• Energy Research
• 2021-2025close
• 7. Clean energy close
• 11. Sustainability close
• Chinese close

Cyanobacterial biomass is important for biofuel and biofertilizer, however, biomass production requires expensive chemical growth nutrients. To address this issue, we explored the useof inexpensive growth nutrient media from an integrated manure-seawater system for cyanobacterial biomass production. Salt-tolerant cyanobacterial strain HSaC and salt-sensitive cyanobacterial strain LC were tested to evaluate the potential of integrated manure-seawater media for sustainable cyanobacterial biomass production. As a prerequisite for seawater experiments, strain HSaC was grown at different NaCl concentrations (0 mM, 60 mM, 120 mM, 180 mM, 240 mM and 300 mM) to identify the optimum salt concentration. The highest biomass yield and photosynthetic pigment contents were obtained at 120 mM NaCl concentration. The highest exo-polysaccharide (EPS) content was obtained at 180 mM NaCl concentration. The treatments for the manure-seawater media were cow manure, pig manure, chicken manure and BG11, each with distilled water, diluted seawater and non-diluted seawater. The highest biomass and photosynthetic pigment yield for cyanobacterial strains LC and HSaC were obtained from 0.5 dS/m and 10 dS/m diluted seawater integrated with cow manure, respectively, but pig and chicken manure performed poorly. Overall, the biomass production and photosynthetic pigment results from cow manure-seawater were relatively better than those from the reference media (BG11). Based on the current findings, it is concluded that the growth nutrients from integrated cow manure-seawater can wholly substitute for the BG11 without affecting cyanobacterial growth, thereby reducing the usage of expensive chemical growth media. Thus,The results of study help to enhance the biomass production of both salt-sensitive and salt-tolerant cyanobacteria for sustainable biofuel and biofertilizer production. Cyanobacterial biomass is important for biofuel and biofertilizer, however, biomass production requires expensive chemical growth nutrients. To address this issue, we explored the useof inexpensive growth nutrient media from an integrated manure-seawater system for cyanobacterial biomass production. Salt-tolerant cyanobacterial strain HSaC and salt-sensitive cyanobacterial strain LC were tested to evaluate the potential of integrated manure-seawater media for sustainable cyanobacterial biomass production. As a prerequisite for seawater experiments, strain HSaC was grown at different NaCl concentrations (0 mM, 60 mM, 120 mM, 180 mM, 240 mM and 300 mM) to identify the optimum salt concentration. The highest biomass yield and photosynthetic pigment contents were obtained at 120 mM NaCl concentration. The highest exo-polysaccharide (EPS) content was obtained at 180 mM NaCl concentration. The treatments for the manure-seawater media were cow manure, pig manure, chicken manure and BG11, each with distilled water, diluted seawater and non-diluted seawater. The highest biomass and photosynthetic pigment yield for cyanobacterial strains LC and HSaC were obtained from 0.5 dS/m and 10 dS/m diluted seawater integrated with cow manure, respectively, but pig and chicken manure performed poorly. Overall, the biomass production and photosynthetic pigment results from cow manure-seawater were relatively better than those from the reference media (BG11). Based on the current findings, it is concluded that the growth nutrients from integrated cow manure-seawater can wholly substitute for the BG11 without affecting cyanobacterial growth, thereby reducing the usage of expensive chemical growth media. Thus,The results of study help to enhance the biomass production of both salt-sensitive and salt-tolerant cyanobacteria for sustainable biofuel and biofertilizer production.

Direct charge radioisotope battery having the advantages of long service lifetime, simple structure, high open circuit voltage and easily miniaturized, is a promising source for the great power of Micro-Electro-Mechanical System. Although the beta sources are the main choice for direct charge nuclear battery in the present studies,but no systematic analysis and comparison on beta sources is presented. In this work, the properties of six beta sources (including 3H(Ti3H2), 14C, 35S, 45Ca, 63Ni and 147Pm) were studied by software simulation and theoretical calculation. This study includes the differences of energy conversion efficiency and the theoretical output power for direct charge nuclear battery. The calculated results showed that the energy conversion efficiency was positively correlated with the average energy of emitted radioactive particles, and the theoretical output power was negatively correlated with half-life of beta source. 147Pm was the preferred choice considering long life, the energy conversion efficiency and the theoretical output power. Direct charge radioisotope battery having the advantages of long service lifetime, simple structure, high open circuit voltage and easily miniaturized, is a promising source for the great power of Micro-Electro-Mechanical System. Although the beta sources are the main choice for direct charge nuclear battery in the present studies,but no systematic analysis and comparison on beta sources is presented. In this work, the properties of six beta sources (including 3H(Ti3H2), 14C, 35S, 45Ca, 63Ni and 147Pm) were studied by software simulation and theoretical calculation. This study includes the differences of energy conversion efficiency and the theoretical output power for direct charge nuclear battery. The calculated results showed that the energy conversion efficiency was positively correlated with the average energy of emitted radioactive particles, and the theoretical output power was negatively correlated with half-life of beta source. 147Pm was the preferred choice considering long life, the energy conversion efficiency and the theoretical output power.

