Energies

Research

13 pages, 12433 KiB

Open AccessArticle

Piezoelectric Sensors Pressed by Human Footsteps for Energy Harvesting

by Kyrillos K. Selim, Idris H. Smaili, Hossam M. Yehia, M. M. R. Ahmed and Demyana A. Saleeb

Energies 2024, 17(10), 2297; https://doi.org/10.3390/en17102297 - 10 May 2024

Viewed by 1027

Human footsteps are a sustainable energy source that is derived from kinetic energy. As a result, in this study, piezoelectric sensors placed beneath floor tiles were excited by human footsteps to provide practical electrical energy. A simple rectifying circuit with a filter was [...] Read more.

Human footsteps are a sustainable energy source that is derived from kinetic energy. As a result, in this study, piezoelectric sensors placed beneath floor tiles were excited by human footsteps to provide practical electrical energy. A simple rectifying circuit with a filter was used to capture electrical power. The floor tile is 455 mm in length and 405 mm in width. Two light-emitted diodes were lit up as the actual load by utilising electrical energy obtained from the kinetic energy generated by human footsteps. The greatest attainable power that could be extracted from the suggested floor tile was 249.6 milliwatts, with an approximate cost of $10.2. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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18 pages, 1424 KiB

Open AccessArticle

Determinants of the Efficiency of Electricity Generation in Latin America and Caribbean Countries Using a Cragg’s Regression Model

by Sebastian Cuadros, Yeny E. Rodríguez and Javier Contreras

Energies 2023, 16(23), 7875; https://doi.org/10.3390/en16237875 - 1 Dec 2023

Viewed by 731

Abstract

Measuring and understanding the evolution of the electricity generation efficiency sector is a relevant task for policymakers. This study focuses on assessing the determinants of electricity generation efficiency across 24 countries in Latin America and the Caribbean between 2000 and 2020. A hurdle [...] Read more.

Measuring and understanding the evolution of the electricity generation efficiency sector is a relevant task for policymakers. This study focuses on assessing the determinants of electricity generation efficiency across 24 countries in Latin America and the Caribbean between 2000 and 2020. A hurdle model was employed to account for the censored nature of the dependent variable. The findings show a positive impact of opening up the electricity sector in fully efficient countries. Market liberalization and the involvement of privately owned power plants contribute to efficiency gains in inefficient countries. Additionally, the tariff protectionism level exhibits positive effects for completely efficient and inefficient countries. These results provide valuable insights, as less-efficient countries can glean strategies from their more efficient counterparts to enhance their electricity generation efficiency. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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22 pages, 1455 KiB

Open AccessArticle

Governance and Performance in Romanian Energy Companies

by Adrian Doru Bigioi and Cristina Elena Bigioi

Energies 2023, 16(13), 5041; https://doi.org/10.3390/en16135041 - 29 Jun 2023

Cited by 1 | Viewed by 996

Abstract

The energy sector is essential to a country’s economy and social life. In recent years, the energy market in Romania has experienced a certain dynamism, influenced by multiple factors such as regional conflicts, national and EU energy legislation, liberalization of the energy market, [...] Read more.

The energy sector is essential to a country’s economy and social life. In recent years, the energy market in Romania has experienced a certain dynamism, influenced by multiple factors such as regional conflicts, national and EU energy legislation, liberalization of the energy market, and increasing demand for energy products. These factors determined a sharp increase in electricity, gas, and oil prices in Romania in recent years. Based on the above, the present study aims to analyze Romanian energy companies’ financial performances and determine whether there is any correlation between their governance and their performance. In order to fulfill the research objectives, financial performance data were extracted and analyzed for a number of 43 energy companies in Romania, considering the financial statements prepared up to 31 December 2021. Using the scoring method, governance indices were determined for each company. Finally, using a linear regression model, we analyzed the correlation between governance and performance of the 43 companies. The results of the study indicate that there is a direct correlation of moderate intensity between the two variables, with the performance of energy companies being higher if they have implemented a governance system. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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23 pages, 9423 KiB

Open AccessArticle

Enhanced Power Quality in Single-Phase Grid-Connected Photovoltaic Systems: An Experimental Study

by Abdellah Benabdelkader, Azeddine Draou, Abdulrahman AlKassem, Toufik Toumi, Mouloud Denai, Othmane Abdelkhalek and Marwa Ben Slimene

Energies 2023, 16(10), 4240; https://doi.org/10.3390/en16104240 - 22 May 2023

Cited by 1 | Viewed by 1303

Abstract

The main aim of the research work presented in this paper consists of proposing an effective control scheme for a grid-connected single-phase photovoltaic (PV) system to enhance not only the power quality at the point of common coupling (PCC) but also to operate [...] Read more.

