Expressway self-consistent energy system based on ammonia energy storage and operation method thereof

Abstract

The invention discloses a highway self-consistent energy system based on ammonia energy storage and an operation method of the highway self-consistent energy system, and belongs to the technical field of comprehensive energy systems. The system comprises an energy supply part, an electricity-hydrogen conversion unit, an ammonia energy storage unit, a multi-energy flow load part and a cascade energy utilization unit, the cascade energy utilization unit comprises a solid oxide fuel cell module, a micro gas turbine, a waste heat boiler and a heat storage tank; the solid oxide fuel cell module uses ammonia in an ammonia storage tank for first-stage power generation; high-temperature waste gas is guided into the micro gas turbine for second-stage power generation; medium and low temperature waste heat discharged by the micro gas turbine is captured by the waste heat boiler and stored in the heat storage tank; and heat energy in the heat storage tank is used for cold-state start preheating of the ammonia synthesis module in the ammonia energy storage unit by a start preheating loop. According to the system, energy gradient utilization of first-stage power generation, second-stage power generation and third-stage heat supply is achieved, the multi-energy flow load requirements of electricity, heat and hydrogen can be met at the same time, and the total energy efficiency, the self-consistent rate and the green low-carbon level of the system are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of integrated energy system technology, specifically to a renewable energy storage and utilization system, and particularly to a self-consistent energy system for highways using ammonia as the energy storage carrier and its operation method. Background Technology

[0002] As critical infrastructure, highways are the main arteries of transportation, and their operation (such as tunnel lighting and ventilation, roadside monitoring, information boards, and service areas) consumes a large amount of energy. With the growth of traffic volume and the advancement of electrification (such as electric vehicle charging stations), the energy consumption and carbon emissions of highway systems are continuously rising, making their green transformation imperative.

[0003] To achieve the goals of "carbon peaking" and "carbon neutrality" in the transportation sector, the following challenges are currently faced: First, carbon dependence on traditional power grids. Currently, highway systems mainly rely on traditional distribution networks for power. However, traditional power grids (especially in areas dominated by thermal power) have high carbon emission factors. Therefore, directly using grid power cannot achieve truly low-carbon operation. Second, the challenge of matching renewable energy with complex loads. Highways have abundant wind and solar energy resources along their routes (such as slopes, medians, and service area roofs). However, the load composition of highway systems is extremely complex and diverse. This includes high-reliability baseline loads operating 24 hours a day, such as tunnel lighting, monitoring, and communications; high-power impact loads occurring randomly, such as service area charging piles and tunnel emergency fans; and highly seasonal loads such as winter snow melting. The output of these renewable energy sources (e.g., diurnal and seasonal fluctuations) cannot be perfectly matched with the aforementioned diverse and complex loads in terms of time scale and power characteristics, leading to the forced abandonment of a large amount of renewable energy and making it difficult to utilize effectively.

[0004] To achieve energy self-sufficiency, energy storage systems are essential. Currently, mainstream electrochemical energy storage is suitable for short-term intraday energy shifts, but its manufacturing costs, resource consumption, and recycling process itself have a certain carbon footprint, and it cannot economically solve long-term, large-scale energy shifts. Although "green hydrogen" is a low-carbon path, hydrogen storage currently has limitations in terms of cost, energy round-trip efficiency, and system complexity, making it difficult to economically achieve large-scale, long-term applications. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the purpose of this invention is to provide a self-consistent energy system for highways based on ammonia energy storage and its operation method, which uses ammonia as an energy storage medium to solve the problem of renewable energy storage in self-consistent energy systems for highways.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A self-consistent energy system for highways based on ammonia energy storage includes: The power supply section is configured to provide electrical energy; A multi-energy flow load section, wherein the multi-energy flow load section is configured to consume electrical energy, thermal energy or hydrogen energy; An electro-hydrogen conversion unit, wherein the electrical input terminal of the electro-hydrogen conversion unit is connected to the power supply section, and is used to consume electrical energy to produce hydrogen; The ammonia energy storage unit includes a PSA nitrogen generator 7 for producing nitrogen, a synthetic ammonia module 8 for synthesizing hydrogen and nitrogen into liquid ammonia, and an ammonia storage tank 9 for storing liquid ammonia, which are connected in sequence. A cascade energy utilization unit, comprising: Solid oxide fuel cell module 10, whose fuel input terminal is connected to the ammonia storage tank 9, is used to generate electricity in the first stage using ammonia fuel; A micro gas turbine 11, the input end of which is connected to the waste heat output end of the solid oxide fuel cell module 10, is used to generate electricity in the second stage using the high-temperature waste gas of the solid oxide fuel cell module 10. Waste heat boiler 12, whose heat input end is connected to the waste heat output end of the micro gas turbine 11, is used to capture medium and low temperature waste heat after the second stage of power generation; The heat storage tank 13 is connected to the heat output end of the waste heat boiler 12; The preheating circuit is activated. The preheating circuit is connected to the heat output terminal of the heat storage tank 13 and the preheating input terminal of the ammonia synthesis module 8, and is used to provide heat to the ammonia synthesis module 8 when it is started from a cold state. The multi-energy flow load portion includes one or more of the following combinations: Electrical loads include tunnel lighting, monitoring and communication systems, emergency fans, or charging stations; Heat load, including winter road snow melting systems or building heating; Hydrogen load, including hydrogen refueling stations.

