigeria are highlighted. Among others, promotion of clean energy alternatives, investments and financial incentives, sustainable renewable energy policy and energy transition plan, and legislative backing are identified as factors that could accelerate the commercial production and adoption of solid biofuel in Nigeria. Full article

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26 pages, 10957 KiB

Open AccessArticle

Effect of the Ground Albedo on the Estimation of Solar Radiation on Tilted Flat-Plate Surfaces: The Case of Saudi Arabia

by Ashraf Farahat, Harry D. Kambezidis and Styliani I. Kampezidou

Energies 2023, 16(23), 7886; https://doi.org/10.3390/en16237886 - 2 Dec 2023

Cited by 3 | Viewed by 1774

Abstract

This work investigates the influence of ground albedo on the solar radiation obtained by surfaces mounted on fixed-tilt-to-south, one-axis, and two-axis systems. To do this, estimation of the solar radiation difference is performed by applying real albedo and zero albedo. This is achieved [...] Read more.

This work investigates the influence of ground albedo on the solar radiation obtained by surfaces mounted on fixed-tilt-to-south, one-axis, and two-axis systems. To do this, estimation of the solar radiation difference is performed by applying real albedo and zero albedo. This is achieved within Saudi Arabia at 82 selected sites. Annual, seasonal, and monthly mean solar energy differences are computed as a function of the site’s number, latitude, and local near-real ground albedo. The great variation in the ground-albedo values at the 82 sites (0.1–0.46) could be thought of as having a significant effect on the solar radiation levels received on the three tracking modes. This analysis shows quite the opposite; zero-albedo ground diminishes solar radiation levels by 1.43%, 3.50%, and 3.20%, respectively, for the three modes. Therefore, in most solar engineering applications, a ground albedo of 0.2 (considered a reference) can be used without losing accuracy. This is the main conclusion of the study, which must, however, be applied with caution in areas with snow cover, especially for mode-III tracking systems. In such situations, the increase in solar radiation levels may be up to 15% (but ≈3.5% for mode-I and -II systems instead). Full article

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12 pages, 4114 KiB

Open AccessArticle

Methane Production from a Rendering Waste Covered Anaerobic Digester: Greenhouse Gas Reduction and Energy Production

by Nanh Lovanh, John Loughrin, Graciela Ruiz-Aguilar and Karamat Sistani

Energies 2023, 16(23), 7844; https://doi.org/10.3390/en16237844 - 29 Nov 2023

Cited by 1 | Viewed by 1597

Abstract

Livestock wastes can serve as the feedstock for biogas production (mainly methane) that could be used as an alternative energy source. The green energy derived from animal wastes is considered to be carbon neutral and offsetting the emissions generated from fossil fuels. In [...] Read more.

Livestock wastes can serve as the feedstock for biogas production (mainly methane) that could be used as an alternative energy source. The green energy derived from animal wastes is considered to be carbon neutral and offsetting the emissions generated from fossil fuels. In this study, an evaluation of methane production from anaerobic digesters utilizing different livestock residues (e.g., poultry rendering wastewater and dairy manure) was carried out. An anaerobic continuous flow system (15 million gallons, polyethylene-covered) subjected to natural conditions (i.e., high flow rate, seasonal temperatures, etc.) containing poultry rendering wastewater was set up to evaluate methane potential and energy production. A parallel pilot-scale plug-flow anaerobic digestion system (9 m³) was also set up to test different feedstocks and operating parameters. Biogas production was sampled and monitored by gas chromatography over several months of operation. The results showed that methane production increased as the temperature increased as well as depending on the type of feedstock utilized. The covered rendering wastewater lagoon achieved an upward of 80% (v/v) methane production. The rates of methane production were 0.0478 g per g of COD for the poultry rendering wastewater and 0.0141 g per g of COD for dairy manure as feedstock. Hence, a poultry processing plant with a rendering wastewater flow rate of about 4.5 million liters per day has the potential to capture about two million kilograms of methane for energy production per year from a waste retention pond, potentially reducing global warming potential by about 50,000 tons of CO₂ equivalent annually. Full article

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15 pages, 6709 KiB

Open AccessArticle

Easy and Scalable Syntheses of Li_1.2Ni_0.2Mn_0.6O₂

by Pier Paolo Prosini, Annalisa Aurora, Livia Della Seta and Claudia Paoletti

Energies 2023, 16(22), 7674; https://doi.org/10.3390/en16227674 - 20 Nov 2023

Viewed by 1332

Abstract

Solid-state and sol-gel syntheses were selected as easy and scalable methods to prepare a lithium-rich cathode material for lithium-ion batteries. Among the extended family of layered oxides, Li_1.2Ni_0.2Mn_0.6O₂ was chosen for its low nickel content and [...] Read more.

