Prospects of key technologies of integrated energy systems for rural electrification in China

0 Introduction

Providing beautiful rural construction has become the focus of China’s new socialist rural construction approach,and a new upsurge in rural revitalization has occurred nationwide.The construction of rural energy systems is one of the core pillars supporting such rural revitalization.Rural production and living demands for a variety of energy are becoming increasingly intense,and require the promotion of effective improvements for rural energy technologies [1].

Integrated energy systems can improve the utilization of functional system infrastructure,improve energy efficiency,and relieve energy pressure through organic coordination among subsystems.As an efficient and clean secondary energy,electricity can be centrally converted to other forms of energy to realize multi-energy complementary services.In view of problems such as the contradiction between the supply and demand in rural energy,rural electrification systems often adopt new renewable energy technologies,smart grid technologies,and ubiquitous power “Internet of Things” technologies to improve the service level of rural power supply and consumption [2].In reference [3],the author introduced the overall objectives,basic principles,and key tasks of rural electrification,but did not analyze the characteristics of rural energy systems.Reference [4]analyzed the characteristics of rural resource supply and consumption modes,but did not propose key technologies.In reference [5],the author analyzed the characteristics of a rural distribution network,but did not consider multi-energy coupling.In reference [6],the economic and environmental benefits of large-and medium-sized biogas centralized gas supply systems were analyzed,but the multi-energy complementarity was not considered. [7-8]considered multi-energy complementarity and established a rural microgrid model,but did not deeply analyze the energy consumption characteristics of rural users,and did not consider rural electrification.It can be seen from the above references that most of the research on the characteristics of rural energy systems is at the policy level,whereas research on the characteristics at the technical level remain scarce.Most studies only consider integrated energy systems or rural electrification independently.However,the combination of an integrated energy system and rural electrification is more in line with the actual scenario.

Therefore,in this study,an integrated energy system for rural electrification in China (IESREIC) is investigated,while considering the relevant characteristics.The IESREIC is a rural energy system with a high-quality rural distribution network as its core; the goals are to realize multi-energy coupling and complementary utilization,meet the demands for agricultural production and multi-energy loads,increase the proportion of power consumption,adjust measures to local conditions,and adopt advanced physical information technologies and management modes to improve energy efficiency.

According to the situation in China,the key technologies of the IESREIC are discussed,as follows.(1) First,this study summarizes the differences between the rural and urban areas in China,e.g.,in the regional characteristics and natural resource endowments.(2) Then,the development characteristics of the IESREIC are studied.(3) Key technologies related to the planning and operation,energy value sharing,infrastructure,management,and control platforms are introduced.(4) Demonstration projects and business models are given for the IESREIC.

1 Development Characteristics of Integrated Energy System for Rural Electrification in China (IESREIC)

According to the current situation in China,the following rural characteristics can be determined [9].(1) At present,urban and rural developments in China are unbalanced,and rural developments are generally inadequate.There are great differences between the rural and urban areas.Industrial differences lead to differences in the load characteristics.The energy utilization efficiency of rural users is low.Urban areas are densely populated,whereas rural areas are more dispersed,leading to significant differences in the pipeline layout and load distribution [10].Moreover,rural infrastructure tends to be relatively backward [11].The rural distribution network is often relatively weak,the power supply quality is poor,and the degree of electrification and intelligence is insufficient [12].(2) In view of China’s vast territory,there are regional differences between rural areas.The southern region is mountainous and watery,and the rural load space is scattered.Most of the northern areas are plains,and the rural areas have a large population.Affected by the climate,the demand for the heat load is large in winter [13].Thus,the regional differences result in differences in the topography,temperature,and climate,and the affect energy consumption.(3) In China,the rural areas are vast and rich in natural resources (and in biomass energy).Some rural areas are also rich in renewable energies,such as water and geothermal energy,and non-renewable energies,such as coal and natural gas [14].By analyzing the rural characteristics,including the differences between urban and rural areas,regional differences,and natural resources,we can obtain the following development characteristics of the IESREIC for the future,in line with national conditions.

