The core components of an SOFC system are the cells, the stacks in which the cells are assembled and electrically connected, and the power generation module that provides appropriate stack operating conditions. The integration of each component technology is a key issue in terms of realizing an SOFC system. Based on this understanding, NTT, Toho Gas and Sumitomo Precision Products have been collaborating on the integration of their technologies.

The technical features of the new SOFC module are high-performance stacks, an advanced heat flow design, and enhanced heat insulation. The stacks were developed using a planar SOFC design with high power output and durability, enabling highly efficient and stable power generation. The advanced heat flow design allows the optimum use of heat, with heat loss minimized by exchanging exothermic heat from the stack for air heating and other endothermic processes.

The design also contributed to isothermal control of the SOFC stack temperature, aiding stable operation. In addition, the enhanced heat insulation minimized the unused heat emission and contributed to the highly efficient operation.

As a result, thermally self-sustainable SOFC operation was confirmed for hundreds of hours with a stable power output and an electrical conversion efficiency of 56% (LHV). A top-level efficiency of 59% (LHV) – claimed to be a new world record – was also realized for a short period of time.

The companies want to further improve durability and lower costs, but they aim to have a product ready within two years that can be used in places like convenience stores and family restaurants to help reduce lighting and heating expenses.