The main aim of the research work presented in this paper consists of proposing an effective control scheme for a grid-connected single-phase photovoltaic (PV) system to enhance not only the power quality at the point of common coupling (PCC) but also to operate with a maximum power point tracking (MPPT) controller. Moreover, an orthogonal signal generator (OSG) module for effective grid synchronization, a current reference generation controller, and a PWM generating block have also been designed and included in this paper. The proposed control strategy allows the MPPT controller to switch to faulty mode and maintains the voltage according to network requirements using an adaptive neuro-fuzzy inference system (ANFIS)-based control whenever a fault occurs at the PCC. The performance of the analyzed control strategy, which is based on the static compensation of the DC-link voltage fluctuations in a grid-connected inverter powered by PV, is further explored through simulations in MATLAB, and the results are included in this paper. Moreover, the control scheme is implemented experimentally using a dSPACE DS 1104 control board and then assessed on a small laboratory-scale single-phase PV system that is subjected to some fault scenarios. The simulation and experimental results have shown improved power quality and robustness against grid fluctuations, resulting in better dynamic performance. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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15 pages, 1357 KiB

Open AccessArticle

Estimating the Drivers of the Cost of Saved Electricity in Utility Customer-Funded Energy Efficiency Programs

by Sean Murphy and Natalie Mims Frick

Energies 2023, 16(5), 2177; https://doi.org/10.3390/en16052177 - 24 Feb 2023

Cited by 1 | Viewed by 1502

Abstract

Energy efficiency programs funded by utility customers provide an electricity resource in most U.S. states, but their scale and cost of saving electricity varies significantly by state. In this paper, we explore the drivers of the cost of saved electricity in these programs [...] Read more.

Energy efficiency programs funded by utility customers provide an electricity resource in most U.S. states, but their scale and cost of saving electricity varies significantly by state. In this paper, we explore the drivers of the cost of saved electricity in these programs with an econometric model and nearly a decade of data reported by efficiency program administrators. We found strong evidence for economies of scale and weak evidence for diseconomies of scale, which suggests that states with low levels of efficiency savings relative to retail sales can increase the size of their efficiency programs without large increases to the cost of saved electricity. We discuss examples of energy efficiency forecasting and potential modeling in light our econometric analysis and identify methodological improvements relevant to utilities and grid operators. This paper provides insights into the economics of customer-funded efficiency programs that will support regulators, utilities, and policymakers to utilize energy efficiency as a resource. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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28 pages, 5415 KiB

Open AccessArticle

Experimental Investigation of Impacts of Initial Pressure Levels on Compression Efficiency and Dissolution in Liquid Piston Gas Compression

by Barah Ahn and Paul I. Ro

Energies 2023, 16(4), 1921; https://doi.org/10.3390/en16041921 - 15 Feb 2023

Cited by 2 | Viewed by 1499

Abstract

Understanding how the pressure level affects the efficiency of liquid piston gas compression is essential for a greater applicability of the technology in compressed air energy storage. To explore the impacts, compression starting at three different initial pressure levels (1, 2, 3 bar) [...] Read more.

Understanding how the pressure level affects the efficiency of liquid piston gas compression is essential for a greater applicability of the technology in compressed air energy storage. To explore the impacts, compression starting at three different initial pressure levels (1, 2, 3 bar) with a pressure ratio of 2 is performed, and how isothermal compression efficiencies are affected depending on the initial pressures is analyzed. Under the experimental conditions, higher initial pressure leads to lower isothermal efficiency. Air dissolution during the compression is also investigated because the chamber is a pressure-varying and a liquid-containing environment, where the gas solubility changes during the process. Evaluating the dissolution is critical as it affects the energy output when the compressed air is expanded to regenerate the energy. The changes in the air mass and the retrievable volume of the air after expansion are quantified based on Henry’s law. For a compression at higher pressure, because the air solubility is proportional to pressure, a greater reduction in the air mass and volume percentages is expected. This trend of the mass decreasing with the pressure level leads to less energy output than the originally intended output when the stored energy is retrieved in a discharging process. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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35 pages, 1633 KiB

