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This paper focuses on a hydrogen fuel cell power generation system integrated with photovoltaic (PV) generation, energy storage, and distribution network subsystems, conducting an economic and environmental adaptability analysis. Based on load balance, a mathematical model for the hydrogen fuel cell integrated energy system is established, and four scenarios are constructed: grid-powered, grid + fuel cell, grid + fuel cell + PV, and grid + fuel cell + PV + energy storage. The analysis results show that under the single-rate electricity pricing model, by 2030, the annual costs of Scenarios 3 and 4 are 11.46% and 12.67% lower than Scenario 1, respectively; by 2035, they are reduced by 19.32% and 20.43%, respectively. Under the two-part pricing model, by 2030, the annual costs of Scenarios 3 and 4 are 21.28% and 26.50% lower than Scenario 1, respectively; by 2035, they are reduced by 27.72% and 32.36%, respectively. These quantitative results indicate that the integration of hydrogen fuel cells with PV and energy storage systems can significantly reduce costs and promote their application and development in residential buildings.

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.

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.

ZEHs (Zero Energy House) featuring energy-efficient designs and on-site renewable integration are being widely developed. This study introduced Japanese ZEHs with well-insulated thermal envelopes and investigated their detailed operational performances through on-site measurements and simulation models. Measurement data show that ZEHs effectively damped the variation of indoor air temperature compared to conventional houses, presenting great ability to retain inside heat energy, and are expected to potentially deliver energy flexibility as a virtual thermal energy storage medium. We developed a simplified thermal resistance–capacitance model for a house heating system; response behaviors were simulated under various scenarios. Results compared the variations of indoor temperature profiles and revealed the dependence of load flexibility on the building’s overall heat loss performance. We observed that overall heat loss rate played a crucial role in building heat energy storage efficiency; a well-insulated house shortened the heat-up time with less energy input, and extended the delayed period of indoor temperature under intermittent heating supply; a high set-point operative temperature and a low ambient temperature led to lower virtual thermal energy storage efficiency. The preheating strategy was simulated as an effective load-shifting approach in consuming surplus PV generation; approximately 50% of consumed PV generation could be shifted to replace grid import electricity for room heating during the occupied period.

Reasonable regional integrated energy planning is an important prerequisite for the construction of a Near-Zero Carbon Emission Demonstration District (NCEDD). An integrated energy planning scheme that is based on a three-step planning method with the objective of achieving an NCEDD is proposed in this paper. First, the planning objectives should be determined. After that, the planning strategies should be established. Finally, the planning approaches should be proposed according to the previously determined objectives and strategies. A case study considering the integrated energy planning of the Meishan International Near-Zero Carbon Emission Demonstration District (MINCEDD) is investigated to explain the planning method. In addition, the planning results, which are indicated as indexes, are explained, analyzed, and compared to the ones of other districts. The indexes include a proportion of renewable energy to primary energy (73% by 2030 and 108% by 2050), a proportion of renewable power to total power consumption (98% by 2030 and 111% by 2050), and CO2 emission reduction rates (70% by 2030 and 100% by 2050) and are more advanced than other districts in China. This planning scheme and method can provide a reference for the integrated energy planning of NCEDDs in developed urban areas.

The increasing penetration of renewable energy decreases grid flexibility; thus, decentralized energy management or demand response are emerging as the main approaches to resolve this limitation and to provide flexibility of resources. This research investigates the performance of high energy efficiency appliances and grid-integrated distributed generators based on real monitored data from a social demonstration project. The analysis not only explores the potential cost savings and environmental benefits of high energy efficiency systems in the private sector, but also evaluates public grid load leveling potential from a bottom-up approach. This research provides a better understanding of the behavior of high decentralized efficient energy and includes detailed scenarios of monitored power generation and consumption in a social demonstration project. The scheduled heat pump effectively lifts valley load via transforming electricity to thermal energy, its daily electricity consumption varies from 4 kWh to 10 kWh and is concentrated in the early morning over the period of a year. Aggregated vehicle to home (V2H) brings flexible resources to the grid, by discharging energy to cover the residential night peak load, with fuel cost savings attributed to 90% of profit. The potential for grid load leveling via integrating the power utility and consumer is examined using a bottom-up approach. Five hundred thousand contributions from scheduled electrical vehicles (EVs) and fuel cells provide 5.0% of reliable peak power capacity at 20:00 in winter. The outcome illustrates the energy cost saving and carbon emission reduction scenarios of each of the proposed technologies. Relevant subsidies for heat pump water heater systems and cogeneration are essential customers due to the high initial capital investment. Optimal mixes in structure and coordinated control of high efficiency technologies enable customers to participate in grid load leveling in terms of lowest cost, considering their different features and roles.