Wind turbine roll decay curves Wind turbine roll decay curves

With the objective of carbon neutrality, renewable energy resources gradually become the main power supply, whose variability poses great challenges to the operation and optimization of the system, especially to the power distribution network. In order to solve the problem of reactive power caused by high penetration of renewable energy sources, a centralized optimization model is proposed, which takes reactive power optimization and “generation-network-load-storage” multi-energy integration into account. The model aims at optimizing the operating cost and minimizing network losses and carbon emissions of the system. Reactive power compensation, regulation of energy storage, and energy conversion are considered to achieve safe and low-carbon economic dispatch of the power and gas systems. An improved second-order cone relaxation method is used for the convex relaxation of non-linear equality constraints concerned with the distribution network. The switching capacity produced by discrete reactive power compensators can be exactly linearized by the application of the big M approach. The simulation results demonstrate that the proposed method could effectively compensate the reactive power required by the grid-connection point of wind turbine, coordinate the energy interaction between the power and gas, thus improving the stability and elasticity of the distribution network after integration of large-scale renewable energy sources, which helps promote the consumption of renewable energy.

The resource utilization of solid waste is an important way to achieve energy saving and emission reduction. A lauric acid (LA)/raw fly ash (RFA)-diatomite(DT)/carbon nanotubes(CNT) composite form-stable phase change materials (FSPCM) for thermal energy storage were prepared via simple direct impregnation method, in which LA, RFA-DT binary matrix and CNT were employed as phase change materials(PCMs), the supporting material, and thermal conductive additive, respectively. The loading capacity, structure and thermal properties of FSCPCM were investigated through the diffusion-oozing testing, Fourier transform infrared spectrometer (FTIR), differential scanning calorimetry (DSC), thermo gravimetry analysis (TGA) and paperless recorder, respectively. The results show that the RFA-DT binary material can effectively prevent the leakage of LA. When the mass fraction of LA in composite is 28%, the FSPCM without leakage can be obtained. What’s more, the utilization rate of RFA reaches 55%. The FTIR demonstrates that FSPCM has good compatibility between its four components, LA, RFA-DT, and CNT. The melting onset temperature of FSPCM is 45.79 ℃ measured by DSC, and the corresponding latent heat of FSPCM is determined as 51.06 J/g. TGA analysis shows LA/RFA-DT has good thermal stability. The storage/release performance curve indicates that when mass fraction of CNT is added with 5%, the melting and solidification time of LA/RFA-DT/CNT are decreased by 60% and 62.5%, respectively, indicating that the heat transfer performance is remarkably improved.

Supercapacitors have become a new type of energy storage device widely used due to their high efficiency, fast speed and good cycle stability, and electrode material is a key issue restricting their development. The porous niobium nitride fibers were prepared by electrospinning combined with reduction nitride technology using pentachloride as raw material, and Nb4N5||Nb4N5 symmetrical button capacitance was prepared. In order to improve the electrochemical performance of electrode material, NaHCO3 was added into Na2SO4 electrolyte. The results show that the prepared niobium nitride fiber exhibits a tetragonal phase, continuous and porous on the surface. The porous niobium nitride electrode has two mechanisms of electric double layer and pseudocapacitive energy storage. The specific capacitance of the capacitor increases to 187 F·g-1 with the NaHCO3 addition of 15 mmol·dm-3. The buffering effect inhibits the dissolution of niobium nitride, effectively reduces the solution resistance, the solution impedance R1 and the diffusion impedance WR reduce to 1.22 Ω and 1.47 Ω respectively and the ionic conductivity improves. The carrier concentration increases to 6.58×1024 cm3, and the relaxation time of the capacitor is shortened to 0.24 s at the same time.