Solid-state and sol-gel syntheses were selected as easy and scalable methods to prepare a lithium-rich cathode material for lithium-ion batteries. Among the extended family of layered oxides, Li_1.2Ni_0.2Mn_0.6O₂ was chosen for its low nickel content and the absence of cobalt. Both synthesis methods involved two heating steps at different temperatures, 600 and 900 °C. The first step is needed to decompose the metal acetates, which were selected as precursors, and the second step is needed to crystallise the material. To obtain a material with well-defined defects, the rate of heating and cooling was carefully controlled. The materials were characterised by X-ray diffraction, SEM coupled with EDS analysis, and thermal analysis and were finally tested as cathodes in a lithium semi cell. The solid-state synthesis allowed us to obtain better structural characteristics with respect to the sol-gel one in terms of a well-formed hexagonal layer structure and a reduced Li⁺/Ni²⁺ disorder. On the other hand, the sol-gel method produced a material with a higher specific capacity. The performance of this latter material was then evaluated as a function of the discharge current, highlighting its good rate capabilities. Full article

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12 pages, 2043 KiB

Open AccessArticle

Formulation of an Efficiency Model Valid for High Vacuum Flat Plate Collectors

by Eliana Gaudino, Antonio Caldarelli, Roberto Russo and Marilena Musto

Energies 2023, 16(22), 7650; https://doi.org/10.3390/en16227650 - 18 Nov 2023

Viewed by 1126

Abstract

High Vacuum Flat Plate Collectors (HVFPCs) are the only type of flat plate thermal collectors capable of producing thermal energy for middle-temperature applications (up to 200 °C). As the trend in research plans is to develop new Selective Solar Absorbers to extend the [...] Read more.

High Vacuum Flat Plate Collectors (HVFPCs) are the only type of flat plate thermal collectors capable of producing thermal energy for middle-temperature applications (up to 200 °C). As the trend in research plans is to develop new Selective Solar Absorbers to extend the range of HVFPC application up to 250 °C, it is necessary to correctly evaluate the collector efficiency up to such temperatures to predict the energy production accurately. We propose an efficiency model for these collectors based on the selective absorber optical properties. The proposed efficiency model explicitly includes the radiative heat exchange with the ambient, which is the main source of thermal losses for evacuated collectors at high temperatures. It also decouples the radiative losses that depend on the optical properties of the absorber adopted from the other thermal losses due to HVFPC architecture. The model has been validated by applying it to MT-Power HVFPC manufactured by TVP-Solar. The dissipative losses other than thermal radiation were found to be mostly conductive with a linear coefficient k = 0.258 W/m²K. The efficiency model has been also used to predict the energy production of HVFPCs equipped with new, optimized Selective Solar Absorbers developed in recent years. Considering the 2019 meteorological data in Cairo and an operating temperature of 250 °C, the annual energy production of an HVFPC equipped with an optimized absorber is estimated to be 638 kWh/m². Full article

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34 pages, 1554 KiB

Open AccessReview

Kernel-Based Biodiesel Production from Non-Edible Oil Seeds: Techniques, Optimization, and Environmental Implications

by Kavitha Munisamy Sambasivam, Praveen Kuppan, Lafiya Shanavas Laila, Viswanaathan Shashirekha, Krishnamurthi Tamilarasan and Sudharsanam Abinandan

Energies 2023, 16(22), 7589; https://doi.org/10.3390/en16227589 - 15 Nov 2023

Cited by 6 | Viewed by 2973

Abstract

Biodiesel represents a renewable alternative to conventional diesel, offering comparable potential. This paper delves into the production of biodiesel from non-edible oil seeds, emphasizing kernel-based feedstocks for their sustainable qualities. We discuss the critical stages of kernel separation and degumming, offering an in-depth [...] Read more.

