Development Of Clean Energy Technologies Research Articles

Self-operation and low-carbon scheduling optimization of solar thermal power plants with thermal storage systems

Photo thermal power generation, as a renewable energy technology, has broad development prospects. However, the operation and scheduling of photo thermal power plants rarely consider their internal structure and energy flow characteristics. Therefore, this study explains the structure of a solar thermal power plant with a thermal storage system and analyzes its main energy flow modes to establish a self-operation and low-carbon scheduling optimization model for the solar thermal power plant. The simulation results of the example showed that for the self-operating model oriented towards power generation planning and peak valley electricity prices, the existence of a thermal storage system could improve the power generation capacity and revenue of the photovoltaic power plant. For example, when the capacity of the thermal storage system was greater than 6 h, the penalty for insufficient power generation in the simulation result was 0 $, and the maximum increase in revenue reached 84.9% as the capacity of the thermal storage system increased. In addition, when the capacity of the thermal storage system increased from 0 to 8 h, the comprehensive operating cost decreased from 1635.2 k $ to 1224.6 k $, and the carbon emissions decreased from 26.4 × 103 ton to 22.1 × 103 ton. Compared with the existing literature, this study provides a more comprehensive and systematic solution through detailed energy flow analysis and optimization model. The research has practical and far-reaching significance for promoting the development of clean energy technology, improving the sustainable utilization of renewable energy, and optimizing the overall performance of the energy system.

Optimization of a parametric product design using techno-economic assessment and environmental characteristics with application to an electric traction motor

Accelerating the development of clean energy technologies is required to move towards a sustainable future. New design approaches are being proposed to help accelerate these developments. This study proposes and improves a novel design framework that incorporates life cycle assessment (LCA) and techno-economic assessment (TEA) with an optimization-based design model of a discrete product at early stage. Objective functions for mass, energy consumption, and two metrics relating to manufacturer and consumer economic interests are considered; these objectives are minimized using a Pareto-like approach. An electric traction motor for an electric vehicle is used as a discrete product case study. The approach demonstrates the utility of considering four-objectives in the design problem, uncertainty analysis via Monte Carlo simulation, and the power of employing LCA and TEA methods. Future work may explore a broader range of objective functions to cover different challenges that inhibit the development of clean energy technologies.

Evaluating the potential benefits of float solar photovoltaics through the water footprint recovery period

In the context of higher demands on the development of clean energy technologies due to the issue of water shortage in China and the implementation of the 2060 carbon-neutral objective, floating photovoltaic (FPV) systems present novel opportunities for transforming the energy structure through land conservation and enhancement of power generation efficiency compared to conventional solar systems. However, there is currently a lack of comprehensive analysis on the potential benefits of FPV. Utilizing reservoir databases and employing a professional FPV system design, a methodology for determining the water footprint recovery period was introduced, which enables the assessment of potential FPV benefits. The water footprint recovery period for constructing FPV on 909 reservoirs in China was found that ranges from 1.86 yr to 10.48 yr. It is found that reservoir evaporation, latitude, and climate are closely related to the water footprint recovery period of FPV. Furthermore, by implementing FPV panels with an optimal tilt angle, covering 30% of the area in each reservoir, the annual electricity generation can amount to 1429.19 TWh, leading to savings of 5.76 billion m3 of water. This achievement corresponds to 19.41% of the national electricity consumption and a 6.86% reduction in the national residential water consumption in 2020. The overall economic benefit is 5.61 myriads RMB, equivalent to 5.76% of the national GDP. These benefits are unevenly distributed and mainly concentrated in areas with more reservoirs. The anticipated enhancement of FPV system benefits is foreseen with the ongoing development and implementation of future reservoir power infrastructure and energy storage technology. These results demonstrate the significant potential of installing FPV systems on the reservoirs in China. This study proposes a method to comprehensively evaluate the comprehensive benefits of constructing FPV in China and conduct a thorough analysis of the feasibility of FPV, which could provide reference for the development of regional industries and the achievement of sustainable development goals (SDGs).

