Method for evaluating full-life-cycle environmental impact by using biochar as soil conditioner

Abstract

The invention relates to a full life cycle environmental impact evaluation method using biochar as a soil conditioner, and the environmental sustainability of the biochar as the soil conditioner is evaluated through a life cycle evaluation method to obtain a final environmental sustainability result of the biochar and environmental impact results of different stages. The influence of the biochar on human health, ecological systems and resources is examined, and a scientific basis is provided for popularization of biochar use and environmental decision.

Description

Technical Field

[0001] The present invention relates to the technical field of biochar application, and in particular to a method for evaluating the environmental impact of biochar as a soil conditioner over its entire life cycle. Background Art

[0002] Biochar is a carbon-rich material produced by the pyrolysis of waste biomass under oxygen-deficient or oxygen-limited conditions. Biochar as a soil conditioner has become a new strategy for achieving environmental sustainability. It will help achieve at least four Sustainable Development Goals (SDGs): sustainable waste management (SDG12.5), reducing risks to human health (SDG3.9), mitigating climate change (SDG13), and promoting sustainable production and utilization (SDG12.2). First, the preparation of biochar by pyrolysis of waste biomass can achieve the sustainable resource utilization of agricultural or industrial waste; secondly, using biochar as a soil conditioner can effectively reduce the emission rate of carbon dioxide in the soil and play a role in carbon fixation. At the same time, biochar can also be used as an alternative fertilizer to reduce the use of chemical fertilizers. By-products produced during the preparation of biochar, such as bio-oil and syngas, can be used to produce agricultural machinery fuel to achieve resource recycling.

[0003] Although biochar has certain potential in achieving environmental sustainability, a comprehensive quantitative assessment of its environmental impact throughout its life cycle is needed to identify the contribution of different stages of its life cycle to environmental impact. Life cycle assessment is a mature quantitative environmental impact analysis method that is increasingly used in environmental sustainability assessment. For example, CN116843220A discloses an environmental impact assessment method for corn straw-based ethyl levulinate, including determining the research boundary of the evaluation system and dividing the evaluation system into four stages; performing an inventory analysis of energy consumption, environmental gas emissions and key environmental indicators in each stage, and calculating the energy consumption and environmental gas emissions of each stage; calculating the environmental impact potential of each stage; and quantitatively evaluating the environmental impact of each sub-stage based on the calculation results. This invention applies the life cycle assessment method to the environmental impact assessment of corn straw-based ethyl levulinate.

[0004] However, most of the current research on the environmental impact assessment of the biochar life cycle is aimed at the biochar preparation process, while there are fewer studies on the environmental sustainability assessment of the actual application process of biochar. CN115895704A discloses a method for evaluating the impact of catalytic biomass preparation of liquid fuel and its application on land use change, wherein the steps of catalytic hydrothermal preparation of liquid fuel include pretreatment, hydrothermal reaction, catalytic reaction, etc., which can shorten the time for biomass preparation of liquid fuel, reduce preparation costs, and obtain a higher conversion rate; the invention also establishes a life cycle analysis model framework for indirect land use change by evaluating the impact of the application of biomass liquid fuel on land use change. However, for the preparation of biochar from pyrolysis waste biomass with a high degree of resource utilization, there is still a lack of environmental sustainability assessment research on its actual application process.

[0005] Therefore, in order to solve the problems of missing application process and inconsistent assessment framework of biochar environmental impact assessment in the above studies, it is urgent to provide a full life cycle environmental sustainability assessment method for biochar of different raw material types as soil conditioner, which is of great significance for promoting the large-scale use of biochar and promoting the realization of sustainable development goals. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a full life cycle environmental impact assessment method for biochar as a soil conditioner, realize the judgment of the environmental sustainability of the biochar application process, and promote the large-scale use of biochar.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a full life cycle environmental impact assessment method for biochar as a soil conditioner, the full life cycle environmental impact assessment method comprising the following steps:

[0009] (1) Determination of evaluation objectives and scope: Determination of evaluation objectives, functional units, and life cycle stages; the life cycle stages include biochar raw material collection and transportation, biochar preparation, biochar application, and by-product application;

[0010] (2) Inventory data analysis: creating an inventory and analyzing the input and output data during the life cycle phase described in step (1);

[0011] (3) Environmental impact assessment: The analysis results of the inventory described in step (2) are divided into the ReCiPe endpoint model, and three endpoint damage categories are obtained through classification and characterization of environmental damage categories;

[0012] (4) Interpretation of results: Based on the evaluation objectives and scope, explain the environmental sustainability results and environmental impact results at different stages.

