Energies

Article

20 pages, 5724 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Dynamic Accumulation of the Quaternary Shale Biogas in Sanhu Area of the Qaidam Basin, China

by Zeyu Shao, Shijie He, Lili Hou, Yuchao Wang, Cong Tian, Xiaoxue Liu, Yuru Zhou, Mianzhu Hao and Caihua Lin

Energies 2022, 15(13), 4593; https://doi.org/10.3390/en15134593 - 23 Jun 2022

Cited by 7 | Viewed by 1738

Abstract

Biogas resources in the Sanhu area of the Qaidam Basin have great potential, but there are few studies on biogas from shale, especially on the accumulation conditions of shale biogas. The study of biogas accumulation conditions of quaternary shale in the Sanhu area [...] Read more.

Biogas resources in the Sanhu area of the Qaidam Basin have great potential, but there are few studies on biogas from shale, especially on the accumulation conditions of shale biogas. The study of biogas accumulation conditions of quaternary shale in the Sanhu area is of great significance to the theory of biogas accumulation and the guidance of exploration and development. This paper takes Quaternary shale in the Sanhu area as the research object. It is analyzed from multiple perspectives of shale hydrocarbon generation conditions, reservoir conditions, as well as hydrodynamic and structural conditions. Through the experiments of soluble organic carbon analysis and porosity and permeability analysis, the accumulation conditions of shale biogas reservoirs are clarified. The results show that the quaternary shale has a high soluble organic carbon content and high salinity formation water, which is conducive to late methane biochemical generation. Quaternary shale has the characteristics of high porosity and low permeability, mainly developing intergranular pores and intragranular pores. The large pore volume and specific surface area provide a lot of storage space for free gas and adsorbed gas, and the reservoir conditions are good. Under the structural characteristics of high in the south and low in the north and the action of formation hydrodynamics, biogas migrated from the south and deep to the north of the basin. The north slope is the main biogas-rich zone. On the whole, the quaternary shale in the Sanhu area has the characteristics of continuous hydrocarbon generation and dynamic accumulation, which has huge resource potential and exploration and development value. Full article

(This article belongs to the Special Issue New Challenges in Unconventional Oil and Gas Reservoirs)

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16 pages, 4121 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Generating 3D Geothermal Maps in Catalonia, Spain Using a Hybrid Adaptive Multitask Deep Learning Procedure

by Seyed Poorya Mirfallah Lialestani, David Parcerisa, Mahjoub Himi and Abbas Abbaszadeh Shahri

Energies 2022, 15(13), 4602; https://doi.org/10.3390/en15134602 - 23 Jun 2022

Cited by 11 | Viewed by 2753

Abstract

Mapping the subsurface temperatures can efficiently lead to identifying the geothermal distribution heat flow and potential hot spots at different depths. In this paper, an advanced adaptive multitask deep learning procedure for 3D spatial mapping of the subsurface temperature was proposed. As a [...] Read more.

Mapping the subsurface temperatures can efficiently lead to identifying the geothermal distribution heat flow and potential hot spots at different depths. In this paper, an advanced adaptive multitask deep learning procedure for 3D spatial mapping of the subsurface temperature was proposed. As a result, predictive 3D spatial subsurface temperatures at different depths were successfully generated using geolocation of 494 exploratory boreholes data in Catalonia (Spain). To increase the accuracy of the achieved results, hybridization with a new modified firefly algorithm was carried out. Subsequently, uncertainty analysis using a novel automated ensemble deep learning approach for the predicted temperatures and generated spatial 3D maps were executed. Comparing the accuracy performances in terms of correct classification rate (CCR) and the area under the precision–recall curves for validation and whole datasets with at least 4.93% and 2.76% improvement indicated for superiority of the hybridized model. According to the results, the efficiency of the proposed hybrid multitask deep learning in 3D geothermal characterization to enhance the understanding and predictability of subsurface spatial distribution of temperatures is inferred. This implies that the applicability and cost effectiveness of the adaptive procedure in producing 3D high resolution depth dependent temperatures can lead to locate prospective geothermally hotspot active regions. Full article

(This article belongs to the Section H2: Geothermal)

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21 pages, 6004 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Differential Capacity as a Tool for SOC and SOH Estimation of Lithium Ion Batteries Using Charge/Discharge Curves, Cyclic Voltammetry, Impedance Spectroscopy, and Heat Events: A Tutorial

by Peter Kurzweil, Wolfgang Scheuerpflug, Bernhard Frenzel, Christian Schell and Josef Schottenbauer

Energies 2022, 15(13), 4520; https://doi.org/10.3390/en15134520 - 21 Jun 2022

Cited by 23 | Viewed by 6713

Abstract

State-of-charge (SOC) and state-of-health (SOH) of different cell chemistries were investigated using long-time cycle tests. This practical guide illustrates how differential capacity dQ/dU (capacitance) obtained from discharge curves, impedance spectra, and cyclic voltammograms can be used for the instant diagnosis [...] Read more.

State-of-charge (SOC) and state-of-health (SOH) of different cell chemistries were investigated using long-time cycle tests. This practical guide illustrates how differential capacity dQ/dU (capacitance) obtained from discharge curves, impedance spectra, and cyclic voltammograms can be used for the instant diagnosis of lithium-ion batteries without fully charging and discharging the cell. The increase of dU/dQ is an early indicator of upcoming heat events and deep discharge. The criterion dQ/dU = dU/dQ = 1 could serve as an indicator for “full charge”. The frequency response of capacitance correlates with the available charge of the battery and reflects overcharge events and deep discharges long before the battery fails. It is not necessary to measure down to extremely low frequencies because the charge transfer pseudocapacitance of around 10 Hz reflects well the SOC. Computer-aided calculation methods for the evaluation of measurements in industrial environments and for the training of students are presented. Full article

(This article belongs to the Special Issue Recent Advances in Lithium-Ion Batteries and Supercapacitors)

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22 pages, 10713 KiB

Open AccessEditor’s ChoiceArticle

Pit Lakes Affected by a River Contaminated with Brines Originated from the Coal Mining Industry: Evolution of Water Chemistry in the Zakrzówek Horst Area (Krakow, Southern Poland)

by Jacek Motyka, Kajetan d’Obyrn, Ondra Sracek, Adam Postawa and Michał Źróbek

Energies 2022, 15(12), 4382; https://doi.org/10.3390/en15124382 - 16 Jun 2022

Cited by 4 | Viewed by 2129

Abstract

Long-term coal mining activities in the Upper Silesia significantly affect the environment in southern Poland. Discharges of brines (with TDS reaching over 110 g/L) from mines are the main source of pollution of many rivers in Poland, including the Vistula River. The Zakrzówek [...] Read more.

Long-term coal mining activities in the Upper Silesia significantly affect the environment in southern Poland. Discharges of brines (with TDS reaching over 110 g/L) from mines are the main source of pollution of many rivers in Poland, including the Vistula River. The Zakrzówek horst is a small geological structure composed of the Upper Jurassic limestones. These limestones were exploited in several quarries. In the largest one (the “Zakrzówek” quarry), exploitation reached the depth of 36 m below the water table, i.e., about 32 m below the average water level in Vistula River which flows 700 m from the quarry. An important part of this inflow into quarries came from the contaminated Vistula River, with a chloride concentration over 2 g/L. The exploitation ceased in 1991, and dewatering ended in 1992. In the old quarry area, pit lakes appeared, which are unique because they present an example of a post-mining site affected by the riverine water contaminated with brines. Investigations of physicochemical parameters of water in the Zakrzówek area were carried out in the period of 1990–2020. Results showed that the largest pit lake was initially meromictic with a distinct stratification. After several years, holomictic conditions developed due to the surface layer freshening and convective mixing. Full article

(This article belongs to the Special Issue Impact of Mine Activity on Water Environment)

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15 pages, 1188 KiB

Open AccessEditor’s ChoiceArticle

Perspectives of Biodiesel Development in Poland against the Background of the European Union

by Piotr Bórawski, Lisa Holden, Marek Bartłomiej Bórawski and Bartosz Mickiewicz

Energies 2022, 15(12), 4332; https://doi.org/10.3390/en15124332 - 13 Jun 2022

Cited by 5 | Viewed by 3614

Abstract

Biofuels are becoming more important in the renewable energy sources mix. Liquid biofuels are products of agriculture. Bioethanol can be prepared from corn, beetroot and other plants. Biodiesel is mainly made from rapeseed. This paper presents information about biodiesel development in Poland, as [...] Read more.

Biofuels are becoming more important in the renewable energy sources mix. Liquid biofuels are products of agriculture. Bioethanol can be prepared from corn, beetroot and other plants. Biodiesel is mainly made from rapeseed. This paper presents information about biodiesel development in Poland, as well as some background information about its development in the European Union (EU). We analyzed the data about biofuels in the literature, and provide statistical data about liquid biofuel in Poland and other countries of the EU. The aim of the study is to assess the viability of liquid biofuel development in Poland. The base for biodiesel production in Poland and the EU is rapeseed. The production yields and sown area of rapeseed increased in Poland from 2005–2020. This was due to integration and European Union policies which aim to supply clean energy. The energy mix in Poland differs from that of the EU. Solid biofuels have made up the biggest share of renewable energy sources in Poland (73.4%) and the EU (40.1%). Poland has smaller share of wind energy, biogas, heat pump, water energy, solar anergy, municipal waste and geothermal energy in its renewable energy sources compared to the rest of the EU. Only with solid and liquid biofuels is the share of renewable energy sources larger in Poland compared to the EU averages. Poland has decreased its share of solid biofuels and water energy among its renewable energy sources, while other sources have increased. Poland is investing to increase its renewable energy sources. To analyze the opportunities for biodiesel production in Poland, we used the scenario method of analysis. We outlined three scenarios. The first is increasing the production of biodiesel by 3% each year for the next three years. The second is production remains unchanged, i.e., at the 2020 level. The last scenario is decreasing production by 3% each year. According to the first scenario, the total demand for rapeseed for energy and food purposes will be 375 thousand tons in 2025. Such a scenario is very likely to occur because of the growing demand for biodiesel and edible oil. The current situation with Ukraine and the Russian Federation will create an increase in demand for rapeseed, leading to higher prices. Full article

(This article belongs to the Special Issue Energy Crops Production in Central and Eastern Europe)

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18 pages, 1789 KiB

Open AccessEditor’s ChoiceArticle

Changes in Energy-Related Carbon Dioxide Emissions of the Agricultural Sector in Poland from 2000 to 2019

by Zbigniew Gołaś

Energies 2022, 15(12), 4264; https://doi.org/10.3390/en15124264 - 10 Jun 2022

Cited by 7 | Viewed by 1547

Abstract

This paper analyzes the changes in carbon dioxide (CO₂) emissions related to energy consumption in the Polish agricultural sector between 2000 and 2019. Based on the Logarithmic Mean Divisia Index (LMDI), the changes in agricultural CO₂ emissions are viewed in [...] Read more.

This paper analyzes the changes in carbon dioxide (CO₂) emissions related to energy consumption in the Polish agricultural sector between 2000 and 2019. Based on the Logarithmic Mean Divisia Index (LMDI), the changes in agricultural CO₂ emissions are viewed in the context of changes in six factors, i.e., CO₂ emission intensity, substitution of fossil fuels, penetration of renewable energies, energy intensity, labor productivity and number of employees. The analysis demonstrated that total energy consumption declined over the study period; this was related to a reduction in the intake of energy derived from solid fossil fuels (−1.05%), crude oil (−1.01%), electricity (−4.89%), and heat (−1.37%), and to an increased consumption of natural gas (5.78%) and biofuels (0.82%). Furthermore, it follows from the analysis that changes in CO₂ emissions witnessed in that period were consistent with changes in energy consumption levels; this resulted from a negligible transformation of the energy mix (largely determined by fossil fuels). Generally, CO₂ emissions declined over the study period at a rate comparable (−0.9%) to that of the reduction in energy consumption (−1.03%). In light of the LMDI method, the reduction in CO₂ emissions from fuel consumption in the Polish agricultural sector was mainly driven by a reduction in energy intensity and in employment. Conversely, rapid growth in labor productivity was the key factor in increasing carbon dioxide emissions. Compared to these impacts, changes in other factors (i.e., emission intensity, energy mix and penetration of renewable energies) had an extremely small or marginal effect on the variation in CO₂ emissions. Full article

(This article belongs to the Special Issue Sustainable Agriculture and Food Supply: Scientific, Economic and Policy Analysis)

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18 pages, 2100 KiB

Open AccessEditor’s ChoiceArticle

Development and Comparison of Thermodynamic Equilibrium and Kinetic Approaches for Biomass Pyrolysis Modeling

by Sahar Safarian, Magnus Rydén and Matty Janssen

Energies 2022, 15(11), 3999; https://doi.org/10.3390/en15113999 - 29 May 2022

Cited by 21 | Viewed by 4261

Abstract

Biomass pyrolysis is considered as a thermochemical conversion system that is performed under oxygen-depleted conditions. A large body of literature exists in which thermodynamic equilibrium (TE) and kinetic approaches have been applied to predict pyrolysis products. However, the reliability, accuracy and predictive power [...] Read more.

