Abstract
Energy storage technology serves as an effective means to alleviate the pressure of integrating large-scale renewable energy sources into the grid. It addresses the challenges posed by the intermittent and uncontrollable nature of renewable energy generation from wind and solar power. This paper studies the optimal configuration of different energy storage modes in the Beipanjiang River basin, utilizing a hybrid energy storage system combining electrochemical energy storage (EES) and hydrogen energy storage to optimize the operation of photovoltaic (PV) systems. With the objective of minimizing the net present value (NPV) cost of the energy storage system, subject to constraints on the energy storage capacity and maximum charging and discharging power, we analyze the economic benefits of different types of energy storage devices and conduct optimal configuration. Based on the operational analysis using the HOMER Pro software, we determine the optimal energy storage capacity configuration. Subsequently, according to the prevailing price standards in Guizhou Province, China, we analyze its economics across multiple application scenarios, including the power generation side, power grid side, and financial leasing mode. The economic benefits and revenue models under each application mode are derived, providing valuable solutions for the practical application of energy storage in photovoltaic power stations in this region.
1. Introduction
The integration of renewable energy sources, such as wind and solar power, into the power grid has been accelerating globally. However, the intermittent and uncontrollable nature of these energy sources poses significant challenges to grid stability and power supply reliability. Energy storage technology offers a promising solution to these challenges. By storing excess energy generated during peak production periods and releasing it during low production periods, energy storage can effectively smooth out the fluctuations in renewable energy output, enhancing grid stability and power supply reliability.
2. Literature Review
Previous studies have proposed various energy storage configurations to optimize the operation of renewable energy systems. However, most of these studies focused solely on optimizing the energy storage cost or maximizing annual revenue, without delving into the economic benefits of energy storage on the power generation side and power grid side after obtaining the optimal energy storage capacity. Furthermore, these studies did not analyze and summarize the different capacity configuration schemes for energy storage systems in single and hybrid storage modes.
3. Methodology
3.1 Study Area and Data
This paper takes a photovoltaic power station in the Beipanjiang River basin of Guizhou Province, China, as a case study. The photovoltaic installed capacity of this power station is 1300 MW.
3.2 Hybrid Energy Storage System
A hybrid energy storage system combining electrochemical energy storage and hydrogen energy storage is utilized in this study. The objective function is to minimize the NPV cost of the energy storage system, subject to constraints on the energy storage capacity, maximum charging and discharging power, system power balance, distributed energy output power, electrochemical energy storage capacity and charging and discharging, hydrogen energy storage system, and renewable energy utilization rate.
3.3 Optimal Configuration Analysis
Based on the HOMER Pro software, we conduct operational analysis to determine the optimal energy storage capacity configuration. The economics of the optimal energy storage configuration are then analyzed across multiple application scenarios, including the power generation side, power grid side, and financial leasing mode.
4. Results and Discussion
4.1 Optimal Energy Storage Capacity Configuration
The analysis results show that, from an economic configuration perspective, priority should be given to using single electrochemical energy storage as the optimal energy storage solution. When the photovoltaic power station has an installed capacity of 1300 MW, configuring a 137 MWh lithium-ion battery represents the economically optimal configuration scheme.
Table 1: Optimal Configuration of Lithium-ion Battery
| Photovoltaic Installed Capacity (MW) | Lithium-ion Battery Capacity (MWh) | NPV Cost (Billion Yuan) |
|---|---|---|
| 1300 | 137 | Optimal |
Table 2: Optimal Configuration of Hydrogen Energy Storage Fuel Cell
| PV (MW) | Fuel Cell (MW) | NPV Cost (Billion Yuan) | Average Energy Cost (Yuan/kWh) | Operating Cost (Billion Yuan/a) | Initial Investment Cost (Billion Yuan) |
|---|---|---|---|---|---|
| 1300 | 100 | 46.2 | 0.1824207 | 0.291 | 42.53 |
4.2 Economics Analysis Across Multiple Application Scenarios
4.2.1 Power Grid Side
Configuring energy storage on the power grid side can mitigate the impact of the uncertainty of renewable energy generation on the grid, thereby enhancing grid security and stability. The profit model for energy storage power stations generally involves earning revenue through participation in ancillary services, which can be divided into peak shaving and frequency regulation. The economy of energy storage power stations is closely related to their frequency regulation performance and the compensation prices for ancillary services offered by the power grid.
Table 3: Compensation Standards for Energy Storage in Guizhou Province
| Region | Energy Storage Entry Threshold | Peak Shaving Compensation Standard (Yuan/kWh) | AGC Regulation Capacity Compensation Standard (Yuan/MWh) | Mileage Declaration Range (Yuan/MW) |
|---|---|---|---|---|
| Guizhou | Capacity of 10 MW/1h and above | 0.648 | 10 | 3.5-15 |
Based on the compensation standards and relevant parameters, the analysis shows that for energy storage configured on the power grid side, better economic indicators can be achieved.
4.2.2 Power Generation Side
Energy storage has the highest application proportion on the power generation side, mainly functioning to stabilize output, smooth out peaks and valleys, and facilitate renewable energy consumption. The analysis compares the economic benefits of two business models involving energy storage with a pure photovoltaic model.
Table 4: Comparison of Business Models on the Power Generation Side
| Business Model | Annual Revenue (Billion Yuan) | IRR (Internal Rate of Return) |
|---|---|---|
| Photovoltaic only | 5.02 | 7% |
| Photovoltaic + Energy Storage Configuration | 3.72 | 5.18% |
| Photovoltaic + Energy Storage Configuration + Grid Compensation | 4.03 | 5.6% |
4.2.3 Financial Leasing Mode
Under the direct financial leasing mode, the enterprise finances 1.388 billion yuan from a financial leasing company to purchase energy storage system equipment. The financial leasing company purchases the equipment at a 10% discount and then leases it to the enterprise.
Table 5: Economic Assessment of Energy Storage Power Station System under Financial Leasing Mode
| Parameter | Value |
|---|---|
| Financing Amount | 1.388 Billion Yuan |
| Financing Period | 5 Years |
| Repayment Method | Regular payment of quarterly interest, equal principal |
| Financing Interest Rate | 6.5%/Year |
| Handling Fee | 2%/Year |
The analysis results show that under this financing mode, the enterprise can achieve positive economic benefits.
5. Conclusions and Recommendations
This paper presents the optimal energy storage configuration scheme for photovoltaic power station in the Beipanjiang River basin, with a focus on economic benefits. By modeling different energy storage modes and photovoltaic power generation systems, the study analyzes the economically optimal configuration for single electrochemical energy storage, single hydrogen energy storage, and a hybrid of both. The results show that configuring a 137 MWh lithium-ion battery is the economically optimal solution when the photovoltaic power station has an installed capacity of 1300 MW. Furthermore, the paper analyzes the economics of this configuration across multiple application scenarios, including the power generation side, power grid side, and financial leasing mode, and proposes specific recommendations.
In conclusion, energy storage technology plays a crucial role in optimizing the operation of renewable energy systems. By conducting comprehensive analysis and configuration of energy storage systems, significant economic benefits can be achieved across multiple application scenarios. The findings of this paper provide valuable insights and guidance for the practical application of energy storage in photovoltaic power stations.