Biodiesel represents a renewable alternative to conventional diesel, offering comparable potential. This paper delves into the production of biodiesel from non-edible oil seeds, emphasizing kernel-based feedstocks for their sustainable qualities. We discuss the critical stages of kernel separation and degumming, offering an in-depth examination of seed distribution, attributes, pretreatment, and oil extraction methodologies. Additionally, the paper considers the status of life cycle assessment (LCA) associated with biodiesel. Furthermore, it outlines the necessary steps toward sustainable biodiesel production and underscores the importance of integrating a sustainable circular bioeconomy in biodiesel synthesis. Full article

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16 pages, 899 KiB

Open AccessArticle

Economic Analysis of Large-Scale Renewable Energy (RE) Source Investment Incorporating Power System Transmission Costs

by Deukyoung Lee and Sung-Kwan Joo

Energies 2023, 16(21), 7407; https://doi.org/10.3390/en16217407 - 2 Nov 2023

Cited by 2 | Viewed by 5901

Abstract

Recently, the proportion of renewable energy (RE) sources in a power system has been increasing worldwide to reduce carbon emissions. To effectively accommodate renewable energy, there is a growing need to develop integrated planning strategies for both renewable energy sources and transmission lines [...] Read more.

Recently, the proportion of renewable energy (RE) sources in a power system has been increasing worldwide to reduce carbon emissions. To effectively accommodate renewable energy, there is a growing need to develop integrated planning strategies for both renewable energy sources and transmission lines in a power system, taking into account the location-specific characteristics of renewable energy. Economically viable and rapid system expansion plans are required to resolve the problem of delayed integration of renewable energy into existing power system, which arises due to inadequate transmission facilities. To address these problems, this paper presents an integrated economic evaluation method that considers the inherently uncertain output characteristics of renewable energy, contingent on location, the costs associated with installing transmission lines, and environmental benefits. The case study is conducted using a modified power system in Korea. In the case study, it is assumed that by integrating solar power generators in a low-demand area and wind power generators in a high-demand area, wind power plants have higher construction costs than solar power generators. However, the transmission costs for wind power plants are lower than those for solar power generators due to the regional characteristics of the power grid in the installation areas because renewable energy in high-demand areas typically requires less additional power infrastructure than in low-demand areas. The results of this study show that the net benefit for the wind power plant is estimated at USD 225.4 M, while the solar power plant yields a net benefit of USD 22.9 M in the example system. These results demonstrate the effectiveness of the proposed method, underscoring its potential to mitigate the challenges faced in the practical implementation of renewable energy projects. Full article

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15 pages, 895 KiB

Open AccessArticle

An Agricultural Biogas Plant as a Thermodynamic System: A Study of Efficiency in the Transformation from Primary to Secondary Energy

by Krzysztof Pilarski, Agnieszka A. Pilarska, Alicja Kolasa-Więcek and Dariusz Suszanowicz

Energies 2023, 16(21), 7398; https://doi.org/10.3390/en16217398 - 2 Nov 2023

Cited by 5 | Viewed by 1576

Abstract

Using a wide range of organic substrates in the methane fermentation process enables efficient biogas production. Nonetheless, in many cases, the efficiency of electricity generation in biogas plant cogeneration systems is much lower than expected, close to the calorific value of the applied [...] Read more.

Using a wide range of organic substrates in the methane fermentation process enables efficient biogas production. Nonetheless, in many cases, the efficiency of electricity generation in biogas plant cogeneration systems is much lower than expected, close to the calorific value of the applied feedstock. This paper analyses the energy conversion efficiency in a 1 MWel agricultural biogas plant fed with corn silage or vegetable waste and pig slurry as a feedstock dilution agent, depending on the season and availability. Biomass conversion studies were carried out for 12 months, during which substrate samples were taken once a month. The total primary energy in the substrates was estimated in laboratory conditions by measuring the released heat (17,760 MWh·year⁻¹), and, in the case of pig slurry, biochemical methane potential (BMP, (201.88 ± 3.21 m³·Mg VS⁻¹). Further, the substrates were analysed in terms of their chemical composition, from protein, sugar and fat content to mineral matter determination, among other things. The results obtained during the study were averaged. Based on such things as the volume of the biogas, the amount of chemical (secondary) energy contained in methane as a product of biomass conversion (10,633 MWh·year⁻¹) was calculated. Considering the results obtained from the analyses, as well as the calculated values of the relevant parameters, the biomass conversion efficiency was determined as the ratio of the chemical energy in methane to the (primary) energy in the substrates, which was 59.87%, as well as the electricity production efficiency, as the ratio of the electricity produced (4913 MWh·year⁻¹) to the primary energy, with a 35% cogeneration system efficiency. The full energy conversion efficiency, related to electricity production, reached a low value of 27.66%. This article provides an insightful, unique analysis of energy conversion in an active biogas plant as an open thermodynamic system. Full article

