Energy planning of renewable applications in high-rise residential buildings integrating battery and hydrogen vehicle storage

Highlights

• Hybrid renewable energy with battery and hydrogen vehicle systems are developed.

• Two energy management strategies with different energy storage priority are compared.

• Multi-objective optimizations on supply, grid and system cost are conducted.

• Four decision-making strategies are studied for stakeholders with different concerns.

• Techno-economic-environmental feasibility is analyzed applied in high-rise buildings.

Abstract

This study presents a robust energy planning approach for hybrid photovoltaic and wind energy systems with battery and hydrogen vehicle storage technologies in a typical high-rise residential building considering different vehicle-to-building schedules. Multiple design criteria including the supply performance, grid integration and lifetime net present value are adopted to size the hybrid system and select the optimal energy management strategy. Four decision-making strategies are further applied to search the final optimum solution for major stakeholders with different preferences. The study result indicates that the energy management strategy with battery storage prior to hydrogen storage is suitable for hybrid systems with large photovoltaic, wind and battery installation capacities to achieve the optimum supply-grid integration-economy performance. The energy management strategy with hydrogen storage prior to battery storage has a wider applicability, and this strategy should be selected when focusing on the supply-grid integration or supply-economy performance. The annual average self-consumption ratio, load cover ratio and hydrogen system efficiency are about 84.79%, 76.11% and 77.06% respectively in the end-user priority case. The annual absolute net grid exchange is about 4.55 MWh in the transmission system operator priority case. The lifetime net present value of the investor priority case is about 3.64 million US$, 29.88% less than the equivalent priority case. Final optimum solutions show positive environmental impacts with negative annual carbon emissions. Such a techno-economic-environmental feasibility analysis of the hybrid system provides major stakeholders with valuable energy planning references to promote renewable applications in urban areas.

Introduction

Renewable energy is playing an expanding role in the power sector [1] and providing about 27.3% of global electricity generation accumulating to 2588 GW at the end of 2019 [2]. It has been adopted as a global-scale decarbonisation pathway towards the low-carbon power supply and sustainable environment especially in crucial sectors with high carbon emissions and energy consumption such as the building and transport. Most carbon emissions in Hong Kong are attributed to electricity generation (70%) and transport (16%) sectors, while 90% of electricity is consumed by buildings [3]. More than half of the total energy consumption of Hong Kong is attributed to the residential (21%) and transport (31%) sectors in 2017, and the energy and electricity consumption of the residential sector shows a continuous rise from 2007 to 2017 by 9.6% and 15.7% respectively [4]. The local government has therefore launched ambitious plans to achieve an absolute carbon reduction of 26–36% by 2030 benchmarked with 2005. It is significant to accelerate renewable energy development as it accounts for only 0.2% of total local electricity consumption in 2017 [4], while 3−4% of the renewable energy supply has been planned [3]. The hybrid renewable energy and storage systems with complementary photovoltaic (PV) and wind power combined with lithium-ion battery storage and hydrogen vehicles are thus developed for power supply to high-rise residential buildings.

Batteries have been widely adopted for renewable energy storage in buildings given its fast response, high efficiency and low environmental impact [5], while hydrogen is attracting increasing attention in many economic sectors given its low-carbon characteristics. The lower heating value of hydrogen is about 120 MJ/kg (3 times of gasoline), which makes it an attractive transport fuel. But hydrogen needs to be compressed or liquefied as the energy intensity of hydrogen is relatively low at 0.01 MJ/L (1/3 of natural gas) [6]. This study adopts a vehicle integrated hydrogen storage system consisting of the alkaline electrolyzer, compressor, hydrogen storage tank and proton exchange membrane fuel cell (PEMFC) for the hybrid renewable energy system. The alkaline electrolyzer has been used since the 1920s as a commercial and mature technology with a relatively low initial cost (500–1400 US$/kW) compared with other electrolyzers such as the proton exchange membrane electrolyzer (1100–1800 US$/kW) and solid oxide electrolyzer (2800–5600 US$/kW) [7]. The electrical efficiency of alkaline electrolyzer at the lower heating value is about 63–70% depending on the technology performance and supply power, and it is projected to be increased to 70–80% in the long-term development. The hydrogen fuel cell costs 1600 US$/kW for a 1 MW PEMFC unit with an electrical efficiency of 50–60% and it is predicted to be reduced to about 425 US$/kW by 2030 [8]. It is therefore technically and economically promising to develop hybrid renewable energy and storage systems integrating the building and transport sectors.