Biomass pyrolysis is considered as a thermochemical conversion system that is performed under oxygen-depleted conditions. A large body of literature exists in which thermodynamic equilibrium (TE) and kinetic approaches have been applied to predict pyrolysis products. However, the reliability, accuracy and predictive power of both modeling approaches is an area of concern. To address these concerns, in this paper, two new simulation models based on the TE and kinetic approaches are developed using Aspen Plus, to analyze the performance of each approach. Subsequently, the results of two models are compared with modeling and experimental results available in the literature. The comparison shows that, on the one hand, the performance of the TE approach is not satisfactory and cannot be used as an effective way for pyrolysis modeling. On the other hand, the results generated by the new model based on the kinetic approach suggests that this approach is suitable for modeling biomass pyrolysis processes. Calculation of the root mean square error (RMS), to quantify the deviation of the model results from the experiment results, confirms that this kinetic model presents superior agreement with experimental data in comparison with other kinetic models in the literature. The acquired RMS for the developed kinetic method in this paper varies within the span of 1.2 to 3.2 depending on temperature (400–600 °C) and various feedstocks (pine spruce sawdust, bagasse, wood bark, beech wood and paddy straw). Full article

(This article belongs to the Special Issue Pyrolysis and Gasification of Biomass and Waste)

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27 pages, 1657 KiB

Open AccessEditor’s ChoiceArticle

Optimal Deployment of Mobile MSSSC in Transmission System

by Zhehan Zhao and Alireza Soroudi

Energies 2022, 15(11), 3878; https://doi.org/10.3390/en15113878 - 24 May 2022

Cited by 1 | Viewed by 2249

Abstract

With the rapid development of the renewable energy source (RES), network congestion management is increasingly important for transmission system operators (TSOs). The limited transmission network capacity and traditional intervention methods result in high RES curtailment. The near-term, powerful, and flexible solutions, such as [...] Read more.

With the rapid development of the renewable energy source (RES), network congestion management is increasingly important for transmission system operators (TSOs). The limited transmission network capacity and traditional intervention methods result in high RES curtailment. The near-term, powerful, and flexible solutions, such as advanced flexible AC transmission systems (FACTS), are considered to mitigate the risks. The mobile modular static synchronous series compensator (MSSSC) is one of the grid-enhancing solutions. The mobility of the solution allows it to offer fast deployment and seasonal redeployability with limited cost. The demonstration of the mobile MSSSC solution has shown significant benefits for RES curtailment reduction, network congestion alleviation, and facilitating the demand and RES connection. For unlocking the true value of the mobile solution, they should be optimally allocated in the transmission networks. This paper develops a security-constrained DCOPF-based optimisation tool to investigate the optimal allocation of the mobile MSSSC solution in transmission networks. A linear mobile MSSSC model with the operation dead-band was introduced that can be used in large-scale realistic power system planning. The proposed model was implemented in the IEEE 118-bus system to assess the performance of the mobile MSSSC. Full article

(This article belongs to the Special Issue Advanced Energy Systems Planning and Scheduling in Energy Markets: The Role of Flexibility for the Energy Transition)

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23 pages, 5039 KiB

Open AccessEditor’s ChoiceArticle

Scenarios to Decarbonize Austria’s Energy Consumption and the Role of Underground Hydrogen Storage

by Marcel Clemens and Torsten Clemens

Energies 2022, 15(10), 3742; https://doi.org/10.3390/en15103742 - 19 May 2022

Cited by 14 | Viewed by 3768

Abstract

The European Union is aiming at reaching greenhouse gas (GHG) emission neutrality in 2050. Austria’s current greenhouse gas emissions are 80 million t/year. Renewable Energy (REN) contributes 32% to Austria’s total energy consumption. To decarbonize energy consumption, a substantial increase in energy generation [...] Read more.

The European Union is aiming at reaching greenhouse gas (GHG) emission neutrality in 2050. Austria’s current greenhouse gas emissions are 80 million t/year. Renewable Energy (REN) contributes 32% to Austria’s total energy consumption. To decarbonize energy consumption, a substantial increase in energy generation from renewable energy is required. This increase will add to the seasonality of energy supply and amplifies the seasonality in energy demand. In this paper, the seasonality of energy supply and demand in a Net-Zero Scenario are analyzed for Austria and requirements for hydrogen storage derived. We looked into the potential usage of hydrogen in Austria and the economics of hydrogen generation and technology and market developments to assess the Levelized Cost of Hydrogen (LCOH). Then, we cover the energy consumption in Austria followed by the REN potential. The results show that incremental potential of up to 140 TWh for hydropower, photovoltaic (PV), and wind exists in Austria. Hydropower generation and PV is higher in summer- than in wintertime, while wind energy leads to higher energy generation in wintertime. The largest incremental potential is PV, with agrivoltaic systems significantly increasing the area amenable for PV compared with PV usage only. Battery Electric Vehicles (BEV) and Fuel Cell Vehicles (FCV) use energy more efficiently than Internal Combustion Engine (ICE) cars; however, the use of hydrogen for electricity generation significantly decreases the efficiency due to electricity–hydrogen–electricity conversion. The increase in REN use and the higher demand for energy in Austria in wintertime require seasonal storage of energy. We developed three scenarios, Externally Dependent Scenario (EDS), Balanced Energy Scenario (BES) or Self-Sustained Scenario (SSS), for Austria. The EDS scenario assumes significant REN import to Austria, whereas the SSS scenario relies on REN generation within Austria. The required hydrogen storage would be 10.82 bn m³ for EDS, 13.34 bn m³ for BES, and 18.69 bn m³ for SSS. Gas and oil production in Austria and the presence of aquifers indicates that sufficient storage capacity might be available. Significant technology development is required to be able to implement hydrogen as an energy carrier and to balance seasonal energy demand and supply. Full article

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18 pages, 1300 KiB

Open AccessEditor’s ChoiceArticle

Correlation between the Production of Electricity by Offshore Wind Farms and the Demand for Electricity in Polish Conditions

by Arkadiusz Dobrzycki and Jacek Roman

Energies 2022, 15(10), 3669; https://doi.org/10.3390/en15103669 - 17 May 2022

Cited by 8 | Viewed by 3105

Abstract

Energy transition forcing a change in the structure of the electricity generation system is a particularly difficult task in countries such as Poland, where the dominant source of energy is fossil fuels. Due to the nature of renewable sources (stochastic and seasonally variable), [...] Read more.

Energy transition forcing a change in the structure of the electricity generation system is a particularly difficult task in countries such as Poland, where the dominant source of energy is fossil fuels. Due to the nature of renewable sources (stochastic and seasonally variable), it is necessary to study their impact on the power system. Much research was conducted on this subject. They consider modelling power systems in terms of dealing with an increasing amount of renewable energy sources, stabilization of electricity generation or environmental aspects. This article examines one of the key sources of future power systems—offshore wind turbines (OWT). The influence of offshore wind sources on the power system in the fields of stability of generation, methods of regulatory strategies, and economics were examined. One of the aspects that are less considered is the correlation of energy production in OWT with energy demand and with generation in other renewable energy sources, especially in the region of the southern Baltic Sea and the distribution of energy demand in countries such as Poland. The key aspect of the research is to fill this gap. The obtained results indicate that the average monthly power generation in OWT is strongly positively correlated with the demand, and the hourly average is positively correlated moderately. Correlation between generation in OWT and photovoltaic sources is very high negative, and between onshore and offshore wind turbines is highly positive. The study indicates that the OWT has a significant potential for the development and replacement of conventional sources, due to the very high capacity and a positive correlation with demand. Moreover, future offshore wind farms can cooperate with photovoltaic sources as these sources complement each other. On the other hand, a significant saturation of the system with offshore and onshore wind sources may pose a threat to the power system due to their positive correlation. Full article

(This article belongs to the Special Issue Renewable Offshore Energies)

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18 pages, 3750 KiB

Open AccessEditor’s ChoiceArticle

Flexibility Quantification and the Potential for Its Usage in the Case of Electric Bus Depots with Unidirectional Charging

by Amra Jahic, Felix Heider, Maik Plenz and Detlef Schulz

Energies 2022, 15(10), 3639; https://doi.org/10.3390/en15103639 - 16 May 2022

Cited by 1 | Viewed by 1710

Abstract

One of the crucial steps for a successful integration of electric bus fleets into the existing electric power systems is the active and intelligent usage of their flexibility. This is important not only for reducing the eventual negative effects on the power grid [...] Read more.

One of the crucial steps for a successful integration of electric bus fleets into the existing electric power systems is the active and intelligent usage of their flexibility. This is important not only for reducing the eventual negative effects on the power grid but also for reducing energy and infrastructure costs. The first step in the optimal usage of flexibility is its quantification, which allows the maximum provision of flexibility without any negative effects for the fleet operation. This paper explores the available flexibility of large-scale electric bus fleets with a concept of centralized and unidirectional depot charging. An assessment of available positive and negative flexibility was conducted based on the data from two real bus depots in the city of Hamburg, Germany. The analysis shows the biggest flexibility potential was in the period from 16:00 h to 24:00 h, and the smallest one was in the periods from 08:00 h to 16:00 h, as well as from 02:00 h to 08:00 h. The paper also gives an overview of the possible markets for flexibility commercialization in Germany, which can provide an additional economic benefit for the fleet operators. A further analysis of the impact of parameters such as the timeline (working day or weekend), charging concept, ambient temperature, and electrical preconditioning provides an additional understanding of available flexibility. Full article

(This article belongs to the Special Issue Coherent Security Planning for Power Systems)

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21 pages, 2918 KiB

Open AccessEditor’s ChoiceArticle

Integration of Hydrothermal Carbonisation and Anaerobic Digestion for the Energy Valorisation of Grass

by Aaron E. Brown, James M. Hammerton, Miller Alonso Camargo-Valero and Andrew B. Ross

Energies 2022, 15(10), 3495; https://doi.org/10.3390/en15103495 - 10 May 2022

Cited by 11 | Viewed by 2257

Abstract

The integration of hydrothermal carbonisation (HTC) and anaerobic digestion (AD) can overcome some of the disadvantages of thermal or biological processing alone. This study aims to investigate integrated HTC-AD across a range of integration strategies and HTC processing temperatures (150 °C, 200 °C [...] Read more.

The integration of hydrothermal carbonisation (HTC) and anaerobic digestion (AD) can overcome some of the disadvantages of thermal or biological processing alone. This study aims to investigate integrated HTC-AD across a range of integration strategies and HTC processing temperatures (150 °C, 200 °C and 250 °C) to improve the energy conversion efficiency (ECE) of grass, compared to AD alone. The separation of hydrochars (HCs) for combustion and process waters (PWs) for digestion appears to be the most energetically feasible HTC-AD integration strategy, compared to HC or HTC-slurry AD. Hydrochars represent the greater energy carrier with between 81–85% of total energy output. The ECE of grass was improved from 51% to 97% (150 °C), 83% (200 °C) and 68% (250 °C) through integrated HTC-AD. Therefore, lower HTC processing temperatures yield more favourable energetics. However, higher HTC temperatures favour more desirable HC properties as a combustion fuel. The hydrochar produced at 250 °C (HC-250) displayed the highest HHV (25.8 MJ/kg) and fixed carbon: volatile matter ratio (0.47), as well as the greatest reduction in slagging and fouling potential (ash flow temperature > 1550 °C). Overall, integrated HTC-AD is an effective energy valorisation strategy for grass. A compromise exists between the quality of hydrochar and the energetic balance. However, at 250 °C the process remains energetically feasible (EROI = 2.63). Full article

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23 pages, 2488 KiB

Open AccessEditor’s ChoiceArticle

Calorific Value of Festuca rubra Biomass in the Phytostabilization of Soil Contaminated with Nickel, Cobalt and Cadmium Which Disrupt the Microbiological and Biochemical Properties of Soil

by Jadwiga Wyszkowska, Edyta Boros-Lajszner and Jan Kucharski

Energies 2022, 15(9), 3445; https://doi.org/10.3390/en15093445 - 9 May 2022

Cited by 13 | Viewed by 2152

Abstract

The choice of optimal plant species for phytoremediation and organic fertilization plays an important role in stabilizing the functions of soils contaminated with heavy metals. The influence of nickel, cobalt and cadmium on the biomass yield and calorific value of Festuca rubra, [...] Read more.