[0007] The power supply components include wind power generation equipment 1, photovoltaic power generation equipment 2, a backup power distribution network 3, and a diesel generator 4 for emergency supplementation.

[0008] The electro-hydrogen conversion unit includes an electrolyzer 5, which consumes electrical energy from the power supply section to produce hydrogen; and a hydrogen storage tank 6, which buffers hydrogen.

[0009] It also includes an energy management system (EMS), which is communicatively connected to the energy supply section, the multi-energy flow load section, the electro-hydrogen conversion unit, the ammonia energy storage unit, and the cascade energy utilization unit, and is used to coordinate and regulate the electrical energy, hydrogen energy, ammonia energy, and thermal energy within the highway self-consistent energy system.

[0010] The operation method of a highway self-consistent energy system based on ammonia energy storage includes: Hydrogen production step: This step uses the electrical energy from the power supply section to produce hydrogen through electrolysis cell 5; Nitrogen generation step: This step produces nitrogen gas using a PSA nitrogen generator 7; Ammonia synthesis step: In this step, hydrogen and nitrogen are synthesized into liquid ammonia through ammonia synthesis module 8 and stored in ammonia storage tank 9; Cascaded power generation and heat recovery steps: This step occurs when the multi-energy flow load portion requires energy supply. a. Start the solid oxide fuel cell module 10 and directly use the ammonia in the ammonia storage tank 9 as fuel for the first stage of power generation; b. The high-temperature exhaust gas discharged from the SOFC module 10 is introduced into the micro gas turbine 11 for second-stage power generation; c. The low-temperature waste heat discharged from the micro gas turbine 11 is introduced into the waste heat boiler 12 for heat recovery and buffered in the heat storage tank 13; Start-up preheating step: This step involves preheating the ammonia synthesis module 8 using the heat energy captured in the heat storage tank 13 when the ammonia synthesis module 8 needs to be started from a cold state.

[0011] The method further includes a multi-energy flow supply step. The electrical energy generated by the SOFC module 10 and the micro gas turbine 11 is supplied to the electrical load; The heat energy in the heat storage tank 13 is supplied to the heat load; The hydrogen produced in the hydrogen production step is supplied to the hydrogen load.

[0012] The method wherein the hydrogen production step preferentially uses the surplus electrical energy generated by the wind power generation equipment 1 and the photovoltaic power generation equipment 2 in the energy supply section.

[0013] The method further includes an energy management step, which monitors the status of each unit of the highway self-consistent energy system in real time through an energy management system (EMS) and coordinates the energy flow in the hydrogen production, ammonia synthesis, cascade power generation and heat recovery steps.

