Renewable and Sustainable Energy Reviews最新文献

Despite the advances in solar forecasting methods, and their ever-increasing accuracy, little is known about their value for real applications, e.g., bidding in the electricity market, power system operations, and household electricity bill reduction. This work comprehensively reviews the value of solar forecasts and the cost of their errors across the different applications available in the literature. Most works analysed the economics of solar forecast at the transmission level, either from the electricity market perspective or the system operations perspective. When compared with the levelised cost of electricity of photovoltaic (PV) systems, the value of solar forecasts and the cost of their errors are considerable. Recommendations on how to minimise and adapt to solar uncertainty and variability are also discussed. The measures will not only help mitigate the cost of forecast errors but also enable better integration of PV and other variable generation. Different system/market operators and regulators can consider the different suggestions based on their unique circumstances.

Solar Chimney Power Plants (SCPP) are among the promising solar thermal electricity generation technologies. Equipped with a Thermal Energy Storage (TES) system, such technologies can overcome variations in the main driving factors such as solar radiation and ambient air temperature. This article presents a comprehensive semi-analytical model of a TES to predict the time-dependent performance of an SCPP. By introducing a Quality Factor of power generation (QF) that includes energy conversion efficiency and capacity factor, the effects of 15 TES materials have been studied on the plant performance. Results indicate no significant difference between water TES and clay or soil type, and water-filled bags or tubes are relatively ineffective in improving performance compared to them. Among the various TES materials analyzed, a type of wet soil, i.e., the specific wet mixture of clay, sand, and silt in closed and dark-colored bags, show excellent performance in both QF enhancement and having low Heat Penetration Depth (HPD) simultaneously. The QF and HPD are directly affected by thermal effusivity and thermal diffusivity, respectively. Implementing wet soil TES for the studied power plant (Manzanares) enhances the QF from 7.46 % (for limestone soil) to 10.95 %. Water-filled bags demonstrate a heat penetration depth of 0.4 m, while wet soil exhibits a slightly greater depth of 0.5 m. Furthermore, water-filled bags experience a broader temperature range of 40 °C, whereas wet soil undergoes a comparatively smaller temperature variation of 26 °C. Furthermore, the capacity factor raises from 41.18 % to 61.07 % when utilizing wet soil TES compared to water-filled bags.

The utilization of renewable fuel alternatives holds promise for reducing the financial burden of regulatory compliance and the social responsibility associated with greenhouse gas emissions. Hydrothermal liquefaction (HTL) is one of the most versatile technologies for converting renewable biomass feedstocks (especially in the wet state) into biofuel (biocrude oil) in a compact plant. Therefore, this review is devoted to thoroughly reviewing and critically discussing biocrude oil production from biomass feedstocks through the HTL process. This review starts by discussing the principles of biomass HTL processing and product upgrading, aiming to provide a grounded and broad understanding of current developments in this domain. The data reported in the published literature are analyzed and visualized in order to scrutinize the effects of the main process parameters on the quantity, quality, cost, and environmental impacts of resultant biofuels. Higher biocrude oil yields are obtained at temperatures, pressures, and residual times between 300 and 350 °C, 24–27 MPa, and 15–25 min, respectively. Concerning yield and calorific value, biocrude oil derived from homogeneous catalysts demonstrates figures of 23.6 % and 32.1 MJ/kg, whereas that from heterogeneous catalysts exhibits percentages of 66.8 % and 40 MJ/kg, respectively. The challenges and prospects for the future development of biocrude oil are also discussed. HTL has a long way to go before being used for biofuel production on a large scale. Future studies appear to be directed towards the use of HTL technology under the biorefinery framework to maximize the exploitation of biomass into value-added products, while minimizing waste generation.

