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Abstract: To develop a scenario, easily traceable even for ordinary citizens, toward the national challenge target of 80% CO2 reduction by 2050, we have proposed a new model that calculates the total CO2 emission based on the final consumption. Using the model, we have tested appropriate (locally available) technology based sub-scenarios: (1) energy saving through electrification of all transportation; (2) promotion of wood utilization for housing; (3) introduction of renewable energies; and (4) efficient energy recovery from wastes. Applying the scenarios to the Kyoto-city as a case study, we have found that local 80% CO2 emission reduction could be possible using appropriate technologies including emission reduction from construction of private and public infrastructures, and shifting our final consumption mode into low CO2 emission has a significant impact. We have also argued that it is of interest to examine the future socio-economic change that would influence on people’s consumption behavior. [Copyright &y& Elsevier]

• Combining PV and EV in a city scale can reduce CO 2 emission by 60–74%. • The PV + EV systems can save energy costs by 22–37% in Kyoto City in 2030. • EV penetration policy should be reinforced integrating with PV systems. • Roof-top PV + EV system in a city-scale is defined as Solar-EV City. • Citizen's decision-making process is key to build PV + EV systems. To minimize the impacts of climate change, it is increasingly clear that global CO 2 emissions should be eliminated by 2050 and that leading low-carbon cities should reach net zero emissions by 2040. However, the precise pathways by which they can reach such ambitious goals have yet to be identified. As costs of photovoltaics (PV), batteries, and electric vehicles (EVs) are likely to keep falling, they can jointly play a key role for deep decarbonization. Here, we conduct a techno-economic analysis of a city-scale energy system with roof-top PV, batteries, and EVs for Kyoto City, Japan. We find that aggressive EV adoption and the use of EVs for electricity storage could help roof-top PV penetration in the city with substantially lower costs than just deploying PV and batteries alone or allowing EV to charge only. CO 2 emissions from vehicle and electricity usage in the city could be reduced by 60–74% if the entire current car fleet is replaced by EVs while also reducing energy costs by 22–37% by 2030. The largest challenge of a city-wide "PV + EV" system (named as "Solar-EV city") is its implementation. We explore how it could be realized in Kyoto through peer-to-peer (P2P) power trading/blockchain technology initially on a community scale as smart microgrids, then gradually expanding/converging into a city-wide. For the transition to decentralized power systems, citizen's decision-making process is one of the keys to overcome social, institutional, and regulatory barriers. [ABSTRACT FROM AUTHOR]

Finding economical and sustainable pathways for the deployment of renewables is critical for the success of decarbonizing energy systems. Because of the variable nature of renewable energy, however, the integration of renewables becomes increasingly costly and difficult as the renewable penetration becomes higher. The recent rise of electric vehicles (EVs) provides us with an opportunity to increase self-consumption of solar photovoltaic (PV) at households with substantially lower additional costs. In this paper, an environmental techno-economic assessment of residential PV systems is conducted with battery or EVs allowing charging and discharging (Vehicle to Home: V2H) in Kyoto, Japan, and Shenzhen, China, incorporating the cost projections of these technologies towards 2030. It is found that "PV + EV" (V2H) becomes highly cost-effective towards 2030 in Kyoto in comparison with "PV only", "PV + battery", and "EV charge". In the region of lower electricity costs such as Shenzhen, switching to EVs from gasoline vehicles is the most cost-effective option during 2020s. Finally, it is found that "PV + EV" has the highest CO 2 emission reduction potential across all the technology combinations considered, owing to EV charging of carbon-free electricity from PV. To facilitate a rapid household decarbonization, policy makers should reinforce policies to enhance the penetration of combined technologies of "PV + EV" (V2H) towards 2030. • PV + EV becomes highly cost-effective towards 2030 in Kyoto. • Switching to EV is the most cost-effective option in Shenzhen during 2020s. • PV + EV has the highest decarbonization potentials. [ABSTRACT FROM AUTHOR]