[0014] Ammonia, as an energy storage medium, has the advantages of easy large-scale, low-cost storage and transportation. "Green ammonia," synthesized from renewable energy (green electricity) through water electrolysis to produce "green hydrogen," which is then combined with nitrogen, produces no carbon emissions throughout its entire life cycle. Constructing a self-sustaining energy system for highways with ammonia energy storage at its core can solve the aforementioned long-term, large-scale, low-cost energy storage needs, enabling highway systems to break free from dependence on fossil fuel power grids and achieve low-carbon, self-sustaining operation. The beneficial effects of this invention are: This invention aims to solve the challenges of renewable energy absorption, long-term storage, and matching with diverse multi-energy flow loads along highways. The self-sufficient energy system for highways in this invention utilizes ammonia (NH3) as the energy storage medium, overcoming the difficulty of economically and scalably achieving long-term, cross-seasonal energy storage using traditional energy storage solutions. It constructs a hybrid power generation architecture combining solid oxide fuel cells and micro gas turbines, enabling secondary power generation from high-temperature waste heat. The discharged medium- and low-temperature waste heat is captured by waste heat boilers and thermal storage tanks, achieving cascaded energy utilization. This system can efficiently absorb renewable energy and simultaneously meet the complex multi-energy flow requirements along highways, including high reliability baselines, high-power surges, and strong seasonal heat loads, in the form of electricity, heat, and hydrogen multi-energy flows, greatly improving the system's energy self-sufficiency and green, low-carbon level. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a self-consistent energy system for highways based on ammonia energy storage, provided by the present invention.

[0016] Figure label: 1. Wind power generation equipment; 2. Photovoltaic power generation equipment; 3. Power distribution network; 4. Diesel generator; 5. Electrolyzer; 6. Hydrogen storage tank; 7. PSA nitrogen generator; 8. Ammonia synthesis module; 9. Ammonia storage tank; 10. Solid oxide fuel cell module; 11. Micro gas turbine; 12. Waste heat boiler; 13. Thermal storage tank. Detailed Implementation

[0017] The following will be combined with the appendix Figure 1 The preferred embodiments of the present invention will be described in detail below. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0018] like Figure 1 As shown, this invention provides a self-consistent energy system for highways based on ammonia energy storage, the system comprising: One power supply section. This section prioritizes the use of renewable energy power generation equipment, such as wind power equipment 1 and photovoltaic power generation equipment 2. Simultaneously, to ensure the reliability of energy supply, the system can also be connected to the distribution network 3 as a backup power source, and is equipped with a diesel generator 4 for emergency supplementation.

[0019] The multi-energy flow load section is configured to consume electrical energy, thermal energy, or hydrogen energy; An electro-hydrogen conversion unit, wherein the electrical input terminal of the electro-hydrogen conversion unit is connected to the power supply section, and is used to consume electrical energy to produce hydrogen; the electro-hydrogen conversion unit includes an electrolyzer 5, used to consume electrical energy (especially surplus renewable energy) from the power supply section to produce hydrogen; and a hydrogen storage tank 6, used to buffer hydrogen.

[0020] The ammonia energy storage unit includes a PSA nitrogen generator 7 for producing nitrogen, a synthetic ammonia module 8 for synthesizing hydrogen and nitrogen into liquid ammonia, and an ammonia storage tank 9 for storing liquid ammonia, which are connected in sequence. When the power generation of renewable energy (wind power generation equipment 1 and photovoltaic power generation equipment 2) exceeds the system load demand, the surplus electricity is sent to the electricity-hydrogen conversion unit.

[0021] 1. In this unit, electrolyzer 5 is started up, consuming surplus electrical energy to electrolyze water to produce hydrogen.

[0022] 2. The produced hydrogen can be temporarily stored in hydrogen storage tank 6.

[0023] 3. At the same time, the PSA nitrogen generator 7 in the ammonia storage unit separates and purifies nitrogen from the air.

[0024] 4. Hydrogen from hydrogen storage tank 6 and nitrogen from PSA nitrogen generator 7 are fed together into ammonia synthesis module 8. Under high temperature, high pressure, and the action of a catalyst, the two react to produce liquid ammonia.

[0025] 5. The synthesized liquid ammonia is then stored in ammonia storage tank 9. The liquid ammonia in ammonia storage tank 9 can be easily stored on a large scale, at low cost, for long periods (e.g., across day and night, across weeks, and even across seasons), thus solving the problems of renewable energy consumption and time shifting.

