In order to commercialize on-site PAFC power plants, Toshiba/IFC/ONSI group, Fuji Electric, and Mitsubishi Electric have been developing PAFC technology for many years. The years were spent tring to establish the reliability of the cells. However, every manufacturer has produced a power plant which has already exceeded 20,000 hours of cumulative operation time. Primarily discussed in this paper are an outline of cogeneration type 200kW class PAFC power plants made by Mitsubishi Electric, the determining factors of cell life, and cell technologies developed to increase reliability of the cell.

The MCFC power generation system is developed under the New Sunshine Project of MITI. A 1000kW pilot plant which has four 250kW stacks of external reforming type is under construction and will generate the power in 1998FY. On the other hand, the internal reforming type has a plan of 200kW stack development until 1999FY. Recent stack tests show average cell voltages of 0.78V to 0.8V in the conditions of 150mA/cm², 80% fuel utilization of LNG reformed gas under normal pressure, and cell degradation rates of about 5mV/1000h for 15000 hours operation for the both. A commercialized MCFC plant will require to have the stack which has over 0.8V average cell voltage, 2mV/1000h degradation rate and 40000 hours life. The stack life improvement is improtantly, but it is able to catch this targets until 1999FY by the improvements of cathode dissolution, electrolyte plate stability and the optimization of separator structure.

A 2 kW class combined cell stacked module (182 cm² × 4× 17) was examined. An output power of 2.47 kW and output power density of 0.20 W /cm² were obtained at the current density of 0.3 A/cm².

As concerning basic researches for improving thermal cycle characteristics, we investigated two materials, sealing materials and separator materials to improve the thermal cycle characteristics. A silica/alumina-based sealing material was used for the gas seal, and deterioration of the V-I characteristics was quite small after 12 thermal cycles. A heat-resisting ferritic alloy was tested to use as a separator in order to bring the thermal expansion coefficient of the separator

closer to that of the electrolyte. High performance was obtained for 2000 hours at 900℃ in an endurance test and deterioration of the cell perlormance was quite small after a thermal cycle.

On the other hand, it was calculated that a life of 40,000h can be achieved by suppressing chromium diffusion to a cathode from an alloy separator by a cathode second layer.

This paper presents the status of polymer electrolyte fuel cells in Japan, focusing on the recent progress of fundamental and component technologies, that is, membrane properties, electrode fabrication, membrane/electrode bonding, separator design, CO poisoning and membrane humidification. Much progress has been made for the past three years in Japan. Also some new ideas are being developed in universities and companies

In a world rapidly running out of fossil fuel, the second law of thermodynamics together with the exergy principle may well turn out to be the central scientific truth of the twenty-first century. So far, traditional exergy analysis has focused simply on the absolute exergy and the trifling of mathematical formulae, only offering the magnitude of the exergy loss and some guidance, instead of detailed specific information on internal phenomena of each process. Here, we demonstrate a new method of exergy analysis, called EUD (Energy-Utilization Diagram) methodology by analyzing a current combined cycle plant and comparing it with the JIS method. It is clear that the graphical exergy analysis based on EUD is very easy and intuitive and that it may give important information even for a complex system.

Current status of so called cold fusion (new hydrogen energy) research is reviewd. Researches in last 7 years after March 1989 have established the following facts: a) There happen surely anomalous excess heats sometimes in heavy water electrolyses with Pd cathodes. b) During the excess heat generation, no correspondingly intense d-d fusion takes place. c) Excess heat correlates with D/Pd>0.85, electrolysis current density > 0.2 A/cm² and dynamic loading condition. d) No correlations in-situ with primarily emitted radiations (charged particles) are observed. e) A few un-identified reports on He-4 production as nuclear ash which have never been claimed should be many times duplicated by future efforts. The key for the future of new hydrogen energy is resolving "nuclear or chemical issue" for excess heat.

Hydrogen energy has drawn attention for its cleanliness, as well as its amount of reserve. At present, however, it cannot be said that hydrogen energy can compete with other energy sources, due to economical reasons.

Up to now, analyses of hydrogen energy have focused mainly on its technical aspects. In this paper, the market aspects of hydrogen use is highlighted. The future market of hydrogen energy is analyzed, taking into consideration such factors as demand, economy, energy, security, environmental aspects, etc.