• Energy Research
• 7. Clean energy close
• 11. Sustainability close
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Abstract Compared with other traditional energy sources, renewable energy, which results the less pollution and has numerous resources, is a significant factor in addressing the current issues of the serious environmental pollution and the resource depletion. Large-scale renewable energy integrated to the grid could bring change in both morphological structure and operation modes of energy transmission. Therefore, it is necessary to research the evolution mechanism of the future transmission network with a high proportion of the renewable energy. In this paper, an evolution framework of power system with high proportion of renewable energy is proposed. Firstly, a network equivalence and simplification based on power transfer distribution factors (PTDFs) is proposed, which can effectively simplify the decision-making process of evolution of large-scale power system. Then, an annual production simulation (8760 h) which takes into account renewable energy and load fluctuations is used to find out the bottleneck of the power grid. Based on the above methods, evolution strategy of power system with high proportion of renewable energy is studied for finding out optimal expansion strategy. A real power system of Zhejiang province is used as a test system. Test results demonstrate the feasibility of the proposed evolution framework.

In this paper, a numerical method coupling moment method with circuit theory is used to analyze the influence of the grounding material's property on the performance of grounding grids. It can be seen that for a large grounding grid, when the soil resistivity is small, the influence of both resistivity and permeability of grounding material on the performance of grounding grids is great. If the frequency is not very high, the grounding material's resistivity can affect the performance of the grounding grid obviously. If the frequency is very low or very high, the effect of the grounding material's permeability on the performance of the grounding grid is small, while the effect is obvious at other frequency.

This paper presents a new concept of Static Synchronous COMpensator (STATCOM) based on a Hybrid Cascaded Multilevel Converter (HCMC). The HCMC consists of a two- level voltage converter and a wave-shaping circuit formed by cascaded H-bridge Sub-Modules (SM). Firstly, the operation principle and overall control strategy of HCMC are presented. After that, some key parameters including size of capacitors, numbers of sub-modules are in-depth analyzed. And then, a thorough comparison between the proposed HCMC-based STATCOM and conventional cascaded H-bridge based STATCOM is made, which turns out that the proposed HCMC-based STATCOM requires less number, size and stored energy of capacitors and has less power loss. Finally, a 35 kV/±50 Mvar HCMC-based STATCOM simulation model is constructed in PSCAD/EMTDC software platform. The simulation results validate the feasibility of the proposed HCMC-based STATCOM and the correctness of the analysis.

Hierarchical TiO(2) nanostructures would be desirable for preparing dye-sensitized solar cells because of their large amount of dye adsorption and superior light harvesting efficiency, as well as efficient charge separation and transport properties. In this study, rutile TiO(2) nano-branched arrays grown directly on transparent conductive glass (FTO) were prepared by a facile two-step wet chemical synthesis process, using a simple aqueous chemical growth method involving immersing the TiO(2) nanorod arrays in an aqueous TiCl(4) solution as seeds, which were prepared by a hydrothermal method. The dye-sensitized solar cells based on the TiO(2) nano-branched arrays which were only about 3 μm in length show a short-circuit current intensity of 10.05 mA cm(-2) and a light-to-electricity conversion efficiency of 3.75%, which is nearly three times as high as that of bare nanorod arrays, due to the preferable nanostructure, which not only retains the efficient charge separation and transport properties of the nanorod arrays, but also can improve the amount of dye adsorption due to the increased specific surface area from the nanobranches.