As climate change intensifies, the adverse impacts of extreme weather events on energy supply systems will increase. Here, we collected energy grid utility datasets to illustrate causes and recovery processes of extended power outages induced by typhoon events in Japan. We also assessed the performance of demand-side solutions to enhance home energy resilience using household load profiles. We show that power outages present similar recovery curves, with full restoration times highly dependent on maximum wind velocities and affected regions. Ensuring a 24-hour self-energy supply is essential to mitigate outage impacts. Further, our results highlight the importance of off-grid energy storage or production in sustaining critical household energy loads under extended outage conditions. Building electrification scenarios challenges meeting increased demand under power outages. Building electrification and resiliency should be designed in tandem to improve energy security. Findings shed light on the effectiveness of demand-side solutions in enhancing Japan’s home energy resilience. In Japan, extreme typhoon events trigger extended power outages, and self-power generations help meet critical loads and improve home energy resiliency, according to an analysis that uses energy utility datasets and household load profiles.

In the existing station network planning of distributed energy systems (DESs), most of them determined the location of energy station in the alternative station site, there was a lack of a mature energy station location optimization method, and the factor load was not considered in the division of energy supply scope. This paper aimed to propose an optimal site approach for distributed energy stations based on Voronoi diagram, in which all possible candidates of energy station locations were considered. The candidate sites could be any point in the whole area. Simultaneously, after analyzing the limitations of the traditional energy supply partition method, we proposed a new energy supply partition optimization method, relative-load-distance. It was found that the annual cost of the whole system was significantly reduced by 1%, although the cost of the network in the optimized supply area was increased, compared with the supply area obtained by the partition method based on the principle of minimum distance. In addition, by adjusting the coefficient K in the relative-load-distance, the effectiveness of the optimization method in DES planning was verified.

The building sector contributes a large ratio of final energy consumption, and improving building energy efficiency is expected to play a significant role in mitigating its carbon dioxide emission. Herein, we collected the on-site measurement data to investigate the techno-economic performances of different heat pump types that exist in building space heating projects in Qingdao, China. An in-depth analysis revealed the temperature variations of measured low-grade heat sources over the whole heating supply period, and urban sewage water shows high stable heat energy quality compared with seawater and geothermal heat resources. Operational behaviors including cycling inlet and outlet temperature of the selected heat pumps were illustrated, and analysis evaluated detailed effects of operational parameters on energy efficiency performances. Then the relationship between COPs distributions of heat pumps and operational conditions was examined further, and the positive effect of the rising temperature of heat sources on energy efficiency improvement of heat pump is highlighted when the heating supply temperature is higher. Furthermore, we analyzed the economic and carbon emission performance of the heat pump system, and results show that electricity price plays a vital role in the lifespan energy cost saving potential, and the heat pump could serve as a promising approach in reducing CO2 related to the building space heating. Finally, we recommended suggestions for improving the overall energy efficiency and cost competitiveness of decentralized heat pump systems for building space heating.

This paper proposes a new network topology design method that considers all the road nodes, energy stations and load centers to ensure the distribution of pipes along the road. The traditional graph theory and Prim Minimum Spanning Tree (MST) are used to simplify the map and minimize the length of the pipeline. After analyzing the limitations of the traditional network topology model, Point-to-Point (PTP), we present a new model, Energy Station-to-Load Point (ESLP). The model is optimized by minimum cost, not the shortest path. Finally, Pipe Diameter Grading (PDG) is proposed based on ESLP by solving for the pipe diameter that gives the minimum cost under different load demands in the process of optimization. The network design method is effectively applied in a case, and the results show that the path of the optimized plan is 1.88% longer than that of the pre-optimized plan, but the cost is 2.38% lower. The sensitivity analysis shows that the cost of pipeline construction, project life and electricity price all have an impact on the optimization results, and the cost of pipeline construction is the most significant. The difference between the different classifications of pipelines affects whether PDG is effective or not.