Vol. 76, No. 3, May 2021

YOTSUYANAGI Tadasu

HOSAKA Hitoshi / KOSAKADA Masayuki

Accompanying the increased momentum toward carbon neutrality worldwide, the electric power and energy industries are expected to play a critical role in the sophistication of various technologies in a wide range of infrastructure systems.

The Toshiba Group has been developing systems and offering services toward the achievement of carbon neutrality by making full use of the following technologies: (1) power generation technologies for renewable energy systems as a major power source, including photovoltaic (PV) power generation, wind turbine, hydroelectric power generation, and geothermal power systems; (2) technologies related to decarbonization of thermal power plants and effective utilization of carbon dioxide (CO₂) emissions; (3) electricity distribution technologies to connect variable renewable energy power sources; (4) technologies for electricity and energy storage systems such as pumped-storage power plants and battery energy storage systems; (5) hydrogen utilization technologies; and (6) technologies for the optimal operation and sophistication of power plants and electricity supply and demand management using digital technologies.

KITAMURA Hideo / IWASA Kiyohiko / FUJITA Koshito

As measures against global warming, demand has been growing for carbon dioxide capture and storage (CCS) technologies that can separate and capture carbon dioxide (CO₂) emitted in the flue gas of various sources and isolate and store the captured CO₂ underground, as well as carbon dioxide capture and utilization (CCU) technologies for the effective utilization of captured CO₂.

Toshiba Energy Systems & Solutions Corporation has been promoting the research and development of CO₂ separation and capture technologies using chemical absorption. We have already applied these technologies to a pilot plant constructed at the Mikawa Power Plant of SIGMA POWER Ariake Corporation, and have been verifying the performance, usability, operability, and maintainability of this approach. Based on the knowledge accumulated through the operation of the pilot plant, we have newly constructed the world’s first large-scale CO₂ capture facility for the treatment of flue gas emitted from the biomass power plant at the Mikawa Power Plant, and evaluated the demonstration facility through test operation. From the results obtained, we have confirmed that this system makes it possible to stably capture more than 600 tons of CO₂ per day and to further suppress atmospheric emissions of amines used in CO₂ absorption solvents, thereby improving environmental performance.

MORI Junji / HAMAGUCHI Koji / IIDA Shoji

The introduction of renewable energy has been progressing in Japan under the feed-in tariff (FIT) scheme launched in 2012. Moreover, the movement toward the realization of carbon neutrality by 2050 is expected to further accelerate the generation of electricity by renewable energy sources. In this context, attention is being increasingly focused on hydroelectric power generation, which not only remains the major source of renewable energy in Japan but also makes it possible to rapidly adjust to output power fluctuations resulting from the widespread adoption of renewable energy sources such as photovoltaic (PV) and wind systems.

Toshiba Energy Systems & Solutions Corporation is making continuous efforts to develop technologies for hydraulic turbines and generators to enhance their functionality and performance in order to improve the operational efficiency of existing systems, based on its experience and technological know-how cultivated through the development of a large number of hydroelectric power generation facilities. We are now working toward the development of systems that can significantly contribute to the stabilization of power grids by integrating artificial intelligence (AI) technologies including weather forecasting and energy balancing technologies to suppress power fluctuations.

TODORI Kenji / MIYAUCHI Hiroyuki

The Japanese government is committed to reducing greenhouse gas emissions to net zero by 2050. In this context, film-based perovskite photovoltaic (PV) cells using material with a perovskite crystal structure are currently attracting attention as next-generation PV cells. Due to their flexibility and lighter weight compared with crystalline silicon PV cells, film-based perovskite PV cells are expected to contribute to an increase in the amount of electricity generated by PV systems by making it possible to expand their application to locations where conventional PV systems cannot be installed.

Toshiba Corporation has been working toward the practical realization of a film-based perovskite PV module with a large area and high efficiency by improving the perovskite layer forming processes. We have now developed a prototype module with dimensions of 24.15 × 29.10 cm that achieves an energy conversion efficiency of 14.1%. Concurrently, we have confirmed the potential of perovskite PV modules through feasibility studies centering around their installation on agricultural greenhouses.

IIO Naotaka / OKAYAMA Fuko / TANIYAMA Yoshihiro

With the aim of realizing carbon neutrality in Japan, the introduction of offshore wind power generation systems is expected to further expand on a large scale from now on. This situation has given rise to the need for technologies to survey wind conditions in order to predict the amount of power generation at installation sites, as well as to realize high-efficiency power transfer over long distances from marine locations to land.