1.1 Clean and diversified energy use of rural residents

Fig.1 Framework of key technology prospect of integrated energy system for rural electrification in China (IESREIC)

With the utilization of rural resources,the consumption patterns of rural heating and cooking with firewood and coal as the leading energy sources have changed.With the advancement of rural electrification,the proportion of electric energy consumption has gradually increased.Some rural users use liquefied petroleum gas.In addition,many rural households are equipped with biogas digesters to promote the utilization of biomass energy.The use of solar water heaters and ground source heat pumps has provided a new way for rural users to obtain heat energy.With the rapid development of household distributed photovoltaic power generation,the use of clean energy by rural residents is increasing,making rural energy use more diversified [15].

1.2 Seasonality and dispersion of village load

In addition,the energy consumption of rural industry is far lower than that of urban industry.Rural production energy consumption includes consumption for agriculture,animal husbandry,forestry,water conservancy,and fishery,with evident seasonal differences [16].With the significant energy consumption from rural residents’ seasonal equipment,the influence of the season is more evident.Moreover,rural residents use less energy at night [16].Therefore,in the process of the planning,evaluation,and operation of the IESREIC,it is necessary to deeply explore the influences on rural load timing.

1.3 Energy supply in villages suitable for local conditions

The resources in different rural areas are different,owing to regional differences.There are abundant wind energy resources in the southeast coastal area and Guangdong coastal area.Thus,in these areas,the development of wind turbines is helpful for solving the problems in rural power consumption.The rural roof areas are large,and therefore suitable for the installation of photovoltaic units.Meanwhile,the Hunan Province and other areas with abundant water resources are suitable for the development of hydropower [17].Tibet (and other regions rich in geothermal resources) can reasonably use ground source heat pumps to obtain domestic heat.The construction of the IESREIC should be adapted to local conditions,and should make full use of local natural resources.

1.4 Coupling and complementation of rural multi-energy

With the utilization of various local resources,the coupling degree of the multi-energy sources should be strengthened.To realize multi-energy coupling and complementarity from the user end,the IESREIC should meet the rural users’ demands for electricity,heat,cold,gas,and other energies,adjust measures to local conditions,develop and make complementary use of traditional and new energies,optimize the layout and build integrated energy supply infrastructures,and realize multi-energy collaborative supply by means of natural gas cogeneration,distributed renewable energy,and intelligent microgrids.From the source side,the IESREIC can make use of the combined advantages of wind energy,solar energy,water energy,biogas,natural gas,and other resources on a large-scale integrated energy basis,so as to promote the construction and operation of complementary wind-solarwater-fire-storage systems [18].

1.5 Guidance of the rural welfare policy

The development of integrated energy for rural electrification has generally been guided by the rural welfare policy.With the proposal of the Rural Revitalization Strategy,the construction of the IESREIC is of great significance.At present,there are subsidies for domestic rural biogas construction.The subsidy for biogas power generation has promoted the development of rural biogas systems.Since 2018,the use of natural gas subsidies has promoted the extension of the rural natural gas pipeline network.Rural household photovoltaic power generation,photovoltaic agricultural greenhouses,and other photovoltaic power generation modes have also been supported and encouraged by the policy,encouraging the use of new energies in rural areas [19].The government’s strong support and corresponding policies have promoted the use of rich local natural resources,guided the development of the IESREIC,and provided welfare for rural users.

The differences between urban and rural areas,regional differences,and rich nature resources determine the development characteristics of the IESREIC.These characteristics also affect the implementation of rural electrification,key technologies in system construction,demonstration projects,and business models.The main framework of this study is shown in Fig.1.

2 Key Technologies of IESREIC

2.1 Planning and Operation Technology of Rural Integrated Energy System

Through the reasonable planning and operation optimization scheduling of the IESREIC,the rural electrification level can be effectively improved.The clean,efficient,and sustainable operation of the system can be ensured.At present,research on the planning and operation of the IESREIC does not fully consider the system level and characteristics.Rural areas have vast spaces,scattered loads,and long energy supply distances.“Regional autonomy” can be used to divide the IESREIC into a rural-level integrated energy system (RLIES) and rural-user-level micro-energy network (RULMEN) for hierarchical planning research,as shown in Fig.2.