[0026] The cascade energy utilization unit is activated when multiple energy flow loads along the highway require energy supply, but renewable energy output is insufficient. The system then activates the ammonia-electricity-heat cascade energy utilization unit. 1. First-stage power generation (SOFC): Liquid ammonia in the ammonia storage tank 9 is transported to the solid oxide fuel cell module 10. In this embodiment, the solid oxide fuel cell module 10 is configured to directly use ammonia (NH3) as fuel at high temperatures. The ammonia undergoes internal reforming (decomposition into N2 and H2) at the high temperature on the anode side of the solid oxide fuel cell (SOFC), and the hydrogen produced from the decomposition then participates in the electrochemical reaction to achieve first-stage power generation. This direct ammonia fuel method simplifies the system structure.

[0027] 2. Second-stage power generation (MGT): After generating electricity, the high-temperature, high-grade exhaust gas emitted by the solid oxide fuel cell module 10 is introduced into the micro gas turbine 11. The micro gas turbine 11 utilizes this high-temperature exhaust gas for expansion and work, realizing second-stage power generation and further improving the overall power generation efficiency of the system.

[0028] Multi-energy flow loads include one or more of the following combinations: 1. Electrical load: The electrical energy generated by the solid oxide fuel cell module 10 and the micro gas turbine 11 is collected and used to supply the electrical load along the route (such as tunnel lighting, monitoring and communication, emergency fans, or service area charging piles).

[0029] 2. Heat load: The low-temperature waste heat discharged by the micro gas turbine 11 after the second stage of power generation is introduced into the heat recovery unit and finally used to supply the heat load (such as winter road snow melting system, service area building heating and domestic hot water, etc.).

[0030] 3. Hydrogen load: When needed, the electrolyzer 5 or hydrogen storage tank 6 can also directly supply hydrogen to meet the hydrogen load (e.g., hydrogen refueling stations serving hydrogen fuel cell vehicles).

[0031] Heat recovery unit. Used to achieve cascaded utilization of energy within the system.

[0032] 1. For example Figure 1 As shown, the low-temperature waste heat discharged by the micro gas turbine 11 after the second-stage power generation is introduced into the waste heat boiler 12 for heat recovery.

[0033] 2. The waste heat boiler 12 efficiently captures heat energy through heat exchange and buffers the heat energy in the heat storage tank 13 by activating the preheating circuit.

[0034] 3. On the one hand, the thermal energy can be supplied to external heat loads (such as snow melting and heating) as described above; on the other hand, it is also used for energy optimization within the system: when the ammonia synthesis module 8 needs to be started from a cold state, the thermal energy stored in the heat storage tank 13 is introduced into the ammonia synthesis module 8 to provide it with start-up preheating, thereby realizing the cascade utilization of energy and reducing the system start-up energy consumption.

[0035] Energy Management System. To ensure the coordinated operation of all the aforementioned units, this system is also equipped with an Energy Management System (EMS). The EMS monitors the operational status of the power supply section, the electro-hydrogen conversion unit, the ammonia storage unit, the cascade energy utilization unit, and the multi-energy flow loads in real time via communication connections. The EMS also monitors the energy storage status of the tanks in real time (such as the pressure of hydrogen storage tank 6, the liquid level of ammonia storage tank 9, and the temperature of thermal storage tank 13). Based on load forecasting data and internal optimization algorithms, the EMS performs unified and coordinated control of electrical energy, hydrogen energy, ammonia energy, and thermal energy within the highway self-sufficient energy system to ensure that self-sufficiency and economic efficiency are optimized while meeting diverse load demands.

