**2. Sustainable society using internal reforming SOFC (IRSOFC) running on biofuels (***Bio***-SOFC)**

Although the conventional large scale power system provides us with a stable electric power supply, the associated large consumption of fossil fuels and release of large amount of waste heat are unfit for social and environmental needs in recent years. Now, the role of biomass, having the largest exploitation potential among renewable energy resources, becomes very important. Of course, the use of edible plants is highly restricted, but the use of organic wastes is highly desirable. Biogas and biodiesel fuels (BDFs) are attractive alternative fuels which can be produced from bio-wastes, and their spread will generate synergistic effects to create new industries and employment in their production and refinement processes.

Among fuel cells, the SOFC is the only technology capable of converting bio-energies directly to electricity without an external fuel reformer (Staniforth et al. 1998). As for the low temperature fuel cells like polymer electrolyte fuel cell (PEFC), the external reforming process is essential prior to electrochemical conversion of biofuels to electricity. Superiority of an IRSOFC running on biofuels (hereafter called *Bio*-SOFC) is described in Fig. 1. By selecting red arrows in this figure social needs are satisfied. Our final goal is to establish a microgrid system as shown in Fig 2 using *Bio*-SOFC as major distributed generators providing heat and power on site. These distributed *Bio*-SOFCs can contribute to leveling of the unstable power supply from solar and wind energies. However, breakthroughs are necessary to realize the *Bio*-SOFC system.