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16 pages, 3852 KiB

Open AccessArticle

Optical Interactions in Bio-Electricity Generation from Photosynthesis in Microfluidic Micro-Photosynthetic Power Cells

by Kirankumar Kuruvinashetti, Hemanth Kumar Tanneru, Shanmugasundaram Pakkiriswami and Muthukumaran Packirisamy

Energies 2023, 16(21), 7353; https://doi.org/10.3390/en16217353 - 31 Oct 2023

Cited by 2 | Viewed by 1498

Abstract

Within the realm of renewable energy sources, biological-based power systems have emerged as pivotal players particularly suited for low- and ultra-low-power applications. Unlike microbial fuel cells (MFCs), which invariably rely on external carbon feedstock, micro-photosynthetic cells (µPSCs) exhibit a unique feature by operating [...] Read more.

Within the realm of renewable energy sources, biological-based power systems have emerged as pivotal players particularly suited for low- and ultra-low-power applications. Unlike microbial fuel cells (MFCs), which invariably rely on external carbon feedstock, micro-photosynthetic cells (µPSCs) exhibit a unique feature by operating independently of organic fuel. They harness the principles of photosynthesis and respiration to generate electricity in both illuminated and dark settings through water-splitting reactions. Here, we present a viable, easy, and cost-effective method to fabricate µPSCs. We meticulously examined the performance of a fabricated µPSC under varying illuminations and even in the absence of light. With an electrode surface area spanning 4.84 cm², the µPSC achieved its peak power output of 200.6 µW when exposed to an illumination of 2 µmolm⁻²s⁻¹ (equivalent to 147 lux). Of the three light intensities studied, 2 µmolm⁻²s⁻¹, 8 µmolm⁻²s⁻¹ (595 lux), and 20 µmolm⁻²s⁻¹ (1500 lux), the µPSC exhibited its optimal performance at a light intensity of 2 µmolm⁻²s⁻¹, establishing this as the ideal operational illumination. Furthermore, intermittent toggling of the illumination had no discernible impact on the µPSC’s performance. However, subjecting it to a dark environment for 30 min resulted in a reduction in the maximum power to 81 µW, marking a significant 119% decrease when compared to the peak power output achieved under 2 µmolm⁻²s⁻¹ illumination. Full article

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22 pages, 6248 KiB

Open AccessFeature PaperArticle

Effects of Parameter Scaling on Archimedes Screw Generator Performance

by Scott Simmons, Guilhem Dellinger and William David Lubitz

Energies 2023, 16(21), 7331; https://doi.org/10.3390/en16217331 - 29 Oct 2023

Viewed by 1883

Abstract

Archimedes screws are an ancient pumping technology that has more recently found use as a technology for hydropower generation. Currently, the literature is lacking reliable data, performance predicting models, and design guidelines. Most performance models presented in the literature are theoretical or were [...] Read more.