(Invited) Transforming Metal-Containing Secondary Resources into Functional Materials for Electrochemical Energy Applications

Transforming metal-containing waste into functional materials for electrochemical energy applications presents an innovative and sustainable solution to address the growing issue of waste management and resource conservation. By utilizing end-of-life products, off-specification materials, waste materials, and spent materials as secondary resources, this approach can effectively reduce environmental impacts and promote the development of clean energy technologies.Gas-diffusion electrocrystallization (GDEx) is a novel electrochemical technology that can be used as a step to selectively recover and convert valuable metals from metal-containing waste streams into functional materials for electrochemical energy applications. By leveraging the electrochemical reduction of gases, such as O2 or CO2, for the in-situ production of oxidizing (H2O2) or reducing agents (H2 and CO)—which may also result in the formation of other chemical species, e.g., alkali (OH–) in aqueous media, GDEx facilitates the precipitation of soluble metal precursors. This process results in the formation of metal nanoparticles with controlled compositions, crystal structures, sizes, morphologies, and compositions, tailored for specific electrochemical applications.In this talk, the principles of the GDEx process will be explained and examples will be provided of its applicability in the direct transformation of metals contained in secondary resources for the production of functional materials for electrochemical applications. Specifically, the production of electrocatalysts for methanol oxidation from the recycling of automotive catalysts leachates will be conveyed, as well as the production of active battery materials for Li-ion batteries, and the recovery of lithium from geothermal brines.Gas Diffusion Electrocrystallization (GDEx) is a novel and sustainable approach to transform waste materials into functional materials for electrochemical energy applications. This innovative method enables the recovery and synthesis of valuable metal nanoparticles (NPs) from waste streams, such as end-of-life products and industrial leachates, for use in electrocatalysis, energy storage, and fuel cells.GDEx will be conveyed as a sustainable and scalable technology for the recovery of critical metals, contributing to a circular economy and reducing the environmental impact of mining and refining activities. The opportunity for producing materials with enhanced performance will be portrayed, together with the portent of a customizable and flexible solution which can be integrated with existing recycling chains.AcknowledgementThis research has received funding from the European Union’s Horizon 2020 and Horizon Europe research and innovation programmes under grant agreements 958302 (PEACOC Project), 101069685 (Rhinoceros Project), 101069644 (LICORNE Project), 101058163 (CRM-Geothermal Project), and 101091715 (FIREFLY Project).ReferencesPrato M.R.A., Van Vught V., Chayambuka K., Pozo G., Eggermont S., Fransaer J., Dominguez-Benetton X. (2020) Synthesis of material libraries using gas diffusion electrodes. J. Mater. Chem. A, 8:11674-11686. DOI:10.1039/D0TA00633E.Martinez Mora O., Pozo G., Leon-Fernandez L.F., Fransaer J., Dominguez-Benetton X. (2023) Synthesis of platinum group metal nanoparticles assisted by CO2 reduction and H2 cogeneration at gas-diffusion electrodes. RSC Sustain., 2023, Accepted Manuscript. DOI: 10.1039/D3SU00046J

Ultrathin heteroatom-doped CeO2 nanosheet assemblies for durable oxygen evolution: Oxygen vacancy engineering to trigger deprotonation

The manipulation of oxygen vacancies (OVs) in metal oxides has progressively emerged as a versatile strategy for improving their catalytic performance. In this study, we aim to enhance the oxygen evolution reaction (OER) performance of cerium oxide (CeO2) by doping heteroatoms (Fe, Co, Ni) to generate additional OVs. We systematically analyzed both the morphology and electronic structure of the obtained CeO2 catalysts. The experimental results revealed the self-assembly of two-dimensional (2D) CeO2 nanosheets, with an approximate thickness of ∼1.7 nm, into 2D nanosheet assemblies (NSAs). Moreover, the incorporation of heteroatoms into the CeO2 matrix promoted the formation of OVs, resulting in a significant enhancement of the OER performance of CeO2. Among them, the Co-doped CeO2 NSAs sample displayed the highest activity and durability, with almost negligible activity loss during extended operating periods. The roles of heteroatom doping in improving OER activity were explored by DFT calculations. The produced OVs improve the adsorption of hydroxyl groups (OH−), promote the deprotonation process, and increase more active sites. These findings suggest that doping CeO2 with heteroatoms is a promising strategy for improving electrocatalytic OER activity, with great potential for the development of clean energy technologies, including but not limited to water splitting and fuel cells.

