Energy storage system based on biogas power generation and method thereof

Abstract

The present application relates to biogas power generation technical field, specifically relates to a kind of energy storage system and method based on biogas power generation.It includes multi-source power generation system, high-pressure energy storage system and digitized control system, and multi-source power generation system includes photovoltaic power generation unit, wind power generation unit and biogas power generation unit.Biogas power generation unit is realized dynamic complementation with photovoltaic, wind power generation unit by high-pressure energy storage system: when photovoltaic, wind power generation surplus, high-pressure energy storage system is driven by waste electricity to raise biogas pressure to 1.5-10bar, and the biogas after pressure boosting is stored as high-grade energy storage medium after pressure swing adsorption purification;When photovoltaic, wind power generation shortage, high-pressure purified biogas drives gas turbine to generate electricity to make up power gap, or high-purity biogas is output as grid-connected natural gas, to realize the efficient conversion of energy.The present application constructs "photovoltaic-wind power-biogas-energy storage" four-dimensional collaborative architecture, realizes multi-energy complementary closed loop operation, improves system energy efficiency and power supply stability.

Description

Technical Field

[0001] This invention relates to the field of biogas power generation technology, and more specifically to an energy storage system and method based on biogas power generation. Background Technology

[0002] While remote rural areas possess abundant solar and wind energy resources that could effectively alleviate electricity shortages, photovoltaic and wind power are significantly intermittent and volatile due to the alternation of day and night and weather conditions, leading to a prominent mismatch between power supply and demand. During periods of abundant sunshine or strong winds, power generation far exceeds real-time demand, resulting in substantial excess electricity (i.e., "waste electricity"). Because existing energy storage technologies rely heavily on chemical batteries, their high cost, limited environmental adaptability (such as performance degradation due to temperature fluctuations), and short lifespan prevent the effective storage or utilization of large amounts of waste electricity, ultimately causing a serious waste of renewable energy resources. Biogas power generation, with its stable gas production, can compensate for the volatility of wind and solar power, but most rural areas currently still operate with independent energy architectures, failing to build multi-energy complementary systems to improve overall efficiency. Furthermore, rural energy storage technologies rely excessively on chemical batteries, facing bottlenecks such as high cost, poor environmental adaptability (such as performance degradation due to temperature fluctuations), and short lifespan, hindering the efficient utilization of renewable energy.

[0003] A few technologies use existing biogas digesters as a transitional energy storage medium to replace battery storage systems. However, the basic storage technology used in their production process involves increasing biogas production by heating the biogas digester, and then directly transferring the biogas to a biogas tank for storage. This biogas has a low grade and low energy density, resulting in a low waste electricity utilization rate and extremely limited output for work.

[0004] Therefore, there is an urgent need for an energy storage system and method based on biogas power generation to solve the above problems. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by providing an energy storage system and method based on biogas power generation. It realizes biogas as a high-grade energy storage medium and, through the dynamic complementarity of coupling biogas power generation with wind and solar systems, not only optimizes energy storage efficiency and improves the overall energy efficiency of the system, but also achieves the stabilization and controllability of energy output.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: An energy storage system based on biogas power generation includes a multi-source power generation system and a high-voltage energy storage system. The multi-source power generation system includes a photovoltaic power generation unit, a wind power generation unit, and a biogas power generation unit. The power output of the photovoltaic power generation unit and the wind power generation unit is obtained through the multi-source power generation system. The high-pressure energy storage system is activated when the power output of the multi-source power generation system is in surplus. The excess power of the photovoltaic power generation unit or the wind power generation unit drives the compressor to pressurize the biogas to 1.5-10 bar. The pressurized biogas is then purified by a pressure swing adsorption device to obtain high-quality biogas and stored in a high-pressure biogas tank. The biogas power generation unit starts when the power output of the multi-source power generation system is insufficient, and its operating modes include: Low-pressure mode: The upgraded biogas in the first range enters the gas turbine for power generation; High-pressure mode: The upgraded biogas from the second range is output as grid-connected natural gas.

[0007] This system addresses the intermittency and volatility of photovoltaic and wind power, while leveraging the relatively stable production of biogas, by constructing an energy storage system based on biogas power generation. A compressor pressurizes the biogas, which then undergoes pressure swing adsorption (PSA) under high pressure to obtain biogas with a higher methane concentration. Through this compression and purification process, the biogas is upgraded, increasing its ability to perform external work and its calorific value. The biogas is then stored in a high-pressure biogas tank as the core energy storage medium. The core energy storage medium of this system is high-pressure purified biogas, characterized by high pressure, high calorific value, and high energy density.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, the high-voltage energy storage system also includes: the excess electricity from the photovoltaic power generation unit or the wind power generation unit is used to heat the biogas digester, thereby increasing the fermentation reaction temperature and thus increasing the gas production.