Archimedes screws are an ancient pumping technology that has more recently found use as a technology for hydropower generation. Currently, the literature is lacking reliable data, performance predicting models, and design guidelines. Most performance models presented in the literature are theoretical or were developed and evaluated using laboratory-scale data. This paper presents novel experimental and numerical simulation data to the literature from screw generators with a wide range of sizes (laboratory to full-scale powerplant scale) and orientations. The data suggest that the components of power production (pressure-driven and viscous/friction) scale differently depending on system size, configuration, and operating conditions. So, for the robust validation of models and the development of reliable design guidance, data from a wide range of sizes and configurations are crucial. The paper presents data collected from laboratory experiments, field measurements from operating powerplants, and data from numerical simulations. The numerical simulations were evaluated for accuracy with experimental data, then used to collect performance data from a wide range of screw geometries and scales. The length-scale (diameter), number of blades, fill height of water, inclination angle, and surface roughness were all varied. The data gathered in these experiments were analyzed and used to develop back-of-the-envelope estimations for the effect of each parameter on overall system performance; the relationships are intended to serve as a useful reference for designers, though they should not be used in lieu of a design model. The length-scale and number of blades were related to power in a way that could be reasonably approximated with a constant value. The fill height, inclination angle, and surface roughness were related to power in a way that could be approximated reasonably with first-order polynomial fits. Altogether, this paper presents much-needed, novel data to the literature; the data are integral for future model development and evaluation. Full article

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44 pages, 6740 KiB

Open AccessFeature PaperReview

Sustainable Energy Development: History and Recent Advances

by Joseph Akpan and Oludolapo Olanrewaju

Energies 2023, 16(20), 7049; https://doi.org/10.3390/en16207049 - 11 Oct 2023

Cited by 17 | Viewed by 7020

Abstract

Sustainable energy development (SED) is a crucial component of the Sustainable Development Goals (SDG), aiming to maintain economic and social progress while protecting the environment and mitigating climate change’s effects. SED serves as a transition paradigm for sustainable development, providing a blueprint for [...] Read more.

Sustainable energy development (SED) is a crucial component of the Sustainable Development Goals (SDG), aiming to maintain economic and social progress while protecting the environment and mitigating climate change’s effects. SED serves as a transition paradigm for sustainable development, providing a blueprint for energy peace and prosperity for people and all uses. This article presents the history of SED and then uses a critical discourse approach to summarize existing review studies in SED. Ten interlinked themes of SED are identified, with two of them considered to be among the least studied in existing SED reviews and in the current global discussion around climate change. This study explores these two themes, which include energy financing and the need for 100% renewable energy (RE), a sub-theme of decarbonization strategy working towards the 1.5–2.0 °C scenario. The study suggests that the current G20 countries’ contributions, if maintained continuously per annum, in addition to 80% more funding from private investment compared to the amount in the 1.5 °C scenario financial requirements for clean energy, are sufficient to limit global warming. In addition to the present drive for 100% RE, the article also discusses emerging issues, such as energy storage options with an indication of hydrogen as the most promising, other energy-related development agendas, and the need for regional security stability to prevent energy wars. Selected SED decarbonization strategies are presented across the power, transport, building, and industrial sectors. The study concludes with progress and directions for future research, mainly the need for re-defining nationally determined contribution (NDC) through an emissions budgeting and centralized global or regional emissions stock-taking strategy working towards the 1.5 °C scenario. Full article

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18 pages, 1073 KiB

Open AccessFeature PaperArticle

Selection of Photovoltaic Panels Based on Ranges of Criteria Weights and Balanced Assessment Criteria

by Paweł Ziemba

Energies 2023, 16(17), 6382; https://doi.org/10.3390/en16176382 - 3 Sep 2023

Cited by 5 | Viewed by 1423

Abstract

In recent years, the share of PV (photovoltaic) panels in the generation of renewable energy has been dynamically growing. During this time, the Polish government introduced numerous programs to assist households in switching to PV panels as the primary source of energy. Therefore, [...] Read more.

In recent years, the share of PV (photovoltaic) panels in the generation of renewable energy has been dynamically growing. During this time, the Polish government introduced numerous programs to assist households in switching to PV panels as the primary source of energy. Therefore, the aim of the article is to indicate the PV panels that are best suited to work for individual users in households in Poland. PV panels were assessed using the PROSA multi-criteria decision analysis method, supported by a stochastic approach, based on the Monte Carlo method. This approach made it possible to choose the most balanced solutions, in terms of individual criteria, and to take into account the uncertainty and imprecision of the weights of the assessment criteria. In particular, the use of reliable weight ranges in the Monte Carlo simulations allowed the construction of a whole spectrum of evaluation and ranking models. These models indicate the PV panels that best meet the requirements and have the best balance between the individual assessment criteria. As a result of the research, it was found that the requirements of PV installations in households in Poland are best met by panels produced in China and in the Chinese–Polish cooperation. Panels of Polish production ranked further down, which means that Polish producers do not offer products that are tailored to the needs of PV installations for households in Poland. Full article

