Carbon neutral energy system containing plume geothermal carbon sequestration equipment and optimization configuration method thereof

Abstract

The application discloses a carbon-neutral energy system containing plume geothermal carbon sequestration equipment and an optimal configuration method thereof, and the system comprises a wind-solar generator set, a gas turbine, a plume geothermal carbon sequestration equipment, an auxiliary boiler, a heat exchange equipment, an absorption refrigerating machine and an electric refrigerating machine. The optimal configuration method firstly models the carbon-neutral energy system; then establishes a carbon sequestration equipment and thermal power plant income distribution model by using Nash cooperation game optimization under a carbon trading system; and finally, the installed capacity of each equipment of the carbon-neutral energy system is solved by using a carnivorous plant algorithm (CPA) optimization. The method provided by the application can effectively improve energy utilization rate, reduce system operation cost, realize carbon dioxide sequestration and utilization, and achieve the system carbon-neutral target.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of multi-energy utilization of integrated energy systems, and particularly relates to carbon dioxide sequestration and utilization under a carbon trading system, and in particular to a carbon-neutral energy system containing a plume geothermal carbon sequestration device and an optimal configuration method thereof. BACKGROUND

[0002] In recent years, reducing greenhouse gas emissions and mitigating the greenhouse effect have become increasingly popular at home and abroad. Carbon capture, utilization and storage (CCUS) technology is an important way to reduce greenhouse gas emissions. The current mainstream CCUS capture technologies include pre-combustion capture, post-combustion capture and oxy-combustion capture. The CCUS utilization technologies mainly include chemical utilization, biological utilization and geological utilization. With the increasing demand for CO2 emission reduction in various countries, reducing the cost of each link of CCUS has become a research hotspot for CCUS technology innovation. The main problems that restrict the large-scale deployment and commercialization of CCUS technology are policy support and high capture cost.

[0003] Secondly, the current CCUS projects generally adopt an independent operation mode and have less connection with integrated energy systems. In his book “The Third Industrial Revolution”, American scholar Rifkin mentioned that CCUS technology should be built in an interconnected energy network, which is an important link in multi-energy conversion and system carbon reduction. SUMMARY

[0004] In view of the above research problems, the present application discloses a carbon-neutral energy system containing a plume geothermal carbon sequestration device and an optimal configuration method thereof.

[0005] The present application discloses a carbon-neutral energy system containing a plume geothermal carbon sequestration device. The carbon-neutral energy system adds a plume geothermal carbon sequestration device in a combined cooling and heating system. The plume geothermal carbon sequestration device has both energy storage and carbon sequestration functions.

[0006] The energy supply system provides energy through wind power and photovoltaic, natural gas and power grid. The energy supply system includes a wind-solar generator set, a thermal power plant and a natural gas unit.

[0007] The energy conversion system converts the energy provided by the energy supply system into electrical load, cold load and heat load, and the energy conversion system comprises a gas turbine, a heat recovery unit, an auxiliary boiler, a heat exchange device, an absorption refrigerator, an electric refrigerator, a plume geothermal carbon sequestration device; the natural gas unit provides energy for the gas turbine and the auxiliary boiler; the wind and solar power generator and the thermal power plant provide electrical energy for the carbon neutral energy system, and the CO2 generated by the thermal power plant is captured by the plume geothermal carbon sequestration device; the plume geothermal carbon sequestration device comprises a salt water and carbon dioxide separator, a high-pressure turbine, a condenser, a compressor, a pump and a well.

[0008] The plume geothermal carbon sequestration device is improved on the basis of the traditional ground source heat pump, and a system using supercritical CO2 fluid (31.1 degrees Celsius, 7.38 MPa) as a working medium and CO2 as an underground working fluid generates a buoyancy-driven thermosyphon, and even when a small amount of heating is added in the reservoir, there is a difference in the density of CO2 between the injection well and the production well, and the high mobility (inverse kinematic viscosity) of CO2 in the reservoir is beneficial to the flow of fluid. The thermosyphon can eliminate the parasitic pumping required in the conventional thermal liquid device, thereby reducing the cost.