[0010] Furthermore, the fermentation temperature is increased to 50-60℃.

[0011] Furthermore, the biogas produced by the biogas digester is used for energy storage in the high-pressure energy storage system.

[0012] Furthermore, it also includes a digital control system for dynamically optimizing the energy storage strategy of the high-voltage energy storage system and the energy output strategy of the biogas power generation unit.

[0013] Furthermore, the digital control system includes: The data acquisition module collects real-time data on power generation, biogas parameters, and grid demand. The forecasting module predicts power generation and energy demand for the next 24 hours based on meteorological data and historical operating data, and determines whether the power supply is in surplus or shortage. The optimization module uses a linear programming algorithm to calculate the optimal energy storage and energy output strategy; The execution module automatically adjusts the operating status of the compressor, heater, photovoltaic power generation unit, and wind power generation unit.

[0014] This invention also provides a distributed energy storage method based on biogas power generation, comprising the following steps: S1: Obtain the power output of photovoltaic power generation units and wind power generation units through a multi-source power generation system; S2: Real-time monitoring of power supply and demand status to determine whether there is a power surplus or shortage; S3: When there is a power surplus, execute the energy storage operation of the high-voltage energy storage system, including: S31: Use surplus electricity to drive a compressor to pressurize biogas to 1.5-10 bar. After pressurization, the biogas is purified by pressure swing adsorption and then stored in a high-pressure biogas tank. S32: Use surplus electricity to drive a heater to heat the biogas digester, raising the fermentation temperature to increase gas production; S4: When there is a power shortage, perform energy output operations of the biogas power generation unit, including: S41: When the pressure of the upgraded biogas is 1-3.5 bar, it is used to drive a gas turbine to generate electricity; S42: When the pressure of upgraded biogas is 6-10 bar, it is used for natural gas grid connection output; S5: Dynamically optimizes energy storage and energy output strategies through a digital control system.

[0015] Furthermore, the fermentation temperature is increased to 50-60℃.

[0016] The beneficial effects of this invention are: 1. This invention utilizes high-pressure purified biogas as a high-density energy storage medium, breaking through the energy efficiency bottleneck of traditional biogas. Traditional biogas has limited energy utilization capacity due to its low energy grade and insufficient energy storage density. This invention increases the biogas pressure to 1.5-10 bar using a compressor and combines this with pressure swing adsorption purification technology to achieve a methane purity of over 99% (at 10 bar), significantly improving its calorific value. High-pressure purified biogas combines high pressure and high calorific value, achieving an energy storage density 4.67 times that of atmospheric pressure biogas (at 3.5 bar), greatly improving the power generation efficiency of gas turbines (10% efficiency increase) and power generation per unit volume. Furthermore, high-pressure biogas can be directly used as grid-connected natural gas, further expanding energy utilization pathways.

[0017] 2. This invention utilizes high-pressure biogas technology, leveraging the synergistic effect of pressure boosting and pressure swing adsorption (PSA) purification to significantly enhance process efficiency. The high-pressure environment substantially improves the adsorption capacity of the PSA unit for carbon dioxide, and methane purification efficiency increases exponentially with increasing pressure (reaching 99% methane purity at 10 bar). Simultaneously, the integrated design of compression and purification reduces energy redundancy in the process, forming a highly efficient "compression and purification integrated" process. Experimental data shows that when the fermentation temperature is increased to 50℃, biogas production increases by 50% compared to 30℃, further synergizing with high-pressure energy storage to achieve dual optimization of energy storage capacity and energy quality, providing a reliable guarantee for the efficient conversion and stable output of renewable energy.