[0013] The method for evaluating the environmental impact of the biochar as a soil conditioner provided by the present invention evaluates the environmental sustainability of the biochar as a soil conditioner through the life cycle assessment method (LCA), and establishes a life cycle environmental sustainability evaluation model for the biochar as a soil conditioner, selects functional units, and the data types include the input and output data of materials, resources, and energy involved in the whole life cycle stages such as biochar raw material collection and transportation, biochar preparation, biochar application, and by-product application. Based on the above data, a life cycle inventory (LCI) is compiled, and the ReCiPe2016V1.03 endpoint impact assessment method is used to quantify environmental sustainability, thereby comprehensively scoring the environmental sustainability of the biochar. The present invention realizes the judgment of the environmental sustainability of the biochar application process, promotes the large-scale use of biochar, and promotes the realization of sustainable development goals.

[0014] Preferably, the evaluation goal of step (1) is to evaluate the environmental sustainability of biochar as a soil conditioner through life cycle assessment.

[0015] Preferably, the functional unit in step (1) is 1 ton of biochar.

[0016] Preferably, the biochar raw material collection and transportation stage in step (1) specifically includes: obtaining the biochar raw material using mechanical equipment, packaging and loading, transporting to the pyrolysis plant and unloading.

[0017] Preferably, the biochar preparation stage in step (1) includes raw material pretreatment and pyrolysis.

[0018] The raw material pretreatment and pyrolysis process are both carried out in a pyrolysis plant.

[0019] Preferably, the raw material pretreatment is grinding or cutting the biochar raw material.

[0020] Grinding or cutting the biochar raw material can improve the subsequent pyrolysis efficiency.

[0021] Preferably, a drying step is further included after the raw material pretreatment and before pyrolysis.

[0022] Preferably, the calculation formula for the heat required for drying is as follows:

[0023] H d =(Mass water ×T×C p-water +Mass feedstock ×T×C p-feedstock +ΔH vap ×Mass water ) / K.

[0024] Where: Hd Indicates the heat required for drying, MJ / kg; C p-water Indicates the specific heat capacity of water, kJ / (kg·℃); C p-feedstock Indicates the specific heat capacity of biochar raw materials, kJ / (kg·℃); Mass water Indicates the mass of water in the biochar raw material, kg; Mass feedstock represents the mass of biochar raw material, kg; T represents the drying temperature, °C; ΔH vap It represents the heat of vaporization of water, which is 2260 kJ / kg at 100°C; K represents the drying heat loss coefficient.

[0025] Preferably, the calculation formula for the heat required for pyrolysis is as follows:

[0026] H p =ΔH vap ×Mass water +Mass water ×C p-water ×(T p -T).

[0027] Where: H p Indicates the heat required for pyrolysis, MJ / kg; T p Indicates the pyrolysis temperature, °C.

[0028] The dried biochar raw material will be slowly pyrolyzed in an anaerobic environment. The heat required for pyrolysis includes the heat required to evaporate the remaining water in the biochar raw material and the heat required to heat it to the pyrolysis temperature.

[0029] Preferably, the biochar application stage in step (1) includes transportation, spreading and soil improvement.

[0030] Preferably, the improved soil includes biochar carbon fixation and biochar as an alternative fertilizer.

[0031] Preferably, the carbon fixation amount of the biochar is calculated as follows:

[0032] C CS =Mass b ×C b ×C s ×3.67.

[0033] Where: C CS Indicates soil carbon sequestration, kgCO 2e ;Mass b Indicates the mass of biochar, kg; C b Indicates the carbon content in biochar, %; C s Indicates carbon stability in biochar, %; 3.67, C-CO2 conversion coefficient.

[0034] Preferably, the calculation formula for the amount of chemical fertilizer offset by the biochar as a substitute fertilizer is as follows:

[0035] F BC =F a -F a ×(1-P N,P,K ).

[0036] Among them: F BC Indicates the amount of fertilizer offset by biochar, kg; F a Indicates the original amount of fertilizer applied, kg; P N,P,K It indicates the rate of change of N, P and K content in soil after using biochar.

[0037] Preferably, the by-product application in step (1) includes converting bio-oil and pyrolysis gas into electricity, and the converted electricity is used to offset the electricity consumed in the biochar preparation stage.