The choice of optimal plant species for phytoremediation and organic fertilization plays an important role in stabilizing the functions of soils contaminated with heavy metals. The influence of nickel, cobalt and cadmium on the biomass yield and calorific value of Festuca rubra, heavy metal concentrations in soil and plants and the microbiological, biochemical and physicochemical proprieties of soil were analyzed in a pot experiment. The tolerance index (TI) describing Festuca rubra’s ability to tolerate heavy metals, as well as the translocation (TF), accumulation (AF) and bioaccumulation (BF) factors of heavy metals in Festuca rubra were calculated. The experiment was conducted in two series: In soil fertilized and not fertilized with compost. Nickel and cobalt significantly inhibited the growth and development of Festuca rubra. The experiment demonstrated that this plant species can be grown on soil contaminated with heavy metals. Festuca rubra contained on average 46.05% C, 34.59% O, 5.91% H, 3.49% N, 0.19% S and 9.76% ash. Festuca rubra has a stable calorific value which is not affected by heavy metals; therefore, biomass harvested from heavy metal-polluted soil can be used for energy generation. The calorific value of Festuca rubra ranged from 15.924 to 16.790 MJ kg⁻¹ plant d.m., and the heat of combustion from 17.696 to 18.576 MJ kg⁻¹. It has a stable calorific value which is not affected by heavy metals, therefore biomass harvested from heavy metal-polluted soil can be used for energy generation. Festuca rubra is particularly useful for the phytostabilization of soil contaminated with cadmium and cobalt. Compost minimizes the adverse effects of heavy metal pollution on the microbiological, biochemical and physicochemical properties of soil. Full article

(This article belongs to the Special Issue Biomass Energy for Environmental Sustainability)

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17 pages, 6188 KiB

Open AccessEditor’s ChoiceArticle

SST-Based Grid Reinforcement for Electromobility Integration in Distribution Grids

by Charukeshi Joglekar, Benedict Mortimer, Ferdinanda Ponci, Antonello Monti and Rik W. De Doncker

Energies 2022, 15(9), 3202; https://doi.org/10.3390/en15093202 - 27 Apr 2022

Cited by 5 | Viewed by 2194

Abstract

Electric Vehicles (EVs) are gaining acceptance due to the advantages they offer in the reduction of nitrogen oxide and carbon dioxide emissions. The need for emission reduction and the potential of EVs for these reductions is reflected in the current sustainable mobility policies [...] Read more.

Electric Vehicles (EVs) are gaining acceptance due to the advantages they offer in the reduction of nitrogen oxide and carbon dioxide emissions. The need for emission reduction and the potential of EVs for these reductions is reflected in the current sustainable mobility policies of the EU as well as the German government. Increasing the penetration of EVs in the grid requires an expansion of EV charging infrastructure, which in turn requires either grid reinforcement or solutions for more efficient use of existing infrastructure to avoid or postpone grid reinforcement. Distribution transformers face increased loading due to EV charging and need to be protected from overloading during peak load periods to ensure continuity of service. Therefore, transformers are one of the components that are upgraded or replaced as a part of grid reinforcement. In this paper, we propose the connection of a Solid-State Transformers (SST) between two buses operating at the same-voltage level as an alternative to replacement or upgrading of conventional transformer as well as to prevent their overloading. We analyse how the proposed topology can be useful to reduce the impact of EV integration on the overloading of distribution transformers and node voltage violations in the distribution grid. Full article

(This article belongs to the Special Issue Monitoring and Control of Active Electrical Distribution Grids and Urban Energy Grids: Volume II)

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30 pages, 4315 KiB

Open AccessEditor’s ChoiceArticle

Assessment of Environmental Loads in the Life Cycle of a Retail and Service Building

by Daniel Tomporowski, Robert Kasner, Wojciech Franus and Krzysztof Doerffer

Energies 2022, 15(9), 3144; https://doi.org/10.3390/en15093144 - 25 Apr 2022

Cited by 1 | Viewed by 1608

Abstract

In order to achieve the European Union’s climate and energy goals, investments are required, mainly in the areas of energy efficiency, renewable energy sources and infrastructure. Buildings are responsible for almost half of total energy consumption, and nearly 80% of them are energy [...] Read more.

In order to achieve the European Union’s climate and energy goals, investments are required, mainly in the areas of energy efficiency, renewable energy sources and infrastructure. Buildings are responsible for almost half of total energy consumption, and nearly 80% of them are energy and ecologically inefficient. The policy of European countries is increasingly more focused on facilities with the highest potential in the areas of energy and matter saving and the possibly circular economy. The aim of the work was to assess the environmental loads occurring in the life cycle of an existing retail and service building. The analysis was performed using the Life Cycle Assessment (LCA) method. By using the IMPACT 2002+ model, it has become possible to assess the impact of the life cycle of the studied facility on human health, environmental quality, climate change and raw material resources. The highest level of negative consequences in the above-mentioned areas was recorded for the life cycle with the disposal in the form of landfill storage. The operational stage was the stage in the life cycle that caused the most harmful impacts on the environment. Therefore, it is necessary to optimize the ecological and energy consumption of resources, for example, by selecting the size and cubature of the facility for its function, maintaining good technical condition, introducing improvements in the usage processes or implementing solutions aimed at reducing media consumption. As a result of the conducted analyses, it can be noticed that in the future, the reduction in energy consumption in the operation of buildings will be of fundamental importance. Full article

(This article belongs to the Special Issue Energy Efficiency Improvements in Buildings to Achieve Climate Goals)

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20 pages, 4442 KiB

Open AccessEditor’s ChoiceArticle

A Nature-Inspired Algorithm to Enable the E-Mobility Participation in the Ancillary Service Market

by Davide Falabretti and Francesco Gulotta

Energies 2022, 15(9), 3023; https://doi.org/10.3390/en15093023 - 20 Apr 2022

Cited by 9 | Viewed by 1532

Abstract

In the present paper, a tool is proposed to optimally schedule the charging requests of a fleet of carsharing Electric Vehicles (EVs) in an urban area, to enable their participation in the Ancillary Service Market. The centralized scheduler minimizes the imbalance of an [...] Read more.

In the present paper, a tool is proposed to optimally schedule the charging requests of a fleet of carsharing Electric Vehicles (EVs) in an urban area, to enable their participation in the Ancillary Service Market. The centralized scheduler minimizes the imbalance of an EV fleet with respect to the power commitment declared in the Day-Ahead Market, providing also tertiary reserve and power balance control to the grid. The regulation is carried out by optimizing the initial charging time of each vehicle, according to a deadline set by the carsharing operator. To this purpose, a nature-inspired optimization is adopted, implementing innovative hybridizations of the Artificial Bee Colony algorithm. The e-mobility usage is simulated through a topology-aware stochastic model based on carsharing usage in Milan (Italy) and the Ancillary Services requests are modeled by real data from the Italian electricity market. The numerical simulations performed confirmed the effectiveness of the approach in identifying a suitable schedule for the charging requests of a large EV fleet (up to 3200 units), with acceptable computational effort. The benefits on the economic sustainability of the E-carsharing fleet given by the participation in the electricity market are also confirmed by an extensive sensitivity analysis. Full article

(This article belongs to the Special Issue Planning, Operation and Control of Power Grids with Penetration of Renewable Energy Sources)

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18 pages, 4214 KiB

Open AccessEditor’s ChoiceArticle

Power Hardware-in-the-Loop Test of a Low-Cost Synthetic Inertia Controller for Battery Energy Storage System

by Sergio Bruno, Giovanni Giannoccaro, Cosimo Iurlaro, Massimo La Scala and Carmine Rodio

Energies 2022, 15(9), 3016; https://doi.org/10.3390/en15093016 - 20 Apr 2022

Cited by 20 | Viewed by 4326

Abstract

In the last years, the overall system inertia is decreasing due to the growing amount of energy resources connected to the grid by means of power inverters. As a consequence, reduced levels of inertia can affect the power system stability since slight variations [...] Read more.

In the last years, the overall system inertia is decreasing due to the growing amount of energy resources connected to the grid by means of power inverters. As a consequence, reduced levels of inertia can affect the power system stability since slight variations of power generation or load may cause wider frequency deviations and higher rate of change of frequency (RoCoF) values. To mitigate this trouble, end-user distributed energy resources (DERs) interfaced through grid-following inverters, if opportunely controlled, can provide additional inertia. This paper investigated the possibility of improving the control law implemented by a low-cost controller on remotely controllable legacy DERs to provide synthetic inertia (SI) contributions. With this aim, power hardware-in-the-loop simulations were carried out to test the capability of the proposed controller to autonomously measure frequency and RoCoF and provide SI actions by controlling an actual battery energy storage system. Full article

(This article belongs to the Special Issue Power System Dynamic and Stability Issues in Modern Power Systems Facing Energy Transition)

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16 pages, 4587 KiB

Open AccessEditor’s ChoiceArticle

Hybrid Solid Oxide Fuel Cell/Gas Turbine Model Development for Electric Aviation

by Joshua A. Wilson, Yudong Wang, John Carroll, Jonathan Raush, Gene Arkenberg, Emir Dogdibegovic, Scott Swartz, David Daggett, Subhash Singhal and Xiao-Dong Zhou

Energies 2022, 15(8), 2885; https://doi.org/10.3390/en15082885 - 14 Apr 2022

Cited by 13 | Viewed by 3023

Abstract

A thermodynamic model was developed and validated to analyze a high-performance solid oxide fuel cell and gas turbine (SOFC-GT) hybrid power system for electric aviation. This study used a process simulation software package (ProMax) to study the role of SOFC design and operation [...] Read more.

A thermodynamic model was developed and validated to analyze a high-performance solid oxide fuel cell and gas turbine (SOFC-GT) hybrid power system for electric aviation. This study used a process simulation software package (ProMax) to study the role of SOFC design and operation on the feasibility and performance of the hybrid system. Standard modules, including compressor, turbine, heat exchanger, reforming reactor, and combustor were used from the ProMax tool suite while a custom module was created to simulate the SOFC stack. The model used an SOFC test data set as an input. Additional SOFC stack performance effects, such as pressure, temperature, and utilization of air and fuel, were added from open source data. System performance predictors were SOFC specific power, fuel-to-electricity conversion efficiency, and hybrid system efficiency. Using these input data and predictors, a static thermodynamic performance model was created that can be modified for different system configurations and operating conditions. Prior to creating the final aircraft performance model, initial demonstration models were developed to validate output results. We used the NASA SOFC model as a benchmark, which was created with their Numerical Propulsion System Simulator (NPSS) software framework. Our output results matched within 1% of both the NASA model and open source SOFC performance data. With confidence gained in the accuracy of this model, a 1-MW SOFC-GT hybrid power system was constructed for an aircraft propulsion concept. Overall hybrid system efficiencies of > 75% FTE were observed during standard 36,000 feet cruise flight conditions. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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26 pages, 6182 KiB

Open AccessEditor’s ChoiceArticle

A Comparative Study of Time Series Forecasting of Solar Energy Based on Irradiance Classification

by Jayesh Thaker and Robert Höller

Energies 2022, 15(8), 2837; https://doi.org/10.3390/en15082837 - 13 Apr 2022

Cited by 9 | Viewed by 5059

Abstract

Sustainable energy systems rely on energy yield from renewable resources such as solar radiation and wind, which are typically not on-demand and need to be stored or immediately consumed. Solar irradiance is a highly stochastic phenomenon depending on fluctuating atmospheric conditions, in particular [...] Read more.