[0018] 3. This invention integrates photovoltaic, wind power, biogas power generation, and high-voltage energy storage systems, overcoming the limitations of independent operation of traditional energy systems and forming a two-way dynamic coupling mechanism between surplus wind and solar power and the biogas system. During periods of power surplus, excess photovoltaic and wind power is used to drive biogas pressurization, purification, fermentation, and heating, converting intermittent renewable energy into high-grade biogas energy storage. During periods of power shortage, high-voltage biogas power generation or grid connection effectively compensates for the volatility gap in wind and solar power generation. This collaborative architecture not only constructs a four-dimensional collaborative architecture of "solar-wind-biogas-storage" to achieve multi-energy complementary closed-loop operation, but also significantly improves the overall energy efficiency and power supply stability of the system, solving problems such as high grid peak-shaving pressure and high wind and solar curtailment rates in remote areas. Attached Figure Description

[0019] Figure 1 This is a flowchart of the biogas-based energy storage system described in an embodiment of the present invention; Figure 2 The relationship between methane purity in biogas after pressure swing adsorption and adsorption pressure; Figure 3 Thermodynamic principle diagram for improving the power generation efficiency of gas turbines using high-pressure biogas; Figure 4 The relationship between the power generation efficiency of the gas turbine and the change in the inlet biogas pressure; Figure 5 The relationship between the power generation per unit volume of biogas at atmospheric pressure and the pressure of the imported biogas; Figure 6 The thermodynamic principle (temperature-entropy diagram) that improves the efficiency and power generation of gas turbines through methane purification. Figure 7 The relationship between the gas production rate of anaerobic fermentation and the fermentation temperature is shown. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0022] In the description of this application, the term "for example" is used to mean "used as an example, illustration, or description." Any embodiment described as "for example" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use the invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that the invention can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of the invention with unnecessary detail. Therefore, the invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0023] Example like Figure 1 As shown, an energy storage system based on biogas power generation includes a multi-source power generation system, a high-voltage energy storage system, and a digital control system. The multi-source power generation system includes a photovoltaic power generation unit, a wind power generation unit, and a biogas power generation unit; the power output of the photovoltaic power generation unit and the wind power generation unit is obtained through the multi-source power generation system; The high-pressure energy storage system is activated when the power output of the multi-source power generation system is in surplus. The excess power of the photovoltaic power generation unit or the wind power generation unit drives the compressor to pressurize the biogas to 1.5-10 bar. The pressurized biogas is then purified by a pressure swing adsorption device to obtain high-quality biogas and stored in a high-pressure biogas tank. The biogas power generation unit starts when the power output of the multi-source power generation system is insufficient, and its operating modes include: Low-pressure mode: 1-3.5 bar of upgraded biogas is fed into the gas turbine for power generation; High-pressure mode: Upgraded biogas at 6-10 bar is output as grid-connected natural gas; The digital control system is used to dynamically optimize the energy storage strategy of the high-voltage energy storage system and the energy output strategy of the biogas power generation unit. The digital control system includes: The data acquisition module collects real-time data on power generation, biogas parameters, and grid demand to determine whether the power supply is in surplus or shortage. The forecasting module predicts power generation and energy demand for the next 24 hours based on meteorological data and historical operating data. The optimization module uses a linear programming algorithm to calculate the optimal energy storage and energy output strategy; The execution module automatically adjusts the operating status of the compressor, heater, photovoltaic power generation unit, and wind power generation unit.

[0024] In a preferred embodiment, the high-pressure energy storage module further includes: the excess electricity from the photovoltaic power generation unit or the wind power generation unit is used to heat the biogas digester, raising the fermentation reaction temperature to 50-60°C to increase the gas production, and the biogas produced by the biogas digester is used for energy storage in the high-pressure energy storage module.

[0025] The high-voltage energy storage module of the present invention uses waste electricity such as surplus electricity from renewable energy sources (such as photovoltaic and wind power) to drive a compressor to pressurize biogas, increasing the biogas pressure from 1 bar to 1.5-10 bar, and then purifying it through a pressure swing adsorption device.

[0026] The pressure swing adsorption (PSA) purification device primarily purifies biogas by decarbonizing it, increasing the purity of methane and the calorific value of the biogas. Its effectiveness is significantly influenced by biogas pressure. Under high pressure, the PSA purification device significantly increases the adsorption capacity of carbon sources, producing biogas with a higher methane concentration. Figure 2 As shown, the purity of methane in biogas under different pressure swing adsorption (PSA) conditions is given. It can be seen that when the pressure reaches 10 bar, the methane purity can reach 99%, which is comparable to the level of grid-connected natural gas.

