Concentrating solar power (CSP) is one of the major technologies for converting sunlight to electricity. It could offer a utility-scale, relatively stable and dispatch-able electricity, as well as combined heat and power supply with a very low environmental impact. With large-scale deployment in the near future, CSP could function as a peak power source to provide ancillary services for wind power, photovoltaic power generation and other intermittent power supply, CSP power plants has a potential to provide the base-load in the long run. Through decades of efforts, the CSP industry is expected to become a mass-deployed renewable energy generation option worldwide over the next decade. The technological research and industry development of CSP in China, however, are lagged far behind. In addition, China hasn't issued any clear incentives for solar thermal power industry, which directly leads to an indefinite postponing of a number of projects.

Mass, momentum and energy transfer in the internal structure of porous media are basic processes of life, natural phenomena and production. Questions about heat transfer in porous media involve many fields of science, which have aroused researcher's wide attention and they also have done a lot of works on this. Effective thermal conductivity method is to view porous media as a continuous medium. The actual solid skeleton and all kinds of heat transfer model in porous media (heat conduction, convection and radiation) can be converted into an integrated heat conduction problem. It has already become the most commonly used approach in the porous medium heat transfer issue. Recent years, the bubble type porous medium (such as the metal foam, ceramic foam or graphite foam) has attracted widespread attention. Researches on the effective thermal conductivity (ETC) of bubble type porous media are reviewed in this article. Three kinds of research methods are introduced, including experimental testing, theoretical derivation and numerical simulation. Finally, the problems existing in the research of effective thermal conductivity are discussed. Experimental testing method does have high accuracy but it is difficult to determine the contribution of each heat transfer model to the ETC and the cost of the testing is high. Although theoretical derivation method has clear physical meaning and wide applicability, the results have larger deviation and some resulting correlations include coefficient based on experience or experimental data. The results of the numerical simulation are close to the experimental data but the complexity lies in the model construction.

Mixed molten salts are considered as promising media for both heat transfer and thermal energy storage because of several advantages including wide applicable temperature range, low viscosity, good fluidity, low vapor pressure, relatively high density and heat capacity and low cost, This paper outlines the principle of the use of molten salts as sensible heat storage materials and provide a review of the state-of-the-art development the materials. Particular attention is drawn on the type and characteristic of commonly molten salt, technical principle, development status of key technologies such as molten salt heat storage medium and equipment and application in solar thermal power generation and intermittent of waste heat utilization. It is concluded that preparing and researching thermal or flowing properties high temperature molten salt, perfevting the molten salt heat storage system, improving heat storage efficiency, weakening corrosivity and improving the system reliability are among the important aspects for future research.

The maximum power of photovoltaic power generation system varies with the changes of the external environment and is unable to meet the power requirements of loads. In order to solve this problem, this paper established the structure of photovoltaic power generation system based on energy storage, introduced the operation principle of photovoltaic power generation system, analyzed the relationship between the power and the DC bus voltage, and designed passive energy storage system and active energy storage system to buffer the power for satisfying control target. The simulation results show that the active energy storage system has better regulation of power than the passive energy storage system. Through the bi-directional DC-DC converter automatically switching control for storing energy, the power of photovoltaic power generation system is well matching with the power of loads, and DC voltage is also stability.

The work reported in this paper concerns preparation of paraffin wax based composite phase change materials (PCMs) for waste heat recovery. Surface modified fly ash was used as the PCM carrier and water-free ethanol as the solvent and the solution intercalation was used to prepare the composite materials. The fly ash modification was done by using citric acid, which did not affect the structure of the fly ash. The modification process was found to be able to remove impurities of fly ash and improve the adsorption capacity of PCMs. A series of experiments were conducted to characterize the prepared composite materials using DSC, FT-IR and SEM. The DSC results showed that the best composite material had a melting latent heat of 84.23 kJ/kg with the melting temperature of 53.63 ℃. The FT-IR analyses showed good chemical stability of composites, and the leakage of melted paraffin from the composites could be prevented through the capillary force and surface tension between paraffin and fly ash. By using a heat exchanger, the PCMs were tested for the recovery of industrial waste heat. It was shown that the outlet water temperature of the heat exchanger could be maintained approximately constant for a few hours.

