Nippon Telegraph and Telephone Corp.

Company Overview

In mid-2009, Nippon Telegraph and Telephone Corp., Toho Gas Co. and Sumitomo Precision Products Co. have jointly developed a 3-kW-class power generation module for commercial use with SOFCs. A power generation trial with town gas as the fuel achieved a world’s top-level electrical conversion efficiency of 59% lower heating value (LHV).

The first commitment period of the Kyoto Protocol (2008 to 2012) has arrived and greenhouse gas reduction is an urgent worldwide task. Fuel cell systems have the potential to generate clean electrical power and so help to reduce CO₂ emissions.

Fuel cell systems can create reliable electrical power with high conversion efficiency utilizing fuels like city gas, regardless of power generating size. As a result, SOFC technologies hold promise as future clean power sources. The cells that operate as power generating elements, the stacks in which the cells are constructed and electrically linked, and the power generation module that ensures proper stack operating conditions are the basic components of a SOFC system. When it comes to developing a SOFC system, the integration of each component technology is critical. NTT, THG, and SPP have been cooperating on the integration of respective technologies based on this understanding.

The technical features of the power generation module reported here are (1) high-performance stacks, (2) an advanced heat flow design, and (3) enhanced heat insulation. As a result, thermally self-sustainable operation was confirmed for hundreds of hours with a stable power output and an electrical conversion efficiency of 56% (LHV). A world’s top-level efficiency of 59% (LHV) was also realized for a short period of time.

The technological features are as follows: (1) High performance stacks were developed using planar SOFCs that have a high power output and durability. This enabled the module to achieve highly efficient and stable power generation. (2) An advanced heat flow design provides for the most efficient utilization of heat. Exothermic heat from the stack was exchanged for air heating and other endothermic activities to reduce heat loss. The design also aided the stack's stability by allowing for isothermal control of the temperature. (3) Improved heat insulation reduced unneeded heat emissions and contributed to the operation's high efficiency.

Financial Highlights (FY 2024)

Company's Business Segments

• Integrated ICT Business : The principal services in the Integrated ICT Business are Mobile Phone Services, Domestic Inter-Prefectural Communications Services, International Communications Services, Solutions Services, System Development Services and Related Services.
• Regional Communications Business : The principal services in the Regional Communications Business are Domestic Intraprefectural Communications Services, Related Ancillary Services.
• Global Solutions Business : The principal services in the Global Solutions Business are System Integration Services, Network System Services, Cloud Services, Global Data Center Services, Related services.
• Others (Real Estate, Energy and Others) : Others include the Real Estate Business, Energy Business and others.