Fig.2 Framework of hierarchical and distributed operation and planning

As shown in Fig.3,at present,the rural power grid is the backbone of the RLIES,and the other energy networks are imperfect.The rural power grid has a long power supply radius,wide area,and small and scattered load.The grid structure is relatively fixed.Power equipment planning (as supplemented by network planning) is often used as the main planning method,and less consideration is given to the access of new load nodes,or to the new construction and expansion of power lines.The reliability of the power grid operation is low,and there is a lack of a reasonable optimal dispatching scheme.In reference [20],a planning model was established for the integration of distributed generation into a rural power grid.The use of a biogas turbine and gas turbine deepened the coupling between the gas network and power grid.Therefore,the RLIES also involves planning the locations and capacities of rural energy stations or energy equipment,energy network structures,and so on.It is also necessary to consider the operation characteristics of each energy coupling equipment.In addition,when planning in areas with drainage loads,it should be considered that long-term blackouts are not allowed.Referring to the active distribution network [21],the planning and operation model of the RLIES,as represented by optimization objectives and equality and inequality constraints,can be expressed as follows:

In the above xRIES and yRIES are the decision variables and state variables of the planning operation,respectively.The related parameters are listed in Table1.

Fig.3 Hierarchical structure chart of IESREIC

Table1 Integrated energy system for rural electrification in China (IESREIC) hierarchical collaborative planning operation model

Level Rural-level integrated energy system (RLIES)[24]Rural-user-level micro-energy network (RULMEN) [25]Features Rural distribution network is the backbone At the user side of the rural distribution network x Expansion of distribution network (main);Orientation and selection of pipelines;Location of energy stations;Selection and sizing of equipment;Output of each energy equipment Selection,sizing and output of energy equipment y Voltage; Pressure; Power flow Power conversion Inequality constraints Equipment selection;Equipment output constraints;Transmission capacity constraints;Voltage and pressure constraints Energy conversion device selection and output constraints Equality constraints Networks power flow constraints;Power balance constraints of energy devices Power balance constraints

As shown in Fig.3,the RULMEN is located at the end of the user side of the rural distribution network.Through the configuration of various energy equipment,the multi-energy needs of users can be met.We focus on equipment configuration planning and equipment operation optimization schemes,and rarely involve energy network planning.Reference [22]established a capacity allocation and operation optimization model for general energy equipment.Reference [23]established an RULMEN model including electrical conversion energy storage devices,and proposed an equipment capacity planning method with the minimum cost and annual CO2 emissions.In the planning of the RULMEN,the models and capacities of the energy conversion equipment can be selected based on the uncertainty model for the source load,i.e.,according to the local policies and conditions,with the goal of economy,environmental protection,reliability,and safety.The optimal output scheme for each equipment is determined,aiming to realize the local absorption of renewable energy.The RULMEN planning and operation model can be represented by optimization objectives,equality,and inequality constraints [21],as follows:

Here,xRMCN and yRMCN are the decision variables and state variables of the planning operation,respectively.The related parameters are listed in Table1.

For the IESREIC,there is a connection relationship between the RLIES and RULMEN,accompanied by power interactions.By referring to the hierarchical optimal dispatching model of the active distribution network,interactive variables can be introduced to obtain the hierarchical collaborative planning and operation model.Thus,the planning and operation model of RLIES is as follows [26]:

The operation planning model of the k-th connected RULMEN is as follows:

In the above,i is the number of RULMENs connected to the end of the RLIES,k ∈i.kz is the k-th interactive variable of the RULMENs.

