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Shading on photovoltaic (PV) modules due to shadows, covering, dust, etc., usually characterized as semi-transparent, will significantly affect the power generation capacity. No systematic study has considered the impact of semi-transparent coverings on the power generation capacity of PV modules. This paper covers a single cell in the PV module using a covering with a transmittance of 18.55% and systematically investigates its impact on the power generation capacity. The open-circuit voltage (Voc) of the PV module is nearly unaffected by semi-transparent coverings because the covered cell can be considered as working at a lower irradiance and thus can output a voltage close to that of the uncovered cell. The short-circuit current (Isc) is significantly affected by coverings because it is co-contributed by the photocurrent (evaluated based on the covering ratio R and transmittance) and the reverse bias current ΔIsc (the covered cell is in a reverse bias state). The ΔIsc increases with R because more charge accumulates at the bi-ends of the covered cell; but, it decreases at full covering, which implies that in a partially covered case the uncovered part contributes more to ΔIsc than the covered part. The fill factor (FF) of the PV module first increases and then decreases with R, as the equivalent resistance of the covered cell increases rapidly with R, which replaces the wire resistance in dominating the series resistance of the PV module when R > 0.6. This work is of great theoretical significance in analyzing the output characteristics of PV modules under real conditions.

This study is a product of the Africa Infrastructure Country Diagnostic (AICD), a project designed to expand the world's knowledge of physical infrastructure in Africa. The AICD provides a baseline against which future improvements in infrastructure services can be measured, making it possible to monitor the results achieved from donor support. It also offers a more solid empirical foundation for prioritizing investments and designing policy reforms in the infrastructure sectors in Africa. The book draws upon a number of background papers that were prepared by World Bank staff and consultants, under the auspices of the AICD. The main findings were synthesized in a flagship report titled Africa's infrastructure: A time for transformation, published in November 2009. Meant for policy makers, that report necessarily focused on the high-level conclusions. It attracted widespread media coverage feeding directly into discussions at the 2009 African union commission heads of state summit on infrastructure.

ABSTRACT Capacity mechanisms serve as tools for controlling investment dynamics in various electric power generation technologies. Investment cycles, price spikes, and capacity and reserve shortages are among the challenges faced by different capacity mechanisms. In this manuscript, an improved capacity certificate mechanism is proposed to mitigate the challenges facing the dynamics of investment in electric power generation. Capacity certificates are introduced as tradable credits for electricity consumption. Under this mechanism, each generation unit can issue capacity certificates proportional to its production capacity and sell them in the capacity market to cover some of its costs. Additionally, each consumer must purchase capacity certificates corresponding to their consumption. Generation units must also acquire and provide capacity certificates relative to their retired capacity. In this mechanism, consumers will participate in production investments, and production capacity will be viewed as a capital asset. The proposed method also considers the possibility of demand‐side participation in the capacity certificate market. In fact, existing consumers can issue capacity certificates in proportion to their demand reduction. Thus, in the proposed method, in addition to partially solving the problem of financing for investment in electricity generation, the significant role of the demand sector in the capital market is also considered. The proposed mechanism has been simulated using Vensim software based on the system dynamics theory and compared with existing energy market mechanisms that only use price caps and capacity payments. The simulation results show that, under an energy‐only market with a price cap of 500 $/MWh and an annual demand growth rate of 1.5%, the system experiences recurring capacity shortages and investment cycles. While a capacity payment mechanism partially mitigates these problems, the proposed capacity certificate mechanism eliminates shortage events over the entire simulation horizon and stabilizes generation investment.

Based on containers as heavy objects, a framework-based gravitational energy storage system is designed, where the container is lifted to a certain height to store gravitational potential energy, which is then released to drive a generator for power generation. The system utilizes existing port infrastructure, reducing the manufacturing cost of heavy blocks and offering good environmental adaptability. The results show that framework-based gravitational energy storage systems have high feasibility in port energy supply, providing stable power output and improving energy efficiency. Through optimization analysis of storage efficiency, power generation efficiency, and other parameters, this study provides theoretical and technical support for achieving sustainable green development in ports. This paper firstly describes the design and operating principles of the system, followed by a detailed indoor test analysis. Subsequently, the test results are specifically analyzed. Finally, practical implications and future development directions are discussed.