Sustainable energy systems rely on energy yield from renewable resources such as solar radiation and wind, which are typically not on-demand and need to be stored or immediately consumed. Solar irradiance is a highly stochastic phenomenon depending on fluctuating atmospheric conditions, in particular clouds and aerosols. The complexity of weather conditions in terms of many variable parameters and their inherent unpredictability limit the performance and accuracy of solar power forecasting models. As renewable power penetration in electricity grids increases due to the rapid increase in the installation of photovoltaics (PV) systems, the resulting challenges are amplified. A regional PV power prediction system is presented and evaluated by providing forecasts up to 72 h ahead with an hourly time resolution. The proposed approach is based on a local radiation forecast model developed by Blue Sky. In this paper, we propose a novel method of deriving forecast equations by using an irradiance classification approach to cluster the dataset. A separate equation is derived using the GEKKO optimization tool, and an algorithm is assigned for each cluster. Several other linear regressions, time series and machine learning (ML) models are applied and compared. A feature selection process is used to select the most important weather parameters for solar power generation. Finally, considering the prediction errors in each cluster, a weighted average and an average ensemble model are also developed. The focus of this paper is the comparison of the capability and performance of statistical and ML methods for producing a reliable hourly day-ahead forecast of PV power by applying different skill scores. The proposed models are evaluated, results are compared for different models and the probabilistic time series forecast is presented. Results show that the irradiance classification approach reduces the forecasting error by a considerable margin, and the proposed GEKKO optimized model outperforms other machine learning and ensemble models. These findings also emphasize the potential of ML-based methods, which perform better in low-power and high-cloud conditions, as well as the need to build an ensemble or hybrid model based on different ML algorithms to achieve improved projections. Full article

(This article belongs to the Special Issue Advances in Wind and Solar Farm Forecasting)

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22 pages, 805 KiB

Open AccessEditor’s ChoiceArticle

Model Predictive Supervisory Control for Integrated Emission Management of Diesel Engines

by Johannes Ritzmann, Christian Peterhans, Oscar Chinellato, Manuel Gehlen and Christopher Onder

Energies 2022, 15(8), 2755; https://doi.org/10.3390/en15082755 - 8 Apr 2022

Cited by 4 | Viewed by 1689

Abstract

In this work, a predictive supervisory controller is presented that optimizes the interaction between a diesel engine and its aftertreatment system (ATS). The fuel consumption is minimized while respecting an upper bound on the emitted tailpipe NO_x mass. This is achieved by [...] Read more.

In this work, a predictive supervisory controller is presented that optimizes the interaction between a diesel engine and its aftertreatment system (ATS). The fuel consumption is minimized while respecting an upper bound on the emitted tailpipe NO_x mass. This is achieved by optimally balancing the fuel consumption, the engine-out NO_x emissions, and the ATS heating. The proposed predictive supervisory controller employs a two-layer model predictive control structure and solves the optimal control problem using a direct method. Through experimental validation, the resulting controller was shown to reduce the fuel consumption by 1.1% at equivalent tailpipe NO_x emissions for the nonroad transient cycle when compared to the operation with a fixed engine calibration. Further, the controller’s robustness to different missions, initial ATS temperatures, NO_x limits, and mispredictions was demonstrated. Full article

(This article belongs to the Special Issue Development of Efficient Internal Combustion Engines and Vehicle Powertrains)

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16 pages, 15942 KiB

Open AccessEditor’s ChoiceArticle

Regulated Two-Dimensional Deep Convolutional Neural Network-Based Power Quality Classifier for Microgrid

by Cheng-I Chen, Sunneng Sandino Berutu, Yeong-Chin Chen, Hao-Cheng Yang and Chung-Hsien Chen

Energies 2022, 15(7), 2532; https://doi.org/10.3390/en15072532 - 30 Mar 2022

Cited by 9 | Viewed by 2425

Abstract

Due to the penetration of renewable energy and load variation in the microgrid, the diagnosis of power quality disturbances (PQD) is important to the operation stability and safety of the microgrid system. Once the power imbalance is present between the generation and the [...] Read more.

Due to the penetration of renewable energy and load variation in the microgrid, the diagnosis of power quality disturbances (PQD) is important to the operation stability and safety of the microgrid system. Once the power imbalance is present between the generation and the load demand, the fundamental frequency would deviate from the nominal value. As a result, the performance of the power quality classifier based on the neural network would be deteriorated since the deviation of fundamental frequency is not taken into account. In this paper, the regulated two-dimensional (2D) deep convolutional neural network (CNN)-based approach for PQD classification is proposed. In the data preprocessing stage, the IEC-based synchronizer is introduced to detect the deviation of fundamental frequency. In this way, the 2D grayscale image serving as the input of the deep CNN classifier can be accurately regulated. The obtained 2D image can effectively preserve information and waveform characteristics of the PQD signal. The experiment is implemented with datasets containing 14 different categories of PQD. According to this result, it is revealed that the regulated 2D deep CNN can improve the effectiveness of PQD classification in a real-time manner. Furthermore, the proposed method outperforms the methods in previous studies according to the field verification. Full article

(This article belongs to the Special Issue Power Quality in Smart Grids: Advanced Technology for System Regulation and Analysis)

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17 pages, 2698 KiB

Open AccessEditor’s ChoiceArticle

Intermediate Pyrolysis of Brewer’s Spent Grain: Impact of Gas Atmosphere

by Artur Bieniek, Wojciech Jerzak, Małgorzata Sieradzka, Łukasz Mika, Karol Sztekler and Aneta Magdziarz

Energies 2022, 15(7), 2491; https://doi.org/10.3390/en15072491 - 28 Mar 2022

Cited by 12 | Viewed by 2912

Abstract

This work focuses on the impact of carrier gas on the quantity and quality of pyrolytic products received from intermediate pyrolysis of the brewer’s spent grain. In this study, three types of carrier gases were tested: argon, nitrogen, and carbon dioxide at three [...] Read more.

This work focuses on the impact of carrier gas on the quantity and quality of pyrolytic products received from intermediate pyrolysis of the brewer’s spent grain. In this study, three types of carrier gases were tested: argon, nitrogen, and carbon dioxide at three temperatures of 500, 600, and 700 °C. On the basis of the process conditions, the yield of products was determined. The ultimate analysis of the char was performed, and for selected chars, the combustion properties were determined. Gas chromatography of the organic fraction of oil was performed, and the compounds were determined. Additionally, microscale investigation of the spent grain pyrolysis was performed by thermogravimetric analysis. The results showed that there were no significant differences in product yields in various atmospheres. Char yield changed only with temperature from 28% at 500 °C up to 19% at 700 °C. According to ultimate analysis, the char from CO₂ pyrolysis was approximately 2% richer in carbon and this fact did not influence on the combustion properties of the char. The oil fraction was characterized mainly by acids with a maximum content of 68% at 600 °C in an argon atmosphere and the acid concentration depended on the carrier gas as follows line: Ar > N₂ > CO₂. Full article

(This article belongs to the Special Issue Biomass and Waste Conversion: Latest Advances and Prospects)

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22 pages, 87582 KiB

Open AccessEditor’s ChoiceArticle

Simulators for Designing Energy-Efficient Power Supplies Based on Solar Panels

by Oleg Rekutov, Michail Surkov, Danil Lyapunov, Alexey Muravlev, Alexandra Pravikova, Anton Yudintsev, Victor Rulevskiy, Oleg Bubnov and Victor Pchelnikov

Energies 2022, 15(7), 2480; https://doi.org/10.3390/en15072480 - 28 Mar 2022

Cited by 1 | Viewed by 2009

Abstract

Boosted interest in highly efficient power supplies based on renewables requires involving simulators during both the designing stage and the testing one. It is especially relevant for the power supplies that operate in the harsh environmental conditions of northern territories and alike. Modern [...] Read more.

Boosted interest in highly efficient power supplies based on renewables requires involving simulators during both the designing stage and the testing one. It is especially relevant for the power supplies that operate in the harsh environmental conditions of northern territories and alike. Modern solar panels based on polycrystalline Si and GaAs possess relatively high efficiency and energy output. To save designing time and cost, system developers use simulators for the solar panels coupled with the power converters that stabilize the output parameters and ensure the proper output power quality to supply autonomous objects: namely, private houses, small-power (up to 10 kW) industrial buildings, submersible pumps, and other equipment. It is crucial for the simulator to provide a valid solar panel I-V curve in various modes and under different ambient conditions: namely, the consumed power rating, temperature, solar irradiation, etc. This paper considers a solar panel simulator topology representing one of the state-of-the-art solutions. This solution is based on principles of classical control theory involving a pulse buck converter as an object of control. A mathematical model of the converter was developed. Its realization in MATLAB/Simulink confirmed the adequacy and applicability of both discrete and continuous forms of the model during the design stage. Families of I-V curves for a commercially available solar panel within the temperature range from

- 40

to +25

^{\circ}

C were simulated on the model. A prototype of the designed simulator has shown its correspondence to the model in Simulink. The developed simulator allows providing a full-scale simulation of solar panels in various operating modes with the maximum value of the open circuit voltage 60 V and that of the short circuit current 60 A. Issues of statistical processing of experimental data and cognitive visualization of the obtained curves involving the cognitive graphic tool 2-simplex have also been considered within the framework of this research. The simulator designed may serve as a basis for developing a product line of energy-efficient power supplies for autonomous objects based on renewables, including those operating in northern territories. Full article

(This article belongs to the Special Issue Solar Energy Harvesting in Northern Territories)

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20 pages, 2973 KiB

Open AccessEditor’s ChoiceArticle

Smart Metering Roll-Out in Europe: Where Do We Stand? Cost Benefit Analyses in the Clean Energy Package and Research Trends in the Green Deal

by Silvia Vitiello, Nikoleta Andreadou, Mircea Ardelean and Gianluca Fulli

Energies 2022, 15(7), 2340; https://doi.org/10.3390/en15072340 - 23 Mar 2022

Cited by 28 | Viewed by 13855

Abstract

2020 was a key year for several targets in European energy and climate policy, including the requirement for European countries to deploy smart metering for at least 80% of electricity consumers. This target was set to ease the transition towards a consumer-centered and [...] Read more.

2020 was a key year for several targets in European energy and climate policy, including the requirement for European countries to deploy smart metering for at least 80% of electricity consumers. This target was set to ease the transition towards a consumer-centered and digitalized energy system. In fact, there are numerous applications that are facilitated or are directly linked to smart meters. Among others: demand response programs that enable consumers to be active in the energy market, and remote grid monitoring by the Distribution System Operator. In this paper, we analyze the initial provisions of the Third Energy Package and those of the Clean Energy Package, with particular focus on the recently approved directive on common rules for the internal market for electricity and the newly introduced smart meters specifications. We present the highlights of the national cost–benefit analyses for smart metering roll-out, focusing on the decisions made by the Member States with respect to a potential smart meter roll-out, that was targeted to be completed by 2020 and present the current situation of smart metering roll-out. We also present and categorize some of the R&I smart grid projects realized over recent years, focusing on the ones that deal with smart metering integration in order to depict the smart metering applications and technologies tested on the ground. Therefore, this paper portrays a full picture with respect to smart meters in Europe today and gives insights for monitoring smart metering roll-outs taking into account the current trends in smart metering applications. Full article

(This article belongs to the Special Issue Smart Grid Outlook in Europe: Approaches, Challenges and Opportunities)

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14 pages, 18571 KiB

Open AccessEditor’s ChoiceArticle

A Study on Automatically Target-Chasing Microwave Power Transfer Systems in Multipath Environments

by Naoki Shinohara and Taichi Sasaki

Energies 2022, 15(7), 2343; https://doi.org/10.3390/en15072343 - 23 Mar 2022

Cited by 2 | Viewed by 2090

Abstract

In this paper, we propose novel retrodirective systems to improve the efficiency and safety of microwave power transmission (MPT) systems in multipath environments. The retrodirective system consists of an array antenna with phased conjugation circuits and it sends back the phase-conjugate signal toward [...] Read more.