The above-mentioned hierarchical collaborative planning operation model cannot be solved independently,owing to the interaction variables.The interaction between the RLIES and RULMEN is mainly through power.Referring to the interactive variable relationship between the levels of the active distribution network,the RULMEN can be regarded as the load [26].For the RULMEN,the RLIES can be regarded as the source.The l type of energy consumed by the load in the k node is equal to that generated by the source of the corresponding RULMEN.Therefore,constraints are introduced as follows [27]:

2.2 Energy Value Sharing Technology of Rural Integrated Energy System

Owing to the randomness and intermittence of renewable energy,it is necessary to promote the sharing and coordination of green energy among the various consumers,so as to promote the successful transformation of the energy consumption structure represented by electricity [28].The energy value-sharing technology of the IESREIC comprises the design of a market-oriented multi-energy trading mechanism,and the construction and improvement of the infrastructure required for the market-oriented operation of energy interconnections.The energy value-sharing technology in the IESREIC mainly relies on multi-energy trading and sharing technology in rural areas,including a variety of green renewable energies [29].

At present,research on energy value-sharing technology in integrated energy systems mostly concerns urban areas,and is less concerned with rural areas.When studying the energy value sharing technology of the IESREIC,we should fully consider the characteristics of the energy supply that are suitable for the local conditions.Given the background of the IESREIC,a multi-energy trading and sharing technology should include a variety of green renewable resources,and incorporate the construction of supporting facilities,supporting mechanisms,and supporting platforms.

According to the different characteristics of the rural areas in China,an energy commodity trading mechanism suitable for development and application is proposed.In the plain areas where the rural households and their corresponding energy use are more concentrated,a new centralized multi-energy trading mode is formed.Moreover,a unified market trading mechanism is formed,by relying on a superior energy market to encourage users to participate in the energy market by reducing energy prices and guiding users to realize energy conservation.A multi-functional user response strategy under the interaction of market incentives and user energy use behaviors is established,aiming to realize the active participation of users driven by the market.In the hilly and mountainous areas where the rural households are more scattered and have more distributed energy,a new distributed multi-energy trading mode is formed to make full use of the flexible local consumption of all types of green energy,and to give full play to the advantages of energy storage and transfer of “production and consumption” users [30].Based on the rural/local/user multi-layer market structure,it is possible to develop the energy trading modes among users,improve the economic efficiency and green energy utilization rates of users,and improve the energy consumption structures for users [31].

Therefore,for rural areas with scattered loads and abundant local resources,conducting point-to-point transactions among “production and consumption users”with widely used distributed energy (such as photovoltaic sources and energy storage) can improve the incomes of users,and promote the nearby consumption and balancing of distributed renewable energy.An energy trading technology based on blockchain can be adopted for the IESREIC.The advanced distributed information protection record mechanism of blockchain is used to provide information support for the IESREIC [32].

On this basis,it is necessary to build a community user transaction management and control platform in the market environment,so as to improve the user energy consumption levels and economic benefits of all parties involved.

2.3 IESREIC Infrastructure and Control Platform

The IESREIC has rich types of available energy and diversified structures and incorporates vast territories,scattered users,and seasonal energy demands [24].The current system has some problems,such as a poor utilization of clean energy,a single form of energy consumption,and insufficient interactions between different energy sources.Therefore,to solve the above problems and provide support for IESREIC technical applications,it is necessary to conduct research from two perspectives,i.e.,the rural energy infrastructure and management and control platform,so as to promote the development of the IESREIC with rural electrification as the core.A schematic diagram of the rural energy management and control platform is shown in Fig.4.

2.3.1 Rural Energy Infrastructure

Through the appropriate core infrastructure of the IESREIC,it is possible to make full use of the local natural resources and effectively improve the clean energy utilization efficiency (including the use of distributed energy facilities,energy conversion facilities,and energy storage facilities).Unlike cities,the rural energy infrastructure needs to focus on the relevant equipment that fits the local natural resources,and the relevant equipment must be based on the local industrial activities.The management and control platform should also fully realize the management of local industries.