[0009] The plume geothermal carbon sequestration device power system is composed of a generator, a cooling tower, a pump, a throttle valve and a vertical well. Using a steady-state finite volume approximation, the vertical part of the well is numerically simulated, and the vertical well is subdivided into 100-meter units. This model ignores the fluid pressure loss of the horizontal well in the reservoir. The model starts from the reservoir state determined by the underground reservoir model to the ground surface, and numerically integrates each element (i.e. from state i to state i+1). In each element, the energy balance equation, the momentum equation and the continuity equation are solved simultaneously.

[0010] h i +gz i =h i+1 +gz i+1

[0011] P i +ρ i gz i =P i+1 +ρ i+1 gz i+1 -ΔP loss

[0012]

[0013] where h i is the depth of the i-th layer well, g is the acceleration of gravity, z i is the subdivided well unit, P i is the pressure in the i-th layer unit pipe, ρ i is the fluid density of the i-th layer pipe, and ΔP loss is the pipe pressure loss. Vi For the pipeline fluid flow rate, A is the cross-sectional area of the pipeline, and m is the flow rate. The acquisition of carbon dioxide fluid properties uses a property database Refprop of the National Institute of Standards and Technology (NIST).

[0014] The plume geothermal carbon sequestration device works in the charging function of the energy storage function, the plume geothermal carbon sequestration device uses the abandoned wind and light of the wind and light generator set, uses the compressor, the condenser tower and the pump, pumps the CO2 captured from the thermal power plant into the deep reservoir from the shallow reservoir, and the CO2 in the deep reservoir absorbs geothermal energy.

[0015] The plume geothermal carbon sequestration device works in the discharging function of the energy storage function, the high-temperature and high-pressure CO2 in the deep reservoir rises to the ground through the production well due to the effect of the plume effect, the CO2 expands through the high-pressure turbine to do work and convert geothermal energy into electric energy, the expanded CO2 temporarily flows into the shallow reservoir, and waits for the next charging of the plume geothermal carbon sequestration device.

[0016] Under the carbon trading policy, the relationship between the carbon capture cost of the thermal power plant and the CO2 sequestration profit of the plume geothermal carbon sequestration device is balanced, and the capacity configuration of each device in the system is optimized.

[0017] The application also discloses an optimization configuration method of the carbon-neutral energy system with the plume geothermal carbon sequestration device.

[0018] Step 1: establishing a carbon-neutral energy system model comprising the plume geothermal carbon sequestration device, the wind and light generator set, the auxiliary boiler, the heat exchange device, the absorption refrigeration machine and the electric refrigeration machine;

[0019] Step 2: under the carbon trading system, a Nash cooperation game optimization is adopted to establish a carbon sequestration device and thermal power plant income distribution model, and a Nash equilibrium solution is obtained;

[0020] Step 3: setting a target function and a constraint condition, and adopting a carnivorous plant algorithm (CPA) to optimize and solve the installed capacity of each device of the carbon-neutral energy system.

[0021] Compared with the prior art, the application has the beneficial effects as follows:

[0022] 1. The method can effectively improve the energy utilization rate, reduce the operation cost of the system, realize the sequestration and utilization of carbon dioxide, and achieve the carbon-neutral target of the system.

[0023] 2. The energy system and the plume geothermal carbon sequestration device are interconnected, the plume geothermal carbon sequestration device has two functions of energy storage and carbon sequestration, realizes multi-energy conversion, and reduces the cost. DETAILED DESCRIPTION

[0024] Figure 1A system structure schematic diagram of the present application;

[0025] Figure 2 A plume geothermal carbon sequestration equipment structure diagram designed for the present application;

[0026] Figure 3 An algorithm flowchart of the present application. DETAILED DESCRIPTION

[0027] The technology of the present application is further described below in combination with the drawings.

[0028] The present application relates to an optimal configuration method of a carbon-neutral energy system containing plume geothermal carbon sequestration equipment, specifically comprising:

[0029] Step 1, modeling of a carbon-neutral energy system containing plume geothermal carbon sequestration equipment.

[0030] As shown in Figure 1 The present application can realize an energy system for system carbon neutralization, which is composed of combined heat and power equipment and plume geothermal carbon sequestration equipment. Specifically, the carbon-neutral energy system containing plume geothermal carbon sequestration equipment includes an energy supply system and an energy conversion system, wherein the energy supply system includes wind and light generator sets, thermal power plants, and natural gas units; the energy conversion system includes gas turbines, heat recovery devices, auxiliary boilers, heat exchange equipment, absorption chillers, electric chillers, and plume geothermal carbon sequestration equipment.