This study aims to explore the application of fractional order chaotic system (FOCS), based on the T-S fuzzy model, in the design of secure communication (SC) and this SC system’s role in the construction of efficiency evaluation system for dispatching operation of energy saving and power generation under a low carbon economy (LCE). First, the definition of fractional order differential equations and the stability theory of FOCS are discussed. T-S fuzzy control is introduced to analyse the stability of FOCS. Then, based on the adaptive synchronisation theory, the combined FOCS is designed for SC, and the performance of the system constructed here is analysed in a MATLAB environment. Next, an evaluation index system of the dispatching operation effect of energy saving and power generation under LCE is constructed. The confidential communication system constructed here is used to transmit the index data. The particle swarm optimisation (PSO) algorithm is then used to optimise the back propagation neural network (BPNN) model. The BPNN algorithm based on PSO (PSO-BPNN) is obtained, and the evaluation model is constructed. After training this model, it is applied to the evaluation of the dispatching operation effect for energy saving and power generation in 10 provinces in China. The simulation results show that the FOCS based on the T-S fuzzy model can acquire the criterion of system stability. Furthermore, the constructed SC system can effectively undertake the secure transmission of square and sine waves. The performance of the PSO-BPNN model seems to be better than other algorithms. After analysing the data on energy saving and power generation from 10 provinces in China using this model, the comprehensive evaluation value of province 5 is found to be the highest and good (0.802), while that of province 4 is the lowest and general (0.600). Summarising, the FOCS based on T-S fuzzy model constructed here is applied to the design of SC. This can improve the confidentiality of data transmission and reduce the transmission error. Moreover, the BPNN evaluation model based on PSO can effectively achieve the evaluation of the dispatching operation effect of energy saving and power generation under LCE.

Organo-lead-halide perovskite based solar cells have achieved remarkable advancements in power conversion efficiencies (PCEs) in recent years. Given their attractive properties, possible applications for perovskites are wide ranging and among others, particularly appealing for building integrated photovoltaics (BIPVs). In this study, patterned perovskite films were successfully fabricated based on a microsphere lithography SiO2 honeycomb scaffold template, which was derived by a combination of air-water interface self-assembly and O2 plasma etching. These patterned perovskite films exhibited near-neutral-color and tunable semitransparency, which meet the requisites of semitransparent solar cells for BIPVs application. O2 plasma etching of the microsphere template could effectively improve the active layer average visible transmission (AVT), and the existence of the SiO2 nanoscaffold effectively smoothed the internal trade-off of active layer AVT and device PCE. Solar cell devices fabricated with these optimized patterened perovskite films yielded a maximum PCE of 10.3% with relatively high active layer AVT of 38%. This nanoscaffold patterned perovskite opens up a new strategy for design and fabrication of functional photoelectric device based on organo-lead-halide perovskite.

Abstract China has the advantage of learning from the mistakes made by nations that have developed their nuclear power energy system in the last century. Such mistakes encompass the lack of sustainable development of the nuclear energy and poor planning in the back-end of the nuclear fuel cycle. The present paper studies the evolution of a double strata cycle with fast reactor gradually replacing the LWR. It starts from 2035 and covers the historical development of nuclear energy in China to the year 2100. The paper studies the ADS impact on the NFC and estimates the number and the deploying schedule of the ADS reactors to limit the accumulation of minor actinides. The other aspects considered here are natural uranium resources, fuel utilization efficiency, proliferation and diversion risks, spent fuel production and overall materials flow. Additionally, perturbation calculations were performed to evaluate the impact of the uncertainty on key parameters. The results are discussed in view of the Chinese nuclear fuel cycle plan and their policy implications are thoroughly evaluated.

Abstract An electrochemical model is developed to investigate capacity recovery methods for cycled lithium ion batteries. Different capacity recovery methods are evaluated and compared. The center recovery method for commercial batteries is found to be impractical because it causes severe solid surface concentration gradients which may harm the batteries. On the contrary, the center recovery method for novel batteries with porous current collector sheets is better than the bottom recovery method because smaller solid surface concentration gradients are detected and less relaxation time is required during capacity recovery. Capacity recovery methods which discharge negative electrodes is superior to those which discharge positive electrodes of cycled batteries as smaller solid surface concentration gradients is generated and less relaxation time is required at the same discharging current.

There are substantial differences in carbon footprints across households. This study applied an environmentally extended multiregional input–output approach to estimate household carbon footprints for 12 different income groups of China’s 30 regions. Subsequently, carbon footprint Gini coefficients were calculated to measure carbon inequality for households across provinces. We found that the top 5% of income earners were responsible for 17% of the national household carbon footprint in 2012, while the bottom half of income earners caused only 25%. Carbon inequality declined with economic growth in China across space and time in two ways: first, carbon footprints showed greater convergence in the wealthier coastal regions than in the poorer inland regions; second, China’s national carbon footprint Gini coefficients declined from 0.44 in 2007 to 0.37 in 2012. We argue that economic growth not only increases income levels but also contributes to an overall reduction in carbon inequality in China.