Traditional contact-based piezoelectric energy harvesters often experience increased wear and reduced lifespan due to frequent mechanical contact under high-frequency rotational conditions, leading to diminished output power. To overcome these limitations, this paper proposes a novel non-contact collision-induced self-vibration piezoelectric energy harvester. By utilizing non-contact collisions between the rotating component and the impact pin, the harvester induces self-vibration in the piezoelectric ceramics, effectively avoiding the mechanical wear and stress concentration inherent in traditional contact designs. A theoretical model was developed, and a simulation model was constructed in Simulink to investigate the effects of key parameters, including impact pin mass, pin spring stiffness, torsion spring stiffness, and rotational radius. Based on these studies, innovative measures were proposed and validated. Experimental tests utilizing a single piezoelectric ceramic beam with a collision-induced self-vibration mechanism were conducted to evaluate the performance of individual piezoelectric elements. Additionally, the influence of multi-element structures was analyzed. The non-contact collision design significantly reduced mechanical stress and localized stress concentrations in the piezoelectric material. Weibull analysis confirmed that the non-contact design effectively extended the lifespan of piezoelectric ceramics. Utilizing the self-vibration mechanism induced by angular velocity differences, the novel harvester achieved an output energy of 2.65 mJ per single piezoelectric ceramic at 300 r/min, with output power significantly surpassing that of traditional contact-based designs. Modular designs incorporating multiple piezoelectric ceramics further enhanced power generation capacity. Both experimental and simulation data were collected using a single piezoelectric ceramic to ensure the comparability between the novel device and traditional designs. Results demonstrated that the proposed harvester exhibits longer lifespan and higher efficiency in high-frequency rotational environments, showcasing its broad application potential in efficient mechanical energy harvesting.

To solve real life problems under uncertainty in Economics, Finance, Energy, Transportation and Logistics, the use of stochastic optimization is widely accepted and appreciated. However, the nature of stochastic programming leads to a conflict between adaptability to reality and tractability. To formulate a multistage stochastic model, two types of formulations are typically adopted: the so-called stage-scenario formulation named also formulation with explicit non-anticipativity constraints and the so-called nodal formulation named also formulation with implicit non-anticipativity constraints . Both of them have advantages and disadvantages. This work aims at helping the scholars and practitioners to understand the two types of notation and, in particular, to reformulate with the nodal formulation a model that was originally defined with the stage-scenario formulation presenting this implementation in the algebraic language GAMS. In addition, this work presents an empirical analysis applying the two formulations both without any further decomposition to perform a fair comparison. In this way, we show that the difficulties to implement the model with the nodal formulation are somehow reworded making the problem tractable without any decomposition algorithm. Still, we remark that in some other applications the stage-scenario formulation could be more helpful to understand the structure of the problem since it allows to relax the non-anticipativity constraints.

Abstract Since the government implemented the supply-side structural reform, the growth of electricity consumption in energy-intensive manufacturing industries has been contained in an all-round way, which poses greater challenges to overcapacity in the power sector. It is still a mystery that how to restrain the electricity consumption of energy-intensive manufacturing industry affects the installed capacity of power generation. Thereupon, this paper empirically studies the relationship between electricity consumption of the six energy-intensive manufacturing subsectors and provincial power generation capacity. The empirical results with line loss rate as instrumental variables indicate that the electricity consumption of the six energy-intensive manufacturing subsectors will increase or decrease the installed capacity of power generation by a one-to-one elastic coefficient. In terms of manufacturing subsectors, the power sector’s own electricity consumption has the highest capacity enhancement effect, followed by non-metallic minerals and chemical raw materials manufacturing subsectors. The resolution of overcapacity for power generation is fundamentally to reduce the electricity consumption intensity of the six high-energy-consuming manufacturing subsectors.