(Energy Technology Division Graduate Student Award sponsored by BioLogic) Probing and Engineering Electrode-Electrolyte Interfaces in Electrochemical Energy Storage and Conversion

Climate change demands the development of clean energy technologies, where rechargeable batteries and fuel cells promise a bright future by integrating with solar or wind energy. Li-ion batteries and fuel cells also play essential roles in electrifying transportation in replacement of internal combustion engines. Central to these electrochemical systems is the electrode-electrolyte interface, where (electro)chemical surface reactions or intercalation reactions occur, and its thermodynamic and kinetic properties determine the energy density, power density, and lifetime of the electrochemical devices. However, the molecular structures at the interface and how they promote or suppress the desired reactions remain unclear, hindering the rational design of electrode-electrolyte interfaces to improve the performance of electrochemical devices.This talk focuses on the fundamental understanding of the interfacial (electro)chemical reaction mechanisms at the molecular level and charges transfer kinetics at the electrified interfaces. First, an in situ Fourier-transform infrared spectroscopy (FTIR) method was developed to examine the parasitic reactions between carbonate electrolytes and lithium nickel, manganese and cobalt oxides (NMC) in Li-ion batteries, and unique evidence for dehydrogenation reactions on Ni-rich NMC was revealed, which accounted for interface impedance build-up and battery capacity fading. Based on the proposed mechanism, strategies based on electrolyte non-covalent interactions were demonstrated to improve battery lifetime. In the second part of the talk, the research extended in situ FTIR characterization and electrolyte engineering to electrocatalytic reactions central to fuel cell technologies. An interfacial layer of protic ionic liquids with different acid dissociation constants were found to enhance the oxygen-reduction reaction (ORR), attributed to strengthened hydrogen bonding between ORR products and ionic liquids, revealed by in situ surface-enhanced infrared absorption spectroscopy and density functional theory (DFT) calculations. For the hydrogen evolution reaction (HER), similarly, promoting hydrogen bonding between interfacial water molecules also facilitated proton-coupled electron transfer kinetics, resulting in favorable HER in controllable organic confinements. Finally, this talk will introduce fundamental, theoretical aspects of charge transfer processes at the electrode-electrolyte interface - the kinetic mechanism for ion intercalation. Experimental evidence from a charge-adjusted electrochemical method showed that Li-ion intercalation occurs by coupled ion-electron transfer (CIET), which governs the current-dependent maximum capacity and power density of intercalation batteries. these research efforts have laid a solid foundation for the rational design of electrochemical interfaces employing the physical chemistry of electrodes and electrolytes, for next-generation electrochemical storage devices with improved energy and power density and cycle life.

The effects of a shock to critical minerals prices on the world oil price and inflation

Critical minerals (CMs) such as lithium, cobalt, nickel, and rare earth metals, are essential to the development of clean energy technologies, electronics, and defense and space industries, among others. Demand for these minerals is expected to grow quickly as energy transitions accelerate. As the post-pandemic economic recovery demonstrated, disturbances in CM supplies can also create serious bottlenecks in global supply-chains. In this study, we develop a GVAR model that can examine the consequences of market disturbances from CM price shocks on major global and country-specific macroeconomic indicators. Counterfactual simulations of a CM price shock suggest that that CMs, as a rising industry, are starting to have an impact on the macro level. The industry and its impacts are not fully developed yet but appear to have diverse implications across countries similar in some respects to the current major commodity – oil. A CM price shock has statistically significant implications for inflation in the UK and South Korea. At the same time, geopolitical shocks to crude oil prices have significant implications for CM prices. The cross-price elasticity of oil with respect to CM prices is positive in the United States, where CM's and oil are substitutes, and negative for Saudi Arabia where CMs and oil are compliments. These scenarios indicate the unsuitability of a one size fits all energy policy and a need for closer examination of the national and country specific relationships between the oil and CM sectors.