Many studies have been conducted on the distribution network expansion planning (DNEP) problem in recent years. The primary goal of this issue is to satisfy electric load demand, taking into account economic and technical considerations. In the past, this planning was done in a centralized manner with all the information available. The restructuring of power networks and the emergence of renewable energy sources (RESs), energy storage systems (ESSs), and new market players with different interests have led to extensive changes in the DNEP issue. Subsequently, the solving methods of the DNEP problem will be important because many new goals, constraints, and other factors have caused the problem to become non-linear and non-convex. This paper prepares a comprehensive study on the DNEP problem from different aspects such as objective functions and constraints, design variables, planning horizon and phases, planning and system types, uncertainty, distributed generations (DGs) and storage units, planning level, solving methods, load models, and environmental issues. Finally, future research trends such as handling the conflicts, solving approaches, and other points facing the DNEP problem are suggested.

Which countries best foster low-carbon electricity transitions – authoritarian regimes or democratic societies? Crucial for understanding how transitions unfold is identifying contextual factors conditioning propensity to adopt specific forms of energy production. This research assesses the relationship between quality of governance within 198 countries and domestic electricity production from all major energy sources, across the years 2002–2020. Governance quality is measured via a range of comprehensive, internationally recognised metrics, focusing predominantly on the World Bank's worldwide governance indicators. The data reveal that a future, decarbonised electricity system via wind, solar, and/or nuclear appears most likely in countries where the traditions and institutions by which authority is exercised support good governance. Over the last two decades, the association between electricity from solar and wind and good governance has progressively strengthened globally. Beyond governance, national measures of economic (in)equality are strongly related to electricity production from nuclear and hydropower. These findings offer a point of departure for assessing how governance systems might predispose countries to particular energy choices.

Most existing data-driven power system short-term voltage stability assessment (STVSA) approaches presume class-balanced input data. However, in practical applications, the occurrence of short-term voltage instability following a disturbance is minimal, leading to a significant class imbalance problem and a consequent decline in classifier performance. This work proposes a Transformer-based STVSA method to address this challenge. By utilizing the basic Transformer architecture, a stability assessment Transformer (StaaT) is developed as a classification model to reflect the correlation between the operational states of the system and the resulting stability outcomes. To combat the negative impact of imbalanced datasets, this work employs a conditional Wasserstein generative adversarial network with gradient penalty (CWGAN-GP) for synthetic data generation, aiding in the creation of a balanced, representative training set for the classifier. Semi-supervised clustering learning is implemented to enhance clustering quality, addressing the lack of a unified quantitative criterion for short-term voltage stability. Numerical tests on the IEEE 39-bus test system extensively demonstrate that the proposed method exhibits robust performance under class imbalances up to 100:1 and noisy environments, and maintains consistent effectiveness even with an increased penetration of renewable energy. Comparative results reveal that the CWGAN-GP generates more balanced datasets than traditional oversampling methods and that the StaaT outperforms other deep learning algorithms. This study presents a compelling solution for real-world STVSA applications that often face class imbalance and data noise challenges.

The three-dimensional nature of agrophotovoltaic systems (APV) accounts for the needs of photovoltaic power generation and agricultural production. The combination can solve conflicts among utilization of resources, ecological protection, and agricultural production to achieve low-carbon economic development. However, the economically respond (crop yield and quality) of different species under the decreased light available system is still unclear. To provide insights, we compared agrophotovoltaic and traditional ecosystems to explore the economic feasibility of planting Bupleurum chinense (B. chinense) and Medicago sativa (M. sativa) from the perspectives of light utilization, photosynthetic responses, and land use. The combined system improved the land equivalent ratio, net income and species quality of B. chinense and M. sativa. Both species showed high plasticity, and maintained growth and development by regulating their morphology and photosynthetic parameters. B. chinense in the APV increased its light use efficiency, photosynthetic rate, and root biomass by increasing its height, electron transfer flux, and up-regulating a photosystem I protein (PsaA). M. sativa in the APV allocated more energy to photochemical reactions to improve photosynthetic capacity. It captured and utilized the limited light by reducing leaf mass per unit area and dark respiration, increasing the chlorophyll content, and down-regulating a photosystem II protein (PsbD). Our results showed the importance of species selection based on morphological and photosynthetic responses and provide insights into the selection of appropriate species, efficient resource utilization, and sustainable economic development based on APV.