(1) Distributed energy facilities

At present,there are many studies on the application of distributed energy technologies in rural areas,both at home and abroad.Reference [33]evaluated the possibility of introducing hydropower and photovoltaic power generation into rural areas with uneconomical power supplies.Reference [34]applied biogas and photovoltaic power generation to rural electrification,and verified the technical and economic performance of their hybrid application.The application of off-grid hybrid systems combining photovoltaic/wind energy/biogas/pumped storage for rural electrification in South Africa has been verified technically and economically [35].Under the support of national policies and with the promotion and application of clean energy in rural areas,we should comprehensively consider rural areas in the context of their resources and energy consumption characteristics,vigorously develop and build stronger distributed energy facilities,further strengthen the safe and efficient interactions between source and load,and increase the degree of consumption of clean energy in energy networks.In response to the state’s push for an“Internet plus” smart energy strategy,researchers should improve the function of the photovoltaic cloud network platform,and strengthen the photovoltaic network services [36].

Fig.4 Schematic diagram of rural energy management and control platform

(2) Energy storage facilities

In recent years,owing to the rapid development of energy storage technologies,the application scale of related facilities in rural areas has been increasing.In terms of electric energy storage,with the continuous maturity of lithium battery-related technologies,they are gradually replacing the traditional lead-acid batteries in solar street lamps,with the advantages of a strong over-discharge recovery ability,high charge discharge efficiency,and long service life [37].Reference [38]proposed a distributed energy storage in a station area based on ubiquitous Internet technology.A container design mode was adopted to realize a plug-and-play function for solving a seasonal and intermittent peak load problem.In addition,the social and economic benefits of wind solar energy storage systems relying on rural natural conditions have been verified,and a variety of charging modes have been proposed to provide energy security for various agricultural production tools [39].In terms of cold energy storage and hot energy storage,reference [40]describes the technology for energy storage based on electric ice storage in animal farms,and the technology of energy storage based on residual electric energy recovery and heating in livestock farms.The storage of other forms of energy can be realized through the conversion of energy forms (electricity to cold and electricity to heat) after biogas power generation.Reference[41]introduced the development and utilization of hydrogen energy storage technology,along with its development trends in the energy industry.With the development of the IESREIC,the increasingly complex energy coupling relationships mean that further developments in electricity/gas/cold/hot energy storage technologies,including distributed energy storage,mobile energy storage,and generalized energy storage facilities [42],are needed to support the efficient operation of energy networks and consumption of clean energy resources.

(3) Multi-energy coupling facilities

The main form of energy supply in China’s traditional villages is through the rural power grid; the heat supply is provided by burning coal and straw [43].This mode has low energy consumption efficiency and causes serious pollution.Therefore,a variety of energy coupling facilities are needed to provide energy conversion and complementarity,i.e.,to address these problems.

At present,research studies and applications of multienergy interactive coupling facilities have been developed to some extent.In terms of electric heating facilities,an electrode type vacuum/micro pressure phase change boiler is superior to other electric heating devices in terms of efficiency,cost,operation cost and safety,and has been applied in rural grassroots positions in Aheqi County,Xinjiang [43].In terms of electricity for gas facilities,reference [44]discussed the influences of electrolytic hydrogen production and methanation processes on the practical value of Yunnan.In terms of other forms of energy facilities,a Stirling-engine-based gasification combining cooling,heating,and power systems can reduce pollution and costs [45].In the future,through the further development of multi-energy coupling technologies and facilities,the organic integration of different energy types such as electricity,gas,heat,and cold will provide comprehensive energy management and control,which is conducive to optimizing the energy flow of the source grid load storage side.From the perspective of energy management,owing to problems regarding communication equipment and other aspects,the multi-energy interactive coupling facilities in the IESREIC still lack closer contact.It is necessary to conduct more in-depth research on the interconnection of multi-energy interactive coupling facilities.

2.3.2 Rural Energy Management and Control Platform

With the development of the operation modes and technology for maximizing the utilization of energy resources,the “source-network-storage-load” interaction of the IESREIC becomes frequent,and all types of energy are closely coupled.All types of the corresponding information data are massive and complex,so it is necessary to quickly and accurately perceive and process a large amount of data,and to provide corresponding decision instructions to ensure the safe,economic,and efficient operation of the system.In view of this,cloud computing,big data,artificial intelligence,the Internet of things,and other technologies can be used to optimize,analyze,judge,and make decisions based on massive data [46].On this basis,and with the strong support and development of rural electrification by the state,the rural energy network form is undergoing significant changes,and the numbers and types of multienergy access equipment are becoming increasingly large.There is an urgent need to study integrated energy system management and control platform technology for rural electrification.