[0027] Biogas stored in a high-pressure tank after pressurization, quality improvement, and adsorption purification can significantly improve the power generation efficiency of a gas turbine when used for power generation. This is mainly reflected in the following two aspects: Firstly, the increased biogas pressure will improve the power generation efficiency of the gas turbine. The thermodynamic principle is as follows: Figure 3 As shown in Figure 1-2-3-4-1, the ideal Brayton cycle process of a gas turbine under atmospheric pressure is as follows: [Figure 1-2-3-4-1 is missing from the original text]. The thermodynamic cycle after the biogas pressure is increased is as follows: [Figure 1-2-3-4-1 is missing from the original text]. Figure 1-2As shown in '-3'-4-1, the area enclosed by the curves represents the gas turbine's ability to perform external work. It can be seen that the area increases significantly after the pressure is increased. The efficiency of the gas turbine is positively correlated with the cycle pressure ratio (i.e., the pressure ratio between point 2 and point 1 in the diagram). Therefore, increasing the pressure at point 2 can improve the gas turbine's power generation efficiency.

[0028] After simple calculation, such as Figure 4 As shown, for conventional biogas gas turbines, the power generation efficiency can be increased by 10% when the pressure changes from 1 bar to 3.5 bar. The biogas power generation per unit storage tank volume will also be significantly increased (biogas tank volume is set at 100 m³). Biogas power generation per unit storage tank volume = Biogas flow rate (m³ / h) × Biogas calorific value (kWh / m³) × Power generation efficiency (%) / Storage tank volume (m³) like Figure 5 As shown, the working pressure at 3.5 bar is 4.67 times that at atmospheric pressure.

[0029] Secondly, after passing through a pressure swing adsorption (PSA) device, the purity of methane increases, and the higher the gas pressure, the higher the methane purity. Since the calorific value of methane is significantly higher than other components of biogas, the increased methane purity can increase the calorific value of biogas, leading to a higher combustion temperature within the gas turbine and thus improving the gas turbine's power generation efficiency. Furthermore, the increased methane concentration also increases the energy input of the gas turbine, resulting in a corresponding increase in power generation. The thermodynamic principle is as follows: Figure 6 As shown in the figure. Figure 1-2''-3''-4-1 shows the gas turbine power generation cycle after the methane purity is increased. It can be seen that the area (heat absorption) it covers has increased significantly.

[0030] The increase in biogas production due to increased biogas digester temperature is a synergistic process with the increase in biogas pressure. For example... Figure 7 As shown, the anaerobic fermentation efficiency increases with increasing temperature. For example, at 30℃, the gas production is about 0.33 m³ / (m³·d) (meaning that a 1 cubic meter biogas digester produces 0.33 m³ of gas per day). However, if the biogas temperature is heated to about 50℃, the biogas production can be increased to 0.5 m³ / (m³·d), which is an increase of about 50%.

[0031] This invention also provides a distributed energy storage method based on biogas power generation, comprising the following steps: S1: Obtain the power output from photovoltaic power generation units and wind power generation units through a multi-source power generation system; S2: Real-time monitoring of power supply and demand status to determine whether there is a power surplus or shortage; S3: When there is a power surplus, execute the energy storage operation of the high-voltage energy storage system, including: S31: Use surplus electricity to drive a compressor to pressurize biogas to 1.5-10 bar. After pressurization, the biogas is purified by pressure swing adsorption and then stored in a high-pressure biogas tank. S32: Use surplus electricity to drive a heater to heat the biogas digester, raising the fermentation temperature to 30-50℃ to increase gas production; S4: When there is a power shortage, perform energy output operations of the biogas power generation unit, including: S41: When the pressure of the upgraded biogas is 1-3.5 bar, it is used to drive a gas turbine to generate electricity; S42: When the pressure of upgraded biogas is 6-10 bar, it is used for natural gas grid connection output; S5: Dynamically optimizes energy storage and energy output strategies through a digital control system.

[0032] The working process of this invention is as follows: During periods of electricity surplus, excess electricity stored from sources such as solar and wind power can be stored as energy in the following ways: (1) The biogas is pressurized by a compressor driven by excess electricity and other waste gas. Then, it is subjected to pressure swing adsorption under high pressure to obtain biogas with a higher methane concentration. Through the above compression and purification, the biogas quality is improved, the biogas's external work capacity is increased, and the calorific value of the biogas is increased. The biogas is then stored in a high-pressure biogas tank as the core energy storage medium carrier. (2) Excess electricity from photovoltaic and wind power can also be used to heat biogas digesters, increase the fermentation reaction temperature, improve anaerobic fermentation efficiency, and increase biogas production.