Establishment of a Hydrometallurgical Scheme for the Recovery of Copper, Nickel, and Cobalt from Smelter Slag and Its Economic Evaluation

In pursuit of carbon neutrality, the demand for metals that are necessary for the development of clean energy technologies is rapidly increasing. Metallurgical waste, such as slag, presents a promising secondary source of these key metals. This research aims to develop an eco-friendly hydrometallurgical process to recover Cu, Ni, and Co from discarded copper/nickel slag. High-pressure acid leaching (HPAL) was used to selectively leach Ni, Cu, and Co from the fayalite slag, yielding high leaching efficiencies of 99.9%, 89.4%, and 99.9%, respectively, with low Fe and Si tenors to the pregnant leach solution (PLS). The solvent extraction (SX) technique utilizing LIX 984N was used to selectively extract and enrich copper from the dilute PLS to about 23 g/L Cu with a very low Fe concentration of 0.05 g/L. Potassium amyl xanthate (PAX) solution was used to form Ni and Co xanthate complexes from the raffinate solution. Nickel was selectively recovered using ammonia solution, while the cobalt xanthate complex was thermally decomposed and recovered as cobalt oxide solids of about 25 wt.% Co. A comprehensive process flowsheet is presented. Furthermore, to realize the real application of the developed slag cleaning process, a preliminary economic evaluation was performed.

Fossil Fuel Energy Consumption, Economic Growth, Urbanization, and Carbon Dioxide Emissions in Kenya

The increase in the level of CO2 emissions has triggered the global temperature to rise above the pre industrial levels. The unprecedented climate change has resulted in flooding and droughts that have displaced millions of people from their homes, plunged them into poverty, famine, and stunted economic growth, especially in countries with shoddy infrastructure. The large-scale use of fossil fuels across the globe, increase in urbanization and economic growth are likely to worsen the environmental quality. However, the proponents of the economic growth hypothesis do not admit that the consumption of fossil fuels and urban expansion, increase the level of CO2 emissions in the atmosphere. The current study examines the effects of fossil fuels consumption, economic growth, urbanization and CO2 emissions in Kenya over the period 1971 to 2014. The study follows a formal time series econometric estimation strategy and estimates the long-run model using an autoregressive distributed lag. The study findings show that economic growth and the uptake of fossil fuels increase CO2 emission, while urbanization reduces it. The study recommends phasing out subsidies for conventional energy supply, promoting energy efficiency and accelerating the development of clean energy technologies.

Active acoustic emission sensing for fast co-estimation of state of charge and state of health of the lithium-ion battery

With the rapid development of clean energy technologies, the lithium-ion batteries have emerged as dominant power source. It is of great significance to monitor the state of charge (SOC) and state of health (SOH) accurately and efficiently for ensuing high safety and reliability. This paper proposes an active acoustic emission (AE) sensing technology and demonstrates the feasibility for co-estimation of SOC and SOH of the lithium-ion battery. The proposed method aims to achieve a fast monitoring of SOC and SOH by putting insights into the variation of material properties during operations. In the method, the appropriate power ultrasound is used to excite the battery and trigger elastic waves. A wide AE transducer can actively capture the released AE events of the battery material with different properties in a wide range of frequency band. Therefore, this allows the battery SOC/SOH to be fast characterised during charging, discharging, and ageing. Experimental studies have found that calculated RMS of AE signals in the frequency band 270–300 kHz, around the 7th harmonic of ultrasonic excitation, can successfully achieve the joint estimation of battery SOC and SOH at any operating phases. This new finding can be designed as a standalone method for fast SOC/SOH estimation.

Enhancement of Perovskite solar cells performance using electrochemically grown TiO2 quantum dots

