Spatiotemporal energy network with smart transportations for energy sharing can address regional imbalance distribution of renewable resources, dynamic intermittence and fluctuation of renewable power supply, enhance grid independence, or even provide voltage/power stabilization services to local power grids. Furthermore, difference in regional energy pricing policy can be fully utilised to economically incentivise participation willingness of stakeholders. However, the current literature provides few studies and little knowledge on the topic. In this study, a spatiotemporal energy network in Guangdong-Hong Kong-Macao Greater Bay Area was proposed for regional energy balance with different types of buildings in demand-shortage and renewable-abundant regions, and electric vehicles for daily commuting. Roles of electricity-powered vehicles include renewable charging for clean transportation through Building-to-Vehicle (B2V) interaction, spatiotemporal energy sharing through Vehicle-to-Building (V2B) interaction, voltage/power stabilization of local grids through Vehicle-to-Grid (V2G) interaction. Techno-economic-environmental potentials of the proposed spatiotemporal energy network are evaluated for carbon neutrality transition. Advanced energy pricing policy and energy interaction modes are identified, based on dynamic energy trading and associated cost, among building owners, vehicle owners, and utility companies of power grids. Economic analysis and decision-making on multi-stakeholders are analysed, including external cost with power grids, internal cost, and battery degradation cost. Results showed that the proposed spatiotemporal energy network with the V2G interaction mode can improve the renewable penetration ratio from 0.7 to 0.722, the demand coverage ratio from 0.021 to 0.039, with the decrease in equivalent CO2 emission from 5.04x106 to 4.78x106 kg by 5.2%, and annual import cost from 8.16x106 to 8.0x106 HK$ by 2.0%. However, compared to the isolated system, the spatiotemporal energy network will lead to the increase of battery degradation cost from 0.594x105 to 0.688x105 HK$, by 15.8%, due to the increase in battery charging/discharging cycles. In order to economically incentivise participation willingness of all stakeholders, advanced energy pricing policy and energy interaction modes are identified as Policy 5 and V2G interaction mode, under which vehicles can increase the internal trading cost from 0 to 1.78x105 HK$, overwhelming its battery depreciation cost at 0.688 x105 HK$. This study formulates a spatiotemporal energy network for regional energy balance, contributing to the carbon neutrality transition and development of Guangdong-Hong Kong-Macao Greater Bay Area with frontier energy planning, smart energy interaction and advanced energy price policies.