Large-scale centralized power storage facilities

Around the substation, centralized power storage facilities will be built to reduce load fluctuation and to improve the stability of the power distribution grid.

2. Thermal Energy Storage

TES refers to the temporary storage of thermal energy and is able to increase the utilization of thermal energy equipment. For the cold energy demand in industrial areas, cold energy storage facilities will be built to store cold energy during the valley–load period and will release it during the peak–load period, which can restrain the fluctuation that take place during load cooling and will allow industrial and residential demand to be met.

3. Hydrogen Storage

Hydrogen can be stored directly for use in fuel cells or can be transported to users. In the planned district, hydrogen storage facilities will be built for fuel cell vehicles and residential functions.

4. Compressed Air Energy Storage

In CAES systems, a compressor driven by off-peak or low-cost electricity is used to store energy by compressing air into an air reservoir. Since the self-discharge that is generated by CAES is very low, it can act as a long-term storage device. In addition, the investment cost for CAES is obviously low. In the industrial area, CAES facilities will be planned and constructed for the automobile production industry.

#### 5. The Layout of Energy Storage Facilities

Based on land-use load types, the layout of energy storage facilities is planned as depicted in Figure 16.

o Large-scale centralized power storage facilities

planned and constructed for the automobile production industry.

2. Thermal Energy Storage

3. Hydrogen Storage

residential functions.

depicted in Figure 16.

4. Compressed Air Energy Storage

5. The Layout of Energy Storage Facilities

ferent storage types are listed in Table 13.

be met.

load fluctuation and to improve the stability of the power distribution grid.

Around the substation, centralized power storage facilities will be built to reduce

TES refers to the temporary storage of thermal energy and is able to increase the utilization of thermal energy equipment. For the cold energy demand in industrial areas, cold energy storage facilities will be built to store cold energy during the valley*–*load period and will release it during the peak*–*load period, which can restrain the fluctuation that take place during load cooling and will allow industrial and residential demand to

Hydrogen can be stored directly for use in fuel cells or can be transported to users. In the planned district, hydrogen storage facilities will be built for fuel cell vehicles and

In CAES systems, a compressor driven by off-peak or low-cost electricity is used to store energy by compressing air into an air reservoir. Since the self-discharge that is generated by CAES is very low, it can act as a long-term storage device. In addition, the investment cost for CAES is obviously low. In the industrial area, CAES facilities will be

Based on land-use load types, the layout of energy storage facilities is planned as

According to the load forecast and the capacity of renewable energy sources that will be installed for the planning year (2030), the total capacity of the energy storage facilities will need to be about 300 MWh (electricity) in order to maximize the renewable energy power generation consumption, avoid the generation of renewable energy power generation, and reduce the fluctuations in the peak*–*valley differences. The capacities of the dif-

**Figure 16.** The layout of energy storage facilities. **Figure 16.** The layout of energy storage facilities.

According to the load forecast and the capacity of renewable energy sources that will be installed for the planning year (2030), the total capacity of the energy storage facilities will need to be about 300 MWh (electricity) in order to maximize the renewable energy power generation consumption, avoid the generation of renewable energy power generation, and reduce the fluctuations in the peak–valley differences. The capacities of the different storage types are listed in Table 13.

**Table 13.** The capacities of different storage types.


#### *4.4. The Planning Safeguard Measures*

The MINCEDD planning scheme was proposed for the planning period from 2020 to 2050. The planning safeguard measures are under development by local governemnts and organizations currently. However, in order to achieve the planned scheme, safeguard measures in terms of technical measures and policies and subsidies are proposed in this article. Additionally, it is suggested that the local governemnts and organizations should make safeguard measures based on these measures.

#### 4.4.1. Technical Measures

An integrated energy management platform is planned to be constructed to provide technical support for the realization of the planning scheme. As a district integrated energy service provider, it is considered to build a comprehensive energy monitoring and management platform based on 5G mobile internet. This platform is used as the hardware foundation, which can be combined with big data analysis to promote the implementation of energy conservation management and user behavior for energy conservation in the MINCEDD.

The platform is connected to the users to collect energy demand data and to the district energy supply system to collect the energy supply data from renewable energy systems, gas distributed energy supply systems, waste heat utilization systems, and energy storage systems. Hence, the comprehensive management and dispatch of energy demand and supply can be achieved through the platform. There are four modules for the operation of the platform, which are listed in Table 14.



#### 4.4.2. Policies and Subsidies

The energy planning indexes that consist of renewable and clean energy capacity, energy conservation parameters for building, industrial and traffic sectors, grid capacity, and storage capacity can be included into land grant clauses during land bidding. After that, the indexes are committed to be implemented by developers or constructors during the construction period, whereby the planning indexes can be achieved.

Apart from the land grant clauses, policies and subsidies are formulated to ensure that the planning approaches are carried out (see Table 15).



