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Energy sharing within building complexes depends greatly on the complex load adaptability and policy support. However, most building complex microgrid research concentrates on configuration and operation optimization, rather than energy contributions from different users. The objective of this study is to analyze energy sharing ability and load adaptability for a building complex comprising multiple building types, under transaction liberalization restrictions in different energy markets. The specific research for this study is a smart community in Kitakyushu, Japan, with 49 buildings of different types. The complex's microgrid system in this study comprises photovoltaic, battery, and vehicle to grid services. We obtained six representative typical clusters by reducing the 49 buildings' dimensionality using principal components and clustering, then Monte Carlo simulation to predict permissible discharge capacities for vehicle to grid (V2G) services. We propose three demand-side liberalization scenarios: self-use, photovoltaic feed-in tariffs (FITs), and free trade; optimizing system configuration under different scenarios using a genetic algorithm. Results confirm that shopping malls achieve best economic benefits with self-use scenario; whereas office building adaptability is more significant for the other scenarios. These results will contribute to user selection and system design for building complex microgrid systems. [ABSTRACT FROM AUTHOR]

Electrolytic hydrogen storage technology of renewable energy is considered as one of the important measures to realize the high proportion of renewable energy. However, developing this technology has been slow due to the cost. This study proposes highlighting the environmental advantages of renewable power combined with a carbon tax at the national level to expand the application space of hydrogen storage technology. First, the economy and technical characteristics of hydrogen storage technology and conventional energy-storage technology were compared. Then, Japan's top 10 power companies, which account for 90% of the power supply, were taken as the research objects. The proportion of change in renewable power after introducing a carbon tax was studied, taking the weighted minimum of the feed-in tariffs as the optimization objective. The contribution of hydrogen storage technology to the change in renewable power share was analyzed. Next, a sensitivity analysis was conducted on the fossil energy price and cost of renewable power equipment that affects the research. Finally, the contribution of a carbon tax and hydrogen storage technology to Japan's emission reduction target was calculated and analyzed. The results showed that the characteristics of long-distance transportation of hydrogen energy and making renewable energy have economic advantages under the current carbon tax (5–6 JPY/kg-CO2). The cost of liquified natural gas (LNG) and the investment of photovoltaic (PV) have a significant impact on the weighted minimum feed-in price, which can make the development of hydrogen storage technology no longer rely on the setting of carbon tax. The results obtained in this study provide a theoretical reference for the application of hydrogen storage technology in the high proportion of renewable energy consumption. At the same time, it can also provide data reference for large-scale construction of renewable energy in regions where solar and wind energy resources are not excellent. [ABSTRACT FROM AUTHOR]

Hydrogen energy is considered one of the main measures of zero carbonization in energy systems, but high equipment and hydrogen costs hinder the development of hydrogen energy technology. The objectives of this study are to quantify the environmental advantages of hydrogen energy through a carbon tax and study the application potential of hydrogen energy technology in a regional distributed energy system (RDES). In this study, various building types in the smart community covered by Japan's first hydrogen energy pipeline are used as an example. First, ten buildings of five types are selected as the research objectives. Subsequently, two comparative system models of a regional distributed hydrogen energy system (RDHES) and an RDES were established. Then, by studying the optimal RDHES and RDES configuration and combining the prediction of future downward trends of fuel cell (FC) costs and energy carbon emissions, the application effect of FC and hydrogen storage (HS) technologies on the demand side was analyzed. Finally, the adaptability of the demand-side hydrogen energy system was studied by analyzing the load characteristics of different types of buildings. The results show that, when the FC price is reduced to 1.5 times that of the internal combustion engine (ICE), the existing carbon tax system can sufficiently support the RDHES in gaining economic advantages in some regions. Notably, when the carbon emissions of the urban energy system are reduced, the RDHES demonstrates stronger anti-risk ability and has greater suitability for promotion in museums and shopping malls. The conclusions obtained in this study provide quantitative support for hydrogen energy promotion policies on the regional demand side and serve as a theoretical reference for the design and adaptability research of RDHESs. [ABSTRACT FROM AUTHOR]

Emergency power system refers to a system that is composed of self-generating equipment in the building. By providing power support for emergency events such as power outages, it can keep the energy safety assurance. Usually, emergency power systems are independent and redundant. As a backup, their utilization rates are extremely low, resulting in excessive redundancy causing a lot of waste of resources and equipment. In this paper, a model integrating stand-alone emergency power systems with micro-network was proposed to improve power supply reliability in a more economic manner. Integrated emergency power system with the dispatch strategy of self-priority was established based on reliability and power demand of buildings simulated through Monte Carlo method. To evaluate the impact of integration, the total cost of integrated emergency power system was calculated including economic loss during power outages and system costs. Finally, genetic algorithm was used to obtain the optimal capacity and dispatch strategy of the integrated emergency power system by minimizing the total cost. Results showed that the reliability was improved, and the total cost was reduced to 80.05% by integrated emergency power system in the illustrated case. [ABSTRACT FROM AUTHOR]