Recently, hydrogen vehicles (HVs) have experienced an unprecedented development as a promising alternative for clean energy solution. Over 12,900 fuel cell electric cars are registered worldwide by the end of 2018 with an 80% increment in the year, although still small compared with the accumulated 5.1 million battery vehicles. Nearly half of HVs are sold in the U.S., followed by 23% in Japan and 14% in China, while most HVs are manufactured by Toyota, Honda and Hyundai. There are 376 publicly available hydrogen refueling stations with 100 in Japan, followed by 60 in Germany and 44 in the U.S. [9], but the number is still small compared with the 5.2 million charging points (90% private chargers) for battery vehicles by the end of 2018 [10]. HVs can be refueled in 3–5 min, much shorter than that of battery vehicles (can be 3–6 h) and fuel cells could have a lower material footprint than lithium batteries. The cruise range of HVs can be over 400 km, longer than that of battery vehicles with a global average around 250 km [6]. A promising global development of HVs is anticipated in the near future to achieve a low-carbon transport sector. The Korean government aims to achieve 6.2 million HVs and 1200 refueling stations by 2040 and make hydrogen economy a driving force of innovation growth [11]. About 20,000–50,000 HVs and 400–1000 refueling stations are projected by 2028 in France and 1000 refueling stations will be constructed in Germany [9]. Up to 1 million fuel cell electric vehicles and 1000 hydrogen refueling stations will be developed by 2030 in China to launch the hydrogen transport in ten cities following exiting battery vehicles [12]. A similar plan is outlined by the California Fuel Cell Partnership to encourage the development of low-carbon hydrogen in California [13]. Japan also planned to have 0.2 million HVs and 320 refueling stations by 2025 with accumulated HVs of 0.8 million by 2030 [14]. Hydrogen Council anticipates more than 400 million hydrogen cars, 15–20 million hydrogen trucks and 5 million hydrogen buses all over the world by 2050 [15].

Feasibility and optimization studies on battery and hydrogen storage based renewable energy systems for building power supply have aroused increasing attention in recent years with an accelerating development of battery and hydrogen technologies in energy storage and transportation.

The technical and economic feasibility of employing battery and hydrogen storage based renewable energy systems for building power supply has been investigated based on case studies and parametric analyses. A standalone plug-in hybrid electric vehicle charging station powered by PV and wind energy with fuel cell storage is tested showing that the lifetime and cost of the fuel cell system are more favorable than that of the battery system [16]. A demonstration project with the solar PV and fuel cell electric vehicle in a residential building was set up in the Netherlands to study the net zero-energy and vehicle-to-grid operations. It is found that the annual grid imported electricity can be reduced by 71% with the integration of the fuel cell vehicle [17]. The technical and economic performance of a PV-wind system with vehicle integrated hydrogen storage is analyzed for a zero-emission single family house in Finland considering the system net present value and operational carbon emissions [18]. The vehicle integrated hydrogen storage and battery storage are designed for solar and wind systems in a practical office center of the Netherlands. This study validated the feasibility of using electric vehicles as the power backup as well as the flexibility and cost-effectiveness of fuel cell vehicles over battery vehicles [19]. The power generation planning of isolated microgrids with diesel and renewable energy sources is presented considering the integration of electric vehicles and cooking systems. The economic and environmental benefits of the renewable energy system for a remote community in Ecuador are demonstrated based on the HOMER analysis [20]. The impact of vehicle-to-building interactions and vehicle charging strategies on the performance of zero-emission office buildings is analyzed. The author reports that the matching capability and building-vehicle interactions can be significantly improved by expanding the vehicle charging boundary to remote parking sites [21].