[0036] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-consistent energy system for highways based on ammonia energy storage, characterized in that, include: The power supply section is configured to provide electrical energy; A multi-energy flow load section, wherein the multi-energy flow load section is configured to consume electrical energy, thermal energy or hydrogen energy; An electro-hydrogen conversion unit, wherein the electrical input terminal of the electro-hydrogen conversion unit is connected to the power supply section, and is used to consume electrical energy to produce hydrogen; The ammonia energy storage unit includes a PSA nitrogen generator (7) for producing nitrogen, a synthetic ammonia module (8) for synthesizing hydrogen and nitrogen into liquid ammonia, and an ammonia storage tank (9) for storing liquid ammonia, which are connected in sequence. A cascade energy utilization unit, comprising: A solid oxide fuel cell module (10) has its fuel input end connected to the ammonia storage tank (9) for generating electricity using ammonia fuel in the first stage; A micro gas turbine (11) is connected at its input end to the waste heat output end of the solid oxide fuel cell module (10) for generating electricity in the second stage using the high-temperature waste gas of the solid oxide fuel cell module (10). Waste heat boiler (12), whose heat input end is connected to the waste heat output end of the micro gas turbine (11), is used to capture the medium and low temperature waste heat after the second stage of power generation; A heat storage tank (13) is connected to the heat output end of the waste heat boiler (12); The preheating circuit is started, which is connected to the heat output end of the heat storage tank (13) and the preheating input end of the ammonia synthesis module (8) and is used to provide heat to the ammonia synthesis module (8) when it is started in a cold state.

2. The system according to claim 1, characterized in that: The multi-energy flow load portion includes one or more of the following combinations: Electrical loads include tunnel lighting, monitoring and communication systems, emergency fans, or charging stations; Heat load, including winter road snow melting systems or building heating; Hydrogen load, including hydrogen refueling stations.

3. The system according to claim 1, characterized in that: The power supply components include wind power generation equipment (1), photovoltaic power generation equipment (2), a backup power distribution network (3), and a diesel generator (4) as an emergency supplement.

4. The system according to claim 1, characterized in that: The electro-hydrogen conversion unit includes an electrolyzer (5) for producing hydrogen by consuming electrical energy from the power supply section; and a hydrogen storage tank (6) for buffering hydrogen.

5. The system according to claim 1, characterized in that: It also includes an energy management system (EMS), which is communicatively connected to the energy supply section, the multi-energy flow load section, the electro-hydrogen conversion unit, the ammonia energy storage unit, and the cascade energy utilization unit, and is used to coordinate and regulate the electrical energy, hydrogen energy, ammonia energy, and thermal energy within the highway self-consistent energy system.

6. The operation method of a highway self-consistent energy system based on ammonia energy storage as described in any one of claims 1 to 5, characterized in that, include: Hydrogen production step: This step uses the electrical energy of the power supply section to produce hydrogen through an electrolyzer (5); Nitrogen generation step: This step produces nitrogen gas using a PSA nitrogen generator (7); Ammonia synthesis step: This step synthesizes hydrogen and nitrogen into liquid ammonia through the ammonia synthesis module (8) and stores it in the ammonia storage tank (9); Cascaded power generation and heat recovery steps: This step occurs when the multi-energy flow load portion requires energy supply. a) Start the solid oxide fuel cell module (10) and directly use the ammonia in the ammonia storage tank (9) as fuel for the first stage of power generation; b) The high-temperature exhaust gas discharged from the SOFC module (10) is introduced into the micro gas turbine (11) for second-stage power generation; c) The low-temperature waste heat discharged from the micro gas turbine (11) is introduced into the waste heat boiler (12) for heat recovery and buffered in the heat storage tank (13); Start-up preheating step: This step is to preheat the ammonia synthesis module (8) by using the heat energy captured in the heat storage tank (13) when the ammonia synthesis module (8) needs to be started in a cold state.

7. The method according to claim 6, characterized in that: It also includes multi-energy flow supply steps, The electrical energy generated by the SOFC module (10) and the micro gas turbine (11) is supplied to the electrical load; The heat energy in the heat storage tank (13) is supplied to the heat load; The hydrogen produced in the hydrogen production step is supplied to the hydrogen load.

8. The method according to claim 6, characterized in that: The hydrogen production step preferentially uses the surplus electrical energy generated by the wind power generation equipment (1) and photovoltaic power generation equipment (2) in the energy supply section.

9. The method according to claim 6, characterized in that: It also includes an energy management step, which uses an energy management system (EMS) to monitor the status of each unit in the highway self-consistent energy system in real time and coordinate the energy flow in the hydrogen production, ammonia synthesis, cascade power generation and heat recovery steps.

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