[0038] Preferably, the electricity converted from the bio-oil and pyrolysis gas is the sum of the heat generated by the bio-oil multiplied by the bio-oil power conversion coefficient and the heat generated by the pyrolysis gas multiplied by the pyrolysis gas power conversion coefficient.

[0039] Preferably, the inventory data in step (2) comes from field research project data and a life cycle inventory general database.

[0040] If the inventory data is unavailable, it can be obtained from the literature based on actual conditions, including life cycle inventory data of energy, natural resources, materials, transportation, etc., and the input and output data of each stage can be calculated based on functional units.

[0041] Preferably, the analysis in step (2) is a process of selecting the most similar geographical origins and technical factors from the field survey project data and the life cycle inventory general database.

[0042] Preferably, the environmental damage categories in step (3) include global warming-human health, global warming-terrestrial ecosystems, global warming-freshwater ecosystems, stratospheric ozone depletion, ionizing radiation, ozone formation-human health, formation of fine particulate matter, ozone formation-terrestrial ecosystems, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, human carcinogenic toxicity, human non-carcinogenic toxicity, land use, scarcity of mineral resources, scarcity of fossil resources, water resource consumption-human health, water resource consumption-terrestrial ecosystems and water resource consumption-aquatic ecosystems.

[0043] Preferably, the three endpoint damage categories in step (3) include human health, ecosystems and resources.

[0044] Preferably, the calculation formula of the environmental impact assessment result in step (3) is as follows:

[0045]

[0046] Of which: LCIA c represents the life cycle environmental sustainability impact; CF represents the characterized impact factor in the ReCiPe endpoint model; LCI represents the life cycle inventory data; c represents the substance category, and i represents the impact category.

[0047] Preferably, the result interpretation in step (4) is to identify, quantify, verify and evaluate the information provided by the environmental sustainability results and the environmental impact results at different stages, and to judge and analyze the environmental sustainability according to the evaluation objectives and scope.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The method for evaluating the environmental impact of the biochar as a soil conditioner provided by the present invention evaluates the environmental sustainability of the biochar as a soil conditioner through the life cycle assessment method (LCA). The established life cycle environmental sustainability evaluation model of the biochar as a soil conditioner takes the production of 1 ton of biochar as a functional unit, and the data types include the input and output data of materials, resources, and energy involved in the whole life cycle stages such as biochar raw material collection and transportation, biochar preparation, biochar application, and by-product application. A life cycle inventory (LCI) is compiled based on the above data, and the ReCiPe 2016V1.03 endpoint impact assessment method is used to quantify environmental sustainability, so as to comprehensively score the environmental sustainability of the biochar. The present invention realizes the judgment of the environmental sustainability of the biochar application process, promotes the large-scale use of biochar, and promotes the realization of sustainable development goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a schematic diagram of the life cycle stages provided by Example 1 of the present invention;

[0051] Figure 2 This is a standardized evaluation result diagram of the life cycle end impact at different stages provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0053] The present invention provides a full life cycle environmental impact assessment method for biochar as a soil conditioner, the full life cycle environmental impact assessment method comprising the following steps:

[0054] (1) Determination of evaluation objectives and scope: Determine the evaluation objectives, functional units, and life cycle stages; the evaluation objective is to evaluate the environmental sustainability of biochar as a soil conditioner through life cycle assessment; the functional unit is 1 ton of biochar.

[0055] The life cycle stages include biochar raw material collection and transportation, biochar preparation, biochar application and by-product application; the biochar raw material collection and transportation stage specifically includes: using mechanical equipment to obtain biochar raw materials, packaging and loading, and then transporting them to the pyrolysis plant and unloading; the biochar preparation stage includes raw material pretreatment, drying and pyrolysis; the raw material pretreatment is grinding or cutting the biochar raw materials.

[0056] The calculation formula for the heat required for drying is as follows:

[0057] H d =(Mass water ×T×C p-water +Mass feedstock ×T×C p-feedstock +ΔH vap ×Mass water ) / K.

[0058] Where: H d Indicates the heat required for drying, MJ / kg; C p-water Indicates the specific heat capacity of water, kJ / (kg·℃); C p-feedstock Indicates the specific heat capacity of biochar raw materials, kJ / (kg·℃); Mass water Indicates the mass of water in the biochar raw material, kg; Mass feedstock represents the mass of biochar raw material, kg; T represents the drying temperature, °C; ΔH vap It represents the heat of vaporization of water, which is 2260 kJ / kg at 100°C; K represents the drying heat loss coefficient.