[0031] The devices that can provide electric load include gas turbines, plume geothermal carbon sequestration equipment, and a standby power grid (thermal power plant). The devices that can provide cold load include absorption chillers and electric chillers. The devices that can provide heat load include auxiliary boilers and heat exchange equipment. In the system, the gas turbine is connected to the heat recovery device, and the waste heat after power generation of the gas turbine is recovered by the heat recovery device and can be provided to the heat load. When the required heat load of the system cannot be met, the auxiliary boiler is started to burn to meet the heat load. Wind power and photovoltaic power are connected to the power supply load line. When wind power and photovoltaic power have electric load that cannot be consumed, the part of electric load that cannot be consumed enters the plume geothermal carbon sequestration equipment, which condenses CO2 in the shallow reservoir and pumps it into the deep reservoir. When the power provided by wind power and photovoltaic power is lower than the electric load, the plume geothermal carbon sequestration equipment preferentially opens the production well to extract high-pressure and high-temperature CO2 in the deep reservoir to generate power to meet the electric load demand. When the energy stored by wind power and photovoltaic power and the plume geothermal carbon sequestration equipment cannot meet the electric load, the gas turbine is started to supply power.

[0032] A plume geothermal carbon sequestration equipment model building diagram is shown in Figure 2As shown, the plume geothermal carbon sequestration apparatus includes a brine and carbon dioxide separator, a high pressure turbine, a generator, a condenser tower, a compressor, a pump, and wells (injection and production wells). The plume geothermal carbon sequestration apparatus is improved over a conventional ground source heat pump to use supercritical CO2 fluid (31.1 degrees Celsius, 7.38 megapascals) as the working medium. A system that uses CO2 as the underground working fluid creates a buoyancy driven thermosyphon, even with a small amount of heating in the reservoir, there is a difference in CO2 density between the injection and production wells, and the high mobility (inverse kinematic viscosity) of CO2 in the reservoir facilitates fluid flow. The thermosyphon eliminates the parasitic pumping requirements of conventional hydrothermal devices, thereby reducing costs.

[0033] Using a steady state finite volume approximation, numerical simulations of the vertical portion of the well in the plume geothermal carbon sequestration apparatus are performed, subdividing the vertical well into 100 meter elements; the model ignores fluid pressure losses in the horizontal well in the reservoir; the model starts from the reservoir state determined from the subsurface reservoir model to the surface, numerically integrating each element from state i to state i+1; in each element, the energy balance equation, the momentum equation, and the continuity equation are simultaneously solved;

[0034] h i +gz i = h i+1 +gz i+1

[0035] P i +ρ i gz i = P i+1 +ρ i+1 gz i+1 -ΔP loss

[0036]

[0037] where h i is the depth of the ith layer well, g is the acceleration of gravity, z i is the subdivided well element, P i is the pressure in the ith layer element pipe, ρ i is the density of the fluid in the ith layer pipe, ΔP loss is the pipe pressure loss; V i is the pipe fluid flow rate, A is the pipe cross-sectional area, and m is the flow rate; the carbon dioxide fluid properties are obtained using a property database Refprop from the National Institute of Standards and Technology.

[0038] The plume geothermal carbon sequestration device works in the charging function of the energy storage function. The plume geothermal carbon sequestration device uses the abandoned wind and light of the wind-solar generator set, uses the compressor, the condenser tower and the pump, pumps the CO2 captured from the thermal power plant into the deep reservoir from the shallow reservoir, and the CO2 in the deep reservoir absorbs geothermal energy;

[0039] The plume geothermal carbon sequestration device works in the discharging function of the energy storage function. The high-temperature and high-pressure CO2 in the deep reservoir rises to the ground through the production well due to the effect of the plume effect. The CO2 expands through the high-pressure turbine to do work and convert geothermal energy into electrical energy. The expanded CO2 temporarily flows into the shallow reservoir and waits for the next charging of the plume geothermal carbon sequestration device.

[0040] Step 2, establish a carbon sequestration device and thermal power plant income distribution model based on Nash game theory.