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46 pages, 12004 KiB

Open AccessArticle

System Hydrodynamics of a 1 MW_th Dual Circulating Fluidized Bed Chemical Looping Gasifier

by Paul Dieringer, Falko Marx, Jochen Ströhle and Bernd Epple

Energies 2023, 16(15), 5630; https://doi.org/10.3390/en16155630 - 26 Jul 2023

Cited by 5 | Viewed by 1759

Abstract

Chemical looping gasification (CLG) is a novel dual-fluidized bed gasification technology that allows for the production of high-calorific syngas from various solid feedstocks (e.g., biomass). Solid circulation between the two coupled fluidized bed reactors, serving the purpose of heat and oxygen transport, is [...] Read more.

Chemical looping gasification (CLG) is a novel dual-fluidized bed gasification technology that allows for the production of high-calorific syngas from various solid feedstocks (e.g., biomass). Solid circulation between the two coupled fluidized bed reactors, serving the purpose of heat and oxygen transport, is a key parameter for the CLG technology, making system hydrodynamics the backbone of the gasification process. This study serves the purpose to provide holistic insights into the hydrodynamic behavior of the dual-fluidized bed reactor system. Here, special focus is placed on the operational principles of the setup as well as the entrainment from the circulating fluidized bed (CFB) reactors, the latter being the driving force for the solid circulation inside the entire reactor system. Using an elaborate dataset of over 130 operating periods from a cold flow model and 70 operating periods from a 1 MW_th CLG pilot plant, a holistic set of ground rules for the operation of the reactor setup is presented. Moreover, a novel easily-applicable approach, solely relying on readily-available live data, is presented and validated using data from the 1 MW_th chemical looping gasifier. Thereby, a straightforward estimation of solid entrainment from any CFB setup is facilitated, thus closing a crucial research gap. Full article

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17 pages, 2919 KiB

Open AccessArticle

Energy-Exergy–Economic (3E) -Optimization Analysis of a Solar System for Cooling, Heating, Power, and Freshwater Generation System for a Case Study Using Artificial Intelligence (AI)

by Mohammad Reza Assari, Ehsanolah Assareh, Neha Agarwal, Milad Setareh, Nazanin Alaei, Ali Moradian and Moonyong Lee

Energies 2023, 16(13), 4873; https://doi.org/10.3390/en16134873 - 22 Jun 2023

Cited by 3 | Viewed by 1480

Abstract

In this research, analysis of a cogeneration system harnessing solar energy with the purpose of producing electricity and freshwater is carried out. A parabolic trough collector (PTC), a reverse osmosis (RO) desalination system and a steam Rankine cycle are considered as the primary [...] Read more.

In this research, analysis of a cogeneration system harnessing solar energy with the purpose of producing electricity and freshwater is carried out. A parabolic trough collector (PTC), a reverse osmosis (RO) desalination system and a steam Rankine cycle are considered as the primary modules of the system. Optimization is conducted on the basis of the Non-Dominated Sorting Genetic Algorithm II (NSGA-II), while the Engineering Equation Solver (EES) is used to cope with the presented thermodynamic model. Sensitivity analysis of different key parameters including pump and turbine efficiencies, pump and turbine inlet pressures, evaporator pinch point and inlet temperature and, finally, solar radiation are calculated. A location with high solar energy potential is selected to explore the feasibility of installing the designed system. The case study results show that the maximum level of freshwater production happens during June and July due to an increased sunlight and ambient temperature. Annual electricity and distilled water production of 260,847.6586 MW and 73,821.34 m³ are calculated, respectively. Furthermore, the optimum results regarding the cost rate and exergy efficiency were found to be 35.26 $/h and 12.02%, respectively. Full article

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24 pages, 12168 KiB

Open AccessFeature PaperArticle

Experimental Development of the Horizontal Drain Water Heat Recovery Unit

by Sabina Kordana-Obuch and Mariusz Starzec

Energies 2023, 16(12), 4634; https://doi.org/10.3390/en16124634 - 10 Jun 2023

Cited by 4 | Viewed by 2316

Abstract

The increase in energy demand, the scarcity of resources, as well as the adverse environmental impact of burning fossil fuels make it necessary to diversify the energy sources used. This also applies to the residential sector, which accounts for a significant proportion of [...] Read more.