[0059] The calculation formula for the heat required for the pyrolysis is as follows:

[0060] H p =ΔH vap ×Mass water +Mass water ×C p-water ×(T p -T).

[0061] Where: H p Indicates the heat required for pyrolysis, MJ / kg; Tp Indicates the pyrolysis temperature, °C.

[0062] The biochar application stages include transportation, spreading and soil improvement; the soil improvement includes biochar carbon fixation and biochar as an alternative fertilizer.

[0063] The carbon fixation amount calculation formula of the biochar is as follows:

[0064] C CS =Mass b ×C b ×C s ×3.67.

[0065] Where: C CS Indicates soil carbon sequestration, kgCO 2e ;Mass b Indicates the mass of biochar, kg; C b Indicates the carbon content in biochar, %; C s Indicates carbon stability in biochar, %; 3.67, C-CO2 conversion coefficient.

[0066] The calculation formula for the amount of chemical fertilizer offset by the biochar as a substitute fertilizer is as follows:

[0067] F BC =F a -F a ×(1-P N,P,K ).

[0068] Among them: F BC Indicates the amount of fertilizer offset by biochar, kg; F a Indicates the original amount of fertilizer applied, kg; P N,P,K It indicates the rate of change of N, P and K content in soil after using biochar.

[0069] The by-product application includes the conversion of bio-oil and pyrolysis gas into electricity, and the converted electricity is used to offset the electricity consumed in the biochar preparation stage; the electricity converted from the bio-oil and pyrolysis gas is the sum of the heat generated by the bio-oil multiplied by the bio-oil electricity conversion coefficient and the heat generated by the pyrolysis gas multiplied by the pyrolysis gas electricity conversion coefficient.

[0070] (2) Inventory data analysis: Create an inventory and analyze the input and output data of the life cycle stage process described in step (1); the inventory data comes from the field research project data and the life cycle inventory universal database; the analysis is the process of selecting the most similar geographical sources and technical factors from the field research project data and the life cycle inventory universal database; the unit process data list of each life cycle stage is shown in Table 1.

[0071] Table 1

[0072]

[0073]

[0074] (3) Environmental impact assessment: The analysis results of the inventory described in step (2) are divided into the ReCiPe endpoint model, and three endpoint damage categories are obtained through classification and characterization of environmental damage categories;

[0075] The environmental damage categories include global warming-human health, global warming-terrestrial ecosystems, global warming-freshwater ecosystems, stratospheric ozone depletion, ionizing radiation, ozone formation-human health, formation of fine particulate matter, ozone formation-terrestrial ecosystems, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, human carcinogenic toxicity, human non-carcinogenic toxicity, land use, scarcity of mineral resources, scarcity of fossil resources, water resource consumption-human health, water resource consumption-terrestrial ecosystems and water resource consumption-aquatic ecosystems; the three endpoint damage categories include human health, ecosystems and resources.

[0076] The calculation formula of the environmental impact assessment result is as follows:

[0077]

[0078] Of which: LCIA c represents the life cycle environmental sustainability impact; CF represents the characterized impact factor in the ReCiPe endpoint model; LCI represents the life cycle inventory data; c represents the substance category, and i represents the impact category.

[0079] (4) Interpretation of results: By identifying, quantifying, testing and evaluating the information provided by environmental sustainability results and environmental impact results at different stages, environmental sustainability is judged and analyzed based on the evaluation objectives and scope.

[0080] Example 1

[0081] This example provides a method for evaluating the environmental impact of biochar as a soil conditioner throughout its life cycle. The application of straw biochar to a certain farmland is selected as the research object of this example. The goal of this example is to evaluate the environmental sustainability of soil improvement with crop straw biochar through life cycle assessment. The functional unit is 1 ton of straw biochar. The life cycle stages are as follows: Figure 1As shown, it includes four stages: biochar raw material collection and transportation, biochar preparation, biochar application, and by-product application. The biochar raw material collection and transportation stage includes the use of mechanical equipment to harvest crop straw from farmland, package and load it, and then transport it to the pyrolysis plant and unload it. The biochar preparation stage includes raw material pretreatment, drying, and slow pyrolysis. Pretreatment refers to the cutting and crushing of crop straw. The biochar application stage includes the transportation of biochar, the spreading of biochar, and the carbon sequestration produced by biochar after application, as well as its role as an alternative fertilizer. The by-product application stage includes the conversion of bio-oil and pyrolysis gas into electricity as the input electricity for the biochar preparation process.

