As more and more wind turbines and farms are constructed in Japan, utility companies have introduced a grid code, which is effective in controlling the grid frequency. We designed a hybrid system by combining charge/discharge properties of lead-acid batteries with long life, and a power control of wind turbines to ensure the code. We also constructed a wind farm with this system in Shiura, Japan, which went into operation in January 2010. This system showed reduction in wind farm power fluctuation, and that battery capacity can be maintained for 17 years.

Geothermal energy is considered a comparatively abundant renewable energy resource. The geothermal power generation system has negligible environmental impact (approximately 0.015kg-CO 2 /kWh), and it is expected to help prevent carbon dioxide emissions to the atmosphere. On the other hand, in our institute, we have developed general purpose software (EnergyWin™) to analyze the thermal efficiencies of power generation systems easily and rapidly. Such software can not only analyze the plant performance but also investigate the effect of the performance-deteriorated equipment or air condition change on power output quantitatively. Using this software, we have developed a new plant performance analysis system based on actual operation data for geothermal power plants. Then, applying the system to existing facilities, we have analyzed the plant performance and evaluated the effectiveness of the plant maintenance strategy during periodic inspection for consistency.

This paper describes the wind direction characteristics of the wind collector used for our 8th model of the vertical axis wind turbine using the mechanism of a bird’s wing. The 8th model is divided into two sections top and bottom. Each section looks like a Savonius wind turbine. The blade is divided into seven rows of plates. Each 0.18mm stainless plate has only one side attached to the frame. Wind from the outside enlarges the space between the blades, and passes through. However, wind from the inside closes the space. In the wind collector, four wind collection boards are located every 90 degrees around this wind turbine. In an earlier paper, it was confirmed that these collection boards collected 1.6 times the wind and resulted in twice the output. In this paper, the variations in the wind collector characteristics due to the wind direction are clarified experimentally. A wind tunnel experiment using six different wind directions shows that the output increases for four wind directions and decreases for one wind direction. Additionally, the computer simulation confirms the wind direction and the wind speed distribution around the wind turbine when the wind collection boards are in place.

The reduction in cost of energy from wind turbines requires many technical contributions from all areas of Wind Energy Conversion Systems. The concept of a telescopic blade has been analyzed to improve rotor blade performance. The effect of a step change is significant for any extension. The current simulation model in WT Perf with a Prandtl tip and hub loss model over-predicts the rotor performance. The correlations developed herein for telescopic blades with step change in the blade chord are in good agreement with the experimental data. The maximum loss for a rotor blade with a step change occurs when the extension is equal to the root blade chord.

In the last five years the electric grid worldwide has seen increasing amounts of installed wind generation capacity. Over the last five years, North America (USA and Canada) has witnessed wind capacity grow at an annual rate of over 30%. At the same time, increasing investments in smart grid technologies have enabled improvements in energy products such as Demand Response (DR). The utility industry, system operators and regulators are investing heavily to understand and determine the impacts of increasing wind penetration on the power system. As explored below, an often neglected, but important point of interest to the authors has been the effect of increased cycling of large fossil, formerly base loaded power plants due to increasing penetration of variable wind or solar power. Various types of DR programs have been implemented by utilities and system operators and these DR programs may be classified based on the time it takes to call upon a DR event or the energy market that the programs are allowed to participate within. Hence, we may have a “slow” DR that participates in a Day-Ahead market and the events are called upon well in advance. On the other hand, “fast” DR programs would participate in Real-Time and Ancillary Services markets. DR from a power dispatch perspective can be considered a “virtual power plant” providing energy, ancillary service and capacity in energy markets. Energy benefits of DR have been explored extensively, especially in terms of reduced fuel costs due to reduction in demand. In this paper we explore the conceptual use and value of DR in providing benefits associated with reduced damage to a fleet of fossil-fueled power plants if it is used to reduce startups and/or load following/cycling.

