Elsevier

Energy

Volume 230, 1 September 2021, 120728
Energy

Techno-economic and environmental evaluation of grid-connected and off-grid hybrid intermittent power generation systems: A case study of a mild humid subtropical climate zone in China

https://doi.org/10.1016/j.energy.2021.120728Get rights and content

Highlights

  • The technical, economic, and environmental models of hybrid energy systems are presented.

  • The grid-connected systems are economical than off-grid systems for the building in Guiyang.

  • The Grid/PV/wind hybrid system may be a better choice for the building in Guiyang.

  • The PV/battery system in off-grid systems is a good choice for powering buildings in Guiyang.

  • Wind power is not suitable for the building power supply in Guiyang.

Abstract

In order to promote the development of green buildings, this paper presents a technical, economic, and environmental evaluation of a residential building powered by hybrid intermittent generation systems in a mild humid subtropical climate zone in China. The technical, economic, and environmental mathematical models of hybrid systems are addressed. This study selected Guiyang city, which is a typical mild humid climate zone. The results revealed that the 30 kW grid-connected system for the building was the most economical with a net present cost of $ 28,041 and cost of energy of 0.069 $/kWh, whereas this was the least environmentally friendly form of power generation, emitting a maximum amount of CO2 of 26,609 kg/yr. From an economic and environmental perspective, grid/photovoltaic (PV)/wind hybrid systems in on-grid systems may be a better choice for supplying power to buildings in Guiyang. If the extension of the power grid is not feasible, off-grid PV/battery hybrid systems consisting of 115 kW PV units, 80 battery units, and a 30 kW power converter, are more suitable for supplying power to the building. Furthermore, the results indicated that wind power is not suitable for supplying power to buildings in Guiyang, mainly due to relatively low wind speeds.

Introduction

Renewable energy is a resource-rich, environmentally clean and user-friendly resource. The utilization of renewable energy has been recognized as an important new direction for energy consumption, which is gradually transitioning from traditional alternative energy to mainstream energy. One of the most important uses of renewable energy is power generation [1,2]. Wind and solar energy are the two most promising intermittent renewable sources of energy, which creates more and more challenges for the power system because of its variability, intermittency and uncertainty [3]. Faced with the inherent shortcomings of intermittent energy, more than one energy source can be combined to form a hybrid intermittent energy system to enhance the system's reliability [4,5].

Many countries regard the development of renewable energy power generation as a national strategic goal and have greatly promoted the development of renewable energy [6]. In recent years, China has increased its investment in wind power and PV power generation. The electricity generation from onshore wind energy and solar PV energy in China from 2010 to 2018 are shown in Fig. 1 [7]. As can be seen from the figure, the production of onshore wind power and solar PV power continued to increase from 2006 to 2018. The ratio gap between wind and PV power generation gradually narrowed, from 67.08 times in 2010 to 2.01 times in 2018.

Research on the technical and economic implications of hybrid renewable energy power generation plays an important role in promoting the popularization and use of such power generation systems [8]. Kim et al. [9] studied the technical, economic, and environmental feasibility of hybrid systems consisting of renewable energy, a power grid system, and diesel generators on Jeju Island, South Korea. The study found that the most economically feasible system was the grid-connected PV/battery/wind hybrid energy system. Olatomiwa et al. [10] analyzed the technical and economic implications of a hybrid system consisting of solar and wind energy powered for a specific remote mobile base station in Nigeria. They found that the PV/battery/diesel generator (DG) comprising 10 kW of PV arrays, 5.5 kW DG, and 64 units of batteries was the most economically viable option with a total net present cost (NPC) of $69,811 and a cost of energy (COE) of $0.409/kWh.

Al-Ghussain et al. [11] studied the performance and economic viability of wind/PV hybrid energy systems for cement plants. They found that the wind/PV system with lithium-ion batteries was more economically viable and had a higher proportion of renewable fraction (RF) than those without energy storage systems. Anoune et al. [12] used a designed Transient Energy System Simulation Program (TRNSYS) model to determine the size of hybrid energy systems that were used to supply load demand. The proposed sizing model could simulate the annual performance for different configurations of hybrid energy systems with different configurations and give the optimal configuration.

Duman and Güler [13] performed a technical and economic analysis of stand-alone PV light emitting diode (LED) road lighting systems in northern, central and southern Turkey. The results showed that the variation range of the COE for the stand-alone PV LED road lighting system was 0.229–0.362 $/kWh for M4 and 0.254–0.359 $/kWh for M5 road lighting, depending on the solar potential of the area. The investment of stand-alone PV road lighting systems in the three regions was not feasible under the current conditions. Murugaperumal and Raj [14] studied the optimal design and the technical and economic viability of a hybrid renewable energy system for rural electrification. The results showed that the hybrid renewable energy systems in remote areas constituted an economical and effective solution to promote sustainable development in rural areas.

Mazzeo et al. [15] proposed a new energy-economy-environment multi-criteria decision making approach for hybrid renewable energy system optimization, which was based on a new set of dimensionless indicators and served as a standard for future applications. The study noted that specific incentives to develop wind energy systems and longer-life battery systems for specific loads could make hybrid systems more economically competitive. Mazzeo et al. [16] provided a global geographic mapping and optimization of an off-grid and on-grid hybrid wind-PV energy system based on techno-economic indicators for a typical office building area. The energy reliability and economic benefits of the optimal systems were geographically located on a global scale.