The increase in energy demand, the scarcity of resources, as well as the adverse environmental impact of burning fossil fuels make it necessary to diversify the energy sources used. This also applies to the residential sector, which accounts for a significant proportion of global energy consumption. Particular attention should be paid to water heating, as the importance of this process in the energy balance of buildings is steadily increasing. One of the methods used to decrease energy consumption for heating water is to recover heat from greywater. However, commercially available horizontal drain water heat recovery (DWHR) units are characterized by low effectiveness, which creates a need for further research to improve it. The aim of the paper was to evaluate the possibility of improving the effectiveness of a circular horizontal DWHR unit through the use of baffles. Six different baffle models for installation in the greywater section of the heat exchanger were analyzed. The tests were conducted under the assumption of the installation of the DWHR unit on the horizontal shower waste pipe. They showed that the effectiveness of the unit equipped with baffles was higher by several to as much as 40% compared to the DWHR unit without baffles. This is tantamount to an increase in annual financial savings resulting from greywater heat recovery, as well as a reduction in CO₂ emissions into the atmosphere. However, it was not possible to clearly identify the optimum baffle model. In any case, the selection should consider the hydraulic conditions in the heat exchanger before installing the baffles. The results can provide guidance for companies interested in bringing new equipment and technologies to the market. Full article

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20 pages, 9317 KiB

Open AccessFeature PaperArticle

Influence of Atmospheric Stability on Wind Turbine Energy Production: A Case Study of the Coastal Region of Yucatan

by Christy Pérez, Michel Rivero, Mauricio Escalante, Victor Ramirez and Damien Guilbert

Energies 2023, 16(10), 4134; https://doi.org/10.3390/en16104134 - 17 May 2023

Cited by 5 | Viewed by 2472

Abstract

Wind energy production mainly depends on atmospheric conditions. The atmospheric stability can be described through different parameters, such as wind shear, turbulence intensity, bulk Richardson number, and the Monin–Obukhov length. Although they are frequently used in micrometeorology and the wind industry, there is [...] Read more.

Wind energy production mainly depends on atmospheric conditions. The atmospheric stability can be described through different parameters, such as wind shear, turbulence intensity, bulk Richardson number, and the Monin–Obukhov length. Although they are frequently used in micrometeorology and the wind industry, there is no standard comparison method. This study describes the atmospheric stability of a coastal region of Yucatan, Mexico, using these four parameters. They are calculated using six-month data from a meteorological mast and a marine buoy to determine atmospheric stability conditions and compare their results. The unstable atmospheric condition was predominant at the site, with an 80% occurrence during the measurement period, followed by 12% in neutral and 6% in stable conditions. Wind speed estimations were performed for each atmospheric stability scenario, and the variation in the energy produced was derived for each case. Unstable atmospheric conditions deliver up to 8% more power than stable conditions, while neutral conditions deliver up to 9% more energy than stable conditions. Therefore, considering a neutral state may lead to a considerably biased energy production estimation. Finally, an example calculation indicates that atmospheric stability is a crucial parameter in estimating wind energy production more accurately. Full article

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26 pages, 2174 KiB

Open AccessReview

Pyrolysis of Waste Biomass: Technical and Process Achievements, and Future Development—A Review

by Bartłomiej Igliński, Wojciech Kujawski and Urszula Kiełkowska

Energies 2023, 16(4), 1829; https://doi.org/10.3390/en16041829 - 12 Feb 2023

Cited by 25 | Viewed by 9942

Abstract

Pyrolysis has been applied in the human economy for many years, and it has become a significant alternative to the production of chemical compounds, including biofuels. The article focuses mostly on recent achievements in the technical and processing aspects of pyrolysis. The aim [...] Read more.

