Energy Storage Capacity Planning Method for Improving Offshore Wind Power Consumption

This paper proposes a method of energy storage capacity planning for improving offshore wind power consumption. Firstly, an optimization model of offshore wind power storage capacity planning is established, which takes into account the annual load development demand, the uncertainty of offshore wind power, various types of power sources and line structure. The model aims at the lowest cost of investment, operation and maintenance of the system, and takes lower than a certain abandoned wind level as the strict constraint to obtain two parameters of power capacity and energy capacity of energy storage on the source side. Secondly, taking a coastal power grid as a typical case, the energy storage capacity planning method is verified. Finally, the key factors affecting offshore wind power consumption are summarized, and the sensitivity analysis is carried out from the point of view of the transmission protocol of the transmission lines outside the province and the capacity allocation of the tie lines in the province. This study will be helpful for the planning and operation of the high-proportion of offshore wind energy power systems

Flux Pinning Properties of Single-Grain Bulk GdBCO Superconductors Processed by Different Thicknesses of Y123 Liquid Source

The performance of critical current density of GdBa2Cu3O7−δ (GdBCO or Gd123) superconductor bulk has an important influence on its practical applications. In this work, four single-domain GdBCO superconductor bulks were successfully processed by the modified top-seeded melt-texture growth method. The addition of a YBa2Cu3O7−δ (Y123) liquid source with different thicknesses, 0 mm (S0), 3 mm (S3), 5 mm (S5), 7 mm (S7), was introduced to study the influence on the superconducting properties. GdBCO bulk with the addition of the Y123 liquid source with a 3-mm thickness shows the best superconducting properties. The addition of the Y123 liquid source results in a decrease in the Gd3+ ion concentration required for Gd123 growth; thus, Gd2BaCuO5 (Gd211) particles in the liquid source need a larger self-decomposition to diffuse Gd3+ ions to Gd123 growth front, which refines the size and leads to a homogenous distribution of the Gd211 particles in the bulks. Thus, the more pinning centers of fined Gd211 particles improve the superconducting properties of GdBCO bulk. With increases in the thickness of Y123 liquid source to 5 mm and 7 mm, high RE3+ (Gd3+ and Y3+) concentration can coarsen Gd211 particles and fuse with Gd211 liquid source. The superconducting properties apparently drop. Therefore, the addition of a Y123 liquid source with a suitable thickness is a positive modification to obtain high-performance GdBCO bulk

Joint Planning of Offshore Wind Power Storage and Transmission Considering Carbon Emission Reduction Benefits

There are two situations of transmission redundancy and transmission congestion when large-scale offshore wind farms send power out. The energy storage system can store the power blocked by wind power due to insufficient transmission capacity and release it in the period when the wind power output level is low. In this paper, a full-life-cycle cost model is established for energy storage, and a joint planning model for offshore wind power storage and transmission considering carbon emission reduction benefits is established, which integrates power grid transmission benefits, carbon emission reduction benefits, energy storage construction costs, transmission project construction costs and wind abandonment penalty costs. The channel construction and energy storage configuration scheme with the greatest net benefit can be obtained. The relationship between the transmission channel capacity setting and the energy storage parameter configuration under this model is studied, and the combined effect of transmission channel and energy storage system in improving the level of wind power transmission is analyzed. The sensitivity analysis of the influence of the optimal storage and transmission planning scheme of the offshore wind farms is carried out from the perspectives of transmission line engineering cost and transmission channel curve type

Characteristics of Heavy Metals in Seawater and Sediments from Daya Bay (South China): Environmental Fates, Source Apportionment and Ecological Risks