Perovskite solar cells (PSCs) have been at the center of attention for research and development of clean energy technology. The platform promises high performance with relatively cheap and low-temperature processing. The main hindrance of the platform is low stability and performance degradation due to humidity. Most defects and degradation often stem from interfaces between the perovskite layer (PSVK) and carrier transporting layer. This work aimed to solve such an issue by improving the interface between the Perovskite layer (PSVK) and electron transporting layer (ETL) made of titanium in the Perovskite solution. That is methylammonium formamidinium lead iodide (FA0.3MA0.7PbI3) PSCs using electrochemical grown TiO2 quantum dots (QDs) mixed in Titanium tetraisopropoxide (TTIP). TiO2 QDs have grown electrochemically in potassium chloride (KCl) solution and then mixed in TTIP with various concentrations (0%, 2.5%, 5.0%, 7.5%, and 10%). The photoconversion efficiency (PCE) of PSCs was improved to 14.05 % while 7.5% of TiO2 QDs passivation with the champion performance of 15.72% (a significant improvement from the 0% standard condition). The PSCs also lasted over 200 hours, demonstrating increased stability with the proposed recipe. This work demonstrated the successful delivery of alkaline passivation using TiO2 QDs as an agent for improving PSCs.

The Keys to Clean Energy Technology: Impact of Environmental Taxes on Biofuel Production and Consumption

The growing level of modern environmental problems and the need to ensure energy security creates new challenges for the development of the energy sector. Nowadays, countries must balance their international competitiveness and progress in achievement the Sustainable Development Goals. This provides a necessity for the development of alternative energy technologies. Modern trends in the development of alternative energy indicate a gradual increase in the relevance of biofuel production. At the same time, the development of clean energy technologies needs significant investments, and their commercial implementation is a long process. Moreover, energy industry transformations require significant changes in the functioning of complementary spheres. That makes necessary the use of additional incentives for the development of the bioenergy sector. Thus, an assessment of the impact of environmental taxes on biofuel production and consumption becomes crucial. This research is aimed at the identification of contextual and causal relationships between environmental taxation (transport and energy taxes) and biofuel production and consumption. Contextual links were identified by the methods of bibliometric analysis (VOSviewer and Google Books Ngram Viewer results), while causal links were determined by the methods of panel regression modeling (panel-corrected standard errors model) with a time lag from 0 to 4 years. A sample of nine European countries (Austria, France, Germany, Hungary, Italy, The Netherlands, Poland, Spain, U.K.) was formed for the assessment. The research period includes 2010–2020. The conducted bibliometric analysis proved the presence of a wide range of relationships between environmental taxation and the development of the bioenergy industry. Panel regression modeling proved the existence of a significant impact of environmental taxation on the volumes of biofuel production and consumption. The increase in revenues from transport and energy taxes determines the growth in indicators of biofuel production and consumption. Such effects are medium term for transport taxes and short term for energy taxes. These results made a huge contribution in the development of the system of state regulation methods of alternative energy stimulation and energy production and consumption transformations.

Comprehensive Evaluation of Affordable Cathode Materials in Direct Electrochemical Selenite Reduction

Selenium (Se) is a naturally occurring metalloid that has been widely sourced for health care, clean energy technology development, and agricultural activities. These activities have accelerated Se release into the aquatic environment, urging engineered solutions to mitigate aquatic Se pollution and their ecological impact. Our lab previously demonstrated a direct electrochemical reduction approach to convert 97% of soluble selenite into elemental Se(0) on a gold cathode. This study builds upon our prior success in selenite separation to further explore alternative cathode materials to gold. Six economically competitive materials (Ni, graphite, Cu, Fe, stainless steel, and Ti) were evaluated for key performance parameters, including Se removal efficiency, Faradaic efficiency, energy consumption, and electrode durability. Preliminary cyclic voltammetry scans revealed that Ni and graphite could sustain Se(IV)/Se(0) reduction in diluted water matrices within their electrochemical window. The subsequent 24-h chronoamperometry (CA) test demonstrated 67% selenite removal using a Ni cathode, while graphite offered a better removal efficiency (92%). Separated selenite ions were primarily plated as elemental Se(0) on the cathode surface (Ni & graphite) or within the electrode structure (graphite). While graphite has better selenite removal than Ni, it demands more energy input and has lower Faradaic efficiency (C-3.7% vs. Ni-12.7%). Switching from a CA mode to a chronopotentiometry (CP) mode did not significantly impact selenite removal performance, and the energy consumption was increased by 15%. Continued exfoliation is observed on the graphite electrode surface, potentially due to the expansion of inner gas bubbles and the lattice destruction caused by Se(0) insertion. Our results suggest graphite offers comparable selenite separation performance to a gold cathode. Still, electrode exfoliation and higher energy input due to parasitic reactions must be appropriately addressed in future research efforts.