[0041] After establishing the system model, a carbon sequestration device and thermal power plant income distribution model is established based on Nash game theory. Specifically:

[0042] x=argmax x (f1(x)-d1)(f2(x)-d2)

[0043] In the formula: f1(x) is the carbon tax reduction of the thermal power plant for capturing and handing over carbon dioxide to the plume geothermal carbon sequestration device for sequestration; f2(x) is the tradable carbon dioxide income obtained by the plume geothermal carbon sequestration device for sequestrating carbon dioxide from the waste gas of the thermal power plant; x represents different benefit distribution schemes; d1 and d2 are the worst benefits of the two benefit subjects of the thermal power plant and the plume geothermal carbon sequestration device, which occur in a non-cooperative state. The objective function of the established carbon sequestration device and thermal power plant income distribution model is the maximum total social benefit.

[0044] Step 3, use the carnivorous plant algorithm (CPA) to optimize and solve the optimal configuration of each device in the carbon neutral energy system under the carbon trading system.

[0045] Under the carbon trading policy, the relationship between the carbon capture cost of the thermal power plant and the CO2 sequestration profit of the plume geothermal carbon sequestration device is balanced, and the capacity configuration of each device in the system is optimized.

[0046] After obtaining the Nash equilibrium solution x, the primary energy reduction rate and the annual operating cost reduction rate are used as the objective function to use the carnivorous plant algorithm (CPA) to optimize and solve the optimal configuration of each device in the carbon neutral energy system under the carbon trading system. The steps are as shown in Figure 3 , and specifically include:

[0047] (1) Data initialization, define the capacity of each device with five dimensions, gas turbine capacity x1, plume geothermal carbon capture and storage device capacity x2, electric refrigerator refrigeration coefficient x3, absorption refrigeration machine capacity x4, plume geothermal carbon capture and storage device carbon dioxide storage capacity of thermal power plant x5, define the number of iterations, attraction rate, growth rate, reproduction rate, number of carnivorous plants NCPlant and number of prey NPrey in the group. And initialize the population with size N = NCPlant + NPrey and dimension 5. Calculate the fitness value of N individuals.

[0048] (2) Sort N individuals in ascending order according to fitness, classify the individual ranked NCPlant as carnivorous plants, and classify the remaining NPrey individuals as prey.

[0049] (3) Growth stage, carnivorous plants have the probability of hunting prey, prey have the probability of escaping from carnivorous plants, and update the dimensions of new carnivorous plants or the dimensions of new prey according to the preset attraction rate.

[0050] (4) Reproduction stage, the first ranked carnivorous plant selects the first ranked prey under the preset reproduction rate, absorbs the prey's nutrition, and generates new carnivorous plants.

[0051] (5) Determine whether the number of iterations is reached, if yes, output the optimal configuration result of each device, if not, continue step (6).

[0052] (6) Merge the newly generated carnivorous plants and prey with the previous population, and iterate steps (2), (3) and (4).

Claims

1. An optimized configuration method for a carbon-neutral energy system containing a plume geothermal carbon sequestration device, characterized in that, The method includes the following steps: S1. Modeling of a carbon-neutral energy system with a plume geothermal carbon sequestration device; S2. Establish an optimal revenue allocation model between carbon sequestration equipment and thermal power plants based on Nash game theory; S3. Use the Carnivorous Plant Algorithm (CPA) to optimize the optimal configuration of each device in a carbon-neutral energy system under a carbon trading regime. The carbon-neutral energy system containing the plume geothermal carbon sequestration equipment in step S1 includes a power supply system and an energy exchange system. The power supply system includes wind and solar generators, thermal power plants, and natural gas generators. The energy exchange system includes gas turbines, heat recovery units, auxiliary boilers, heat exchange equipment, absorption chillers, electric chillers, and plume geothermal carbon sequestration equipment. In the carbon-neutral energy system, the heat load is provided by an auxiliary boiler and heat exchange equipment. The gas turbine is connected to a heat recovery unit. The waste heat after the gas turbine generates electricity is recovered and reused by the heat recovery unit to provide the heat load. When the required heat load of the system cannot be met, the auxiliary boiler is activated to meet the heat load. In the carbon-neutral energy system, the electrical load is provided by a plume geothermal carbon sequestration device, a wind and solar power generation system, and a gas turbine. In the wind and solar power generation system, wind and solar power are connected to the power supply load lines. When the wind and solar power have electricity that cannot be absorbed by the load side, this unabsorbed electricity enters the plume geothermal carbon sequestration device, which condenses CO2 from the shallow reservoir and pumps it into the deep reservoir. When the power provided by wind and solar power is lower than the electrical load, the plume geothermal carbon sequestration device prioritizes opening production wells to extract high-pressure, high-temperature CO2 from the deep reservoir to generate electricity and meet the electrical load demand. When the energy stored by wind and solar power and the plume geothermal carbon sequestration device is insufficient to meet the electrical load, the gas turbine is activated to supplement the power supply. In the carbon-neutral energy system, the cooling load is provided by absorption chillers and electric chillers; The formula for the revenue distribution model between the carbon sequestration equipment and the thermal power plant established in step S2 is as follows: ； In the formula: To reduce carbon tax levied on thermal power plants by capturing carbon dioxide and storing it in plume geothermal carbon sequestration equipment; The revenue from sequestering carbon dioxide from exhaust gases of thermal power plants using a plume geothermal carbon sequestration system; These represent different profit-sharing schemes; and The worst-case scenario is the return for the two stakeholders, the thermal power plant and the plume geothermal carbon sequestration equipment, which occurs in a non-cooperative state. The objective function of the revenue distribution model between the carbon sequestration equipment and the thermal power plant established in step S2 is to maximize the total social benefit.