In this paper, we propose novel retrodirective systems to improve the efficiency and safety of microwave power transmission (MPT) systems in multipath environments. The retrodirective system consists of an array antenna with phased conjugation circuits and it sends back the phase-conjugate signal toward the pilot signal transmitted from the receiver. It is usually applied for one receiver MPT system, however, Ossia corp. develops the new retrodirective system in multipath environments named ‘Cota’. We simulated the detail of the Cota system, e.g., one receiver in multipath circumstance, one receiver with obstacle in the multipath circumstance, and multi receiver. Furthermore, we revised the retrodirective system with phase information as well as the amplitude information of the pilot signal to improve the MPT efficiency. We also find effect of the MPT efficiency by phase difference between two pilot signal sources. At last, we carried out the experiments of the retrodirective system in multipath circumstance to prove the simulation results. Full article

(This article belongs to the Special Issue Next Generation Wireless Charging System for Mobile Devices)

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16 pages, 1637 KiB

Open AccessEditor’s ChoiceArticle

Techno-Economic Analysis of Intermediate Pyrolysis with Solar Drying: A Chilean Case Study

by Tobias Zimmer, Andreas Rudi, Simon Glöser-Chahoud and Frank Schultmann

Energies 2022, 15(6), 2272; https://doi.org/10.3390/en15062272 - 21 Mar 2022

Cited by 8 | Viewed by 3528

Abstract

Intermediate pyrolysis can be used to obtain high-quality biofuels from low-value residues such as sewage sludge or digestate. A major obstacle is the high water content of sludgy biomass, which requires an energy-intensive and expensive drying step before pyrolysis. Solar greenhouse drying is [...] Read more.

Intermediate pyrolysis can be used to obtain high-quality biofuels from low-value residues such as sewage sludge or digestate. A major obstacle is the high water content of sludgy biomass, which requires an energy-intensive and expensive drying step before pyrolysis. Solar greenhouse drying is an efficient and sustainable alternative to a thermally heated belt dryer. In this study, a techno-economic assessment of intermediate pyrolysis with solar drying is carried out. Marketable products of the process are bio-oil, a substitute for diesel or heating oil, and bio-char with various possible applications. Chile is chosen as the setting of the study as its 4000 km long extension from north to south gives the opportunity to evaluate different locations and levels of solar irradiation. It is found that solar drying results in higher capital investment, but lower fuel costs. Depending on the location and solar irradiation, solar drying can reduce costs by 5–34% compared to belt drying. The break-even price of bio-char is estimated at 300–380 EUR/ton after accounting for the revenue from the liquid bio-oil. Full article

(This article belongs to the Special Issue Biofuel Value Chains: Innovations and Sustainability)

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26 pages, 1527 KiB

Open AccessEditor’s ChoiceArticle

Minimum-Cost Fast-Charging Infrastructure Planning for Electric Vehicles along the Austrian High-Level Road Network

by Antonia Golab, Sebastian Zwickl-Bernhard and Hans Auer

Energies 2022, 15(6), 2147; https://doi.org/10.3390/en15062147 - 15 Mar 2022

Cited by 12 | Viewed by 3596

Abstract

Given the ongoing transformation of the transport sector toward electrification, expansion of the current charging infrastructure is essential to meet future charging demands. The lack of fast-charging infrastructure along highways and motorways is a particular obstacle for long-distance travel with battery electric vehicles [...] Read more.

Given the ongoing transformation of the transport sector toward electrification, expansion of the current charging infrastructure is essential to meet future charging demands. The lack of fast-charging infrastructure along highways and motorways is a particular obstacle for long-distance travel with battery electric vehicles (BEVs). In this context, we propose a charging infrastructure allocation model that allocates and sizes fast-charging stations along high-level road networks while minimizing the costs for infrastructure investment. The modeling framework is applied to the Austrian highway and motorway network, and the needed expansion of the current fast-charging infrastructure in place is modeled under different future scenarios for 2030. Within these, the share of BEVs in the car fleet, developments in BEV technology and road traffic load changing in the face of future modal shift effects are altered. In particular, we analyze the change in the requirements for fast-charging infrastructure in response to enhanced driving range and growing BEV fleets. The results indicate that improvements in the driving range of BEVs will have limited impact and hardly affect future costs of the expansion of the fast-charging infrastructure. On the contrary, the improvements in the charging power of BEVs have the potential to reduce future infrastructure costs. Full article

(This article belongs to the Special Issue Developments in Electric Vehicle Charging Station Infrastructure)

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21 pages, 2104 KiB

Open AccessEditor’s ChoiceArticle

Scalable Room Occupancy Prediction with Deep Transfer Learning Using Indoor Climate Sensor

by Davor Stjelja, Juha Jokisalo and Risto Kosonen

Energies 2022, 15(6), 2078; https://doi.org/10.3390/en15062078 - 12 Mar 2022

Cited by 11 | Viewed by 5194

Abstract

An important instrument for achieving smart and high-performance buildings is Machine Learning (ML). A lot of research has been done in exploring the ML models for various applications in the built environment such as occupancy prediction. Nevertheless, the research focused mostly on analyzing [...] Read more.

An important instrument for achieving smart and high-performance buildings is Machine Learning (ML). A lot of research has been done in exploring the ML models for various applications in the built environment such as occupancy prediction. Nevertheless, the research focused mostly on analyzing the feasibility and performance of different supervised ML models but has rarely focused on practical applications and the scalability of those models. In this study, a transfer learning method is proposed as a solution to typical problems in the practical application of ML in buildings. Such problems are scaling a model to a different building, collecting ground truth data necessary for training the supervised model, and assuring the model is robust when conditions change. The practical application examined in this work is a deep learning model used for predicting room occupancy using indoor climate IoT sensors. This work proved that it is possible to significantly reduce the length of ground truth data collection to only two days. The robustness of the transferred model was tested as well, where performance stayed on a similar level if a suitable normalization technique was used. In addition, the proposed methodology was tested with room occupancy level prediction, showing slightly lower performance. Finally, the importance of understanding the performance metrics is crucial for market adoption of ML-based solutions in the built environment. Therefore, in this study, additional analysis was done by presenting the occupancy prediction model performance in understandable ways from the practical perspective. Full article

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23 pages, 2951 KiB

Open AccessEditor’s ChoiceArticle

Comparison of the Gaussian Wind Farm Model with Historical Data of Three Offshore Wind Farms

by Bart Matthijs Doekemeijer, Eric Simley and Paul Fleming

Energies 2022, 15(6), 1964; https://doi.org/10.3390/en15061964 - 8 Mar 2022

Cited by 17 | Viewed by 4293

Abstract

A recent expert elicitation showed that model validation remains one of the largest barriers for commercial wind farm control deployment. The Gaussian-shaped wake deficit model has grown in popularity in wind farm field experiments, yet its validation for larger farms and throughout annual [...] Read more.

A recent expert elicitation showed that model validation remains one of the largest barriers for commercial wind farm control deployment. The Gaussian-shaped wake deficit model has grown in popularity in wind farm field experiments, yet its validation for larger farms and throughout annual operation remains limited. This article addresses this scientific gap, providing a model comparison of the Gaussian wind farm model with historical data of three offshore wind farms. The energy ratio is used to quantify the model’s accuracy. We assume a fixed turbulence intensity of

I_{\infty} = 6 %

and a standard deviation on the inflow wind direction of

σ_{w d} = 3 °

in our Gaussian model. First, we demonstrate the non-uniqueness issue of

I_{\infty}

and

σ_{w d}

, which display a waterbed effect when considering the energy ratios. Second, we show excellent agreement between the Gaussian model and historical data for most wind directions in the Offshore Windpark Egmond aan Zee (OWEZ) and Westermost Rough wind farms (36 and 35 wind turbines, respectively) and wind turbines on the outer edges of the Anholt wind farm (110 turbines). Turbines centrally positioned in the Anholt wind farm show larger model discrepancies, likely due to deep-array effects that are not captured in the model. A second source of discrepancy is hypothesized to be inflow heterogeneity. In future work, the Gaussian wind farm model will be adapted to address those weaknesses. Full article

(This article belongs to the Special Issue Fast-Running Engineering Models of Wind Farm Flows)

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20 pages, 3042 KiB

Open AccessEditor’s ChoiceArticle

Characteristics of the Main- and Side-Stream Products of Microwave Assisted Torrefaction of Lignocellulosic Biomass of Different Origination

by Alexandr Arshanitsa, Lilija Jashina, Matiss Pals, Jevgenija Ponomarenko, Yegor Akishin and Maja Zake

Energies 2022, 15(5), 1857; https://doi.org/10.3390/en15051857 - 2 Mar 2022

Cited by 1 | Viewed by 2198

Abstract

In this paper, the yields and composition of solid and condensable products that were obtained by microwave-assisted torrefaction of softwood, wheat straw, and peat fuel pellets, defined as main- and side-stream torrefaction products, were studied. The torrefaction process, at temperatures varied in the [...] Read more.

In this paper, the yields and composition of solid and condensable products that were obtained by microwave-assisted torrefaction of softwood, wheat straw, and peat fuel pellets, defined as main- and side-stream torrefaction products, were studied. The torrefaction process, at temperatures varied in the range of 200–300 °C, was performed using a laboratory-scale torrefactor of original construction. Water-enriched fractions were distilled off from condensable products to isolate tar fractions, the fuel characteristics of which were compared with those of solid fractions. Py-GC/MS/FID, GC/MS/FID, thermal analysis, elemental analysis, and wet chemistry methods were used to characterize the main- and side-stream torrefaction products, with a focus on their valorization according to the biorefinery approach. The simultaneous development of the destruction and condensation processes in lignocarbohydrate complexes during microwave treatment leads to an increase in the relative portion of aromatic compounds in torrefied biomass, increasing the higher heating value (HHV) of the solid fractions. The increase up to 60% of the heat amount that was liberated due to the thermal oxidative conversion of solid fractions vs. that of the non-treated ones was established by DSC tests. The heat that was liberated by the combustion of the tar fractions was much lower than that of solid fractions, which was explained by the composition of tars, influencing their thermal conversion. Full article

(This article belongs to the Special Issue Renewable Energy from Solid Waste)

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30 pages, 8528 KiB

Open AccessEditor’s ChoiceArticle

The Balance of Outlays and Effects of Restructuring Hard Coal Mining Companies in Terms of Energy Policy of Poland PEP 2040

by Jarosław Kaczmarek

Energies 2022, 15(5), 1853; https://doi.org/10.3390/en15051853 - 2 Mar 2022

Cited by 16 | Viewed by 3079

Abstract

The article aimed to present the balance of outlays and the effects of restructuring Polish hard coal mining companies in the face of directions of the Energy Policy of Poland PEP 2040. The research problem is defined by the following question: have the [...] Read more.

The article aimed to present the balance of outlays and the effects of restructuring Polish hard coal mining companies in the face of directions of the Energy Policy of Poland PEP 2040. The research problem is defined by the following question: have the goals of restructuring coal mining companies been achieved (and to what extent), and has the restructuring-related expenditure been economically rational? An answer to this question is based on the verification of five research hypotheses, in particular, have the incurred costs of restructuring contributed to changes to the energy mix (its desired time and degree), reducing related expenditure? The scope of research comprises all companies engaged in the extraction of solid mineral energy resources (the entire industry). An assessment of the restructuring process was conducted from two perspectives related to its time and scope. The first perspective was the restructuring programme as a sub-process of the economic transformation (1990–2020), and economic forecasts until the planned coal phase-out (2021–2049). The second perspective was an analysis of the mechanism that determines companies’ performance after carrying out typical and direct restructuring activities (2007–2021). Two multivariate measures were developed for methodological purposes, and the analysis also made use of a logit prediction model and several financial analysis ratios. The analysis led to the general conclusion that the restructuring of hard coal mining companies was not effective—it did not ensure their independent and effective functioning. In particular, the analysis led to the following conclusions: (1) the restructuring process had different levels of intensity, which allowed for its periodization; (2) the main and increasingly important factor of changes was human labour productivity (as opposed to objectified labour—machines and equipment); (3) the identified mechanism of creating results pointed to the areas of inappropriate management; (4) the previous restructuring costs did not contribute to changing the energy mix, and they are likely to rise until coal phase-out. Full article

(This article belongs to the Special Issue Managing Energy Sector Enterprises: Challenges, Methods and Research Trends)

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34 pages, 12749 KiB

Open AccessEditor’s ChoiceArticle

Piloted Simulation of the Rotorcraft Wind Turbine Wake Interaction during Hover and Transit Flights

by Alexander Štrbac, Daniel Heinrich Greiwe, Frauke Hoffmann, Marion Cormier and Thorsten Lutz

Energies 2022, 15(5), 1790; https://doi.org/10.3390/en15051790 - 28 Feb 2022

Cited by 3 | Viewed by 2232

Abstract

Helicopters are used for offshore wind farms for maintenance and support flights. The number of helicopter operations is increasing with the expansion of offshore wind energy, which stresses the point that the current German regulations have not yet been validated through scientific analysis. [...] Read more.