Ethanol is a feasible medium for diffusion separation of carbon isotopes. In order to obtain the separation coefficient of gas diffusion separation of ethanol, the application of elemental analysis isotope ratio mass spectrometry (EA-IRMS) to measure the carbon isotope abundance in ethanol in gas diffusion separation experiment was studied. Through literature investigation, this study optimized the preparation process of ethanol samples, developed the method of EA-IRMS for the determination of carbon isotope abundance of ethanol, tested the stability, and realized the measurement of carbon isotope abundance of ethanol samples. Based on the separation experiment of gas diffusion method, the carbon isotope abundances of refined ethanol and lean ethanol in multiple separation experiments are obtained. The basic total separation coefficient of carbon isotopes by ethanol diffusion can be calculated by formula derivation. This study provides an analytical basis for the future experiment of diffusion separation of carbon isotopes with ethanol as medium.

As the most complex component in the transmission system, the operating state of the wind turbine gearbox has a tremendous impact on the monitoring of the health status and operation control of the wind turbine equipment. Abnormalities in wind turbines that lead to downtime not only result in a loss of electrical energy, but also a significant increase in maintenance costs. Therefore, with the wind turbine gearbox as the main object of study, the following studies were carried out: For microscopic local conditions in gearbox gear systems, a method for obtaining modal data using finite element simulation analysis of single tooth faults is proposed. Using a combination of deep auto-encoder structures and BP structures for secondary training strategies, a linear and non-linear performance evaluation method is proposed, which takes into account the relationship between performance and efficiency. Hyper-parameter configuration in deep transfer structures is often arbitrary, so a hierarchical transfer network structure hyper-parameter searching method is proposed to address the gearbox planetary system fault classification problem. The algorithm is validated using the classical LeNet-5 reconfiguration transfer application on a modal dataset of the planetary system. Finally, a stability validation and results analysis of the algorithm performance is carried out. A compressed sensing-based sparse signal decomposition method is proposed, and the structure of the transfer network is redesigned to achieve deep migration learning from rolling bearing faults to gear faults. A new network architecture was designed using a plug-and-play attention module. Pre-training models were designed and produced for fault data to improve the accuracy and recognition speed of fault diagnosis model classification. Finally, the effects of the same number of samples in the source and target domains and different distributions of sample features on the performance of the transfer learning method and the effects of hyper-parameters on the final performance of the network structure are verified.

As a basic properties of forest vegetation, forest succession law is the basis of understanding forest community, managing forest and utilizing forest rationally. Typical evergreen broad-leaved forest is a zonal vegetation in the subtropical area of east China. The existing vegetation is mostly in different secondary succession stages due to human and natural disturbance. Plant species composition is an important indicator of the long-term terrestrial ecosystem observation of National Ecosystem Research Network of China (CNERN). It affects the biogeochemical cycle, productivity, carbon sequestration, biodiversity and ecosystem services of forest ecosystems. According to CNERN monitoring standards, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station finished three investigations at three succession plots and established a dataset on species composition during 2008 and 2017. The dataset included species name, abundance, mean diameter and biomass of woody plants in the plot. The species composition database provides critical data for in-depth studies of forest species diversity, structure and function under succession or environment change, and can support forest management and ecosystem service evaluation in this region. As a basic properties of forest vegetation, forest succession law is the basis of understanding forest community, managing forest and utilizing forest rationally. Typical evergreen broad-leaved forest is a zonal vegetation in the subtropical area of east China. The existing vegetation is mostly in different secondary succession stages due to human and natural disturbance. Plant species composition is an important indicator of the long-term terrestrial ecosystem observation of National Ecosystem Research Network of China (CNERN). It affects the biogeochemical cycle, productivity, carbon sequestration, biodiversity and ecosystem services of forest ecosystems. According to CNERN monitoring standards, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station finished three investigations at three succession plots and established a dataset on species composition during 2008 and 2017. The dataset included species name, abundance, mean diameter and biomass of woody plants in the plot. The species composition database provides critical data for in-depth studies of forest species diversity, structure and function under succession or environment change, and can support forest management and ecosystem service evaluation in this region.