Toshiba Energy Systems & Solutions Corporation is aiming to realize an offshore wind power generation system by making use of the following proprietary technologies: (1) an offshore wind condition analysis technology cultivated through its accumulated technologies for the measurement and analysis of wind conditions at onshore sites, and (2) a high-voltage DC (HVDC) power transmission system that can efficiently transfer power from offshore sites. Applying computational fluid dynamics (CFD) analysis using wind condition data measured at a quasi-offshore site, we have confirmed that this analysis technology provides a precise understanding of wind conditions such as the three-dimensional structure of wakes behind wind turbines. We have also developed a modular multilevel voltage-source converter (VSC) suitable for HVDC systems for offshore wind power generation systems, as well as a prototype DC circuit breaker (DCCB) necessary for multiterminal HVDC systems that has achieved high-current and high-speed cutoff performance in current breaking tests.

OTA Hiroyuki / MIZUGUCHI Koji / MURAMATSU Takehiko

Various approaches, such as the utilization of renewable energy as a major power source, conversion to non-fossil energy sources, and expanded application of green hydrogen produced using renewable energy, have been progressing in Japan aimed at achieving carbon neutrality by 2050. Attention has also been increasingly focused in recent years on technologies for the production of chemicals such as plastics using emitted carbon dioxide (CO₂) as a chemical feedstock.

The Toshiba Group is vigorously promoting the practical realization of power-to-chemicals (P2C) through the electrochemical conversion of CO₂ contained in exhaust gases and the atmosphere into carbon monoxide (CO) using green renewable energy, as well as the production of fuels and chemicals synthesized from CO and green hydrogen. We have obtained positive results in our efforts to increase the size of CO₂ electrolysis cells through the development of a cathode catalyst with an electrode area of 400 cm² that achieves a faradaic efficiency of more than 96%. The application of P2C to the production of aviation fuel as a replacement for fossil-derived fuel is expected to reduce the amount of CO₂ emitted from this source by about 80% in the future.

KONO Motoki / YABUKI Masanori / YAMASHITA Kyohei

With the rising awareness of global environmental issues, technologies for the effective use of hydrogen energy, which will play a key role in achieving carbon neutrality, have been attracting attention in recent years. Demand has therefore been growing for further expansion and diversification of these technologies accompanying the widespread dissemination of hydrogen fuel cell systems for automobiles, buses, and stationary systems.

In response to this situation, Toshiba Energy Systems & Solutions Corporation is actively promoting the development of pure hydrogen fuel cell systems. We have now developed the H2Rex™ as our latest-model 100 kW stationary pure hydrogen fuel cell system, which achieves reductions of 40% in size and 67% in cost compared with the former products. We have also developed a megawatt-class stationary pure hydrogen fuel cell system employing the integrated management of multiple 100 kW units and demonstrated highly efficient operation of this system. With the objective of expanding the application of these technologies, we have launched development of the H2Rex™-Mov pure hydrogen fuel cell module for large-scale transportation vehicles and implemented the basic design of a module for maritime vessels.

TSUZUKI Yoshiyuki / OHIRA Hidetaka / TAKAHASHI Shintaro

The introduction of state-of-the-art artificial intelligence (AI) models to mission-critical systems in the social infrastructure and manufacturing fields not only enhances operation and maintenance services by detecting signs of abnormalities and reducing labor for inspection work, but also makes it possible to offer users new value. These AI systems are now faced with the need for quality management so as to maintain highly reliable AI models.

In order to implement quality management taking the characteristics of each AI model into consideration, Toshiba Corporation has developed techniques to evaluate the noise robustness of AI models incorporated into AI systems through evaluation of their inference performance using quantitative indexes together with conventional techniques. These quantitative evaluation techniques can contribute to the improvement of reliability of AI systems in operation.

SHIBAYAMA Takeshi / OTA Kunio / SUGIMOTO Mariko

From the viewpoint of decarbonization, motor drive systems with high power output and high efficiency have become a focus of attention due to the fact that the total power consumption of motor drive systems accounts for about 50% of global electricity consumption.

With this as a background, Toshiba Corporation has developed and released an open-end winding motor drive system in which a motor with open-end windings is connected to two inverter circuits and selectively driven by one or both inverter circuits according to the output power conditions. This system achieves a decrease in the circuit current responsible for efficiency degradation compared with conventional motor drive systems, as well as a reduction in device cost. We have developed a small motor suitable for this driving method and confirmed that the electromagnetic noise generated by the inverter circuits is smaller than that of conventional motor drive systems.