Pyrolysis has been applied in the human economy for many years, and it has become a significant alternative to the production of chemical compounds, including biofuels. The article focuses mostly on recent achievements in the technical and processing aspects of pyrolysis. The aim of the review is to present the latest research on the process of waste biomass pyrolysis to fuel production. The paper describes the mechanisms of the pyrolysis process, composition, and properties of the obtained fractions, namely pyrolysis gas, bio-oil, and biochar. Additionally, the technical aspects of the pyrolysis process are mentioned, with particular attention to the construction of the reactors. The process of waste biomass pyrolysis allows for obtaining many chemical compounds (second-generation biofuels). Optimization of the pyrolysis process allows obtaining the desired products that are applied in the chemical industry, energy, and transport. The application of pyrolysis gas, oil, and biochar as valuable chemical compounds are related to the intensifying effects of climate change, biofuel production, and waste management in accordance with the principles of sustainable development. In recent years, there has been large-scale research into the use of renewable energy sources through pyrolysis. This will make it possible to significantly reduce the carbon footprint and produce second-generation biofuels in a sustainable manner. Current research into the mechanisms of pyrolysis processes is promising, and will therefore provide access to clean and low-cost compounds that will have broad applications in the energy, chemical, agricultural, and transportation industries. Full article

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21 pages, 3312 KiB

Open AccessReview

Sustainable Biofuels from First Three Alcohol Families: A Critical Review

by Muhamad Norkhizan Abdullah, Ahmad Fitri Yusop, Rizalman Mamat, Mohd Adnin Hamidi, Kumarasamy Sudhakar and Talal Yusaf

Energies 2023, 16(2), 648; https://doi.org/10.3390/en16020648 - 5 Jan 2023

Cited by 12 | Viewed by 1867

Abstract

With its unique qualities, such as infinite supply, high octane number, and capacity to cut greenhouse gas emissions, alcohol is a viable alternative fuel for SI engines. This review article aims to reveal to readers the effects of alcohol on the performance, combustion [...] Read more.

With its unique qualities, such as infinite supply, high octane number, and capacity to cut greenhouse gas emissions, alcohol is a viable alternative fuel for SI engines. This review article aims to reveal to readers the effects of alcohol on the performance, combustion behavior, and emission characteristics of SI engines by collecting the outcomes from previous research. This article looks at methanol, ethanol, and butanol fuel qualities. The performance of SI engines with butanol, ethanol, and methanol combined with gasoline is investigated in terms of brake torque, brake power, fuel consumption, thermal efficiency, volumetric efficiency, mean effective pressure, and coefficient of variation under various conditions. Second, in-cylinder pressure, mass fraction burnt, ignition delay, pressure increases, and heat release rates are also used to evaluate the combustion characteristic. Finally, the article discusses pollutant emissions such as CO, CO₂, NO_x, UHC, and exhaust gas temperature. Methanol, ethanol, and butanol mixed with gasoline increased fuel consumption and lowered spark-ignition engines’ thermal efficiency. When alcohol was combined with gasoline, most research found that CO, NO_x, and UHC emissions were reduced due to improved combustion. Full article

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2022

Jump to: 2024, 2023

27 pages, 6766 KiB

Open AccessReview

Power Plant Cycles: Evolution towards More Sustainable and Environmentally Friendly Technologies

by Andrés Meana-Fernández, Juan M. González-Caballín, Roberto Martínez-Pérez, Francisco J. Rubio-Serrano and Antonio J. Gutiérrez-Trashorras

Energies 2022, 15(23), 8982; https://doi.org/10.3390/en15238982 - 28 Nov 2022

Cited by 6 | Viewed by 4808

Abstract

The scarcity of energy and water resources and rising temperatures due to climate change has set the focus on improving the energy efficiency of power plant thermodynamic cycles to adapt to higher heat sink temperatures and use fewer resources for energy production. In [...] Read more.

The scarcity of energy and water resources and rising temperatures due to climate change has set the focus on improving the energy efficiency of power plant thermodynamic cycles to adapt to higher heat sink temperatures and use fewer resources for energy production. In this work, a review of power production thermodynamic cycles is presented: from Brayton to Rankine and combined cycles, alongside particular cycles such as Organic Rankine Cycles, Kalina, Goswami or the more recently developed Hygroscopic Cycle. The efficiency of these cycles and their possible improvements are considered, as well as their environmental impact. Costs associated with existing power plants found in the literature have also been included in the study. The main existing facilities for each cycle type are assessed, and the most sustainable options in terms of resource consumption (fuel, water, etc.) and future perspectives to ensure both their energy efficiency and sustainability are identified. Full article

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