Over the years, numerous studies have explored the green synthesis of ethylene. Within this context, the focus of this perspective shifts toward plasma technology, which has demonstrated the capability to convert methane into ethylene. Plasma catalysis creates distinctive physical and chemical environments, particularly at normal temperature and pressure, distinguishing it from alternative methods. Nevertheless, the utilization of atmospheric pressure plasma is intricate, posing scientific challenges in the realms of physics and chemistry. In this viewpoint, various key performance aspects are evaluated, encompassing methane conversion efficiency, ethylene selectivity, and specific energy input. These scientific pros and cons are then assessed for their readiness for industrial-scale implementation. Initially, the potential for small-scale ethylene production is examined, leveraging existing robust process technologies to unlock fresh market and supply chain opportunities. Subsequently, the sustainability of plasma technology for green ethylene production is compared to conventional ethylene production and alternative green ethylene production methods, including biomass-based approaches. Contrary to perhaps optimistic expectations, current literature evidence does not uniformly favor the latter, indicating the potential for plasma-based green ethylene processes. Additionally, this paper underscores the importance of considering Environmental, Social, and Governance factors that influence business decisions. Finally, this review underscores plasma technology as a potentially promising approach for green ethylene synthesis from methane, offering unique advantages under normal conditions while simultaneously presenting scientific challenges. It assesses its viability for small-scale production and benchmarks its sustainability against conventional and alternative methods, emphasizing the importance of a sustainable future for the green petrochemical industry.

The wettability of porous media strongly affects the trapping mechanism and storage capacity during CO₂ geological storage. Various novel measuring methods have been proposed recently with the development of imaging techniques. This review describes the state-of-the-art wettability characterization at different scales in three aspects: conventional laboratory-based contact angle characterization to analyze the porous external surface properties, pore-scale contact angle analysis to summarize the wettability of the porous inner surface based on micromodels and X-ray microtomography, and overall wettability evaluation through nuclear magnetic resonance and thermodynamic contact angle and topology analysis. The impact of the pore structure, mineral composition, and surface roughness on pore-scale wettability is described, including contact angle hysteresis and mixed wettability. The wettability in various pore events and wettability alternation with various storage conditions and fluid displacement patterns provide a description of reservoir properties. This review also illustrates the feasibility of multiscale wettability descriptions. Future studies should focus on the interrelation among the contact angles at different scales. How the contact angle of a porous surface, especially at the pore scale, changes under reservoir conditions and the mechanism of wettability alternation still need to be further investigated. Additionally, the impact of rock wettability on storage capacity in practical applications is concluded. Future research will focus on methods to control wettability in actual storage sites to enhance economic benefits and ensure safety.

The aim of this study is to investigate how pre-treatment of herbaceous straw biomass for ash control affects the release of nitrogen species during combustion and gasification. To comprehend the formation of NO and its precursors, NH₃ and HCN, the release of these species was investigated and compared under both combustion and gasification-like conditions at 950 °C. The effects of various upgrading methods, such as torrefaction, water-leaching, a combination of leaching and torrefaction, and CaCO₃ addition, were studied. The assessment of nitrogen release was divided into two consecutive conversion steps – devolatilization/pyrolysis and ash/char reactions. The release of nitrogen is highly dependent on the reaction conditions. For instance, the emissions of NO from the combustion conditions (3 vol% O₂) for all fuel samples were, on average, six times higher than under gasification conditions (14.5 vol% H₂O and 5 vol% CO₂). The emissions of NO from the combustion and gasification of torrefied biomass were, on average, 20 % higher than those from raw biomass. Water-leaching had a suppressing effect on NO formation during char conversion. Approximately 62 % of the char-N formed NO for raw and torrefied material, whereas only 26 %–35 % was formed for pre- or postwashed samples. The effect of the applied pre-treatment approaches on the release of nitrogen was particularly significant during char conversion. Increasing calcium and decreasing potassium content had catalytic effects, mainly on the conversion of volatile-N to NH₃. The Ca-doped biomass feedstock showed approximate 10 % increase in volatile-N to NH₃ conversion compared to the source material.