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Abstract: The paper analyses the issues for consideration listed in the stock taking document “New Energy Strategy for Europe 2011–2020” and explores the impact of their implementation on the use of renewable energy sources. The main objective of the paper is to introduce and provide a summary of the theoretical and methodological achievements required for an analysis of the implications of such an EU level strategy. It also provides a summary of the results of the analysis of the impacts of the Strategy on a specific field; namely, on the use of renewable energy sources. Contradictions inherent in the Strategy are discussed as well, and a proposal is put forward to aid the resolution of these contradictions. The paper also points out that the further development of the theoretical and methodological achievements may result in the creation of a simulation model, the application of which could effectively aid the process of strategic planning and the testing of strategies prior to approval. Finally, the paper discusses how an EU level and/or a global network of energy security centres could promote the development and implementation of an energy policy ensuring the appropriate utilization of renewable energy sources. [Copyright &y& Elsevier]

Abstract: This paper investigates the potential use of renewable energy sources (various sorts of biomass) and solid wastes (municipal wastes, sewage sludge, meat and bone meal etc.) in a co-gasification process with coal to co-generate hydrogen and electricity with carbon capture and storage (CCS). The paper underlines one of the main advantages of gasification technology, namely the possibility to process lower grade fuels (lower grade coals, renewable energy sources, solid wastes etc.), which are more widely available than the high grade coals normally used in normal power plants, this fact contributing to the improvement of energy security supply. Based on a proposed plant concept that generates 400–500 MW net electricity with a flexible output of 0–200 MWth hydrogen and a carbon capture rate of at least 90%, the paper develops fuel selection criteria for coal blending with various alternative fuels for optimizing plant performance e.g. oxygen consumption, cold gas efficiency, hydrogen production and overall energy efficiency. The key plant performance indicators were calculated for a number of case studies through process flow simulations (ChemCAD). [Copyright &y& Elsevier]

Abstract: This paper describes a method to characterize the fluctuating electricity generation of renewable energy sources (RESs) in a power system and compares the different parameters for California and Germany. Based on this method describing the fluctuation and residual load, the potential contribution of grid-connected vehicles to balancing generation from renewable energy sources is analyzed for a 2030 scenario using the agent-based simulation model PowerACE. The analysis reveals that integrating fluctuating RES is possible with less effort in California because of a higher correlation between RES generation and the load curve here. In addition, RES capacity factors are higher for California and therefore the ratio of installed capacity to peak load is lower. Germany, on the other hand, faces extreme residual load changes between periods with and without supply from RES. In both power system scenarios, grid-connected vehicles play an important role in reducing residual load fluctuation if smart charging is used. Uncontrolled charging or static time-of-use tariffs do not significantly improve the grid integration of RES. [Copyright &y& Elsevier]

Abstract: Hydrogen has been recognized as the most promising future energy carrier. At present, industrial hydrogen production processes are not independent of traditional energy resources, which could easily cause secondary pollution. China has abundant wind energy resources. The total installed capacity of wind power doubled every year in the last five years, and reached 26 000 MW by the end of 2009, but over 9880 MW wind turbines were not integrated into grid because of the peak shaving restraint. In this paper, wind power is directly used in water-electrolytic process by some technical improvements, to design non-grid-connected wind power/water-electrolytic hydrogen production system. The system all works properly, based on not only the wind/grid complementary power supply but also the independent supply of simulation wind power. The large-scale fluctuation of current density has little impact on current efficiency and gas quality, and only affects gas output. The new system can break through the bottlenecks of wind power utilization, and explore a diversified development way of large-scale wind power, which will contribute to the development of green economy and low carbon economy in China. [Copyright &y& Elsevier]

Abstract: Autonomous micro hydro power plants (MHPP) are a reliable solution for supplying small power consumers in areas located far from the distribution grid. When an induction generator (IG) is used in such a power plant, voltage and frequency need to be stabilized. This paper presents a single control structure that ensures both the voltage and frequency regulation of an isolated induction generator (IG). The control structure consists in a voltage source inverter (VSI) with a dump load (DL) circuit on its DC side. The VSI operates at constant frequency, thus stabilizing the IG frequency also. For voltage regulation two cascaded regulators are used, which have as reference the line voltage and the VSI DC voltage, respectively. Simulations and experiments are carried out in order to investigate the reliability of such configuration when supplying static and dynamic loads. [Copyright &y& Elsevier]

Abstract: The use of biomass as a source of energy has been further enhanced in recent years and special attention has been paid to biomass gasification. Due to the increasing interest in biomass gasification, several models have been proposed in order to explain and understand this complex process, and the design, simulation, optimisation and process analysis of gasifiers have been carried out. This paper presents and analyses several gasification models based on thermodynamic equilibrium, kinetics and artificial neural networks. The thermodynamic models are found to be a useful tool for preliminary comparison and for process studies on the influence of the most important fuel and process parameters. They have the advantage of being independent of gasifier design, but they cannot give highly accurate results for all cases. The kinetic-based models are computationally more intensive but give accurate and detailed results. However, they contain parameters that limit their applicability to different plants. [Copyright &y& Elsevier]

Abstract: In almost all geothermal projects worldwide, the rate of extraction of heat energy exceeds the pre-exploitation rate of heat flow from depth. For example, current production of geothermal heat from the Wairakei–Tauhara system exceeds the natural recharge of heat by a factor of 4.75. Thus, the current rate of heat extraction from Wairakei–Tauhara is not sustainable on a continuous basis, and the same statement applies to most other geothermal projects. Nevertheless, geothermal energy resources are renewable in the long-term because they would fully recover to their pre-exploitation state after an extended shut-down period. The present paper considers the general issue of the renewability of geothermal resources and uses computer modeling to investigate the renewability of the Wairakei–Tauhara system. In particular, modeling is used to simulate the recovery of Wairakei–Tauhara after it is shut down in 2053 after a hundred years of production. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the analysis and comparison of the main active techniques for islanding detection used in grid-connected microinverters for power processing of renewable energy sources. These techniques can be classified into two classes: techniques introducing positive feedback in the control of the inverter and techniques based on harmonics injection. Accurate PSIMTM simulations have been carried out in order to perform a comparative analysis of the techniques under study and to establish their advantages and disadvantages according to IEEE standards. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses on the flux distribution of a quasi-single stage solar furnace which consists of a non-imaging focusing heliostat as the primary stage and a much smaller spherical concentrator as a secondary. As the optics of the primary stage heliostat is of non-imaging nature, the analytical method for studying the flux distribution of the hot spot of this type of solar furnace would be complicated. Therefore, a digital simulation approach has been employed. Flux distributions of the hot spot for several different incident angles, which have covered all the extreme cases of operating conditions have been simulated. Simulation result shows that a solar furnace using an 8×8m non-imaging focusing heliostat with 289 mirrors coupled with a spherical concentrator with 0.7m aperture and 27cm focal length is theoretically capable of achieving flux concentration of 25,000 suns. Concentration contours of flux distribution for several interesting cases are presented, the different working areas of high flux footage from 5000 to 15,000 suns have been compiled. [Copyright &y& Elsevier]