The work reported in this paper is on LiNi_0.8Co_0.2O₂ cathode material for lithium-ion batteries applications. A high-density precursor, Ni_0.8Co_0.2(OH)₂, was prepared first by concurrent co-precipitation using nickel sulfate, cobalt sulfate and sodium hydroxide as raw materials. The cathode material was made by high temperature solid state reaction in an air environment. The s as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and constant current electrochemical test (ECT), and the impact of sintering time on the structure, surface morphology and electrochemical properties was investigated. The LiNi_0.8Co_0.2O₂ sample made with n(Li)∶n(Ni+Co)=1.13∶1 and sintered in the air at 700 ℃ for 9 h and then 750 ℃ for 12 h shows optimal electrochemical performance, giving an initial discharge capacity of 153.0 mA·h/g, a capacity of 150.7 mA·h/g at 20th discharge and a capacity retention so high as 98.5% at the rate of 0.5 C from 2.7 V to 4.3 V. These results demonstrate excellent cyclic stability of the material and good potential for use as the cathode material of high power density power batteries.

This paper concerns the effects of water balance in a membrane electrode assembly (MEA) of direct methanol fuel cells (DMFCs) on DMFC performance. The effects of operating conditions including cell temperature, air rate and current density on the water balance are investigated. It is shown that the net water transport coefficient provides the water balance state and can be regulated by the operating conditions. For a single cell stable operation for 200 h can be achieved under optimized operating conditions of 100 mA/cm² at 60℃ and ambient dry air at 80 mL/min.

Compressed air energy storage (CAES) has the potential to improve the quality of renewable electricity from wind and solar energy. Using such a technology, the intermittent renewable electricity can be stored at off peak hours, and released in a steady manner at peak time of electricity grid. This paper considers a CAES system for an electricity storage capacity of 56.58 MW and an output capacity of 154.76 MW. For the selection of turbines for the energy release step, reference is made to the second stage turbine of the GE 9171E configuration. Flue gas temperature of the second stage turbine could reach 812.41 K to satisfy the heat supply requirement for heating the compressed air before entering the first stage turbine. As a result, the high pressure combustor for the first turbine could be removed from the system. The heat consumption for the CAES system could be as low as 3783.96 kJ/(kW·h) and the system energy conversion efficiency could reach 56.11%.

Operating of lithium-ion batteries includes transport of lithium ion in anode, cathode and solid electrolyte interphase. It is important to determine the properties of ionic transport in solid state materials. In this paper, general ionic transport mechanisms in solids, driving force of ion motions, and factors affecting ionic conductivities are summarized briefly. Differences in the transport properties between intrinsic lithium ion in lattice and external lithium ion through lattice or grain boundaries and the size effect are briefly discussed as well.

As an energy storage element, electrochemical capacitors have many advantages including high power density, fast charge and discharge rates, wide range of working temperature, long cycle life, excellent safety and environmental friendliness, and, as a result, attract worldwide attention. Since the patent filed in 1957, several generations of electrochemical capacitors have been developed due to significant progress in electrode materials and electrolytes. Electrochemical capacitors have been playing an important role in a number of application areas. Examples include energy storage, electro mobile and automatic control. This paper first introduces the history and fundamental aspects of the electrochemical capacitors. Then, a brief summary is given of the applications of the devices. Finally, prospect and future research directions of the area are discussed.

Containerized energy storage systems integrate all storage components into one or more standard containers. They are movable, easy to installation and compact and hence have a potential for wide-spread applications. This paper presents a study of containerized type energy storage systems from a company limited. The work includes system design of cooling and aseismicity. Thermal simulations and finite element analyses are performed in the Icepak and CAE software, the results show the effectiveness of the design.