Global antimony supply risk assessment through the industry chain

Antimony is a type of critical metal for the energy transition. The antimony industry chain is distributed among the major developed and developing countries around the world. With the development of clean energy technology, the demand for antimony in photovoltaic and energy storage fields will increase significantly. Considering the significant changes in the global demand for antimony products and the serious supply shortage, people should pay more attention to the supply risk of related products of the antimony industry chain. In this paper, we propose a new integrated index to evaluate the supply risk of antimony industry chain related products, including Herfindahl Hirschman index, global governance index, human development index, global innovation index, and betweenness centrality in complex networks. Meanwhile, seven commodities in the antimony industry chain are selected for empirical analysis from 2011 to 2019. The results show that countries with high supply risks of the industry chain upstream include Canada, France, Germany, India, Japan, Thailand, and the United Kingdom. And, Australia, India, Japan, Thailand, and Vietnam are with high supply risks in the midstream of the industry chain. Meanwhile, Canada, India, Japan, and Thailand are with high downstream supply risks. Some countries, like China, the United States, and Germany, play a core role in different sectors of the industry chain. International competitive relations of countries have caused a high supply risk of products related to the antimony industry chain. The supply risk of the antimony industry chain shows that countries must strengthen industrial division and cooperation to maximize their interests. It is suggested to take the country-specific measures to mitigate supply risks, including establishing national inventories of critical materials, overseas investment, strengthening the guidance of industrial policies, and accelerating infrastructure construction.

Mineral Resource Constraints for China’s Clean Energy Development under Carbon Peaking and Carbon Neutrality Targets: Quantitative Evaluation and Scenario Analysis

With concerns about global warming and energy security, people are reducing fossil fuel use and turning to clean energy technologies. Mineral resources are used as materials for various energy technologies, and with the development of clean energy technologies, the demand for mineral resources will increase. China is a large country with various mineral resources, but its structural supply problem is severe. For China to reach the targets of carbon peaking before 2030 and carbon neutrality before 2060, they have set specific milestones for developing each clean energy industry; thus, the demand for mineral resources in clean energy will increase. We first summarise the mineral resources supply for China’s development of clean energy technologies. We analyse the demand for various mineral resources in specific clean energy technology sectors under the stated policies scenario and sustainable development scenario through scenario setting. Finally, we combine current domestic mineral resource reserves and overseas import channels to analyse China’s mineral resource supply and demand for developing the clean energy industry. Our results show that the surge in clean energy generation and electric vehicle ownership in China between 2020 and 2050 will lead to a significant increase in demand for mineral resources for these technologies and a shortage in the supply of some mineral resources. In particular, the supply of copper, nickel, cobalt, and lithium will be a severe constraint for clean energy development. We also find that secondary recycling of power battery materials in the electric vehicle sector could alleviate China’s resource constraints. The findings of our study provide a better understanding of the kinds of mineral elements that are in short supply on the path of clean energy development in China under carbon peaking and carbon neutrality targets and the future channels that can be used to increase the supply of minerals.

Taking Stock of the Energy and Climate Profile of Germany and the USA: New Potential for Cooperation

Germany and the United States are both important players in international energy and climate policy. They are major international donors in the energy sector, they participate in manifold bi- and multilateral cooperation formats in the realm of energy and climate policy and they have historically both been leaders in clean energy technology development. Notwithstanding, they have very different starting conditions for and approaches to energy and climate policy. While the US is nearly energy independent, in Germany, the Russian war against the Ukraine has highlighted the high dependence on energy imports. Yet, Germany has experienced a strong increase in renewable energy production, fostered by strong state regulation, as it is an essential element of its climate policy. In the US, overall, renewable energy production has grown at a slower pace, also because climate policy has faced curvier roads through the past decades, and political conditions have changed often. This article seeks to take stock of where Germany and the US stand at this moment with their energy systems as well as their climate policies and examines common interests and cooperation potentials that can support sustainability transformations on both sides of the Atlantic.

