This study aims to analyze energy saving effects when introducing an area energy network among houses with fuel cell and photovoltaics. An area energy network is an energy sharing system involving plural houses. Hourly energy data of information obtained from measurements were classified into electric power and hot water based on five actual smart houses located in Fujimi in Kofu City. The average electric power consumption of the object house was 7.5 kWh per day, which was less than 40 % of that of a conventional house. This study investigated five simulation cases. The annual primary energy saving was 156.4 % compared to reference systems. The average electric power-selling rate was increased from 77.7 % to 90.3 % by combining fuel cell with photovoltaics. Results showed that both the generation load factor and the exhaust heat utilization rate of the fuel cells were increased by the area energy network. The amount of annual electric power generation of the fuel cells was increased by 1.45 times because of load leveling with consumer integration. Results of this study show that an area energy network is very useful for the introduction and expanded use of fuel cells.

View full abstract

In order to promote the spread of electric vehicles, a quick charger needs to be arranged. For suitable arrangements, it is necessary to examine the functions of quick charging stations. The aim of this study was to grasp the required numbers of chargers in quick charging station. First, the future total demand of quick charging was estimated using the actual use data of existing charger. Then, the demand was distributed by traffic volume into the charging stations which classified 30 roads. Finally, the required number of charger in quick charging stations was estimated considering the results of wait-time and cost-and-benefit analysis. As results, it was estimated that the thousands of quick charging station needs two or more quick chargers in one charging station.

View full abstract

This paper explores carbon price and LNG price thresholds for investment in power plants and carbon capture and storage (CCS) systems in Japan based on real options approach. We consider the case of a firm having an aged coal power plant. There are five options for the replacement: i) coal power plant, ii) coal power plant w/ CCS, iii) capture ready (CR) coal power plant, iv) gas power plant, and v) gas power plant w/ CCS. The simulation results reveal that the area for the option of “waiting” is relatively large, which means that expected cost of keeping options open is lower than the expected cost of “investing right now.” One should not expect CCS diffusions in the short-term; however, capture ready (CR) coal power plant could be economically viable in a (narrow) range of carbon prices under uncertainty. These results bring a helpful contribution to the discussion on whether the Japanese government should support CCS diffusions, and if so which policies are the most effective ones.

View full abstract

The objective of this study is to evaluate an agrivoltaic system by reflecting the deterioration of rice yield and quality. The agrivoltaic system means introducing photovoltaic power to agricultural fields. By the notification from Ministry of Agriculture, introducing renewable energy to agricultural fields became limitedly possible. However, current agrivoltaic pioneers do not always consider crop quality deterioration brought from a total life cycle shading. We evaluate a deterioration of growing in a paddy field in Chiba prefecture in Japan. Heading time delayed significantly under the shading condition. Number of ears and weight per an ear were also significantly less under PV panels. Utilizing measured data, we modified the conventional crop model, which simulates rice yield, quality and economic efficiency under the shading weather condition. A 20 percent shading reduces the yield by approximately 20 percent. Number of ears per root accounts for 84 percent of the yield, which indicates early period of the growth needs enough amount of solar radiation for improving the rice growth.

View full abstract