[0082] The inventory data of this embodiment is obtained through partial assumptions, field collection, literature collection and formula calculation, and the background data comes from the Ecoinvent 3 database. The inventory data is shown in Table 2.

[0083] Table 2

[0084]

[0085]

[0086] The environmental impact assessment adopts the life cycle impact assessment method and the endpoint impact assessment method of ReCiPe 2016V1.03. The endpoint impact assessment method is to classify and characterize the life cycle inventory results through 17 endpoint environmental damage categories to obtain three types of endpoint damage categories, so as to comprehensively score the environmental sustainability of biochar-improved soil and standardize the results. The calculation results are shown in Tables 3 and 4.

[0087] Table 3

[0088] End point damage category unit Numeric Human Health DALY 3.30E-03 Ecosystem species.yr 2.48E-05 resource USD2013 4.79E+01

[0089] Table 4

[0090] End point damage category Standardized results Sorting Human Health 0.1389 1 Ecosystem 0.0347 2 resource 0.0017 3

[0091] The end-of-life cycle at different stages affects the standardized evaluation results. Figure 2 As shown. Figure 2It can be seen that straw biochar has the greatest impact on human health during its life cycle as a soil conditioner, followed by the ecosystem, and the least impact on resources. In terms of stages, the biochar preparation process is the main process that produces the three environmental impacts, with a contribution rate of 50.0% to human health and ecosystem impacts, and a contribution rate of 47.4% to resource impacts; secondly, the environmental impact contribution of the by-product application process is also relatively large, with a contribution rate of 33.4% to human health, 33.6% to ecosystem impacts, and 31.7% to resource impacts; the biochar application process contributes 16.6% to human health, 16.3% to ecosystem impacts, and 20.9% to resource impacts; the biochar raw material collection and transportation stage has almost no impact on the three environmental impact categories.

[0092] In summary, the method for evaluating the environmental impact of the biochar as a soil conditioner provided by the present invention evaluates the environmental sustainability of the biochar as a soil conditioner through the life cycle assessment method (LCA), and establishes a life cycle environmental sustainability evaluation model for the biochar as a soil conditioner, taking the production of 1 ton of biochar as a functional unit, and the data types include the input and output data of materials, resources, and energy involved in the whole life cycle stages such as biochar raw material collection and transportation, biochar preparation, biochar application, and by-product application. Based on the above data, a life cycle inventory (LCI) is compiled, and the ReCiPe 2016V1.03 endpoint impact assessment method is used to quantify environmental sustainability, thereby comprehensively scoring the environmental sustainability of the biochar, and obtaining the final environmental sustainability results of the biochar and the environmental impact results at different stages. The present invention examines the impact of biochar on human health, ecosystems, and resources, realizes the judgment of the environmental sustainability of the biochar application process, and provides a scientific basis for promoting the use of biochar and environmental decision-making.

[0093] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for evaluating the environmental impact of biochar as a soil conditioner over its entire life cycle, characterized in that: The full life cycle environmental impact assessment method includes the following steps: (1) Determination of evaluation objectives and scope: Determination of evaluation objectives, functional units, and life cycle stages; the life cycle stages include biochar raw material collection and transportation, biochar preparation, biochar application, and by-product application; (2) Inventory data analysis: creating an inventory and analyzing the input and output data during the life cycle phase described in step (1); (3) Environmental impact assessment: The analysis results of the inventory described in step (2) are divided into the ReCiPe endpoint model, and three endpoint damage categories are obtained through classification and characterization of environmental damage categories; (4) Interpretation of results: Based on the evaluation objectives and scope, explain the environmental sustainability results and environmental impact results at different stages.

2. The method for full life cycle environmental impact assessment according to claim 1, characterized in that: The evaluation goal of step (1) is to evaluate the environmental sustainability of biochar as a soil conditioner through life cycle assessment.

3. The method for full life cycle environmental impact assessment according to claim 1 or 2, characterized in that: The functional unit in step (1) is 1 ton of biochar.

4. The method for evaluating the environmental impact of a life cycle according to any one of claims 1 to 3, characterized in that: The biochar raw material collection and transportation stage in step (1) specifically includes: obtaining the biochar raw material using mechanical equipment, packaging and loading, transporting to the pyrolysis plant and unloading.

