Through the difficulty of meeting the demand for electricity caused by the long-term shutdown of nuclear power plants in the wake of the Great East Japan Earthquake in addition to the problem of global warming due to carbon emissions, power plants are demanded of lower environmental impact and higher reliability. Fuji Electric is advancing the development of power plants and new energy technologies as "energy creation" technologies for clean energy creation that is gentle on the environment. At its power plants, Fuji Electric is contributing to preservation of global environments and provision of electrical power through high performance and high reliability in each of the areas of "thermal power," "rotating machines," "hydro power" and "nuclear power." In terms of new energy (renewable energy), Fuji Electric is advancing development in areas such as geothermal power (binary system, flash system) wind power and photovoltaic power (mega solar) to promote widespread use of these forms of power generation.
In this feature we present the various energy creation technologies that contribute to the preservation of global environments and the stable provision of electrical power.

It is predicted that the worldwide demand for energy will grow at a rate of 3.3% per annum as the global economy and population expand. To contribute to the stable supply of energy and reduction of environmental impact, Fuji Electric has carried out various research and development in the field of "energy creation." In the field of thermal power generation, Fuji Electric has taken measures for improving performance and reliability in combined-cycle power generation and coal-fired thermal power generation. In the field of renewable energy, Fuji Electric has been proactively engaged in developments in geothermal power, photovoltaic power, wind power and hydro power, and has been advancing performance enhancement of power-generating facilities and the introduction of new technologies using the excellent power electronics technology developed by Fuji Electric.

In construction of thermal and geothermal power plants, many kinds of elemental technologies are concerned. This paper describes about main technologies in plants completed in recent years. Yoshinoura thermal power plant is Okinawa Electric Power Company’s (OEPC) first LNG-fueled single-shaft combined-cycle thermal power plant, and has the largest capacity generator in Okinawa Island. Governor-free control system is adopted both for gas turbine and steam turbine to enhance response to variation of frequency. The Ulubelu geothermal power plant is the fi rst geothermal power plant developed under the Second phase of Indonesian government’s electricity crash program, and has received attention as a model case. Hybrid gas-extractor facilities and overall optimization in arrangement of major equipment have been achieved.

Geothermal energy is a clean form of energy that produces almost no CO₂ emissions. Fuji Electric has supplied approximately 60 geothermal turbines to power plants in Japan and other countries. We have developed several technologies for improving corrosion-resistance of geothermal turbines, including shot-peening of turbine blade legs and grooves, rotors made from 2% chromium steel and spray-coating technology. In the area of performance-enhancing technology, together with new-generation, low-pressure turbine blades for geothermal energy production and high-load, high-efficiency reaction turbines development, we have also achieved the creation of a high-performance, compact exhaust casing through optimized design. Furthermore, through use of triple-flash power generation, we have achieved the creation of a geothermal turbine with the greatest output for single-unit capacity in the world.

A geothermal hot water binary power-generating system that uses reinjected hot water from a flash geothermal power-generating system as the heat source is able to draw heat from geothermal fluid efficiently, achieving high economic efficiency. However, there are concerns that cooling of thermal water causes silica scaling to adhere to power-plant equipment and wells. Field tests at the steam production well base in Kakkonda geothermal power plant of Tohoku Hydropower & Geothermal Energy Co., Inc. have proven that in thermal water with low silica concentration the speed of silica scaling is not affected by water temperature, because the silica polymerization reaction is halted; thus, practical use of the system is just in sight. Field tests have also proved that intermittent alkaline injection can help to prevent and/or dissolve silica deposits.

With features such as high power-generating efficiency and low CO₂ emission, combined-cycle power generation, combined with gas turbine and steam turbine, is gaining wider use. For Yoshinoura thermal power plant of The Okinawa Electric Power Company, Incorporated, which is a combined-cycle power generating facility, we supplied single-cylinder reheat steam turbines with axial-flow exhaust that feature a clutch between the generator and the steam turbine. Also, for SUR power plant in Oman, we supplied two-cylinder reheat steam turbines with double-sided exhaust that feature exhaust directions are left and right.
As the latest technologies in steam turbines for thermal power plants, we are developing welding technology, USC turbine technologies and technologies to improve reliability of low-pressure blades.

Fuji Electric has a great deal of experience in air-cooled turbine generators for global VPI insulation systems. We designed and built global VPI indirectly hydrogen-cooled turbine generators for Yoshinoura thermal power plant No. 1 and No. 2 of The Okinawa Electric Power Company, Incorporated. These are double-end drive generators for a single-shaft, combined cycle power generation facilities that use many of the same basic construction and manufacturing methods as air-cooled turbine generators. Using data obtained through experience and results from ventilation analysis and strength analysis, we are achieving optimization and increased reliability.
Through each type of test, we are obtaining results that satisfy performance expectations and we are seeing favorable operating conditions at the power plants.