[0033] Through the above two methods, waste electricity from photovoltaic and wind power is stored in high-pressure biogas tanks in the form of biogas upgrading and increasing volume, thus achieving energy storage.

[0034] During periods of power shortage: The stored high-pressure biogas serves as a relatively stable power output system, supplying electricity through gas turbine power generation.

[0035] In summary, this invention utilizes a multi-energy complementary system with high-pressure biogas as the energy storage carrier. By coupling photovoltaic, wind power, and biogas power generation in a coordinated manner, it solves the problems of intermittency and volatility of renewable energy, and achieves dynamic balance of "source-grid-load-storage" and efficient utilization of energy resources.

[0036] While embodiments or examples of this disclosure have been described with reference to the accompanying drawings, it should be understood that the methods, systems, and devices described above are merely exemplary embodiments or examples, and the scope of the invention is not limited by these embodiments or examples, but only by the granted claims and their equivalents. Various elements in the embodiments or examples may be omitted or replaced by their equivalents. Furthermore, the steps may be performed in a different order than that described in this disclosure. Further, various elements in the embodiments or examples may be combined in various ways. Importantly, as the technology evolves, many elements described herein can be replaced by equivalents that appear after this disclosure.

Claims

1. An energy storage system based on biogas power generation, characterized in that, It includes a multi-source power generation system and a high-voltage energy storage system. The multi-source power generation system includes a photovoltaic power generation unit, a wind power generation unit, and a biogas power generation unit. The power output of the photovoltaic power generation unit and the wind power generation unit is obtained through the multi-source power generation system. The high-pressure energy storage system is activated when the power output of the multi-source power generation system is in surplus. The excess power of the photovoltaic power generation unit or the wind power generation unit drives the compressor to pressurize the biogas to 1.5-10 bar. The pressurized biogas is then purified by a pressure swing adsorption device to obtain high-quality biogas and stored in a high-pressure biogas tank. The biogas power generation unit starts when the power output of the multi-source power generation system is insufficient, and its operating modes include: Low-pressure mode: The upgraded biogas in the first range enters the gas turbine for power generation; High-pressure mode: The upgraded biogas in the second range is output as grid-connected natural gas; It also includes a digital control system for dynamically optimizing the energy storage strategy of the high-voltage energy storage system and the energy output strategy of the biogas power generation unit; The digital control system includes: The data acquisition module collects real-time data on power generation, biogas parameters, and grid demand. The forecasting module predicts power generation and energy demand for the next 24 hours based on meteorological data and historical operating data, and determines whether the power supply is in surplus or shortage. The optimization module uses a linear programming algorithm to calculate the optimal energy storage and energy output strategy; The execution module automatically adjusts the operating status of the compressor, heater, photovoltaic power generation unit, and wind power generation unit.

2. The energy storage system based on biogas power generation according to claim 1, characterized in that, The high-pressure energy storage system further includes: the excess electricity from the photovoltaic power generation unit or the wind power generation unit is used to heat the biogas digester, thereby increasing the fermentation reaction temperature and thus increasing the gas production.

3. The energy storage system based on biogas power generation according to claim 2, characterized in that, The fermentation temperature is increased to 50-60℃.

4. The energy storage system based on biogas power generation according to claim 2, characterized in that, The biogas produced by the biogas digester is used for energy storage in the high-pressure energy storage system.

5. A distributed energy storage method based on biogas power generation, comprising the energy storage system according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1: Obtain the power output of photovoltaic power generation units and wind power generation units through a multi-source power generation system; S2: Real-time monitoring of power supply and demand status to determine whether there is a power surplus or shortage; S3: When there is a power surplus, execute the energy storage operation of the high-voltage energy storage system, including: S31: Use surplus electricity to drive a compressor to pressurize biogas to 1.5-10 bar. After pressurization, the biogas is purified by pressure swing adsorption and then stored in a high-pressure biogas tank. S32: Use surplus electricity to drive a heater to heat the biogas digester, raising the fermentation temperature to increase gas production; S4: When there is a power shortage, perform energy output operations of the biogas power generation unit, including: S41: When the pressure of the upgraded biogas is in the first range, it is used to drive the gas turbine to generate electricity; S42: When the upgraded biogas pressure is in the second range, it is used for natural gas grid connection output; S5: Dynamically optimizes energy storage and energy output strategies through a digital control system.

6. The distributed energy storage method based on biogas power generation according to claim 5, characterized in that, The fermentation temperature is increased to 50-60℃.

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