2. The method for optimizing the configuration of a carbon-neutral energy system containing a plume geothermal carbon sequestration device according to claim 1, characterized in that... The plume geothermal carbon sequestration equipment includes a brine and carbon dioxide separator, a high-pressure turbine, a condenser, a compressor, a pump, and a well. The plume geothermal carbon sequestration device uses supercritical CO2 fluid as the working medium. The system using CO2 as the underground working fluid will generate a buoyancy-driven thermosiphon. In the system model of the plume geothermal carbon sequestration device, the steady-state finite volume approximation is used to numerically simulate the vertical part of the vertical well, which is subdivided into 100-meter units. The model ignores the fluid pressure loss of the horizontal well within the reservoir. The model starts from the reservoir state determined by the underground reservoir model and goes to the surface, performing numerical integration on each element from state i to state i+1. In each element, the energy balance equation, momentum equation, and continuity equation are solved simultaneously. ； ； ； in, Let i be the depth of the i-th well layer. It is the acceleration due to gravity. To subdivide well units, Let be the pressure inside the i-th layer unit tube. Let be the fluid density in the i-th layer of the pipe. For pipeline pressure loss; The fluid velocity in the pipe. The cross-sectional area of ​​the pipe. For traffic; When the plume geothermal carbon sequestration device is operating under the charging function of energy storage, the plume geothermal carbon sequestration device utilizes the curtailed wind and solar power of wind and solar generators, and uses compressors, condensers and pumps to pump CO2 captured from thermal power plants from shallow reservoirs into deep reservoirs, where CO2 in deep reservoirs absorbs geothermal energy. When the plume geothermal carbon sequestration equipment is operating in the discharge function of energy storage, the high-temperature and high-pressure CO2 in the deep reservoir rises to the surface through the production well due to the plume effect. The CO2 expands through the high-pressure turbine to do work and convert geothermal energy into electrical energy. The expanded CO2 temporarily flows into the shallow reservoir and waits for the next charging of the plume geothermal carbon sequestration equipment.

