Japan can obtain main energy from sun light in the 21st century. This is because, first, the cost of solar electricity produced in Japan, about ¥21/kWh, is competitive with that of oil-fired power plants if the cost for environmental damage is considered. The capacity of solar electricity within the land is estimated to be 509 GW and one third of this amount can be installed by 2010 to replace the 59 % increase of the supply of nuclear electricity planned to enable the 6% cut of CO₂ emission according to the COP3. The rest of the capacity can serve to cut the capacity of nuclear-and/or fossil-fueled power plants further. Second, the cost of the solar hydrogen including the cost of pipeline tranport from the sun-belt region is estimated to be ¥18-23/Nm³ ($12-18/GJ), the cost of electricity from fuel cells supplied with solar hydrogen to be ¥17/kWh for the cheapest case around 2010, and both are also of competitive prices. Regarding the amount of solar and wind resources in Asia and Australia, we postulate that Japan should design the import of necessary energy to replace fossil and nuclear energy probably with an amount between 20 and 34 EJ/yr of hydrogen for the period 2000-2050.

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Emissions of NO, N₂O, SO₂ and CO in the flue gas from 71 MW PFBC demonstration plant were measured during stationary combustion tests conducted from January to December in 1997. An index of emission gas partial pressure, {PNO/PSO₂· (PCO/PNo) ²} named as ASH^TR-SN, was introduced and plotted against the reverse of the average cyclone temperature (T_c). A linear correlation of Van' t Hoff law was found with high correlation factor of 90.17 % as follows:
ASH^TR-SN index=N₂O/SO₂× (CO/NO) ²= exp (47.3×10³/T_c-50.4)
Also those emissions were measured every five minutes for eight days during a combus-tion test conducted from November 19 to 26 in 1997. The same index of ASH^TR-SN at the transient condition were plotted and found an identical correlation against the reverse of T_c, with high correlation factor of 98.5 % as follows:
ASH^TR-SN index=N₂O/SO₂× (CO/NO) ²=exp (47.7×10³/T_c-49.5)
This correlation indicated that emission gases were mutually influenced by the concentrations of other gases and correlated to the reaction temperature. Since CO is a reductant of CaSO₄ to liberate SO₂ (CaSO₄+CO⇔CaCO₃+SO₂) and also CO is a product from the NO/NCO reaction (NO+NCO⇔N₂O+CO), a temporary reaction formula is introduced as follows to express interaction among emission gases:
CaSO₄+N₂O+2CO⇔CaCO₃+2NO+SO₂+Volatile-C
Since ASH^TR-SN index (=N₂O/SO₂× (CO/NO) ²) is an equilibrium constant for the above reaction formula, concentrations of emission gases may follow Le Chatorie principle and will be estimated at high accuracy under stationary as well as transient conditions.
A key role of CO is also discussed where (SO₂/CO) and (N₂O·CO/ (NO) ²) are individual-ly correlated to T_c.

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he pressure drop across CTF (Ceramic Tube Filter) which is installed at Wakamatsu 71MW PFBC combined cycle power plant, is one of key parameters for both plant operation and performance. The pressure drop was attempted to predict, based on the data obtained with/without pre-cleaning cyclones installed at the upstream of CTF in Phasel and Phase2, respectively. The pressure drop consisted of two components of base line for filter itself and increasing ones with accumulated ash.
The base line pressure drop soon after pulse cleaning (ΔP_base) was estimated based on D'Arcy law using pre-measured L/K (thickness/permeability) values, while the rate of increasing pressure drop with accumulated ash between pulse cleaning interval (dΔP_c/dt) was estimated by Kozeny-Carman equation using ash analysis. Thus, the maximum pressure drop across filters was predicted successfully in both with/without pre-cleaning system from the respective linear correlation. The reason why ΔP_base was much higher without pre-cleaning system (Phase2) is discussed in terms of both characterization of permanent ash layer and behavior of fine ash in CTF during pulse cleaning.

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From a viewpoint of used tires recycling, their pyrolytic conversion into an adsorbent with co-production of gaseous fuels was examined. Crushed used truck tread with diameter of 3mm or less was mixed with potassium hydroxide, and the mixture was cracked under a flow of argon in a thermobalance or a gas flow continuous reaction apparatus. The resulting char was characterized in terms of CHO composition, specific surface area, and absorptive activity. The co-produced gases and liquids were subjected to gas and gel permeation chromatographic analyses to determine the composition and the average molecular weight (Mw), respectively. Sulfur content was measured for all the products. The presence of potassium hydroxide resulted in both increases of gas and char yields with decrease of a tarry product. This implied promoted cracking of tar by potassium hydroxide, although Mw of the remaining tar was increased. More amount of the alkali led to more productions of hydrogen and methane with less evolution of carbon monoxide and dioxide. Also, it allowed the obtained char to have a larger ability of absorption and a smaller content of sulfur. Sulfur contained in tar was likewise decreased with increasing the amount of potassium hydroxide. These results indicated that this system of thermal cracking would be a promising means for re-utilization of used tires.

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The shape memory alloy with the shape memory and superelastic functions has been used for many applications. Authors have proposed a reciprocating heat engine incorporating, as an energy conversion element, shape memory alloy wires. In order to undertake reliable engineering designs and optimum material selection, it is important to clarify the thermo-mechanical properties such as functions and fatigue characteristics. In this paper, the effect of heating temperature and deformation strain on the strain energy and the thermal efficiency of Ti-Ni-Cu shape memory alloy is investigated experimentally. Experiments are carried out by repeating the combination of the thermal cycle and the loading-unloading cycle. Results show that the available strain energy per cycle is insensitive to heating temperature in the low strain range. However, when the deformation strain is larger than 2%, the available strain energy shows a heating temperature sensitivity. It is also mentioned that the degradation of available strain energy shows a heating temperature and increases with increasing in heating temperature. But it is insensitive to the deformation strain. Furthermore, the total available strain energy to failure becomes maximum in the vicinity of 5% strain in every temperature region, and increases with the decrease in heating temperature. The energy conversion efficiency is about 1.2% under the conditions which maximize the total available strain energy.

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