Based on information integration monitoring,as supported by the rural integrated energy data service technology and rural integrated energy management and control service technology,we can further promote the digitalization,networking,and intelligent development of the rural energy management and control platform,from both hardware and software aspects [47].The platform provides multi-energy optimization analysis and control services for integrated energy service providers from the aspects of IESREIC planning,operation,trading,and maintenance.

3 Demonstration Project and Business Model of IESREIC

To solve the problems regarding the poor reliability of the rural distribution network,high network loss rate,low investment benefit of the distribution network,and insufficient clean energy supply,relevant demonstration projects (as shown in Table2) have been studied.It can be seen that different projects face different industries and adopt different business models.The demonstration project and business model of the IESREIC must fully consider local energy use activities,such as agricultural production [48].

To form a replicable business model for typical rural electrification projects,it is necessary to study the investment business models of typical rural electrification projects,and to clarify the investment and financing schemes,income distribution mechanisms,operation and maintenance schemes,and related supporting services of the participants.A public-private partnership (PPP) is a widely used business model for the construction of public infrastructure.In this model,private enterprises and private capital are encouraged to cooperate with the government,participate in the construction of public infrastructure,speed up the construction and effective operation of such infrastructure,and promote the privatization of infrastructure construction projects in China.The PPP mode promotes the diversification of investors,gives full play to the respective advantages of government public institutions and private institutions,makes all parties involved in the project integrate to form a strategic alliance,and plays a key role in coordinating the different interests of all parties.Other mature business models include energy performance contracting,build-transfer,business-to-business,and business-to-customer.

Table2 Demonstration projects for IESREIC

Demonstration project Meaning Areas Smart electric greenhouse in Shouguang [49]Promote the integrated development of smart energy use and agriculture Agricultural production Promotion of stir fried tea with electricity in Anji [50]Reduce environmental pollution and improving tea quality Rural industrial Rural farming,drainage and irrigation electrification project in Qianjiang [51]Realize scientific breeding and management of crayfish and increase income Rural industrial Smart energy project for residents in Jinhu County [52]Reduce the peak load without affecting the comfort of life Rural life Green smart energy new village in Shahe [53]Clean energy supply and reduce energy cost Rural life Guzhu village residential intelligent energy efficiency management [54]Improve the quality and reliability of rural power consumption Rural industrial High efficiency and clean energy utilization of Xiangquan breeding base in Dingxi [55]Improve the quality and efficiency of agricultural products Agricultural production Clean energy supply of Jiebu primary school [56]Clean power and heat for primary schools Rural life High efficiency and clean energy utilization for electrification of Changping ecological forest Ranch [57]Promote the breeding industry to be cleaner and more environmentally friendly Rural industrial Electrification project of domestic sewage treatment plant in Tangwan Town,Yingtan City [58]Make full use of local energy and preferential electricity price to treat township sewage Rural life

Table3 Business models for IESREIC

Business model Operators Parties Projects Agricultural production electrification project [59]scattered farmers;rural collective households;rural cooperative members Operators;Government agencies;provincial integrated energy services Co.,Ltd.(PIESCL)Construction of electrified greenhouse;Agricultural drainage and irrigation Rural industrial electrification project [60]Rural industry company Operators;PIESCL Beef cattle breeding;White tea processing;Homestay tourism;Pig breeding Rural life electrification project [61]The masses;Education administrators;Environmental administrators Social capital;Operators;government agencies;PIESCL Environmental governance;Rural education

To speed up rural electrification,highlight the advantages of an integrated industry chain,and promote rural industrial transformation,based on the characteristics of rural users and the existing business model for integrated energy services,this study introduces a business model for IESREIC projects in the context of three areas:agricultural production,rural industry,and rural life,as shown in Table3.The model fully considers the investment and financing structures,transaction structures,and organization forms of the three rural areas,combines the rural characteristics,realizes matching with various fields,and increases the proportion of electricity consumption.The investment and financing schemes,income distribution mechanisms,operation and maintenance schemes,and related supporting service contents of the participants are clarified.The income sources,core services,basic services,and valueadded services of the development business model are analyzed.Ultimately,a business service management model is constructed for integrating consulting,design,system integration,engineering,operation and maintenance,and other complementary services.