Open AccessArticle

“Is Energy That Different from Labor?” Similarity in Determinants of Intensity for Auto Assembly Plants

by Amir Abolhassani, Gale Boyd, Majid Jaridi, Bhaskaran Gopalakrishnan and James Harner

Energies 2023, 16(4), 1776; https://doi.org/10.3390/en16041776 - 10 Feb 2023

Viewed by 1293

Abstract

This paper addresses the question “Is energy that different from labor?” from the perspective of efficiency. It presents a novel statistical analysis for the auto assembly industry in North America to examine the determinants of relative energy intensity, and contrasts this with a [...] Read more.

This paper addresses the question “Is energy that different from labor?” from the perspective of efficiency. It presents a novel statistical analysis for the auto assembly industry in North America to examine the determinants of relative energy intensity, and contrasts this with a similar analysis of the determinants of another important factor of production, labor intensity. The data used combine two non-public sources of data previously used to separately study key performance indicators (KPIs) for energy and labor intensity. The study found these two KPIs are statistically correlated (the correlation coefficient is 0.67) and the relationship is one-to-one. The paper identifies 11 factors that may influence both energy and labor intensity KPIs. The study then contrasts which of the empirical factors the two KPIs’ share and how they differ. Two novel statistical methods, Huber estimators and Multiple M-estimators, combined with regularized algorithms, are identified as the preferred methods for robust statistical models to estimate energy intensity. Based on our analysis, the underlying determinants of energy efficiency and labor productivity are quite similar. This implies that strategies to improve energy may have spillover benefits to labor, and vice versa. The study shows vehicle variety, car model types, and launch of a new vehicle penalize both energy and labor intensity, while flexible manufacturing, production volume, and year of production improve both energy and labor intensity. In addition, the study found that the plants that produce small cars are more energy-efficient and productive compared to plants that produce large vehicles. Moreover, in a given functional unit, i.e., on a per-unit basis, Japanese plants are more energy-efficient and productive compared to American plants. Plant managers can use the proposed data-driven approach to make the right decisions about the energy efficiency targets and improve plants’ energy efficiency up to 38% using hybrid regression methods, mathematical modeling, plants’ resources, and constraints. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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17 pages, 1464 KiB

Open AccessArticle

Salient Insights on the Performance of EU Member States on the Road towards an Energy-Efficient Future

by Daniela Cristina Momete

Energies 2023, 16(2), 925; https://doi.org/10.3390/en16020925 - 13 Jan 2023

Cited by 1 | Viewed by 1398

Abstract

Energy efficiency plays an important role in energy systems all over the world, representing the most available and cheapest source of energy. Progress in energy efficiency translates into reduced consumption, reduced dependency on external suppliers of fossil fuels, mitigation of climate change, and [...] Read more.

Energy efficiency plays an important role in energy systems all over the world, representing the most available and cheapest source of energy. Progress in energy efficiency translates into reduced consumption, reduced dependency on external suppliers of fossil fuels, mitigation of climate change, and improvement of quality of life. Given its tremendous importance for energy systems and national economies, this paper aims to offer salient insights on the performance of the countries of the European Union (EU-27) towards an energy-efficient future, bearing in mind the quantitative milestones of sustainable development goal 7 (SDG7) of the Agenda for Sustainable Development of the United Nations. The current research offers a new perspective and delivers a comprehensive, robust, and succinct model which provides insights on the performance of EU-27 member states based on appropriate quantitative key performance indicators related to energy efficiency. The results show that about 19% of EU-27 member states are in a leading position, while about 41% of EU-27 member states have modest performance, and about 14% are still lagging. The findings of this paper may open discussions to find better ways to valorise energy efficiency, and may offer support for legislators and other stakeholders in energy systems. Moreover, by benchmarking different types of national practices, the countries which are still struggling to use energy-efficiency measures may find suitable ways to accelerate transition to a more energy-efficient future. Full article

(This article belongs to the Special Issue Analysis of Energy Efficiency: Perspectives and Policies towards Sustainable Development)

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