The market for photovoltaic power generation systems in Japan is expanding to large-scale photovoltaic power generation (mega solar), and the need for high efficiency, high reliability, and compact equipment increases. Fuji Electric supplied a package of mechanical and electronic equipment for Abu mega-solar plant of The Okinawa Electric Power Company, Inc. including devices for a solar power generation system and a remote surveillance control system, which commenced operation in the end of March 2012. We have applied a highly-efficient, high-capacity power conditioner utilizing the power electronics technology and a large-scale surveillance control system.
We are also developing system-interconnection technologies to resolve issues that would arise in the power grid with large-scale implementation of renewable-energy power production through microgrid verifi cation equipment using stable systems etc. for remote islands.

Because the generating power of wind turbines fluctuates according to changes in wind speed, this affects system voltage. To enable large-scale implementation of wind turbines, power system supply quality is demanded. Power conditioning subsystems are available for stabilizing power as a means to compensate for fluctuations in power supply. Using an AT-NPC 3-level conversion circuit, we have greatly reduced switching loss in IGBT devices and also, by halving harmonic components, we have reached 98.1% efficiency, the highest in the industry. Moreover, we have achieved power supply quality sufficient for grid connection by incorporating a fault ride through function so that the system continues to operate without disconnecting even if there is a drop in system voltage due to lightning strike or other causes.

Amid the attention on renewable energy, the market for wind-power generation is expanding on a global scale. At Fuji Electric, we are pushing forward the commercialization of wind-power generation equipment with the aim of achieving highly efficient operation of wind-power plants. We recently completed production and testing of a prototype 3,000 kW permanent magnet synchronous generator, which is the largest class in Japan. This is a low-speed generator for use in direct drive wind-power generation systems. The device incorporates new technology to achieve a suitable structure for weight-reduction, environmental resistance and multi-unit production.
We have obtained favorable prototype test results, and verified that the device sufficiently meets the functional requirements for a windpower generator.

Since the Great East Japan Earthquake, there has been broad investigation into the improvement of the quality of power-source security through introduction of 100 kW fuel cells, which are a highly efficient form of distributable power, and into the use of fuel cells for sewage digester gas power generation, which is a form of renewable energy.
Utilizing technology for switching to independent power during power outages and technology for converting to LP gas, Fuji Electric has developed fuel cells with improved power security and installed them in the Kawasaki Factory. Fuji Electric is also developing fuel cells adapted to meet new needs, such as fuel cells that can operate on both sewage digester gas and utility gas for small-scale sewage treatment plants and fuel cells that meets CE marking requirements for the EU.

For hydraulic turbines and generators, power companies seek products developed for cost reduction, ease of maintenance and low environmental impact. Advanced are being made in the development of water-free and oil-free technologies, which make cooling water and operation oil unnecessary, for hydraulic turbines and the development of technologies for reducing auxiliary machinery and increasing the speed of generators. In response to this, Fuji Electric has applied hybrid servo motors to opening and closing operation of runner vanes as well as guide vanes in hydraulic turbines. We have now expanded the scope of application to include runner blade divergence operation. Also, for high-speed, high-capacity hydraulic turbine generator motors, we have developed and applied strength-analysis technology for rotors, a variable-stiffness vibration control system, and a thrust bearing self-circulation pump system for high-speed generator motors to reduce auxiliary machinery.

There has been an increase in replacement planning for old machinery at hydroelectric power plants. In Korea in particular, existing structures are being appropriated and hydraulic turbines, generators and control equipment is being replaced in turn for the purpose of maintaining facilities and increasing output. At Korea’s Goesan power plant, which has seen more than 50 years of operation, embedded parts such as draft tubes and casings were appropriated, and other old machinery was replaced. Cavitation characteristics and efficiency characteristics of hydraulic turbines were calculated through flow analysis, and thereby conducting performance design surely. Simplifi cation of maintenance was achieved through such measures as employing water-lubricated bearings, water-free mechanical seals and hybridization of guide blade operation for hydraulic turbines as well as employing plastic bearings for generators.

The Fukushima Dai-ichi Nuclear Power Station accident, caused by The Great East Japan Earthquake, has resulted in leakage of radioactive materials and contamination of the environment. Separating highly-contaminated dirt from the total amount of dirt removed for decontamination makes it possible to reduce the volume of dirt that needs to be stored.
In cooperation with Ube Machinery Corporation, Ltd., Fuji Electric developed technology for dry decontamination and volume reduction of contaminated dirt. This technology combines the dry sorting and grinding equipment used in general industry with a radiation measurement device, enabling mass processing. Verification tests using actual contaminated dirt have demonstrated that radiation levels are reduced to less than half after crushing and separation.