3. The method for optimizing the configuration of a carbon-neutral energy system containing a plume geothermal carbon sequestration device according to claim 1, characterized in that... Step S2 yields the Nash equilibrium solution. Then, using the primary energy reduction rate and the annual operating cost reduction rate as the objective functions of step S3, the Carnivorous Plant Algorithm (CPA) is used to optimize the optimal configuration of each device in the carbon-neutral energy system under the carbon trading system. Specifically, this includes the following steps: (3.1) Data initialization, defining the capacity of each device with a dimension of five, including the gas turbine capacity. , capacity of plume geothermal carbon sequestration equipment Electric refrigeration units account for a certain percentage of the cooling load, and their coefficient of performance is [not specified]. Absorption chiller capacity Stream geothermal carbon sequestration equipment for storing carbon dioxide from thermal power plants Define the number of iterations within the group, attraction rate, growth rate, reproduction rate, number of carnivorous plants (NCPlant) and number of prey (NPrey); initialize a population of size N = NCPlant + NPrey with a dimension of 5; calculate the fitness values ​​of N individuals; (3.2) Sort the N individuals in ascending order according to their fitness, take the individual with the highest ranking NPlant and classify it as a carnivorous plant, and classify the remaining NPrey individuals as prey; (3.3) During the growth stage, carnivorous plants have a chance to hunt prey, and prey have a chance to escape from carnivorous plants. The dimensions of new carnivorous plants or new prey are updated according to the preset attraction rate. (3.4) During the reproduction stage, the top-ranked carnivorous plant selects the top-ranked prey under the preset reproduction rate, absorbs the prey's nutrients, and generates a new carnivorous plant. (3.5) Determine whether the number of iterations has been reached. If it has, output the optimal configuration result for each device. If not, continue to step (3.6). (3.6) Merge the newly generated carnivorous plants and prey into the previous population and iterate through (2.2) to (2.4).

4. A method for optimizing the configuration of a carbon-neutral energy system with a plume geothermal carbon sequestration device as described in claim 1, characterized in that: The carbon-neutral energy system includes an energy supply system and an energy conversion system; The energy supply system provides energy through wind and solar power, natural gas, and the power grid. The energy supply system includes wind and solar generator sets, thermal power plants, and natural gas generator sets. The energy conversion system is used to convert the energy provided by the energy supply system into electrical load, cooling load, and heating load. The energy conversion system includes a gas turbine, a heat recovery unit, an auxiliary boiler, heat exchange equipment, an absorption chiller, an electric chiller, and a plume geothermal carbon sequestration device. The natural gas unit supplies energy to the gas turbine and auxiliary boiler. Wind and solar power generators and thermal power plants provide electricity to the carbon neutrality energy system, and the CO2 produced by the thermal power plant is captured by the plume geothermal carbon sequestration device. The plume geothermal carbon sequestration device includes a brine and carbon dioxide separator, a generator, a high-pressure turbine, a condenser, a compressor, a pump, and a well.

5. A carbon-neutral energy system with a plume geothermal carbon sequestration device according to claim 4, characterized in that: In the carbon-neutral energy system, the heat load is provided by an auxiliary boiler and heat exchange equipment. The gas turbine is connected to a heat recovery unit. The waste heat after the gas turbine generates electricity is recovered and reused by the heat recovery unit to provide the heat load. When the required heat load of the system cannot be met, the auxiliary boiler is activated to meet the heat load. In the carbon-neutral energy system, the electrical load is provided by a plume geothermal carbon sequestration device, a wind and solar power generation system, and a gas turbine. The wind and solar power units are connected to the power supply load lines. When the wind and solar power have unabsorbed electricity, this unabsorbed electricity enters the plume geothermal carbon sequestration device, which condenses CO2 from the shallow reservoir and pumps it into the deeper reservoir. When the power provided by wind and solar power is lower than the electrical load, the plume geothermal carbon sequestration device prioritizes opening production wells to extract high-pressure, high-temperature CO2 from the deep reservoir to generate electricity and meet the electrical load demand. When the energy stored by wind and solar power and the plume geothermal carbon sequestration device is insufficient to meet the electrical load, the gas turbine is activated to supplement the power supply. In the carbon-neutral energy system, the cooling load is provided by absorption chillers and electric chillers.

6. A carbon-neutral energy system with a plume geothermal carbon sequestration device according to claim 4, characterized in that, The working process of the plume geothermal carbon sequestration equipment is as follows: When the plume geothermal carbon sequestration equipment is operating in the charging function of energy storage, the plume geothermal carbon sequestration equipment utilizes the curtailed wind and solar power of wind and solar generators, and uses compressors, condensers and pumps to pump CO2 captured from thermal power plants from shallow reservoirs into deep reservoirs, where CO2 in deep reservoirs absorbs geothermal energy. When the plume geothermal carbon sequestration equipment is operating in the discharge function of energy storage, the high-temperature and high-pressure CO2 in the deep reservoir rises to the surface through the production well due to the plume effect. The CO2 expands through the high-pressure turbine to do work and convert geothermal energy into electrical energy. The expanded CO2 temporarily flows into the shallow reservoir and waits for the plume geothermal carbon sequestration equipment to be charged again.

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