A large amount of research has also been conducted on the sizing and design optimization of battery and hydrogen storage based renewable energy systems for building power supply in both standalone and grid-connected conditions. For example, the PV system with hydrogen and retired vehicle battery storage is developed for a typical household in China by optimizing the energy supply reliability, energy waste and system cost. The superiority of Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is explicated in this study compared with the multi-objective evolutionary algorithm based on decomposition [22]. The widely used metaheuristics are further compared in optimizing and sizing a micro-grid hybrid PV-wind-hydro system with supercapacitor storage and hydrogen refueling station for fuel cell vehicles in a New Zealand community. The authors conclude that the moth-flame optimization algorithm gets the best solution in cost effectiveness with a 0.09 US$/kWh levelized cost of electricity [23]. Three operation strategies of the PV-battery-hydrogen system are developed under the pessimistic and optimistic cost scenarios for a multi-apartment building in Sweden, showing that hydrogen storage performs better than battery storage in the net present value under the optimistic cost scenario [24]. The optimal design and operation of the hybrid solar-hydro system with stationary hydrogen storage is also analyzed based on General Algebraic Modeling System (GAMS) for a net-zero energy building to minimize the investment of the solar system. A carbon dioxide reduction of 39,546 kg and cost decline of 50.3% can be achieved by the optimum design [25]. An innovative optimization model is proposed for investment planning of a renewables microgrid with electric vehicles. Case studies of microgrid systems with a 5-year planning horizon show that the vehicle-to-grid technology contributes to the microgrid economy in the long-term operation [26]. A microgrid planning algorithm of renewable energy systems integrating electric vehicles is proposed to maximize renewable generations. It is found that the developed algorithm can reduce the investment cost and carbon emission for residential and campus microgrids cases in Korea [27]. Both single-objective and multi-objective optimizations are conducted to improve the technical, economic and environmental performance of a low-energy building integrated with the PV and battery storage system considering the battery cycling aging, grid relief and time-of-use pricing [28].

Table 1 summaries recent research on the feasibility and optimization study of battery and hydrogen storage (both stationary and mobile types) based renewable energy systems for building applications. It can be identified that few techno-economic feasibility studies focus on high-rise building applications within the urban context considering different transporting schedules of hydrogen vehicle groups. And most existing design optimization studies are limited to stationary hydrogen storage. Moreover, optimum sizing schemes and energy management strategies of hybrid renewable energy systems with battery and hydrogen vehicle storage are seldom presented for major stakeholders considering their different concerns.

Given the identified research gap, this study presents a robust energy planning approach for the hybrid PV-wind-battery-hydrogen system for power supply to high-rise residential buildings integrated with hydrogen vehicles in different cruise schedules. The preferences of key stakeholders are addressed for decision making for different energy management strategies based on the joint TRNSYS and jEplus + EA platform. Major contributions of the present study are shown as below:

• Two energy management strategies of the hybrid PV-wind-battery-hydrogen system with different operation priorities of the battery storage and hydrogen storage are developed and compared for power supply to a typical high-rise residential building integrated with two groups of hydrogen vehicles following different cruise schedules. The energy management strategies and system configurations are optimized considering the system supply performance, grid integration and lifetime net present value based on multi-objective design optimizations.

• Four decision-making strategies based on the minimum distance to the utopia point and analytical hierarchy process methods are adopted to determine the final optimum solutions for major stakeholders (i.e. the end-user, transmission system operator and investor) of hybrid renewable energy and storage systems for high-rise residential building applications within urban contexts.

• The techno-economic-environmental feasibility of four optimum solutions of the hybrid PV-wind-battery-hydrogen system with different concerns under the optimal energy management strategy is analyzed to provide valuable references for key stakeholders to further develop hybrid renewable energy and storage systems in urban areas.