In this paper, in order to solve the problem of intensified heat dissipation in high power electronic devices, a fast transient and intensified heat dissipation technology was put forward by comparing many heat transfer modes based on the analytical study on the existing technologies about heat dissipation at high heat flux density and about fast heat transport. This technology combined spray cooling technology with fast endothermic chemical reaction processes; we summarized the characteristics of media applicable to an environment with transient high heat flux density by comparing various parameters of many sprayed media in the spray cooling process. According to the energy balance of endothermic chemical reactions of relevant media, we determined the media (mainly carbon dioxide hydrate) applicable to the fast transient and intensified heat dissipation technology and presented the conditions for the chemical reactions. We analyzed the methods controlling the instantaneous chemical reaction rate and proposed the structural characteristics of the chemical reactor so as to ensure that the time for heat removal will be control to around 0.01 second. Thus, the problem of fast transient heat dissipation in high power electronic devices, etc. would be radically solved.

As the single unit capacity has been increased, the length of wind turbine blade is becoming longer, and the blade vibration fatigue damage caused by impact of wind turbines has become an important issue of wind turbine security. Therefore, modal analysis and study on the impact of crack on the natural frequency of the wind turbine blade are of great significance. The finite element software ANSYS was used to establish a finite element model of a 1.5MW composite wind turbine blade, with a structure of twisted variable cross-section and hollow core in the first place of this paper. Modal analysis of the model established in this paper showed that the blade vibrates in 3 different forms, they are flap within the rotating plane, flutter vibration perpendicularity to the rotating plane and torsional vibration around the blade shaft. Among all the orders, flap and flutter vibration are predominent in low modes, while torsional vibration appears only in high modes (above the fifth order). Then blade models with cracks in the root were established to analyze the regularity of the blade natural frequencies with the crack location, depth and the variation of the angle. The results showed that: as the location of the crack changed in wingspan direction, the change of frequencies showed two basic trends: one was declining gradually; the other was decreasing and then increasing before decreasing again, and the minimum the maximum value appeared at location around 32.5% and 87.5% of the blade root respectively. As crack depth increased gradually, the frequencies reduced continuously, and compared to crack location, influence of crack depth was more prominent. For slant crack, when the crack angle, that is the angle between the crack section chord line and the foliosine plane, increased, all orders of frequencies gradually increased, indicating that the influence of the crack on the blade stiffness decreases as the angle increases.

The aerodynamics of a straight edged and a swept edged blade are investigated using a commercial CFD code. RANS equations with SST k-ω equation were utilized to study the flow separation along the blades span in a stall region. The analysis results will be used to provide inputs to future designs to improve and to enable better prediction of the stall region. The computations were carried out in a narrow wind speed range of 14 m/s to 16 m/s which as per earlier analysis was near the stall point to further understand the locations of flow separations along the blade span. The study provides some insights in to the flow physics in the region around the wind turbine blade. An FE Analysis was also performed to further understand the maximum stress and displacement regions to further provide inputs to future designs. A comparison of maximum stress, deformation and structural vibration modes for the two blades were also done.

In this paper, building simulation software Energy Plus was used to simulate thermal performance, and PV electricity generation of five kinds of glazing system install on the office building in four cities of China, Harbin, Beijing, Shanghai, and Shenzhen, which represent severe cold zone, cold zone, hot summer and cold winter zone, hot summer and warm winter zone respectively. According to the simulation results, the best glazing system for the severe cold zone Harbin and the cold zone Beijing is double PV system, while natural ventilated PV system for the hot summer and cold winter zone Shanghai, the hot summer and warm winter zone Shenzhen. The energy saving rates of the optimal PV glazing system compared to the local SC at Harbin, Beijing, Shanghai, and Shenzhen are 12.3%, 4.9%, 4.8%, 10% respectively.