Helicopters are used for offshore wind farms for maintenance and support flights. The number of helicopter operations is increasing with the expansion of offshore wind energy, which stresses the point that the current German regulations have not yet been validated through scientific analysis. A collaborative research project between DLR, the Technical University of Munich, the University of Stuttgart and the University of Tübingen has been conducted to examine the sizes of the flight corridors on offshore wind farms and the lateral safety clearance for helicopter hoist operations at offshore wind turbines. This paper details the results of piloted helicopter simulations in a realistic offshore wind farm scenario. The far-wake of rotating wind turbines and the near-wake of non-rotating wind turbines have been simulated with high-fidelity computational fluid dynamics under realistic turbulent inflow conditions. The resulting flow fields have been processed by superposition during piloted simulations in the research flight simulator AVES to examine the flight corridors in transit flights and the lateral safety clearance in hovering flights. The results suggest a sufficient size for the flight corridor and sufficient lateral safety clearance at the offshore wind turbines in the considered scenarios. Full article

(This article belongs to the Special Issue Rotary Wing Aerodynamics)

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21 pages, 12396 KiB

Open AccessEditor’s ChoiceArticle

Design, Energy, Environmental and Cost Analysis of an Integrated Collector Storage Solar Water Heater Based on Multi-Criteria Methodology

by Nektarios Arnaoutakis, Andreas P. Vouros, Maria Milousi, Yannis G. Caouris, Giorgos Panaras, Antonios Tourlidakis, Kyriakos Vafiadis, Giouli Mihalakakou, Christos S. Garoufalis, Zacharias Frontistis, Spiros Papaefthimiou and Manolis Souliotis

Energies 2022, 15(5), 1673; https://doi.org/10.3390/en15051673 - 23 Feb 2022

Cited by 5 | Viewed by 2854

Abstract

The paper presents a design and operation analysis of an Integrated Collector Storage (ICS) solar water heater, which consists of an asymmetric Compound Parabolic Concentrating (CPC) reflector trough, while the water tank comprises two concentric cylinders. The annulus between these vessels is partially [...] Read more.

The paper presents a design and operation analysis of an Integrated Collector Storage (ICS) solar water heater, which consists of an asymmetric Compound Parabolic Concentrating (CPC) reflector trough, while the water tank comprises two concentric cylinders. The annulus between these vessels is partially depressurized and contains a small amount of water in the bottom of the outer vessel which dominantly contributes to the heat transfer from the outer to the inner cylinder. A multi-criteria optimization algorithm is applied to re-evaluate the design specifications of the parabolic surface, thus modifying the design of the entire ICS system and predict the necessary number of units for achieving the highest possible effectiveness with minimized fabrication costs and environmental impacts. The environmental footprint of the device is assessed through Life Cycle Assessment (LCA). The produced thermal energy in conjunction with the environmental and economic results are evaluated as a function of different configuration parameters regarding the water storage conditions, the solar radiation and the total pressure inside the annulus. The ultimate aim of the evaluation process is to offer new perspectives on the design principles of environmentally friendly and cost-effective devices with improved thermal performance. Full article

(This article belongs to the Special Issue Development, Design, Production and Environmental Analysis of Advanced Solar Thermal Collectors and Heat Storage Systems)

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21 pages, 5611 KiB

Open AccessEditor’s ChoiceArticle

Cost Optimal Renewable Electricity-Based HVAC System: Application of Air to Water or Water to Water Heat Pump

by Boris Delač, Branimir Pavković, Marino Grozdek and Luka Bezić

Energies 2022, 15(5), 1658; https://doi.org/10.3390/en15051658 - 23 Feb 2022

Cited by 4 | Viewed by 3130

Abstract

This paper aims to determine cost optimality between heating, ventilation and air conditioning (HVAC) systems operating with air to water heat pumps (AWHP) and water to water heat pumps (WWHP). The analysis is performed for a certain number of heat pump units with [...] Read more.

This paper aims to determine cost optimality between heating, ventilation and air conditioning (HVAC) systems operating with air to water heat pumps (AWHP) and water to water heat pumps (WWHP). The analysis is performed for a certain number of heat pump units with fixed and variable capacity made by four manufacturers available on European market. Simulations are performed in Trnsys software. The results show that heat pump partial load efficiency should not be neglected in analysis of application while the difference in energy consumption and costs can be up to 17%. The requirement for performing analysis on a wider range of units is indicated, especially when heat pump systems with different sources are considered. HVAC system with AWHP units with capacity control is a cost optimal solution for case study nursery building operating on the Croatian coast. The application of the photovoltaic (PV) array sized to cover nonrenewable part of electricity consumed in HVAC system has a return period of 12 years. It is determined that seasonal efficiency indicators from relevant European database do not support unit operation. Full article

(This article belongs to the Special Issue Design and Optimization of Advanced Energy Systems in Nearly Zero Energy Buildings)

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21 pages, 3276 KiB

Open AccessEditor’s ChoiceArticle

Co-Processing Lignocellulosic Biomass and Sewage Digestate by Hydrothermal Carbonisation: Influence of Blending on Product Quality

by Kiran R. Parmar, Aaron E. Brown, James M. Hammerton, Miller Alonso Camargo-Valero, Louise A. Fletcher and Andrew B. Ross

Energies 2022, 15(4), 1418; https://doi.org/10.3390/en15041418 - 15 Feb 2022

Cited by 17 | Viewed by 2496

Abstract

Hydrothermal carbonisation (HTC) can be integrated with anaerobic digestion (AD) for the treatment of digestate, resulting in a solid hydrochar or bio-coal and a process water, which can be recirculated back into AD to produce biogas. The properties of digestate-derived hydrochars do not [...] Read more.

Hydrothermal carbonisation (HTC) can be integrated with anaerobic digestion (AD) for the treatment of digestate, resulting in a solid hydrochar or bio-coal and a process water, which can be recirculated back into AD to produce biogas. The properties of digestate-derived hydrochars do not lend themselves to producing high quality bio-coal and blending with lignocellulosic feedstocks can improve its properties. This study investigates the co-processing of sewage sludge (SS) digestate with three lignocellulosic biomass (grass, privet hedge, and woodchip). The calorific value of the resulting bio-coal is increased following co-processing, although feedstock interactions result in non-additive behaviour. The largest increase in calorific value was observed for co-processing with woodchip. There is evidence for non-additive partitioning of metals during co-processing resulting in only moderate improvements in ash chemistry during combustion. Co-processing also effects the composition of process waters, influencing the potential for biogas production. Experimental biomethane potential (BMP) tests indicate that grass clippings are the most suitable co-feedstock for maintaining both calorific value and biogas production. However, above 200 °C, BMP yields appear to decrease, suggesting the process water may become more inhibitory. Co-processing with wood waste and privet hedge produce the higher CV bio-coal but significantly reduced BMP. Full article

(This article belongs to the Section A: Sustainable Energy)

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13 pages, 4206 KiB

Open AccessEditor’s ChoiceArticle

How to Reduce the Design of Disc-Shaped Heat Exchangers to a Zero-Degrees-of-Freedom Task

by Enrico Sciubba

Energies 2022, 15(3), 1250; https://doi.org/10.3390/en15031250 - 8 Feb 2022

Viewed by 1897

Abstract

The continuous quest for improving the performance of heat exchangers, together with ever more stringent volume and weight constraints, especially in enclosed applications like internal combustion engines and electronic devices, has stimulated the search for compact, high-performance units. One of the shapes that [...] Read more.

The continuous quest for improving the performance of heat exchangers, together with ever more stringent volume and weight constraints, especially in enclosed applications like internal combustion engines and electronic devices, has stimulated the search for compact, high-performance units. One of the shapes that has emerged from a vast body of research is the disc-shaped heat exchanger, in which the fluid to be heated/cooled flows through radial—often bifurcated—channels carved inside a metallic disc. The disc in turn exchanges thermal energy with the hot/cold source (the environment or another body). Several studies have been devoted to the identification of an “optimal shape” of the channels: most of them are based on the extremization of some global property of the device, like its monetary or resource cost, its efficiency, the outlet temperature of one of the fluids, the total irreversibility of the process, etc. The present paper demonstrates that-for all engineering purposes there is only one correct design procedure for such a heat exchanger, and that if a few basic rules of engineering common sense are adopted, this procedure depends solely on the technical specifications (type of operation, thermal load, materials, surface quality): the design in fact reduces to a zero-degree of freedom problem. The procedure is described in detail, and it is shown that a proper application of the constraints completely identifies the shape, size and similarity indices of both the disc and the internal channels. The goal of this study is to demonstrate that-in this, as in many similar cases-a straightforward application of prime principles and of diligent engineering rules, may generate “optimal” designs: these principles guarantee a sort of “embedded optimality”. Full article

(This article belongs to the Special Issue Selected Papers from ECOS 2021—34th International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems)

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20 pages, 4339 KiB

Open AccessEditor’s ChoiceArticle

Energy Recovery from Waste—Closing the Municipal Loop

by Emilia den Boer, Kamil Banaszkiewicz, Jan den Boer and Iwona Pasiecznik

Energies 2022, 15(3), 1246; https://doi.org/10.3390/en15031246 - 8 Feb 2022

Cited by 6 | Viewed by 3657

Abstract

Municipal waste management in the EU has been challenged to a thorough transformation towards a Circular Economy. It is addressed by a number of quantitative policy targets, including a restriction on municipal waste landfilling to 10% in 2035. This paper presents the data [...] Read more.

Municipal waste management in the EU has been challenged to a thorough transformation towards a Circular Economy. It is addressed by a number of quantitative policy targets, including a restriction on municipal waste landfilling to 10% in 2035. This paper presents the data on municipal waste composition in a large Polish city, based on thorough waste sorting analyses. On average, 374 kg of municipal waste is collected per capita in Wroclaw, of which 41% are separately collected fractions. The approach to implement the EU recycling targets until 2035 is presented, including an increase of sorting and recycling efficiency and a significant share of recyclables being retrieved from the residual waste fraction. Notwithstanding the recycling targets, an important stream of residual waste remains, amounting to 200 k ton in 2020 and approx. 130 k ton in 2035, which is available for energy recovery. The respective LHV values range from 8.5 to 7.6 MJ/kg. The results indicate that the residual waste stream, after satisfying the recycling targets, is still suitable for energy recovery through the whole period until 2035. Moreover, it is a necessary step towards closing the materials cycling in the municipal sector and the only option so far to reduce landfilling sufficiently. Full article

(This article belongs to the Special Issue Energy Saving and Zero-Energy Systems: Renewable Energy Technologies, Energy Efficiency, Circular Economy)

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17 pages, 2619 KiB

Open AccessEditor’s ChoiceArticle

Economic and Environmental Potential of Large-Scale Renewable Synthetic Jet Fuel Production through Integration into a Biomass CHP Plant in Sweden

by Anton Fagerström, Omar Abdelaziz, Sofia Poulikidou, Adam Lewrén, Christian Hulteberg, Ola Wallberg and Tomas Rydberg

Energies 2022, 15(3), 1114; https://doi.org/10.3390/en15031114 - 2 Feb 2022

Cited by 3 | Viewed by 3016

Abstract

The potential of bio-electro-jet fuel (BEJF) production with integration into an existing biomass-based combined heat and power (CHP) facility was investigated. The BEJF is produced via Fischer–Tropsch (F–T) synthesis from biogenic CO₂ and H₂ obtained by water electrolysis. Techno-economic (TEA)- and [...] Read more.