In this study, the spatiotemporal distributions, potential sources, and ecological risks of Hg, Cr, and As in seawater, and Hg, As, Zn, Cd, Pb, and Cu in sediments from Daya Bay were investigated. The five-year average concentrations of Hg, Cr, and As in seawater were 0.020 μg/L, 0.79 μg/L, and 2.08 μg/L, respectively. The five-year average concentrations of Hg, As, Zn, Cd, Pb, and Cu in surface sediments were 0.04 mg/kg, 7.34 mg/kg, 63.81 mg/kg, 0.23 mg/kg, 25.60 mg/kg, and 11.78 mg/kg, respectively. Annual variations in Hg, Cr, and As in seawater exhibited different trends. HMs in sediments, such as As, Zn, Pb, and Cu, exhibited similar annual variations, whereas Hg and Cd exhibited different annual variations. The spatial distribution of metal species in seawater and sediments showed significant variability, and the concentrations decreased gradually from the coast to the open sea. The comprehensive potential ecological hazard index (RI) of HMs in sediments indicated a relatively high risk, especially for Hg and Cd contamination. The geoaccumulation indices (Igeo) of As, Zn, Pb, and Cu suggested that these metals did not pollute Daya Bay, whereas those of Cd and Hg indicated mild and moderate pollution. The environmental fates of HMs were discussed based on Pearson correlation analysis, revealing that concentrations of HMs were greatly affected by parameters, such as pH, salinity, dissolved oxygen (DO), and total organic carbon (TOC). Principal component and factor analyses indicated that Hg, Cr, As, and dissolved inorganic nitrogen (DIN) in water originated from similar sources, including domestic sewage and wastewater from fishing ports, runoffs, and outlets. For sediments, it was proposed that Cu, Zn, As, Pb, and TOC exhibited similar sources, including cage culture and waste discharge from outlets. Meanwhile, Hg and Cd originated from other point sources, such as a harbor. The study suggests that sustainable management and economic development be integrated to control pollutant emissions in Daya Bay

Multivariate Analyses and Evaluation of Heavy Metals by Chemometric BCR Sequential Extraction Method in Surface Sediments from Lingdingyang Bay, South China

Sediments in estuary areas are recognized as the ultimate reservoirs for numerous contaminants, e.g., toxic metals. Multivariate analyses by chemometric evaluation were performed to classify metal ions (Cu, Zn, As, Cr, Pb, Ni and Cd) in superficial sediments from Lingdingyang Bay and to determine whether or not there were potential contamination risks based on the BCR sequential extraction scheme. The results revealed that Cd was mainly in acid-soluble form with an average of 75.99% of its total contents and thus of high potential availability, indicating significant anthropogenic sources, while Cr, As, Ni were enriched in the residual fraction which could be considered as the safest ingredients to the environment. According to the proportion of secondary to primary phases (KRSP), Cd had the highest bioavailable fraction and represented high or very high risk, followed by Pb and Cu with medium risks in most of samples. The combined evaluation of the Pollution Load Index (PLI) and the mean Effect Range Median Quotient (mERM-Q) highlighted that the greatest potential environmental risk area was in the northwest of Lingdingyang Bay. Almost all of the sediments had a 21% probability of toxicity. Additionally, Principal Component Analysis (PCA) revealed that the survey region was significantly affected by two main sources of anthropogenic contributions: PC1 showed increased loadings of variables in acid-soluble and reducible fractions that were consistent with the input from industrial wastes (such as manufacturing, metallurgy, chemical industry) and domestic sewages; PC2 was characterized by increased loadings of variables in residual fraction that could be attributed to leaching and weathering of parent rocks. The results obtained demonstrated the need for appropriate remediation measures to alleviate soil pollution problem due to the more aggregation of potentially risky metals. Therefore, it is of crucial significance to implement the targeted strategies to tackle the contaminated sediments in Lingdingyang Bay

Complex assembly, crystallization and preliminary X-ray crystallographic studies of MHC H-2Kd complexed with an HBV-core nonapeptide

In order to establish a system for structural studies of the murine class I major histocompatibility antigen complex (MHC) H-2Kd, a bacterial expression system and in vitro refolding preparation of the complex of H-2Kd with human β2m and the immunodominant peptide SYVNTNMGL from hepatitis B virus (HBV) core-protein residues 87–95 was employed. The complex (45 kDa) was crystallized; the crystals belong to space group P2221, with unit-cell parameters a = 89.082, b = 110.398, c = 47.015 Å, α = β = γ = 90°. The crystals contain one complex per asymmetric unit and diffract X-­rays to at least 2.06 Å resolution. The structure has been solved by molecular replacement and is the first crystal structure of a peptide–H-2Kd complex