Monitoring of photovoltaic (PV) systems is essential for achieving reliable and, maximum yield from solar PV plants. This paper proposes PV plant hierarchy, and a novel near real-time monitoring system combined with a solar tracking controller for utility scale PV installations. Currently, most PV installations employ monitoring at the inverter level, lacking sufficient resolution. Furthermore, the solar tracking and performance monitoring systems are isolated from one another. The proposed design increases monitoring resolution, allowing PV malfunctions to be addressed immediately, effectively optimizing a plant’s power generation. Moreover, the tracker control and monitoring are fused into an inclusive hardware design. Incorporating state-of-the-art electronic sensors, coupled with wireless communication protocols, the resulting system is a robust, accurate sensor and control network. Accessible through the internet, the system will provide a way to monitor and control multiple installations from a centralized location. The collected data enables efficient maintenance scheduling, and long-term performance analysis for utility scale PV plants. The developed system includes string level power measurement sensors, sun tracking actuators, a network of microprocessors and a central processing unit (CPU) for application in utility-scale central inverter PV plants. The basic designs and feasibility of the system are presented in this paper.

The increased integration of wind power into the electric grid poses new challenges due to its fluctuation and volatility. Short term wind power forecasting is one of the most effective ways to deal with it. Various individual non-linear models are proposed to meet the data requirement to forecast short term wind power. However, as every model has its advantage and weakness, when these models are applied to different wind farms, the forecasting accuracy of every model varies because of distinct data character. This paper analyzes individual forecast models like Wavelet Transform and Support Vector Machine (SVM), and then puts forward a complex-valued forecasting model which is based on Artificial Natural Network in accordance with forecasting data provided by National Climatic Data Center in U.S. The existing individual models are matched and trained according to certain means by Natural Network to propose a multistage model. For variable data from different wind farms, the model can adjust and optimize portion of individual models. Compared with each single model, the multistage model has more robust adaptation and faster calculation speed, which can improve the forecasting precision and have more engineering value.

The movement for energy independence coupled with aggressive renewable energy goals and government investment incentives has led the power industry to develop efficient and reliable sources of renewable power. In a power tower system a central Solar Receiver Steam Generator (SRSG) is surrounded by a field of mirrors (heliostats) that focus and concentrate sunlight onto the receiver tubes. The energy from the sunlight is used to generate and superheat steam for electric production. The Ivanpah Solar Electric Generating System (ISEGS) project, located in Ivanpah, CA, consists of three 126 MWg units, to power approximately 140,000 homes. The Ivanpah SRSG’s are forced circulation drum-type boilers with single reheat; located on top of a 400 ft (122 m) steel tower [1]. This paper will discuss the development, constraints, and unique design challenges of the Riley Power Inc. (RPI) SRSG selected for the Ivanpah project. Process descriptions and predicted unit performance are presented, along with comparisons to typical fossil boilers. First of kind concepts and engineering design achievements are discussed for what will be the largest power tower project in the world.

A series of laboratory experiments on self-circulating thermosyphon (SCT) was carried out. The thermosyphon system consists of heating section, condenser, reservoir, and heat exchanging section. The basic performance was elucidated. The present thermosyphon system works by itself under certain conditions of tilting angle of the condenser, the water filling rate, and the input power. The startup time of the present system is remarkably improved. The effect of the buoyancy on the driving force is indicated through the tilting angle of the condenser.

In this paper, a hydroelectric power generator that can extract the water flow energy from the hydroelastic response of an elastically supported rectangular wing is experimentally investigated. An electric motor is used to excite pitching oscillations of the wing. The wing and the electric motor are supported by leaf springs that are designed to function both as a linear guide for the sway oscillations and as elastic elements. The wing mass in the sway direction necessary to achieve a hydroelastic response is obtained by utilizing a mechanical snubber mechanism. The load to generate electricity is provided equivalently by magnetic dampers. In a previous paper, the power generation rate and the efficiency of a single-wing model were examined through experiments, and the feasibility of a flapping wing hydroelectric power generator was verified. In this paper, the influence of neighboring wings is examined by using two experimental apparatuses with the intention of achieving a practical cascade-wing generator. Tests showed that a cascade moving in-phase with neighboring wings with smaller gaps between the wings has a higher rate of electric power generation.