Together with a huge number of other countries, Germany signed the Paris Agreements in 2015 to prevent global temperature increase above 2°C. Within this agreement, all countries defined their own national contributions to CO 2 reduction. Since that, it was visible that CO 2 emissions in Germany decreased, but not so fast than proposed in this German nationally determined contribution to the Paris Agreement. Due to increasing traffic, CO 2 emissions from this mobility sector increased and CO 2 emission from German power generation is nearly constant for the past 20 years, even a renewable generation capacity of 112 GW was built up in 2017, which is much higher than the peak load of 84 GW in Germany. That is why the German National Government has implemented a commission (often called \"The German Coal Commission\") to propose a time line: how Germany can move out of coal-fired power stations. This \"Coal Commission\" started its work in the late spring of 2018 and handed over its final report with 336 pages to the government on January 26th, 2019. Within this report the following proposals were made: ① Until 2022: Due to a former decision of the German Government, the actual remaining nuclear power generation capacity of about 10 GW has to be switched off in 2022. Besides, the \"Coal Commission\" proposed to switch off additionally in total 12.5 GW of both, hard coal and lignite-fired power plants, so that Germany should reduce its conventional generation capacity by 22.5 GW in 2022. ② Until 2030: Another 13 GW of German hard coal or lignite-fired power plants should be switched off. ③ Until 2038: The final 17 GW of German hard coal or lignite-fired power plants should be switched off until 2038 latest. Unfortunately the \"Coal Commission\" has not investigated the relevant technical parameter to ensure a secured electric power supply, based on German's own national resources. Because German Energy Revolution mainly is based on wind energy and photovoltaic, this paper will describe the negligible contribution of these sources to the secured generation capacity, which will be needed for a reliable power supply. In addition, it will discuss several technical options to integrate wind energy and photovoltaic into a secured power supply system with an overall reduced CO 2 emission.

Due to military or other requirements for hypersonic aircraft, the energy supply devices with the advantages of small size and light weight are urgently needed. Compared with the traditional energy supply method, the skutterudite-based thermoelectric (TE) functional structure is expected to generate electrical energy with a smaller structural space in the hypersonic aircraft. This paper mainly focuses on the responded thermal and electrical characteristics of the skutterudite-based TE functional structure (TEFS) under strong heat flux loads. We conduct TE simulations on the transient model of the TEFS with consideration of the heat flux loads and thermal radiation in the hot end and the cooling effect of the phase change material (PCM) in the cold end. We investigate several influential factors on the power generation capacity, such as the phase transition temperature of the PCM, the heat flux loads, the thickness of the TE materials and the thermal conductivity of the frame materials. The results show that better power generation capacity can be achieved with thicker TE materials, lower phase transition temperature and suitable␣thermal conductivity of the frame materials.

Information and communication technologies (ICTs) have been a remarkable success in Africa. Across the continent, the availability and quality of service have gone up and the cost has gone down. In just 10 years dating from the end of the 1990s mobile network coverage rose from 16 percent to 90 percent of the urban population; by 2009, rural coverage stood at just under 50 percent of the population. Although the performance of Africa's mobile networks over the past decade has been remarkable, the telecommunications sector in the rest of the world has also evolved rapidly. Many countries now regard broadband Internet as central to their long-term economic development strategies, and many companies realize that the use of ICT is the key to maintaining profitability. This book is about that challenge and others. Chapters two and three describe the recent history of the telecommunications market in Africa; they cover such issues as prices, access, the performance of the networks, and the regulatory reforms that have triggered much of the investment. This part of the book compares network performance across the region and tries to explain why some countries have moved so much more quickly than others in providing affordable telecommunications services. Chapter four explores the financial side of the telecommunications revolution in Africa and details how the massive investments have been financed and which companies have most influenced the sector. Chapter five deals with the future of the sector. The final chapter synthesizes the main chapters of the book and presents policy recommendations intended to drive the sector forward.