The potential of bio-electro-jet fuel (BEJF) production with integration into an existing biomass-based combined heat and power (CHP) facility was investigated. The BEJF is produced via Fischer–Tropsch (F–T) synthesis from biogenic CO₂ and H₂ obtained by water electrolysis. Techno-economic (TEA)- and life. cycle (LCA)- assessments were performed to evaluate the production cost and environmental impact of the BEJF production route. The BEJF mass fraction reached 40% of the total F–T crude produced. A reduction of 78% in heating demands was achieved through energy integration, leading to an increase in the thermal efficiency by up to 39%, based on the F–T crude. The total production cost of BEJF was in the range of EUR 1.6–2.5/liter (EUR 169–250/MWh). The GWP of the BEJF was estimated to be 19 g CO₂-eq per MJ BEJF. The reduction potential in GWP in contrast to the fossil jet baseline fuel varied from 44% to more than 86%. The findings of this study underline the potential of BEJF as a resource-efficient, cost-effective, and environmentally benign alternative for the aviation sector. The outcome is expected to be applicable to different geographical locations or industrial networks when the identified influencing factors are met. Full article

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30 pages, 5529 KiB

Open AccessEditor’s ChoiceArticle

Multidisciplinary Assessment of a Novel Carbon Capture and Utilization Concept including Underground Sun Conversion

by Andreas Zauner, Karin Fazeni-Fraisl, Philipp Wolf-Zoellner, Argjenta Veseli, Marie-Theres Holzleitner, Markus Lehner, Stephan Bauer and Markus Pichler

Energies 2022, 15(3), 1021; https://doi.org/10.3390/en15031021 - 29 Jan 2022

Cited by 8 | Viewed by 4326

Abstract

The current work investigates the feasibility of a novel Carbon Capture and Utilization (CCU) approach—also known as Underground Sun Conversion (USC) or geo-methanation. The overall objective of the current work is a comprehensive assessment on the technical, economic and legal aspects as well [...] Read more.

The current work investigates the feasibility of a novel Carbon Capture and Utilization (CCU) approach—also known as Underground Sun Conversion (USC) or geo-methanation. The overall objective of the current work is a comprehensive assessment on the technical, economic and legal aspects as well as greenhouse gas impacts to be concerned for establishing USC technology concept. This is achieved by applying multidisciplinary research approach combining process simulation, techno-economic and greenhouse gas assessment as well as legal analysis allows answering questions about technical, economic feasibility and greenhouse gas performance as well as on legal constraints related to large scale CCU using geo-methanation in depleted hydrocarbon reservoirs. CO₂ from the industry and renewable H₂ from the electrolyser are converted to geomethane in an underground gas storage and used in industry again to close the carbon cycle. Process simulation results showed the conversion rates vary due to operation mode and gas cleaning is necessary in any case to achieve natural gas grid compliant feed in quality. The geomethane production costs are found to be similar or even lower than the costs for synthetic methane from Above Ground Methanation (AGM). The GHG-assessment shows a significant saving compared to fossil natural gas and conventional power-to-gas applications. From a legal perspective the major challenge arises from a regulative gap of CCU in the ETS regime. Accordingly, a far-reaching exemption from the obligation to surrender certificates would be fraught with many legal and technical problems and uncertainties. Full article

(This article belongs to the Special Issue Progress in Power-to-Gas Energy Systems)

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29 pages, 4374 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Operational Resilience of Nuclear-Renewable Integrated-Energy Microgrids

by Bikash Poudel, Linyu Lin, Tyler Phillips, Shannon Eggers, Vivek Agarwal and Timothy McJunkin

Energies 2022, 15(3), 789; https://doi.org/10.3390/en15030789 - 21 Jan 2022

Cited by 6 | Viewed by 2976

Abstract

The increasing prevalence and severity of wildfires, severe storms, and cyberattacks is driving the introduction of numerous microgrids to improve resilience locally. While distributed energy resources (DERs), such as small-scale wind and solar photovoltaics with storage, will be major components in future microgrids, [...] Read more.

The increasing prevalence and severity of wildfires, severe storms, and cyberattacks is driving the introduction of numerous microgrids to improve resilience locally. While distributed energy resources (DERs), such as small-scale wind and solar photovoltaics with storage, will be major components in future microgrids, today, the majority of microgrids are backed up with fossil-fuel-based generators. Small modular reactors (SMRs) can form synergistic mix with DERs due to their ability to provide baseload and flexible power. The heat produced by SMRs can also fulfill the heating needs of microgrid consumers. This paper discusses an operational scheme based on distributed control of flexible power assets to strengthen the operational resilience of SMR-DER integrated-energy microgrids. A framework is developed to assess the operational resilience of SMR-DER microgrids in terms of system adaptive real-power capacity quantified as a response area metric (RAM). Month-long simulation results are shown with a microgrid developed in a modified Institute of Electrical and Electronics Engineers (IEEE)-30 bus system. The RAM values calculated along the operational simulation reflect the system resilience in real time and can be used to supervise the microgrid operation and reactor’s autonomous control. Full article

(This article belongs to the Special Issue Latest Advances in Nuclear Energy Systems)

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27 pages, 14420 KiB

Open AccessEditor’s ChoiceArticle

Territorial Cooperation—A Factor Stimulating Baltic Sea Region Energy Transition

by Tomasz Studzieniecki, Tadeusz Palmowski and Remigiusz Joeck

Energies 2022, 15(2), 436; https://doi.org/10.3390/en15020436 - 8 Jan 2022

Cited by 1 | Viewed by 1948

Abstract

Energy transition is a multi-dimensional process of developing sustainable economies by seeking renewable energy sources, saving energy, and improving energy efficiency. This process follows the rules of sustainable development. The article presents an analysis of energy transition in the Baltic Sea Region (BSR) [...] Read more.

Energy transition is a multi-dimensional process of developing sustainable economies by seeking renewable energy sources, saving energy, and improving energy efficiency. This process follows the rules of sustainable development. The article presents an analysis of energy transition in the Baltic Sea Region (BSR) enjoying long-term and intensive territorial cooperation. The region embraces 11 countries diversified in terms of their economic development level and the use of renewable energy sources. The article strives to answer the question of whether territorial cooperation contributes to BSR energy transition, and if so, in what way. Another goal is to identify the transition drivers that arise from the Baltic Sea Region’s unique characteristics. The authors applied the system analysis methodology. The performed literature studies allowed the researchers to identify the attributes of energy transition. Empirical research relied on secondary sources, including the European Union (EU) statistics, The International Renewable Energy Agency (IRENA), the EU Strategy for the Baltic Sea Region (EUSBSR), and related documents. The key role in the conducted research can be attributed to the EU projects database (keep.eu), which enabled identifying the 2016–2020 programmes and projects. The research identified 14 BSR territorial cooperation programmes and 1471 projects conducted under the programmes, including 137 energy transition-related projects. The project results were presented in quantitative and qualitative terms. Full article

(This article belongs to the Special Issue Regional Economic Adaptability and Sustainability Transition)

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16 pages, 13629 KiB

Open AccessEditor’s ChoiceArticle

Performance of Cathodes Fabricated from Mixture of Active Materials Obtained from Recycled Lithium-Ion Batteries

by Hammad Al-Shammari and Siamak Farhad

Energies 2022, 15(2), 410; https://doi.org/10.3390/en15020410 - 6 Jan 2022

Cited by 7 | Viewed by 3877

Abstract

The cathode performance of lithium-ion batteries (LIBs) fabricated from recycled cathode active materials is studied for three scenarios. These scenarios are based on the conditions for separation of different cathode active materials in recycling facilities during the LIB’s recycling process. In scenario one, [...] Read more.

The cathode performance of lithium-ion batteries (LIBs) fabricated from recycled cathode active materials is studied for three scenarios. These scenarios are based on the conditions for separation of different cathode active materials in recycling facilities during the LIB’s recycling process. In scenario one, the separation process is performed ideally, and the obtained pure single cathode active material is used to make new LIBs after regeneration. In scenario two, the separation of active materials is performed with efficiencies of less than 100%, which is the actual case in the recycling process. In this scenario, a single cathode active material that contains a little of the other types of cathode active materials is used to make new LIBs after the materials’ regeneration. In scenario three, the separation has not been performed during the recycling process. In this scenario, all types of cathode active materials are regenerated together, and a mixture is used to make new LIBs. The studies are performed through modeling and computer simulation, and several experiments are conducted for validation purposes. The cathode active materials that are studied are the five commercially available cathodes made of LiMn₂O₄ (LMO), LiCoO₂ (LCO), LiNi_xMn_yCo_(1−x−y)O₂ (NMC), LiNi_xCo_yAl_(1−x−y)O₂ (NCA), and LiFePO₄ (LFP). The results indicate that the fabrication of new LIBs with a mixture of cathode active materials is possible when cathode active materials are not ideally separated from each other. However, it is recommended that the separation process is added to the recycling process, at least for the separation of LFP or reducing its amount in the cathode active materials mixture. This is because of the difference of the voltage level of LFP compared to the other studied active materials for cathodes. Full article

(This article belongs to the Special Issue Lithium-Ion Batteries: Latest Advances, Challenges and Prospects)

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23 pages, 1594 KiB

Open AccessEditor’s ChoiceArticle

Open-Circuit Fault-Tolerant Strategy for Interleaved Boost Converters via Filippov Method

by Cristina Morel, Ahmad Akrad, Rabia Sehab, Toufik Azib and Cherif Larouci

Energies 2022, 15(1), 352; https://doi.org/10.3390/en15010352 - 4 Jan 2022

Cited by 9 | Viewed by 2675

Abstract

Interleaved converters use an increased number of power electronics switches; this may subsequently affect their reliability. However, this is an opportunity to develop fault-tolerant strategies to improve their reliability and to ensure continuity of service. This is why we herein propose, for the [...] Read more.

Interleaved converters use an increased number of power electronics switches; this may subsequently affect their reliability. However, this is an opportunity to develop fault-tolerant strategies to improve their reliability and to ensure continuity of service. This is why we herein propose, for the first time, a mathematical function to simultaneously model the healthy and faulty conditions of each switch, thus enabling a unique model of the system. This model is then used in an original fault-tolerant strategy based upon the peak current control with slope compensation. This method not only extends the stable range of the load variation but also ensures the stability in faulty conditions. Finally, the simulation results validate its effectiveness and confirm the theoretical analysis. Full article

(This article belongs to the Special Issue Fault Diagnosis and Fault-Tolerant Control for Power Systems and Machine Drives in Electrical Transport Systems)

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30 pages, 13876 KiB

Open AccessEditor’s ChoiceArticle

Ensemble Learning for Predicting TOC from Well-Logs of the Unconventional Goldwyer Shale

by Partha Pratim Mandal, Reza Rezaee and Irina Emelyanova

Energies 2022, 15(1), 216; https://doi.org/10.3390/en15010216 - 29 Dec 2021

Cited by 12 | Viewed by 2098

Abstract

Precise estimation of total organic carbon (TOC) is extremely important for the successful characterization of an unconventional shale reservoir. Indirect traditional continuous TOC prediction methods from well-logs fail to provide accurate TOC in complex and heterogeneous shale reservoirs. A workflow is proposed to [...] Read more.

Precise estimation of total organic carbon (TOC) is extremely important for the successful characterization of an unconventional shale reservoir. Indirect traditional continuous TOC prediction methods from well-logs fail to provide accurate TOC in complex and heterogeneous shale reservoirs. A workflow is proposed to predict a continuous TOC profile from well-logs through various ensemble learning regression models in the Goldwyer shale formation of the Canning Basin, WA. A total of 283 TOC data points from ten wells is available from the Rock-Eval analysis of the core specimen where each sample point contains three to five petrophysical logs. The core TOC varies largely, ranging from 0.16 wt % to 4.47 wt % with an average of 1.20 wt %. In addition to the conventional MLR method, four supervised machine learning methods, i.e., ANN, RF, SVM, and GB are trained, validated, and tested for continuous TOC prediction using the ensemble learning approach. To ensure robust TOC prediction, an aggregated model predictor is designed by combining the four ensemble-based models. The model achieved estimation accuracy with R² value of 87%. Careful data preparation and feature selection, reconstruction of corrupted or missing logs, and the ensemble learning implementation and optimization have improved TOC prediction accuracy significantly compared to a single model approach. Full article

(This article belongs to the Special Issue Development of Unconventional Reservoirs 2021)

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20 pages, 3354 KiB

Open AccessEditor’s ChoiceArticle

Traffic and Energy Consumption Modelling of Electric Vehicles: Parameter Updating from Floating and Probe Vehicle Data

by Antonello Ignazio Croce, Giuseppe Musolino, Corrado Rindone and Antonino Vitetta

Energies 2022, 15(1), 82; https://doi.org/10.3390/en15010082 - 23 Dec 2021

Cited by 19 | Viewed by 3254

Abstract

This paper focuses on the estimation of energy consumption of Electric Vehicles (EVs) by means of models derived from traffic flow theory and vehicle locomotion laws. In particular, it proposes a bi-level procedure with the aim to calibrate (or update) the whole parameters [...] Read more.

