Best–Worst Scaling (BWS) was applied to assess Chinese consumer preferences for battery electric vehicle (BEV). Although BEV is becoming familiar to Chinese consumers, the share of passenger electric vehicles for yearly sales in 2020 is still 5.8%. BWS has advantages in obtaining rich information on preferences by identifying “best” and “worst” options. An online questionnaire survey was conducted in mainland China in January 2021, and 2064 samples of Chinese consumers were collected. A BWS object case was applied in this study to compare with the previous Japanese case study. Results of the BWS object case revealed that maximum driving range and convenient charging facilities were the most important factors. Conversely, operation costs, the reduction of carbon dioxide and air pollutants were less important factors. Random parameter logit estimates with interaction-terms demonstrated the preference heterogeneity of attributes except for driving performance and battery life and warranty. The results suggest that Chinese consumer preferences and purchasing behaviors are much diverse. Government programs and companies’ efforts to support financially for increasing charging availability and driving range are required to promote the diffusion of BEV in China.

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In order to analyze the economics of domestic hydrogen production and methane synthesis, an optimized model with power generation and city gas sector was developed and estimated under several CO₂ tax cases. This model includes carbon recycling technology which synthesize methane from CO₂ and hydrogen. In this paper, the conditions for the implementation of hydrogen production and methane synthesis technology in conjunction with daily power supply operations were analyzed. Furthermore, a comparison of the cost competitiveness of domestic and imported hydrogen was also discussed by considering the use of imported hydrogen in the model. Simulation results imply that under high carbon price condition, while the introduction of hydrogen-fired power generation using imported hydrogen progress, the introduction of methane synthesis is very limited, suggesting that it will be difficult to reduce CO₂ emission in the city gas sector.

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As the electrification of the transportation sector is being promoted to achieve carbon neutrality, the promotion of battery electric vehicles (BEVs) has become an urgent issue. One of the concerns about BEVs from the user's point of view is the range anxiety that the vehicle may not be able to reach its destination due to power shortage. However, few studies have clarified the timing of the anxiety felt by users. In this study, a questionnaire survey was conducted on domestic users who switched from an engine vehicle to a BEV. As a result, it was found that the timing at which BEV users felt range anxiety and wanted to recharge their vehicles tended to be influenced by recharging habits based on individual personality factors, rather than environmental factors such as BEV driving experience and the density of rechargers. In addition, the SoC ratio of the timing of wanting to recharge was found to be correlated with the timing of recharging the BEV and the timing of recharging the cell phone.

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In this study, we quantitatively elucidated the popularization mechanism of Japan’s electric vehicle (EV) and plug-in hybrid vehicle (PHV) and conducted a simulation analysis on popularization measures. We found that driving range, total cost relative to gasoline vehicle (GV), and the number of chargers were factors significantly affecting the new vehicle sales ratio of EV and PHV. We also confirmed that the unit price of lithium-ion batteries (LIB) for vehicle decreased by about 24% each time the cumulative productions doubled. As a result of simulation analysis, EV new car sales ratio increased to 26% in 2030 and 62% in 2035 in the case of comprehensive measures. However, PHV new car sales ratio was less than 1% in 2030 and 2035. The most important measure for EV popularization is to promote the development of charging infrastructure.

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For expanding the installation of solar power systems in detached houses, it is important to understand the status of power consumption and solar power generation based on their characteristics. Therefore, we surveyed the electricity consumption, PV capacity, power generation, power sales, and self-consumption rate of detached houses in each year of PV installation, using micro data of survey on carbon dioxide emissions from residential sector. The results show that the average capacity of PV installed before 2010 was 3.9 kW, while the capacity of PV installed in 2013-2014 was 5.5 kW, an increase of more than 30%. On the other hand, it was found that the total floor area of houses has not changed that much. Thus the increase in average PV capacity can be attributed to lowered economic constraints such as reduced PV system costs and the popularity of overloading. In addition, there has been no increase in average capacity of PV installed after 2015, which can be due to new constraints related to the location of PV installations, such as the total floor space of houses.

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Electric vehicle (EV) is expected to be one of the means to reduce the CO₂ emission in transport sector. Due to the extension of the cruising distance of EVs, the battery capacity of EVs is increasing year by year. However, it is necessary to maintain the charging facility on the route to the destination for the spread of EVs. A high-power (e.g.50kW) of DC type, which is called a quick charger (QC) is generally used for the charging on the route. The objective of this study is to evaluate the frequency of the quick charging considering the distribution of the daily travel distance and the battery capacity of EVs. This study investigates how the charging frequency is influenced by the battery capacity and other factors. A model was developed to observe the charging behavior of various EVs thought out a year with a given interval of QCs. The results show that the frequency of the quick charging does not change a lot when the battery capacity is more than a certain level. The monthly charging frequency is once or less when the initial State of Charge(SoC) is enough high with the battery capacity of 30 kWh or larger.

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Variable renewable energy sources (VRE) need to be increased rapidly under the 2050 carbon-neutral policy. New distributed energy resources (DER) management system needs to be developed which can compensate the large VRE output fluctuations in wide areas. Considering internet of thing (IoT) ready DERs, multiple applications (apps.) with no relation of each other will send signals to one DER and coordination scheme will be needed. This paper reports necessary functions of such multi apps. – one DER system and test the functions with an actual electric vehicle charger. Four functions are identified: 1. to set the priority of apps. and to judge whether the operation command is accepted; 2. to make apps. know the situation of the system; 3. to make apps. change their operation by themselves; 4. to specify the app that have caused the operation change of DER. Function 4 is unique and useful for DER aggregators to score the DER activities. Through the experiment and discussions, we recognize these functions will be able to increase aggregators’ business quality.

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