#### **5. Planning Evaluation**

#### *5.1. Indexes Analysis*

5.1.1. Proportion of Renewable Energy to Primary Energy

The authors of [32] propose that the proportion of non-fossil-fuel-based energy consumption increase to 20% by 2020. The current shares of renewable energy sources are 39.3 MW for solar PV, 94.5 MW for onshore wind power, and 32 MW for biomass. During the planning period, the capacities of solar PV and wind power will be increased to 642 MW and 788 MW by 2050. However, the biomass capacity will be kept the same due to the selected location and garbage odor concerns in that area. The total amount of renewable energy that will be used by 2030 is 460 ktce and 890 ktce by 2050. The authors of [32]

estimate that the primary energy consumption will be 625 ktce by 2030 and 650 ktce by 2050. Therefore, the proportions of renewable energy to total primary energy will be 73% by 2030 and 108% by 2050, which are slightly higher than the planning objectives. Table 16 displays the current and planned renewable energy conditions.


**Table 16.** Current and planned renewable energy conditions.

5.1.2. Proportion of Renewable Power to Total Power Consumption

Renewable power can be calculated by multiplying the installed capacity by the amount of power generated per unit capacity that is estimated according to past applications. In 2017, the total amounts of renewable power being consumed were 39.3 MW for solar PV, 94.5 MW for wind power, and 32 MW for biomass. The total amount of existing and planned renewable energy used by 2050 is 600 MW for solar PV, 419 MW for wind power, and 32 MW for biomass, with 1883 GWh of electricity being generated by 2030. The installed capacity of solar PV, wind power, and biomass is expected to be 642 MW, 788 MW, and 32 MW, respectively, by 2050. This can generate 2873 GWh of electricity by 2050. Furthermore, the MINCEDD is expected to consume 1928 GWh and 2581 GWh of power by 2030 and 2050, respectively. Hence, the RP/PC of the MINCEDD is expected to be 98% by 2030 and 111% by 2050. This means that the renewable power generated by 2030 can cover almost all of the electricity consumption in the district. Moreover, as the installed capacity of the renewable power is expected to increase and the electricity consumption is expected to decrease by 2050, the amount of renewable power that is generated will be greater than the electricity consumed. Therefore, the index of RP/RC is over 100%. The surplus of renewable power can be supplied to the national power grid for users outside the MINCEDD. Renewable energy generation is listed in Table 17.

**Table 17.** Current and planned renewable energy generation.


5.1.3. CO<sup>2</sup> Emission Reduction

The 13th Five-Year National Energy Plan and the 13th Five-Year Plan for Low Carbon Development in the Zhejiang province indicated that CO<sup>2</sup> emissions will be reduced by 18% by 2020 compared to 2015 [35]. The reductions in CO<sup>2</sup> emissions can be divided into supply side reductions and demand side reductions. Supply side reductions are caused by the application of renewable energy, hydrogen energy, LNG cascade utilization, and geothermal energy, and demand side reductions are caused by industrial waste energy and distributed energy station applications.

Compared to the current conditions, CO<sup>2</sup> emissions on the supply side are expected to be reduced by 0.46 Mton and 0.77 Mton by 2030 and 2050, respectively. Additionally, on the demand side, reductions of 0.32 Mton by 2030 and 0.44 Mton by 2050 are expected. The authors of [32] estimated that CO<sup>2</sup> emissions from the MINCEDD will be 1.08 Mton by 2030 and 1.20 Mton by 2050, both of which are under the benchmark scenario in which the district is developed without CO<sup>2</sup> reduction measures. The total CO<sup>2</sup> reduction rate is expected to approach 70% and 100%, respectively, by 2030 and 2050. This indicates that the CO<sup>2</sup> emissions in the MINCEDD are expected to be nearly zero by 2050, leading to the MINCEDD being in a near-zero carbon district. The CO<sup>2</sup> reductions for the supply side and demand side are listed in Table 18.


**Table 18.** The CO<sup>2</sup> emission reductions of the source and demand side.

#### *5.2. Indexes Comparison*

The MINCEDD indexes are compared to the similar indexes of the international project and other districts outside of Zhejiang. The results show that the MINCEDD indexes are all more advanced than other indexes.

#### 5.2.1. Indexes Comparison with the International Project

The "*Ningbo Meishan Near-Zero Carbon Emission Demonstration Zone Construction Planning and International Cooperation Research Project Technical Report*" [32] is a preliminary international project that details the energy planning scheme for the MINCEDD. The MINCEDD energy plan that is introduced in this paper is developed based on the four aspects of the demand side, supply side, grid side, and storage side. The results show that the RE/PE is expected to reach 73% and that the RP/PC is expected to reach 98% by 2030. The MINCEDD indexes are more advanced than those determined in the international project (see Table 19).