Abbaszadeh et al. [17] studied the thermo-economic feasibility of an off-grid wind/PV/gas generator hybrid energy system to meet the energy consumption needs of a residential complex in Tehran, Iran. The results showed that, despite an 8% increase in the NPC, fuel consumption and emissions from gas-fired generator operations could be reduced by 53% as a result of using wind turbines. Furthermore, the results showed that using gas generators instead of diesel generators could reduce the NPC by 18%. Jumare et al. [18] conducted a detailed assessment of a grid-connected PV/wind/biogas hybrid energy system in northern Nigeria using the Hybrid Optimization Model for Electric Renewables (HOMER), Microsoft Excel, and Ganzleitliche Bilanz (GaBi) tools. The results showed that, for the grid-connected system, the total energy supply increased by 3%, and the NPC and COE decreased by 68% and 85%, respectively, compared to the off-grid configuration. Shrivastava et al. [19] discussed the economic and environmental implications of a PV-wind-battery hybrid energy system using the HOMER simulation tool. The results showed that the proposed system could meet the power needs of remote areas. Using the HOMER software Murugaperumal et al. [20] employed an optimization design to carry out a technical and economic assessment of a rural electrified hybrid renewable energy system in the Korkadu district of India. The research showed that power generation based on a hybrid renewable energy generation system was a cost-effective and sustainable alternative to the traditional power grid expansion system.

The above literature review highlights that few researchers have compared and evaluated the grid-connected and off-grid hybrid intermittent generation systems in China's mild humid subtropical climate zone from a technical, economic, and environmental perspective. There are few studies on the application of the hybrid intermittent generation system in mild humid subtropical climate zones. The innovations of this paper mainly focus on the novel applications of grid-connected and off-grid hybrid renewable energy systems coupled with solar PV, wind turbines and batteries in a mild humid subtropical climate zone. This paper aimed to analyze the technical and economic feasibility of the grid-connected and off-grid hybrid intermittent power generation system in the mild humid subtropical climate region of China by using the HOMER simulation tool.

The remainder of this paper is organized as follows: Section 2 describes the methodology used in this study; Section 3 outlines the case study of Guiyang; Section 4 presents the results and discussion; Section 5 summarizes the conclusions and future research work.

Section snippets

Renewable energy simulation model

At present, there are many simulation tools for energy systems, such as the System Advisor Model (SAM), photovoltaic system (PVsyst), SOLSIM, improved hybrid optimization by genetic algorithms (iHOGA), HYBRIDS, TRNSYS, and HOMER, etc [21,22]. The SAM was developed by the National Renewable Energy Laboratory (NREL) in Nevada, USA, for the design and financial analysis of renewable energy systems. SAM has been widely used in the design and technical and economic analysis of grid-connected

Study area

Guiyang (26°34′N, 106°43′E, 1064 m above sea level) is located in southwest China on the east side of the Yunnan-Guizhou Plateau and it is the capital of Guizhou Province. The city is an important regional innovation center in southwest China approved by the State Council, and an important ecological leisure and tourism city in China [[44], [45], [46]]. Fig. 4 shows the geographical location of Guiyang [47]. By November 2020, Guiyang had jurisdiction over six districts, three counties and one

Results and discussion

The technical, economic, and environmental analysis of the of grid-connected and off-grid hybrid intermittent power generation systems for a residential building in the suburbs of Guiyang were performed using HOMER software.

Conclusions

In order to study the application of green building in mild humid subtropical climate area of China, this research carried out a technical, economic, and environmental feasibility analysis of a residential building powered by hybrid grid-connected and off-grid intermittent power generation systems in Guiyang of China using HOMER software. The conclusions were as follows:

  • The 30 kW grid-connected system for the building was identified as the most economical with an IC of zero, annual OC of 2194

Credit Author Statement

Chong Li: Data collection, Modeling, Software simulation, Paper writing etc. Yuan Zheng: Research methodology guidance. Zhengyong Li: Technical communication. Lei Zhang: Technical communication. Lin Zhang: Language modification. Yicai Shan: Technical communication. Qinghui Tang: Project assessment.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work is financially supported by the Jiangsu Industry-University-Research Cooperation Project in 2020: Vice President of Science and Technology Cooperation Project (Grant No. BY2020429), the Scientific Research Project of Nanjing Xiaozhuang University (Grant No. 2020NXY13), the “Subject Team Convergence Project” Construction Project of Nanjing Xiaozhuang University-Subject Leader Cultivation Object (New Technologies for Intelligent Information and Electronics) (Grant No. 4190093), the Key

Nomenclature

Ba
Daily autonomy of the batteries (day)
Can, tot
Annual total cost of the system ($)
Cb
Battery storage capacity (kWh)
Ccap
Capital cost of system components ($)
Cfue
System fuel cost ($)
CNPC
Total net present cost of the energy system ($)
CO&M
Operation and maintenance cost of system components ($)
Cp
Performance coefficient of the wind turbine
Crep
Replacement cost of system components ($)
CRF (i, N)
Capital recovery factor
Csal
System salvage value ($)
DOD
Battery depth of discharge
Ed
Total amount of delayed load

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