5. The method for evaluating the environmental impact of a life cycle according to any one of claims 1 to 4, characterized in that: The biochar preparation stage in step (1) includes raw material pretreatment and pyrolysis; Preferably, the raw material pretreatment is grinding or cutting the biochar raw material; Preferably, the raw material further includes a drying step after pretreatment and before pyrolysis; Preferably, the calculation formula for the heat required for drying is as follows: Where: H d Indicates the heat required for drying, MJ / kg; C p-water Indicates the specific heat capacity of water, kJ / (kg·℃); C p-feedstock Indicates the specific heat capacity of biochar raw materials, kJ / (kg·℃); Mass water Indicates the mass of water in the biochar raw material, kg; Mass feedstock represents the mass of biochar raw material, kg; T represents the drying temperature, °C; ΔH vap It represents the heat of vaporization of water, which is 2260 kJ / kg at 100°C; K represents the drying heat loss coefficient; Preferably, the calculation formula for the heat required for pyrolysis is as follows: H p =ΔH vap ×Mass water +Mass water ×C p-water ×(T p -T); Where: H p Indicates the heat required for pyrolysis, MJ / kg; T p Indicates the pyrolysis temperature, °C.

6. The method for evaluating the environmental impact of a life cycle according to any one of claims 1 to 5, characterized in that: The biochar application stage in step (1) includes transportation, spreading and soil improvement; Preferably, the improved soil includes biochar carbon fixation and biochar as an alternative fertilizer; Preferably, the carbon fixation amount of the biochar is calculated as follows: C CS =Mass b ×C b ×C s ×3.67; Where: C CS Indicates soil carbon sequestration, kgCO 2e ;Mass b Indicates the mass of biochar, kg; C b Indicates the carbon content in biochar, %; C s Indicates carbon stability in biochar, %; 3.67, C-CO2 conversion coefficient; Preferably, the calculation formula for the amount of chemical fertilizer offset by the biochar as a substitute fertilizer is as follows: F BC =F a -F a ×(1-P N,P,K ); Among them: F BC Indicates the amount of fertilizer offset by biochar, kg; F a Indicates the original amount of fertilizer applied, kg; P N,P,K It indicates the rate of change of N, P and K content in soil after using biochar.

7. The method for evaluating the environmental impact of a life cycle according to any one of claims 1 to 6, characterized in that: The byproduct application in step (1) includes converting bio-oil and pyrolysis gas into electricity, and the converted electricity is used to offset the electricity consumed in the biochar preparation stage; Preferably, the electricity converted from the bio-oil and pyrolysis gas is the sum of the heat generated by the bio-oil multiplied by the bio-oil power conversion coefficient and the heat generated by the pyrolysis gas multiplied by the pyrolysis gas power conversion coefficient.

8. The method for evaluating the environmental impact of a whole life cycle according to any one of claims 1 to 7, characterized in that: The inventory data in step (2) comes from field research project data and the life cycle inventory general database; Preferably, the analysis in step (2) is a process of selecting the most similar geographical origins and technical factors from the field survey project data and the life cycle inventory general database.

9. The method for evaluating the environmental impact of a life cycle according to any one of claims 1 to 8, characterized in that: The environmental damage categories in step (3) include global warming-human health, global warming-terrestrial ecosystems, global warming-freshwater ecosystems, stratospheric ozone depletion, ionizing radiation, ozone formation-human health, formation of fine particulate matter, ozone formation-terrestrial ecosystems, terrestrial acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, human carcinogenic toxicity, human non-carcinogenic toxicity, land use, scarcity of mineral resources, scarcity of fossil resources, water resource consumption-human health, water resource consumption-terrestrial ecosystems, and water resource consumption-aquatic ecosystems; Preferably, the three endpoint damage categories in step (3) include human health, ecosystems, and resources; Preferably, the calculation formula of the environmental impact assessment result in step (3) is as follows: LCIA c =∑1 n CF c,i ×LCI i ; Of which: LCIA c represents the life cycle environmental sustainability impact; CF represents the characterized impact factor in the ReCiPe endpoint model; LCI represents the life cycle inventory data; c represents the substance category, and i represents the impact category.

10. The method for evaluating the environmental impact of a life cycle according to any one of claims 1 to 9, characterized in that: The result interpretation in step (4) is to identify, quantify, verify and evaluate the information provided by the environmental sustainability results and the environmental impact results at different stages, and to judge and analyze the environmental sustainability according to the evaluation objectives and scope.

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