**Table 19.** Comparison of the MINCEDD indexes and the international project.


#### 5.2.2. Indexes Comparison with Demonstration Districts outside Zhejiang

The MINCEDD was one of the five demonstration project plans for China State Grid in 2019, and the remaining four demonstration projects are the Beidaihe Integrated Energy Demonstration District (IEDD), the Zhengding IEDD, the Lankao IEDD, and the Guzhenkou IEDD [36].

The RE/PE for the Beiudaihe IEDD was 20% for 2020 and is 20% for the Zhending IEDD by 2030. In addition, the CO<sup>2</sup> emission reduction rate is expected to reach 15% by 2030. The RE/PE and the RP/PC for the Lankao IEDD were greater than 60% and 90%, respectively, in 2021. There is no specific energy-related index that has been identified for the Guzhenkou IEDD because the energy plan is focused on an intelligent power grid.

Compared to the indexes above, the indexes of RE/PE and RP/PC of the MINCEDD are higher than that of both the Beidaihe IEDD and Zhending IEDD. The RP/PC of the MINCEDD is expected to be at relatively the same level as that of the Lankao IEDD by 2030. In summary, the indexes of the MINCEDD are relatively more advanced than those of other demonstration districts outside of Zhejiang. The detailed indexes are listed in Table 20.

**Table 20.** The comparison of the MINCEDD indexes and those of other districts outside of Zhejiang.


#### **6. Conclusions and Recommendations**

Energy consumption in developed urban areas is relatively high. Moreover, the renewable energy and carbon sequestration resources in these areas are limited. Integrated energy planning methods and schemes for NCEDDs in urban areas have been proposed in this paper to provide a reference for urban energy planning with near-zero carbon emission objectives.

A three-step planning method was proposed for the integrated energy planning of NCEDDs in urban areas that allows objectives to be determined, planning strategies to be established, and planning approaches to be proposed. Planning strategies include reducing energy demand; improving the energy efficiency of building, industry, and traffic sectors; and utilizing renewable energy sources that have been adapted to local conditions. Approaches are proposed according to these strategies, which encompass reducing energy demand and increasing renewable energy applications on the demand side and supply side, respectively, as well as improving energy interconnection and peak–valley differences in power levels.

The integrated energy planning for the MINCEDD was investigated as a case study to explain the planning method and scheme. The CO<sup>2</sup> emission reduction objectives in the MINCEDD are 0.75 Mton and 1.1 Mton by 2030 and 2050, respectively. The planned results show that annual CO<sup>2</sup> emissions will be reduced by 0.78 Mton by 2030 and 1.21 Mton by 2050 through the implementation of approaches that are related to the supply, demand, grid, and storage points of view. Furthermore, the CO<sup>2</sup> emission rates are expected to approach 70% and 100% by 2030 and 2050, respectively. Compared to the other districts with an integrated energy planning scheme, the renewable energy utilization and CO<sup>2</sup> emission reduction performances are relatively advanced in the MINCEDD.

In addition to the approaches proposed in this case study, other innovative measures can be implemented according to local conditions of the planned district. For example, energy buses (Ebus) (i.e., fifth-generation district energy network) are recommended for future integrated energy planning in urban areas, which provides opportunities for sharing heating and cooling energy under ultra-low temperature conditions compared to those of fourth-generation energy systems. Moreover, these measures can improve system efficiency

by capturing low-grade heat sources and waste heat, which is an advanced heat recovery and energy synergy method that can be implemented in various building types [40].

Moreover, this method is only being used a few cases at present, and its feasibility needs to be verified and improved through continuous use. Therefore, this method should be used reasonably according to the characteristics of the project and should not be copied completely when planning demonstration districts. Although this method can ensure the rationality of the energy plan to a certain extent, it cannot guarantee the implementation of these plans. Therefore, when planning a demonstration district, it is necessary to clarify the implementation factors of the planned energy schemes, including the scenarios, location, stages, capacities, energy efficiencies, etc., of the applications of energy systems. In addition, it is necessary to implement safeguard measures to ensure the implementation of the plan. The safeguard measures can be policy requirements; financial subsidy support, the establishment of management platforms, publicity and guidance; the development of integrated energy service operation models; innovative energy business models; etc. Apart from the technical measures, the three-step planning method and the integrated energy planning scheme should be carried out with policies and incentives issued by the government and organizations to ensure its implementation. Future research into the implementation of this three-step planning method for other NCEDD should be conducted to demonstrate the rationality, feasibility, and limitations of this conducted research. It is suggested that this NCEDD planning case study be used as a reference in future projects.

**Author Contributions:** Writing—original draft preparation, X.X., Y.W., Y.Z. and H.J.; writing—review and editing, X.X.; supervision, Y.R. and J.W.; project administration, Y.R. and K.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Natural Science Foundation of China (No. 51978482).

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **Nomenclature**

