This study develops a mineral resources balance model for evaluating demand and supply structure of mineral resources such as copper, zinc, and lead, to assess sustainable supply of the resources up to 2100. The model constitutes from two parts; one is demand forecast from which the derived demands are exogenously given to the other model, supply side model. The supply side model calculates the amount of such as mineral resource production, recycled materials, and energy consumption via minimizing discounted sum of supply cost of the resources. Results indicate that the demand of copper, zinc, and lead in 2100 increases by some 2 to 5 times compared with those in 2010, and that mineral production peaks out around 2030 to satisfy the demand by scrap recycling. Major part of the energy consumption increase is by copper, which increases by some 3 times in 2090 and by about 10 times in 2100 respectively, compared with those in 2010. This study clarifies that the depletion of copper, zinc, and lead of present day price level would be listed as an agenda in social concerns, and that challenge is reduction of energy consumption growth in mineral metallurgy due to ore grade degradation.

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Our survey on ownership of household refrigerators suggests that replacing old refrigerators with new ones has large potential for CO₂ emission reduction. For 21% of household refrigerators in 2012, the replacement can be paid back within 5 years with 10 Mt-CO₂ emissions reduced per year. We also analyze the sale trend during the eco-points program and after the program. Ordered logit model is applied for the regression between sales rank and the factors of purchaser preference. The eco-point program accelerated the sales of large-size refrigerators. However, we cannot find the statistical difference of the consumer preference to energy-saving performance of refrigerators between the period of eco-point program and that after the program. Next, autoregressive model is applied for analyzing the change of sales amount in the period of eco-points program. The result suggests that the sales amount does not significantly increase during the eco-points program. Finally, we conduct survey of 1000 owners of old refrigerators to know the reasons that they do not replace them. The principal reason is lack of information such that they do not know the replacement can be paid back within the period they allow. Providing appropriate information is primarily required. To lower the cost hurdle for replacement, the payment method such as Green Deal is also promising.

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City-Chino, where the authors are engaged in their work, is located in the slope of Mount Yatsugatake covering altitude ranging from 750 to 2,899m. In this area, water flow from individual source is rather small but experiences a large elevation difference. Accordingly, a small scale impulse type hydroturbine is suitable. In this study, a commercially available micro impulse hydro turbine was tested, whose impeller is interested in because it has an intermediate feature between turgo and pelton impulse turbines. Effects of the water head, number and the diameter of nozzles were tested in a laboratory scale. The generation efficiency for various conditions were measured and correlated with use of the specific rotation speed. In the present study, trial components of an impeller and a nozzle were experimentally manufactured with use of a 3D printer. The obtained impeller attained a comparative performance with the original one. The test nozzle was so produced that its inside diameter was smoothly changed from a thick inlet to a thin outlet. Accordingly, the pressure loss in the nozzle unit was reduced significantly, and thus the new nozzle provided an about 30 % higher efficiency than the original one.

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