(1) Business model of agricultural production electrification project

For demonstration projects of agricultural production electrification,such as the construction of electrified greenhouses or agricultural irrigation and drainage,the organizational structure of the business model is shown in Fig.5.The process is mainly operated by scattered farmers,rural collective households,and rural cooperative members.The power company is responsible for the construction of the power infrastructure,upgrading and reconstruction of distribution networks,organization and approval of provincial integrated energy services Co.,Ltd.(PIESCL),and the provision of comprehensive electrical integration solutions,including feasibility studies,design,equipment procurement,engineering construction,and system development.Operators,government agencies,and PIESCL sign smart contracts for the electrification projects.The smart contract is implemented using blockchain technology.The three parties can supervise the project simultaneously through decentralization,obtain profits and dividends according to a reasonable proportion of contributions,and obtain social benefits.The government can then evaluate the operation effects of the project in the later stages,thereby providing a reference for its subsequent promotion and replication.

Fig.5 Organization structure of business model for agricultural production electrification project

(2) Business model of rural industrial electrification project

For demonstration projects of rural industrial electrification such as beef cattle breeding,white tea processing,homestay tourism,and pig breeding,the organizational structure of the business model is shown in Fig.6.It is mainly operated by rural industrial companies.Relevant social capital,such as farmers’ capital and enterprise capital,participates in rural industrial companies and invests in projects.The government provides policy support.The operator and PIESCL sign an energy contract for the electrification project,and obtain profits and dividends according to a reasonable proportion of contribution.The government should reasonably supervise and evaluate the rural industrial companies and PIESCL.

(3) Business model of rural life electrification project

Fig.6 Organization structure of business model for rural industrial electrification project

Fig.7 Organization structure of business model for rural life electrification project

The business model organization structure for a rural life electrification demonstration project is shown in Fig.7.It is mainly operated by the masses,education administrators,and environmental administrators.Relevant social capital(such as farmer capital and enterprise capital) invest in the construction of the project.Under the support of certain policies,the government allocates funds for construction.Social capital,operators,government agencies,and the PIESCL sign smart contracts for electrification projects,and obtain profits and dividends according to a reasonable proportion of contributions.The government should conduct reasonable supervision and evaluation.

According to the characteristics of the rural load dispersion and local resource differences,blockchain technology can be used to manage energy trading.Moreover,there are many participants in the construction of the IESREIC,and blockchain technology can be used to unify the management of participants who do not trust each other.An integrated energy management system for rural electrification based on blockchain technology is shown in Fig.8 [62].

Fig.8 Integrated energy management system for rural electrification based on blockchain technology

4 Conclusions

To promote the implementation of a “Rural Revitalization Strategy,” it is of great significance to improve rural energy efficiency,ensure the quality of rural users' electricity,promote the construction of rural energy systems,effectively use local natural resources,and develop integrated energy system technologies for rural electrification.

In this study,the Chinese national conditions,urbanrural differences,regional differences,and natural resource endowments are summarized.According to the characteristics of rural areas in China,five development characteristics of the IESREIC are summarized.Based on the above characteristics,key technologies of the IESREIC are proposed,including the planning and operation,value sharing,infrastructure,and management and control platform.The demonstration projects and business models of the IESREIC are described.

In view of the development trends for rural energy systems,it is hoped that the key technologies proposed in this study can promote development and construction and assist in the implementation of the “Rural Revitalization Strategy” in China.Moreover,this study can provide a reference for the construction of rural energy systems in other countries with unbalanced urban and rural developments and rich local resources.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No.51977141) and headquarters technology project of State Grid Corporation of China (No.5400-202025208A-0-0-00).

Declaration of Competing Interest

We declare that we have no conflict of interest.