Does SCO need its own energy charter treaty? From the perspective of Chinese BITs

Abstract Since the reform and opening up, China has developed into a major energy importer and become increasingly dependent on the international energy market. Owing to the impact of shale oil exploration and gas extraction in the USA, the influence of Russia and Organization of the Petroleum Exporting Countries (OPEC) on international oil prices, and the increasing development of clean energy technologies, China’s energy supply and security are facing serious challenges. This international energy landscape highlights the need to strengthen energy investment and cooperation among Shanghai Cooperation Organisation (SCO) Member States. However, energy resources are distributed unevenly among the SCO Member States. Specifically, some Member States are rich in energy resources and highly dependent on energy exports for national economic development, which can form a satisfactory supply and demand relationship with China. Therefore, strengthening energy cooperation in SCO is conducive to not only maintaining energy security in the SCO region but also promoting overall regional development and further deepening the economic interconnectivity. An important prerequisite for strengthening energy cooperation between countries is the legal mechanisms for energy investment protection. However, current legal foundations for energy investment among SCO Member States rely mainly on bilateral investment treaties between Member States, which are largely outdated and inconsistent. Likely, this status quo is not conducive to the stable regional energy cooperation for sustainable operation. The purpose of this article is to examine the need to build a unified legal mechanism for energy investment protection under the SCO framework. Accordingly, China should emphasize this legal mechanism to protect the country’s foreign energy investment in the SCO.

Fundamental Understanding and Construction of Solid‐State Li−Air Batteries

Nonaqueous Li−air batteries with ultrahigh theoretical energy density have attracted much attention in the development of clean energy technology. However, a series of safety challenges including the flammable, volatile organic liquid electrolyte, together with the electrolyte decomposition have greatly hindered their practical development. Solid‐state electrolytes with superior mechanical strength, good chemical stability under open‐air system, wide electrochemical window, nonflammable properties provide a feasible strategy to overcome the safety issues and achieve a stable, applicable Li−air battery system. In this article, a comprehensive review of solid‐state Li−air batteries is provided. Based on the overall understanding of the necessity of developing a solid‐state Li−air battery and ion migration mechanism in solid electrolytes, the construction strategies of solid‐state Li−air battery including cathode fabrication, Li anode optimization, electrolyte design, and the interface regulation between electrodes and electrolyte are presented. The prospects of solid‐state Li−air batteries are also proposed at the end. It is expected that this review would provide a systematic understanding and theoretical guidance in designing and developing safe, stable, applicable solid‐state Li−air batteries.

Research on switching method of low inertia microgrid parallel transformer

The vigorous development of clean energy technology has gradually led to the formation of a new power system. The new power system takes clean energy as the main supply, and has the advantages of clean, low-carbon, flexible and efficient. However, it has low inertia and is easily affected by energy fluctuation, resulting in protection misoperation. Microgrid has small volume and poor anti-interference ability. The magnetizing inrush current generated by parallel transformer during switching is very easy to lead to misoperation of transformer protection, which threatens the stability and safety of the whole power grid. Therefore, are switching method of parallel transformer is proposed. First, close all secondary circuit breakers, and then select the primary circuit breaker of one transformer for initial closing. After the closing is completed, conduct the closing operation again after the delay and phase angle determination. The two switching operations are completed, and the no-load closing operation is completed. Finally, the PSCAD simulation model is established to simulate the AC microgrid to verify the feasibility of this method.

Multi-objective Optimal Operation of Combined Cascade Reservoir and Hydrogen System

As a kind of zero-carbon and high-efficiency energy, hydrogen has attracted more attention with clean energy technology development. However, large-scale green hydrogen application is difficult to promote because of its high production cost. China is rich in water resources, but the utilization rate is low, which causes serious water abandonment problems. This article studies the optimal operation of combined cascade reservoir and hydrogen system to improve the utilization of water resources and the system's economic benefits. In this article, a multi-objective nonlinear model is established. An expanded progressive optimization algorithm is adopted to solve the problem more efficiently and accurately. The weights of objective functions are discussed with data from the Hongru River Basin in China. The rationality and effectiveness of combining cascade reservoir and hydrogen system are verified through the optimal operation of water resources and the optimal allocation of power and hydrogen. In addition, the overall economic benefits and reservoir operation efficiency are improved.