This paper focuses on the estimation of energy consumption of Electric Vehicles (EVs) by means of models derived from traffic flow theory and vehicle locomotion laws. In particular, it proposes a bi-level procedure with the aim to calibrate (or update) the whole parameters of traffic flow models and energy consumption laws by means of Floating Car Data (FCD) and probe vehicle data. The reported models may be part of a procedure for designing and planning transport and energy systems. This aim is to verify if, and in what amount, the existing parameters of the resistances/energy consumptions model calibrated in the literature for Internal Combustion Engines Vehicles (ICEVs) change for EVs, considering the above circular dependency between supply, demand, and supply–demand interaction. The final results concern updated parameters to be used for eco-driving and eco-routing applications for design and a planning transport system adopting a multidisciplinary approach. The focus of this manuscript is on the transport area. Experimental data concern vehicular data extracted from traffic (floating car data and probe vehicle data) and energy consumption data measured for equipped EVs performing trips inside a sub-regional area, located in the Città Metropolitana of Reggio Calabria (Italy). The results of the calibration process are encouraging, as they allow for updating parameters related to energy consumption and energy recovered in terms of EVs obtained from data observed in real conditions. The latter term is relevant in EVs, particularly on urban routes where drivers experience unstable traffic conditions. Full article

(This article belongs to the Special Issue Analysis and Synthesis of Coordinated Control Systems for Automated Road Vehicles)

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16 pages, 7414 KiB

Open AccessEditor’s ChoiceArticle

3 kW Thermoelectric Generator for Natural Gas-Powered Heavy-Duty Vehicles—Holistic Development, Optimization and Validation

by Lars Heber, Julian Schwab and Timo Knobelspies

Energies 2022, 15(1), 15; https://doi.org/10.3390/en15010015 - 21 Dec 2021

Cited by 10 | Viewed by 3231

Abstract

Emissions from heavy-duty vehicles need to be reduced to decrease their impact on the climate and to meet future regulatory requirements. The use of a cost-optimized thermoelectric generator based on total cost of ownership is proposed for this vehicle class with natural gas [...] Read more.

Emissions from heavy-duty vehicles need to be reduced to decrease their impact on the climate and to meet future regulatory requirements. The use of a cost-optimized thermoelectric generator based on total cost of ownership is proposed for this vehicle class with natural gas engines. A holistic model environment is presented that includes all vehicle interactions. Simultaneous optimization of the heat exchanger and thermoelectric modules is required to enable high system efficiency. A generator design combining high electrical power (peak power of about 3000 W) with low negative effects was selected as a result. Numerical CFD and segmented high-temperature thermoelectric modules are used. For the first time, the possibility of an economical use of the system in the amortization period of significantly less than 2 years is available, with a fuel reduction in a conventional vehicle topology of already up to 2.8%. A significant improvement in technology maturity was achieved, and the power density of the system was significantly improved to 298 W/kg and 568 W/dm³ compared to the state of the art. A functional model successfully validated the simulation results with an average deviation of less than 6%. An electrical output power of up to 2700 W was measured. Full article

(This article belongs to the Special Issue Waste Heat Recovery Using Thermoelectric Generators)

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12 pages, 3207 KiB

Open AccessEditor’s ChoiceArticle

Prediction of Stirling-Cycle-Based Heat Pump Performance and Environmental Footprint with Exergy Analysis and LCA

by Umara Khan, Ron Zevenhoven, Lydia Stougie and Tor-Martin Tveit

Energies 2021, 14(24), 8478; https://doi.org/10.3390/en14248478 - 15 Dec 2021

Cited by 5 | Viewed by 3654

Abstract

The use of Stirling-cycle-based heat pumps in high-temperature applications and waste heat recovery at an industrial scale is of increasing interest due to the promising role in producing thermal energy with zero CO₂ emissions. This paper analyzes one such technology as developed [...] Read more.

The use of Stirling-cycle-based heat pumps in high-temperature applications and waste heat recovery at an industrial scale is of increasing interest due to the promising role in producing thermal energy with zero CO₂ emissions. This paper analyzes one such technology as developed by Olvondo Technology and installed at the pharmaceutical company AstraZeneca in Sweden. In this application, the heat pump used roughly equal amounts of waste heat and electricity and generated 500 kW of steam at 10 bar. To develop and widen the use of a high-performance high-temperature heat pump that is both economically and environmentally viable and attractive, various analysis tools such as exergy analysis and life cycle assessment (LCA) can be combined. The total cumulative exergy loss (TCExL) method used in this study determines total exergy losses caused throughout the life cycle of the heat pump. Moreover, an LCA study using SimaPro was conducted, which provides insight into the different emissions and the overall environmental footprint resulting from the construction, operation (for example, 1, 8, and 15 years), and decommissioning phases of the heat pump. The combined results were compared with those of a fossil fuel oil boiler (OB), a bio-oil boiler (BOB), a natural gas-fired boiler (NGB), and a biogas boiler (BGB). Full article

(This article belongs to the Special Issue Alternative and Emerging Cooling and Heating Technologies)

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20 pages, 19511 KiB

Open AccessEditor’s ChoiceArticle

On the Flow Structure and Dynamics of Methane and Syngas Lean Flames in a Model Gas-Turbine Combustor

by Vladimir Dulin, Leonid Chikishev, Dmitriy Sharaborin, Aleksei Lobasov, Roman Tolstoguzov, Zundi Liu, Xiaoxiang Shi, Yuyang Li and Dmitriy Markovich

Energies 2021, 14(24), 8267; https://doi.org/10.3390/en14248267 - 8 Dec 2021

Cited by 7 | Viewed by 2864

Abstract

The present paper compares the flow structure and flame dynamics during combustion of methane and syngas in a model gas-turbine swirl burner. The burner is based on a design by Turbomeca. The fuel is supplied through injection holes between the swirler blades to [...] Read more.

The present paper compares the flow structure and flame dynamics during combustion of methane and syngas in a model gas-turbine swirl burner. The burner is based on a design by Turbomeca. The fuel is supplied through injection holes between the swirler blades to provide well-premixed combustion, or fed as a central jet from the swirler’s centerbody to increase flame stability via a pilot flame. The measurements of flow structure and flame front are performed by using the stereo particle image velocimetry and OH planar laser-induced fluorescence methods. The measurements are performed for the atmospheric pressure without preheating and for 2 atm with the air preheated up to 500 K. The flow Reynolds numbers for the non-reacting flows at these two conditions are 1.5 × 10³ and 1.0 × 10³, respectively. The flame dynamics are analyzed based on a high-speed OH* chemiluminescence imaging. It is found that the flame dynamics at elevated conditions are related with frequent events of flame lift-off and global extinction, followed by re-ignition. The analysis of flow structure via the proper orthogonal decomposition reveals the presence of two different types of coherent flow fluctuations, namely, longitudinal and transverse instability modes. The same procedure is applied to the chemiluminescence images for visualization of bulk movement of the flame front and similar spatial structures are observed. Thus, the longitudinal and transverse instability modes are found in all cases, but for the syngas at the elevated pressure and temperature the longitudinal mode is related to strong thermoacoustic fluctuations. Therefore, the present study demonstrates that a lean syngas flame can become unstable at elevated pressure and temperature conditions due to a greater flame propagation speed, which results in periodic events of flame flash-back, extinction and re-ignition. The reported data is also useful for the validation of numerical simulation codes for syngas flames. Full article

(This article belongs to the Special Issue Advances in Gas Turbine Performance, Heat Transfer and Aerodynamics)

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44 pages, 18654 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Development of an Integrated Performance Design Platform for Residential Buildings Based on Climate Adaptability

by Zhixing Li, Mimi Tian, Yafei Zhao, Zhao Zhang and Yuxi Ying

Energies 2021, 14(24), 8223; https://doi.org/10.3390/en14248223 - 7 Dec 2021

Cited by 10 | Viewed by 2947

Abstract

Building energy waste has become one of the major challenges confronting the world today, so specifications and targets for building energy efficiency have been put forward in countries around the world in recent years. The schematic design stage matters a lot for building [...] Read more.

Building energy waste has become one of the major challenges confronting the world today, so specifications and targets for building energy efficiency have been put forward in countries around the world in recent years. The schematic design stage matters a lot for building energy efficiency, while most architects nowadays are less likely to make energy efficiency design decisions in this stage due to the lack of necessary means and methods for analysis. An integrated multi-objective multivariate framework for optimization analysis is proposed for the schematic design stage in the paper. Here, the design parameters of the building morphology and the design parameters of the building envelope are integrated for analysis, and an integrated performance prediction model is established for low-rise and medium-rise residential buildings. Then, a comparison of the performance indicators of low-rise and medium-rise residential buildings under five typical urban climatic conditions is carried out, and the change patterns of the lighting environment, thermal environment, building energy demand, and life cycle cost of residential buildings in each city under different morphological parameters and design parameters of the building envelope are summarized. Specific analysis methods and practical tools are provided in the study for architectural design to ensure thermal comfort, lighting comfort, low energy consumption, and low life-cycle cost requirement, and this design method can inspire and guide the climate adaptation analysis and design process of low-rise and medium-rise residential buildings in China, improve architects’ perception of energy-saving design principles of low-rise and medium-rise residential buildings on the ontological level, as well as provide them with a method to follow and a case to follow in the actual design process. Full article

(This article belongs to the Special Issue Building Performance Simulation, Energy Efficiency and Renewable Energy Resources for Buildings)

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27 pages, 424 KiB

Open AccessEditor’s ChoiceArticle

EU Carbon Diplomacy: Assessing Hydrogen Security and Policy Impact in Australia and Germany

by Linda Hancock and Linda Wollersheim

Energies 2021, 14(23), 8103; https://doi.org/10.3390/en14238103 - 3 Dec 2021

Cited by 17 | Viewed by 4897

Abstract

Hydrogen is fast becoming a new international “super fuel” to accelerate global climate change ambitions. This paper has two inter-weaving themes. Contextually, it focuses on the potential impact of the EU’s new Carbon Border Adjustment Mechanism (CBAM) on fossil fuel-generated as opposed to [...] Read more.

Hydrogen is fast becoming a new international “super fuel” to accelerate global climate change ambitions. This paper has two inter-weaving themes. Contextually, it focuses on the potential impact of the EU’s new Carbon Border Adjustment Mechanism (CBAM) on fossil fuel-generated as opposed to green hydrogen imports. The CBAM, as a transnational carbon adjustment mechanism, has the potential to impact international trade in energy. It seeks both a level playing field between imports and EU internal markets (subject to ambitious EU climate change policies), and to encourage emissions reduction laggards through its “carbon diplomacy”. Countries without a price on carbon will be charged for embodied carbon in their supply chains when they export to the EU. Empirically, we focus on two hydrogen export/import case studies: Australia as a non-EU state with ambitions to export hydrogen, and Germany as an EU Member State reliant on energy imports. Energy security is central to energy trade debates but needs to be conceptualized beyond supply and demand economics to include geopolitics, just transitions and the impacts of border carbon taxes and EU carbon diplomacy. Accordingly, we apply and further develop a seven-dimension energy security-justice framework to the examples of brown, blue and green hydrogen export/import hydrogen operations, with varying carbon-intensity supply chains, in Australia and Germany. Applying the framework, we identify potential impact—risks and opportunities—associated with identified brown, blue and green hydrogen export/import projects in the two countries. This research contributes to the emerging fields of international hydrogen trade, supply chains, and international carbon diplomacy and develops a potentially useful seven-dimension energy security-justice framework for energy researchers and policy analysts. Full article

(This article belongs to the Special Issue Governance Strategies and Insights to Accelerate the Production and Diffusion of Hydrogen and Fuel-Cell Technologies)

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